Keywords: Germylene -a-Sulfoxide Ligands: Synthesis, Characterization Hemilabile Germylene -b-Sulfoxide Ligand: Synthesis, Characterization and Coordination Properties toward Group VI, VIII and X Transition Metals

l'atmosphère de travail et la disponibilité de chacun qui permet de réaliser la recherche dans un cadre d'exception. Merci à tous ceux qui font marcher le laboratoire. Merci à Maryse et Sérah pour votre aide quotidienne face aux difficultés administratives, merci à Olivier, Isabelle, Christian, Romaric et Julien pour être toujours disponibles. Je tiens à témoigner ma reconnaissance aux membres

Je souhaite aussi remercier Antoine Baceiredo pour m'avoir accueilli dans son équipe pour ma thèse ainsi que pour le soutien scientifique durant ces trois années. Tsuyoshi Kato, pour tous tes précieux conseils et idées, que ce soit par rapport à mon sujet de thèse mais aussi sur mes présentations ; merci aussi infiniment pour l'opportunité de stage doctoral au Japon qui a été d'un enrichissement extraordinaire. Je souhaite aussi remercier Eddy Maerten pour les différents conseils et l'aide que tu m'as apportée, notamment au niveau de l'enseignement.

Je souhaite remercier le docteur Tsukasa Matsuo qui m'a accueilli dans son groupe à Osaka pendant quelques mois à la fin d'année 2017. Ce fut un enrichissement immense de pouvoir découvrir de nouvelles techniques et dynamiques de travail ainsi qu'une nouvelle culture remplie de personnes accueillantes. Je souhaite aussi remercier Naoki et Kazuya qui m'ont bien aidé tout au long de ce séjour. Arigato gozaimasu ! Je veux aussi remercier Sonia pour toutes les analyses de diffractions des rayons-X réalisés (qui sont nombreuses !) et plus particulièrement ta disponibilité pour répondre à mes questions et tenter des analyses avec les plus petits cristaux ! Alexandre, je te dois aussi un grand merci pour tous le temps passé au laboratoire, la semaine comme le week-end. Si j'ai réussi à tenir cette cadence de travail et de ne pas perdre pied dans ce sujet, c'est assurément grâce aux discussions et réflexions que nous avons partagées. Je tiens aussi spécialement à te remercier pour toutes les activités hors laboratoire qui ont fait de ces trois années une expérience que je n'oublierai pas avec nos discussions sur l'actualité, les soirées foot, ton aide avec Antonio pour le déménagement, le voyage à Liverpool avec la communication orale à l'EuCheMS et le match insensé de seconde zone avec un Goodison Park plein. Sam, je veux aussi te remercier de m'avoir aidé sur la partie polymérisation ! Le temps passé avec toi restera aussi mémorable avec ces sorties dans les Pyrénées, à la mer, à jouer au football ou à manger un barbecue ! Je suis content d'avoir fait ces hors laboratoire avec toi et j'espère pouvoir visiter, un jour, ton pays ! Un merci collectif aux membres de l'équipe ECOIH, passés (Noémie, Natalia, Alfredo, Morelia, Tatsuya, Raphael M., Raphael N., Laura, Jérémie et Katia) et présents (Maria, Franck, Aymeric, Jean et Shintaro) pour l'ambiance de travail excellente et les repas du groupe. Maria et Aymeric je tiens aussi à vous remercier particulièrement pour votre soutien les jours précédents et le jour même de la soutenance, cela m'a permis d'avoir une concentration totale sur la défense, merci ! Une pensée à mes compagnons du groupe RU, Antonio, Franky, Richard, Alexandre et Sam, on a finalement réussi à survivre à cette nourriture après toutes ces indigestions ! Les moments et petits concours pronostiques sur la LdC étaient des rendez-vous de midi incontournables et resteront des moments inoubliables de ces trois dernières années ! Cette tradition de midi a perduré après votre départ avec la « Spanish armada », Miguel, Jessica et Sam qui ont dû me supporter ces derniers mois ! Le laboratoire est si grand qu'il est difficile de citer tout le monde et de n'oublier personne. C'est pourquoi je tiens à remercier globalement tous les membres du laboratoire pour Cette thèse est consacrée à l'étude de plusieurs ligands originaux appartenant à la famille des métallylènes, i-e germylènes et stannylènes, avec des fonctions symétriques ou asymétriques. Ces fonctions présentent un atome de soufre commun à toutes les molécules. Les fonctions soufrées ont été incorporées de manières diverses et ont permis d'obtenir différentes propriétés en chimie de coordination ainsi qu'en catalyse.

Le premier chapitre débute dans un premier temps par une introduction sur les rappels historiques du développement de la synthèse des métallylènes. La nature et les propriétés des différents éléments du groupe 14 à bas état d'oxydation sont discutés et démontrent les différences et similarités entre tous les membres de cette famille (Schéma 1). Schéma 1: Les carbènes et les dérivés lourds à l'état libre Dans un second temps, la synthèse de dérivés du germanium (II) y est traitée selon les différentes voies de synthèse. Enfin, la stabilité des germylènes est abordée en discutant des méthodes développées dans la littérature pour stabiliser ces espèces électro-déficientes avec les différents substituants développés ces dernières décennies. L'utilisation des germylènes en chimie de coordination et particulièrement en catalyse est finalement abordée et démontre un engouement de plusieurs groupes et une importante multiplication des publications sur l'application des germylènes en catalyse, notamment ces dernières années. La dernière partie de l'introduction bibliographique est centrée sur la famille des sulfoxydes. Un rappel sur leurs propriétés, réactivités et effets électroniques est abordé ainsi que leurs applications en Cependant, l'addition du carbanion sulfinylé sur le composé AmGeCl n'a pas permis d'obtenir le composé 1a et uniquement un mélange de produits a été identifié en RMN du 1 H.

En effet, la formation de di-iso-propylamine durant la déprotonation laisse place à des réactions secondaires avec le germylène de départ ou le composé désiré. Afin de les éviter, la di-isopropylamine a été éliminée par évaporation, ce qui a permis d'obtenir 1a avec un bon rendement de 72%. Le produit 1a a pu être identifié de façon indubitable par RMN du 1 H avec les signaux caractéristiques des hydrogènes en a du sulfoxyde. Ils apparaissent en effet sous forme d'un signal A-B correspondant à un groupement CH 2 en a d'un centre asymétrique. La RMN du 13 C montre aussi un signal caractéristique pour le carbone qui joue le rôle de pont entre le germanium et le sulfoxyde. En effet, ce carbone est secondaire dans le produit 1a alors qu'il est primaire dans le sulfoxyde de départ.

La réaction a ensuite été étendue à des sulfoxydes et des germylènes possédant différents types de groupements (Schéma 4). 1g-h ont été obtenus selon la même méthode de synthèse que 1a à l'exception de la base employée. Cette fois-ci, le potentiel nucléophile de la base n'est plus un problème et le n-BuLi est utilisé en lieu et place du LDA, et donc d'introduire directement le nucléophile lithié en solution avec le germylène. La synthèse de ces dérivés a permis de comparer la stabilité et l'influence de la fonction sulfoxyde sur le ligand germylène mais aussi de pouvoir les comparer en vue d'applications en chimie de coordination et en catalyse. Il est important de noter que 1h a pu être aussi cristallisé et analysé en diffraction des rayons X grâce à ses propriétés physiques uniques, comparées aux ligands thioéther et sulfoxyde qui se présentent sous forme d'huiles à température ambiante. L'étude de la chimie de coordination de ces différents ligands a ensuite été envisagée à à partir de la propriété de cette famille de germylènes à pouvoir coordiner un métal à travers un groupement fortement s-donneur, le germylène, et un groupement faiblement s-donneur, le sulfoxyde. Dans un premier temps, le tungstène a été choisi comme métal de transition. En effet, il a déjà été démontré dans notre laboratoire en 2012 par Annie Castel et al. qu'un complexe germylène bidente de tungstène peut être obtenu à partir du précurseur W(cod)(CO) 4 .

La réaction de 1b avec le même précurseur de tungstène a permis l'obtention du complexe 3b (Schéma 6). Le complexe bis-germylène 3b a été caractérisé au travers de plusieurs méthodes d'analyses comme la RMN du 13 C, la spectroscopie IR et la diffraction des rayons X. La réaction a été étendue à l'analogue du molybdène et Mo(nbd)(CO) 4 a été choisi comme précurseur (Schéma 7). Ainsi, la même réactivité a pu être observée et le complexe bisgermylène molybdène 4b a été obtenu et caractérisé à travers les mêmes analyses que 3b. Schéma 7: Formation du complexe bis-germylene molybdène 4b L'obtention de complexes bis-germylene tungstène et molybdène en chimie de coordination nous a amené à sélectionner de nouveaux métaux de transition. Dans un premier temps, le ruthénium est apparu comme une excellente alternative. En effet, plusieurs exemples de germylènes coordinés au ruthénium sont décrits dans la littérature et cette observation est aussi valable pour la fonction sulfoxyde. C'est pourquoi Ru(PPh 3 ) 3 Cl 2 a été sélectionné comme précurseur. La réaction avec 1a a permis d'obtenir le complexe bidente 5a avec un rendement raisonnable de 56% (Schéma 8). Enfin, la chimie de coordination a aussi été étudiée avec des métaux tels que le fer, le cuivre et l'or mais aucun complexe n'a pu être caractérisé.

Le troisième chapitre est consacré à la synthèse de nouveaux ligands germylènesulfoxyde avec une nouvelle architecture. Le nouveau design a été rationnalisé grâce aux résultats obtenus à travers la chimie de coordination de la première génération de ligands et de complexes, comme par exemple, l'obtention de bis-germylene pour la coordination du groupe 6 ou l'absence de coordination du soufre du sulfoxyde pour tous les métaux. Ces observations nous ont motivés à augmenter la distance entre les deux groupements afin de savoir si le groupement espaçant le germylene et le sulfoxyde peut avoir une influence sur la chimie de coordination. La formation de ligands germylene-b-sulfoxyde a donc été entreprise. Cependant, la déprotonation en b d'un alkylsulfoxyde n'étant pas facilement accessible, il a été décidé de substituer la position en a avec un groupement t Bu afin de permettre une réaction d'ortholithiation. Le ligand 7 a été obtenu en utilisant la même procédure synthétique que la première génération, c'est-à-dire une substitution nucléophile (Schéma 11).

Schéma 11: Synthèse du ligand germylene-b-sulfoxyde 7a

La structure du produit 7a a pu être déterminée indubitablement par RMN du 1 H et 13 C avec des signaux caractéristiques. L'hydrogène en ortho du germanium apparaît sous forme d'un singulet ainsi que le carbone relié au germanium qui apparaît comme un carbone quaternaire alors qu'il est tertiaire dans le produit de départ.

Enfin, la chimie de coordination de ce ligand a été étudiée avec le même précurseur de tungstène utilisé précédemment (Schéma 12).

Schéma 12: Formation du complexe germylene tungstène 8

Le complexe 8 a été isolé comme un complexe bidente de tungstène avec le soufre du sulfoxyde et le germanium coordinés au centre métallique. La structure a pu être déterminée par RMN du 13 C, en IR et en diffraction des rayons X. Finalement, la réaction a été étendue au molybdène avec le même précurseur utilisé précédemment (Schéma 13). La coordination a ensuite été étudiée avec le ruthénium. Le précurseur Ru(PPh 3 ) 3 Cl 2 a été sélectionné comme précédemment (Schéma 14).

Schéma 14: Formation du complexe bidente germylene ruthénium 10a

De façon surprenante, un complexe à 16 électrons a été obtenu et le complexe de ruthénium 10a a été caractérisé par RMN du 31 P avec un singulet à 38 ppm mais aussi indubitablement caractérisé par spectrométrie de masse. Cependant, la diffraction aux rayons

General handling conditions

All the manipulations have been carried out under inert Argon atmosphere, using the standard Schlenk techniques. The solvents used have been purified by a purificator MBraun SPS-800 over filtrating columns filled with molecular sieves of 0.4 nm, and have been stocked under Argon atmosphere. The solids have been manipulated in glove-box under Argon atmosphere.

The addition of carbonyl monoxide was done by removing the atmosphere of a pressure tube and addition of the gas at 1.5 bars.

Equipment

Nucleus Magnetic Resonance (NMR).

1 H, 13 C, 31 P and 119 Sn were recorded with the following spectrometers: Bruker Avance 300, 400 and 500 MHz. The complete characterization of the products has been done using 1D experiments, as well as 2D analysis, such as COSY ( 1 H -1 H), HSQC ( 1 H -13 C), and NOESY.

The chemical shift has been counted positively verse the low field, and expressed in part per million (ppm). The coupling constant are expressed in Hz. The abbreviations to describe the signals are: s (singlet), d (doublet), t (triplet), dd (doublet of doublets), sept (septuplet), m (multiplet), Ar (aromatic), Ar/q (quaternary aromatic), J AB (coupling constant between A and B) and br (broad signal).

Melting point.

Melting points were measured with a capillary Electrothermal Stuart SMP40 apparatus.

samples have been prepared in the glove-box before the analysis.

Infrared (IR).

IR spectra were measured on a Varian 640-IR FT-IR spectrometer. The samples have been prepared in nujol or in a dichloromethane solution under Argon atmosphere.

X-ray diffraction analysis.

Single-crystal X-ray data were collected at low temperature (193(2)K) on a Bruker-AXS APEX II Quazar diffractometer equipped with a 30W air-cooled microfocus source or on a Bruker-AXS PHOTON100 D8 VENTURE diffractometer, using MoK radiation (λ= 0.71037 Å). The structures were solved by the direct method (SHELXS-97) or by direct intrinsic phasing method (SHELXT) and refined by full-matrix least-squares method on F2. All non-H atoms were refined with anisotropic displacement parameters.

Mass spectroscopy.

The mass spectroscopy analysis was done using two technics, direct chemical ionization (DCI-CH 4 ) methods, and recorded on a GCT Premier Waters mass spectrometer or on a Maldi micro MX microMass in an anthracene matrix (ratio product/matrix: 1/100).

Theoretical calculations.

The theoretical calculations have been carried out by Dr Jean-Marc Sotiropoulos (directeur de recherche in IPREM laboratory at the University of Pau, France).

HPLC analysis.

Determination of ee was performed on a HPLC with a chiralcel OD column at a flow rate of 1 mL/min with a mobile phase of Heptane/i-PrOH (96/4). The two enantiomers were detected with an UV detector at 210 nm with a retention time of 12.4 min and 14.7min.

SEC analysis.

The number-average and weight-average molar masses (Mn and Mw, respectively Chapter I:

General Introduction

Chapter I:

General Introduction

Abstract

Germylenes, heavier analogues of carbenes, have attracted considerable interest the last decades since the breakthrough of NHC. Although the derivatives of the group 14 family should present similarities, some differences are also expected. Still multiples questions are unsolved concerning germylenes and specially their properties as ligands and their possible influence in a catalytic cycle.

In order to obtain a satisfactory answer, many groups have published their results based on the effect of stabilizing substituents on the electronic and steric properties of germylenes. The results showed that the stabilizing substituents have a major effect on the reactivity and so the further applications.

Nevertheless, several groups achieved to obtain stable germylene complexes and applied successfully these complexes as active pre-catalysts. The results obtained from the catalysis and the theoretical studies performed led to envisage germylenes as a novel class of ligands that should be able to present new activity, selectivity or stability properties in catalysis.

I. Historical aspects I.1. General aspects of metallylenes

Catalysis is one of the most important and useful tools of modern chemistry to form polymers, drugs or small molecules to sustain human needs with lower cost in time and energy.

The design of new ligands for transition metals have been widely investigated to obtain novel electronic and steric properties and therefore novel catalytic activity. Therefore, these past decades, several Nobel prizes were attributed to chemists on this field like R. F. Heck, E. organoreagents, organocatalysts and ligands. [7][8][9] Scheme 1: Carbenes and heavier analogues in ground state These divalent species are defined as electron deficient with only 6 electrons on their valence shell. They possess two non-bonding orbitals defined as p π and σ and two different metallylenes can be distinguished depending on the electron distribution between these orbitals p π and σ (Scheme 2): triplet, with unpaired electrons in separate orbitals (nσ1nπ1) and singlet, with both electrons paired (nσ2nπ0). 10 The difference between a triplet and a singlet will fundamentally depend on the energy level of the σ orbital. The ground state of metallylenes depends on the energy gap between p π and σ orbitals (Table 1). 8,11,12 The comparison of dihydrometallylenes showed that only dihydrocarbene is more stable in triplet state compared to all the heavier analogues that are stable in singlet state. This observation can be explained by the size of the ns and np orbitals. The difference changes dramatically with the heavier analogues, np orbitals become larger than ns orbitals as the quantic number increases. The effect on metallylene ground state is to favor the σ orbital and so the singlet state and to induce difficulties to the hybridation. [13][14][15] Another effect observed by the size of the orbitals is the lone pair presenting a larger s character while the empty orbital presents a higher electrophilic character.

I. Negishi

I.2. Synthetic route to germanium (II) species

The general procedure to obtain germylenes proceeds via reduction of the most stable Ge(IV) form to obtain the Ge(II) derivative. The synthetic pathway is essentially based on elimination or reduction reaction of the corresponding dihalogeno precursors (Scheme 3). 16,17 Scheme 3: Synthetic pathways to Ge(II)

The main starting material used for germylenes synthesis is GeCl 2 •dioxane which is obtained from the reduction of GeCl 4 with a reducing agent. This reaction, described by Mironov in 1975, is still used nowadays by trapping the in situ formed GeCl 2 with dioxane.

Another way to obtain functionalized germylenes was described by Herrmann in 1992 by reduction of Ge(IV) dichloride in Ge(II) derivative in a good 75% yield by using two equivalents of lithium as reducing agent (Scheme 4). 18 Latter, Okazaki et al. used the same procedure with lithium naphthalenide to obtain a diarylgermylene from the corresponding dibromodiarylgermane. 19 Scheme 4: Formation of Ge(II) by metallic reduction Synthesis of germylenes via cyclo-elimination reaction was reported by Neumann et al. in 1980 (Scheme 5). 20,21 Dimethylgermylene was formed at 70 °C by releasing the pyrene derivative. However, dimethylgermylene was highly reactive and trapped in situ with several reagents like dimethylbutadiene, (Z)-stilbene or dimethyltindichloride. Retro cyclo-addition was also studied by the group of Okazaki in 1995 (Scheme 6). 22,23 The novel germanium (IV) bearing a germacyclopropane group performed the retro cycloaddition and released the germylene with formation of phenylacetylene. Finally, Ge-C bond cleavage was proposed by the group of Müller in 2016. 24 The addition of NHC to 7silanorbornadienes led to the formation of silylenes stabilized by NHC and calculation study with the germanium derivative suggests that this reaction could be applied to the formation of the corresponding germylenes. However, there are still no reports of this reaction with germanium to date.

R 2 GeX 2 n Red R R Ge Elimination R 2 GeY 1 Y 2 R R Ge + Y 1 Y 2 + Red n X 2 X =

Scheme 6: Synthesis of Ge(II) by elimination reaction

Finally, a synthetic route to generate germanium (II) species via photolysis was studied by the group of Masamune in 1985 (Scheme 7). 25 The intermediate germylene was obtained under irradiation of a disilagermane. However, the diarylgermylene was highly reactive and gave a dimer characterized after quenching with methanol. Nevertheless, formation of the diarylgermylene intermediate was determined by rapid addition of methanol to give the addition product. . 26 It appears that the germylene has a monomeric form in solution and a dimeric form in solid state, the Ge=Ge double bond of the dimeric specie being shown by Raman spectroscopy. However, dimerization reaction can be avoided by increasing the steric hindrance of only one substituent on the moiety as reported by Jutzi in 1991. 27 The publication showed that replacement of one hydrogen atom by a trimethylsilyl substituent can avoid the dimerization reaction in the solid state as observed on the X-ray structure. The first way to stabilize a germylene center is kinetic stabilization, which implies bulky substituents around the germylene center to avoid any electrophilic or nucleophilic attack by using steric hindrance. Several examples are reported in the literature with different substituents (Scheme 9), going from dialkylgermylenes as seen with Lappert and Jutzi, 26,27 cyclic germylenes published by Kira in 1999, 28 mono-arylgermylenes published by Power in 1997 29 to di-arylgermylenes published by Matsuo in 2012. 30 X-ray structures of all germylenes showed a V-shaped geometry with a Ge-C s-bond length of 2.00 to 2.07Å.

Scheme 9: Kinetic stabilization of some selected germylenes Steric hindrance has another impact on the germylenes reactivity. Matsuo et al.

demonstrated the importance of the substituent bulkiness, in 2012, with the synthesis of (Eind) 2 Ge: that possess two bulky Eind groups (Scheme 9). The non-common steric hindrance around the germylene allowed an oxidation reaction and the synthesis of the first example of a stable germanone, heavier analogue of ketone, without stabilization by an intra or inter molecular Lewis base. 30 The second way to stabilize a germylene center is the thermodynamic stabilization.

Two different categories will be discussed and developed due to its wide utilization in germylenes chemistry. The first method of stabilization consists in the p-donating of an aheteroatom in the p empty orbital of the metallylene. Indeed, the strategy employed independently by Öfele and Wanzlick, 31,32 in 1968 to synthetize the first NHC-complex of mercury and chromium, was then used by Arduengo et al. to form the first stable and "bottelable" carbene. 33 The method has been transferred to the heavier analogue by Hermann et al. who reported the synthesis of the NHGe in 1992 (Scheme 10). 18,34 NHGe was obtained independently by nucleophilic substitution of GeCl 2 •dioxane with a dilithium diamide salt and by reduction of the corresponding NHGe IV Cl 2 with two equivalents of Li 0 in 75 % and 80 % yields respectively. X-ray structure showed a planar 5-membered ring with a Ge-N s-bond distance of 1.83 Å. . 42 The lack of X-ray structures, for the first two compounds, surely influenced the fact that they were unnoticed or less cited by other groups. However, X-ray structure of the third one was confirmed as a monomeric planar compound in solid state with no dimerization reaction, Ge-N s-bond presents a distance of 1.86 Å close to the one report by Herrmann two years later. 18 Recently, Cabeza et al. have published a derivative in 67% yield with phosphine arm to obtain a pincer ligand. 43,44 It is important to note that Hahn et al. have reported numerous bidentate and pincer ligands with a NHGe topology. [45][46][47] Scheme 12: Some selected NHGe Finally, the second method of thermodynamic stabilization is based on the donation ability of at least one Lewis base. The lone pair of the Lewis base is overlapping with the germylene empty orbital intramolecularly or intermolecularly (Scheme 13). Many properties can be easily modulated through this method by modification of the steric hindrance, the atom bonded to the metallylene, the nature of the Lewis base or the number of Lewis bases used.

Scheme 13: Different methods of thermodynamic stabilization using an intra or an intermolecular Lewis base

The first germylene stabilized by a nitrogen Lewis base was published by Veith in 1989 (Scheme 14). 48 The polycyclic lithium silylamide salt was reacted with GeCl 2 •dioxane to form the corresponding germylene in 82% yield. The X-ray structure of the germylene was not reported. Nevertheless, its formation was proved via its oxidation with molecular oxygen and sulfur, leading to the germanone dimer and the first stabilized germanethione with 68% and 98% yields respectively. X-ray structure of germanethione showed a trigonal-planar geometry with an additional Ge-N dative bond, two nitrogen are s-bonded with a length of 1.88 Å close Both germylenes were characterized by X-ray crystallography and the structures showed a Ge-C s-bond distance in allowance with the previous reported germylenes by Lappert, Meller and Leung (2.02 and 1.94 Å). However, Ge-N dative bond distances are totally different in both complexes. In the case of Jutzi, the distance is 2.09 Å, closing to the one reported by Veith with also one nitrogen as Lewis base. 48 In the case of Couret, the distances are 2.34 and 2.57 Å, one nitrogen has a common dative bond when the other one presents a larger distance. In 2001, Jutzi et al. published a heteroleptic and a homoleptic germylene stabilized by an ether substituent in 45% and 62% yield. Both germylene were characterized by X-ray crystallography and the structures showed an usual Ge-C s-bond distance (2.00 and 2.06 Å). Moreover, only one oxygen stabilizes the germanium center with a Ge-O distance of 2.07 (heteroleptic) and 2.19 Å (homoleptic). The influence of the steric hindrance on the oxygen atom was investigated by replacing the t-Bu group by i-Pr or Me. Unfortunately, the corresponding germylenes were not stable and the product of insertion into O-Me bond was isolated. In order to force the stabilization with two oxygens, Yamamoto et al. published in 2005 a strained germylene in 72% yield. X-ray structure showed a Ge-O distance of 2.36 and 2.39 Å. More recently, our group reported the stabilization of germanium center with sulfone substituent in 60% yield. [START_REF] El Ezzi | A Bis-Sulfonyl O,C,O Aryl Pincer Ligand and its Tin(II) Complex: Synthesis, Structural Studies, and DFT Calculations[END_REF] X-ray structure showed a distorted seesaw geometry with usual Ge-C distance of 2.03 Å and Ge-O dative bond distance of 2.36 Å. Scheme 16: Lewis base stabilization of some selected germylenes [START_REF] Green | Complexes of an Anionic Gallium(I) N-Heterocyclic Carbene Analogue with Group 14 Element(II) Fragments: Synthetic, Structural and Theoretical Studies[END_REF] They have reported the reaction of anionic gallium(I) Nheterocyclic carbene analogue with Lappert dialkylgermylene dimer, which results in stabilization of the monomeric species in 56% yield. X-ray structure of the compound showed a Ga-Ge distance of 2.54 Å and typical Ge-C distance of 2.08 and 2.09 Å. Germylene is interacting with potassium, chelated by TMEDA, with a typical bond of 3.44 Å as reported by the authors.

Scheme 17: Intermolecular Lewis base stabilization

The same reactivity towards Lappert's germylene dimer was reported with different NHGa in 2007. [START_REF] Rupar | The reactivity of an anionic gallium Nheterocyclic carbene analogue with a solution stable digermene[END_REF] The same year, Baines et al. applied the utilization of NHC as intermolecular Lewis base in the stabilization of dialkylgermylene dimer and dichlorogermylene (Scheme 18). [START_REF] Rupar | Stabilization of a Transient Diorganogermylene by an N-Heterocyclic Carbene[END_REF][START_REF] Rupar | A Germanium(II)-Centered Dication[END_REF] X-ray structures obtained from these compounds showed pyramidal geometry with a Ge-C NHC length of 2.08 and 2.11 Å, in the range of Ge-C s-bond which is particularly short for a dative bond. Scheme 18: Intermolecular Lewis base stabilization of some selected germylenes Stabilization with an intermolecular Lewis base is now well known and has been applied by using a large diversity of stabilizing compounds involving nitrogen, phosphorus, arsenic, oxygen, sulfur and selenium atoms. Scheme 23: 4p delocalized stabilization of some selected germylenes Amidinate based germylenes have been widely explored after the report of Richeson. [START_REF] Chlupatý | Hybrid amidinates and guanidinates of main group metals[END_REF] It can be rationalized by their easiness of their preparation and the possibility to functionalize three different positions (Scheme 24). It is important to note that nitrogen atoms are located at the same distance to germanium in the heteroleptic compound.

Scheme 24: Synthesis of amidinatogermylenes and further functionalizations

The substituent on the nitrogen (R 2 ) can be modulated to offer a large variety of steric hindrances going from the small group, i-Pr, [START_REF] El Ezzi | Iron Complexes with Stabilized Germylenes: Syntheses and Characterizations[END_REF] to the bulky group, Diip. [START_REF] Green | Synthetic, structural and theoretical studies of amidinate and guanidinate stabilised germanium(i) dimers[END_REF] However, the steric hindrance has shown no notable influence on the stabilization or the reactivity of germylenes.

Indeed, the reactivity towards potassium is the same for both t-Bu or Diip group (Scheme 25).

The reaction leads to the formation of the dimer of germanium (I) which is stable and possesses a Ge-Ge single bond with a lone pair on each germanium. [START_REF] Green | Synthetic, structural and theoretical studies of amidinate and guanidinate stabilised germanium(i) dimers[END_REF][START_REF] Nagendran | RGe(I)Ge(I)R Compound (R = PhC(NtBu)2) with a Ge-Ge Single Bond and a Comparison with the Gauche Conformation of Hydrazine[END_REF] Scheme 25: Reactivity of AmGeCl toward metallic reductant

Ar = dipp R 2 N N R 1 R 2 Ge Cl 1) R 1 Li N C N R 2 R 2 2) GeCl 2 .dioxane R 3 Li R 2 N N R 1 R 2 Ge R 3 R 2 N N R 1 R 2 Ge Cl K R 2 N N R 1 R 2 Ge R 1 = Phenyl, R 2 = t Bu R 1 = t Bu, R 2 = Diip THF R 2 N N R 1 R 2

Ge

On the other hand, the substituent on the central carbon of the amidinate group (R 1 )

has an influence on the electronic properties of the metallylene. In comparison, Jones reported in 2008 the formation of the guanidinatechlorogermylene with a di-cyclohexylamine group at R 2 position (Scheme 26). [START_REF] Jones | Synthesis, characterisation and reactivity of germanium(ii) amidinate and guanidinate complexes[END_REF] The amine group enhanced in electron the amidinate ring which increased the donation to the germylene. The consequence was an elongation of the and even to form bidentate or pincer ligands (Scheme 28). [START_REF] Jones | Synthesis, characterisation and reactivity of germanium(ii) amidinate and guanidinate complexes[END_REF][START_REF] Brück | Pushing the σ-Donor Strength in Iridium Pincer Complexes: Bis(silylene) and Bis(germylene) Ligands Are Stronger Donors than Bis(phosphorus(III)) Ligands[END_REF][START_REF] Gallego | Highly Electron-Rich Pincer-Type Iron Complexes Bearing Innocent Bis(metallylene)pyridine Ligands: Syntheses, Structures, and Catalytic Activity[END_REF] Thus, the amidinato system has been extensively studied and used in metallylene chemistry. [START_REF] Green | Synthetic, structural and theoretical studies of amidinate and guanidinate stabilised germanium(i) dimers[END_REF][START_REF] Jones | Synthesis, characterisation and reactivity of germanium(ii) amidinate and guanidinate complexes[END_REF][START_REF] Álvarez-Rodríguez | Amidinatogermylene Complexes of Copper, Silver, and Gold[END_REF][START_REF] Yeong | An Amidinate-Stabilized Germatrisilacyclobutadiene Ylide[END_REF][START_REF] Matioszek | Bis(amidinato)germylenerhodium Complexes: Synthesis, Structure, and Density Functional Theory Calculations[END_REF] Scheme 28: Some selected amidinate based germylenes Transposition to 6p delocalized systems, as seen before with Stobbart, are numerous in the literature. [START_REF] Rodgers | Monomeric derivatives of bivalent germanium: ketoenolate and related chelate compounds[END_REF][START_REF] Leung | Reactions of some organogermanium(II) chlorides[END_REF] However, β-dicetiminates and pyridyl-1-azaallyl appear to be the most used ligands in germylene chemistry. Leung

I.4. Germylenes in coordination chemistry and applications in catalysis

Stable germylenes can be applied in many reactions as reagents, catalysts or ligands.

Interestingly, the method used to stabilize the germylenes plays a preponderant role in any reactions. Indeed, the kinetic stabilization offers steric hindrance to the center, which includes small electronic modification of the germylene. The empty orbital remains very reactive and the lone pair has a high s character. For the thermodynamic stabilization, the electronic is modified, that means the lone pair can be more s-donor and the empty orbital is deactivated.

However, the reactivity of germylenes is well explored compared to their ability to act like sdonor ligands. In comparison, carbenes or silylenes are well known in coordination chemistry and their catalytic processes are well defined. The difference is mainly due to the difficulty of obtaining sufficiently robust germylenes complexes to envision their use in a catalytic cycle.

Germylenes usually have the same type of coordination as Fischer carbene due to the singlet state of the free ligand (Scheme 33). However, Sekiguchi et al. have recently published in 2015 an example of Schrock type complex by coordination of germylenes with group IV metal. Hf=Ge double bond was confirmed by many analysis like DFT calculations, X-ray crystallography and UV measurement. [START_REF] Nakata | A Schrock-Type Germylene Complex: (η5-C5H4Et)2 (PMe3)Hf═Ge(SiMe tBu2)2[END_REF][START_REF] Hlina | Coordination Chemistry of Disilylated Germylenes with Group 4 Metallocenes[END_REF] Scheme 33: Coordination of Fischer and Schrock carbenes

Frenking et al. reported in 1998 a theoretical study on the σ-donor properties of carbenes, silylenes and germylenes with group 11 transition metals, Cu, Ag and Au. [START_REF] Boehme | N-Heterocyclic Carbene, Silylene, and Germylene Complexes of MCl (M = Cu, Ag, Au). A Theoretical Study[END_REF] The study compared the bond dissociation energy between the metal and the group 14 element. The result of the calculations confirmed the general trend that metal-ligand bond strengths is stronger with carbene than silylene than germylene. Another general trend was observed for the metal-ligand bond is stronger with gold than copper than silver. However, Szilvási et al. have published another theoretical study in 2017 on the s-donor and p-acceptor properties of a large panel of germylenes and they compared them with PPh 3 , PCy 3 and basic NHCs. [START_REF] Benedek | Theoretical Assessment of Low-Valent Germanium Compounds as Transition Metal Ligands: Can They Be Better than Phosphines or NHCs?[END_REF] The results confirmed that germylenes are basically less s-donor than NHCs, but better than phosphines in general.

Nevertheless, the calculations also showed that germylenes are better p-acceptors than most of NHCs and phosphines. That is why germylenes can be considered for performing different catalytic steps difficult to develop with other ligands. the first example of diarylgermylenes complexed to a transition metal. [START_REF] Tokitoh | Synthesis and crystal structure of the first base-free diarylgermylene-transition metal mononuclear complexes[END_REF] The pentacarbonyl chromium and tungsten complexes were obtained in low 5.5% and 6.3% yields respectively.

X-ray structure of tungsten complex exhibits a distance for Ge-W bond of 2.59 Å in allowance with tungsten-germylene complex reported latter with a thermodynamic stabilization. [START_REF] Jutzi | Basenstabilisierte Germylene, III. Stickstoff-Germanium-Ylid-Komplexe von Chrom, Molybdän und Wolfram[END_REF][100][101] Scheme 34: Kinetic stabilization of some selected germylene complexes Nowadays, Lewis base stabilization has appeared as an evidence and is mainly used to obtain germylene complexes stable enough to be applied in catalysis. The complexes exhibit a wild diversity of architecture or coordination to transition metal with new properties. On this path, amidinate based germylenes are surely the most used ligands for coordination chemistry due to their easiness to prepare as shown previously. 109 Driess et al. reported in 2014 an iron pincer germylene complex with carbonyl ligands in 39% yield (Scheme 43). [START_REF] Gallego | Highly Electron-Rich Pincer-Type Iron Complexes Bearing Innocent Bis(metallylene)pyridine Ligands: Syntheses, Structures, and Catalytic Activity[END_REF] The complex was obtained by ligand metathesis of PMe 3 with CO gas . IR spectrum exhibits two bands for the carbonyl groups at 1855 and 1805 cm -1 , which showed that germylene have a s-donation close, but still inferior than silylene (1830 and 1778 cm -1 ). However, the results exhibited better donation than NHC (1928 and 1865 cm -1 ) or phosphine (1950 and 1894 cm -1 ) derivative. 110,111 Lewis base stabilization have a remarkable influence on the coordination ability of germanium (II) by boosting s-donation compare to NHGe which was equivalent to phosphine as seen with Herrmann et al. 18 Scheme 43: Formation of iron-carbonyl complex for IR comparison

The first complex was published by Jones et al. in 2008 (Scheme 44). [START_REF] Jones | Synthesis, characterisation and reactivity of germanium(ii) amidinate and guanidinate complexes[END_REF] The tungsten complex was obtained in 56% yield. X-ray structure exhibits a usual Ge Ruthenium and iridium were applied in hydrogen transfer catalysis (Scheme 47). The goal was to reduce a ketone into the corresponding alcohol in protic media. 115 Both of the complexes are active and can reduce cyclohexanone with 55% of conversion after 24h at 50 °C for ruthenium complex, whereas iridium can fully convert the ketone into alcohol after 1.5h at the same temperature. Surprisingly, the catalysis does not need any base as additive to form the active catalyst. Indeed, the proposed catalytic cycle needs the addition of external base to generate a hydride, which is the catalytically active species.

+ O OH t Bu t Bu O O N N Ph Ge N N Ph Ge Ir H Cl t Bu t Bu O O N N Ph Ge N N Ph Ge 1/2 (IrCl(coe) 2 ) 2
This complex was applied in catalytic C-H borylation of benzene using HBPin with one equivalent of cyclooctene (coe) as additive (Scheme 49). Addition of coe enhanced significantly the catalytic activity of the system: without coe, after 24h at 100 °C, a conversion of 46% was observed whereas it increased to 80% with one equivalent of coe. Silylene derivative followed the same behavior with 53% of conversion without coe and 90% with one equivalent. These results were explained by the authors by the fact that coe acts as an H 2 acceptor which has a beneficial effect on the catalytic cycle. Finally, the catalytic activity was compared with phosphines. Dialkylphosphine (P-t-Bu 2 ) and diaminophosphine (P(NCH 2 ) 2 ) analogues were prepared through the same synthetic pathway and showed unambiguously a drop-in activity with conversion of 64% and 21% respectively.

Scheme 49: Application of germylene iridium pincer complex to C-H borylation of benzene

The same year in 2012, Driess et al. have reported a bis-germylene presenting a novel ferrocene linker used to obtain a bidentate cobalt complex in 61% yield (Scheme 50). 117 X-ray structure exhibits a Ge-Co bond length of 2.20 Å, the shortest distance known to date. Latter, Driess et al. published in 2012 two synthesis to obtain a germylene nickel complex (Scheme 51). 118 The first synthetic approach involves a C-Br oxidative addition on nickel (0) (57% yield) when the second consists of a C-H activation with nickel (II) precursor (88% yield).

Scheme 51: Germylene pincer complex of nickel

The complex was used in Sonogashira-Hagihara cross-coupling reaction of iodo-1octene with phenylacetylene (Scheme 52). After 24h of heating at 100 °C, the conversion was up to 53% which was the better result obtained compared to silylene (39 %) and phosphorus (40 %) analogues.

Scheme 52: Application of germylene nickel pincer complex to Sonogashira-Hagihara crosscoupling reaction

The last example of active germylene in catalysis was reported recently by Nagendran et al. in 2018 (Scheme 53). 119 The catalyst is a bis-germylene platinum complex obtained in a quantitative yield from aminotroponiminate-germylene and PtCl 2 (cod). It was characterized by X-ray crystallography and showed a square planar geometry around the platinum center. The platinum complex was applied in cyanosilylation of aldehydes and ketones successfully (Scheme 54). Benzaldehyde was fully reduced in presence of TMSCN at 50 °C after 6h. The method was expanded to a large variety of substituted arylaldehydes and alkylketones. Nevertheless, the catalyst showed no reactivity with arylketone like acetophenone and its substituted derivatives.

Scheme 54: Application of bis-germylene platinum complex to catalytic cyanosilylation of aldehydes and ketones

I.5. Sulfoxides in coordination chemistry, generalities and applications as hemilabile ligands

A large variety of substituents has been used over the years to stabilize germylenes which such properties that finally allowed to obtain stable functionalized germylenes for applications in catalysis. The reports of Driess, Cabeza and Nagendran published over the past years have shown that germylenes can find interesting application in catalysis with novel properties and activities. [START_REF] Brück | Pushing the σ-Donor Strength in Iridium Pincer Complexes: Bis(silylene) and Bis(germylene) Ligands Are Stronger Donors than Bis(phosphorus(III)) Ligands[END_REF]114,118,119 Interestingly, the morphologies of these complexes are limited to mono-dentate, bis-monodentate, bi-dentate and pincer ligands. However, to the best of our knowledge, there is no-report concerning hemilabile bi-dentate ligands with a strong σdonor moiety and a weaker one involving germylenes. Hemilabile concept was introduced by Jeffrey et al. in 1979 with the synthesis of a bis-phosphorus ether ruthenium complex (Scheme 54). 120 X-ray structure showed selective formation of only one isomer, trans phosphorusoxygen complex. Finally, hemilability of the compound was proven by selective substitution

N N i Bu i Bu Ge i Pr N N i Bu i Bu Ge i Pr Pt Cl Cl N N i Bu i Bu Ge i Pr PtCl 2 (cod) R O R' Catalyst (0.25 mol%) CDCl 3 , 50 °C + TMSCN R O CN R' TMS R = alkyl/aryl, R' = H (aldehydes) R = R' = alkyl (ketones)
of ether ligand with carbon monoxide which showed ether has a weaker σ-donor ligand to ruthenium in comparison of phosphine. In order to synthesize a first example of hemilabile germylene ligand, we selected sulfoxide as a valuable weak σ-donor moiety. Indeed, sulfoxide presents two major advantages, a large possibility of coordination through sulfur or oxygen atoms and the presence of a stereogenic center when the sulfur atom is substituted by two different groups (Scheme 56). It is relevant to note that X-ray crystallography revealed a S-O bond distance of sulfoxide modified upon coordination, passing from ~1.49 Å to 1.47 Å in S-bonded complexes and 1.53 Å in oxygen-bonded complexes. 127 Another important physical property of sulfoxide is their characteristics by IR spectroscopy. Indeed, IR stretching band of sulfoxide are found at approximatively 1000 to 1050 cm -1 , whereas sulfoxide coordinating a transition metal is totally different. The band is between 1050 and 1200 cm -1 when sulfur is coordinated and the band is below 1000 cm -1 when oxygen is coordinated. 132,133 The analysis of an IR spectrum can provide useful data to determine if the sulfoxide is free or if it is coordinated by sulfur or oxygen atoms.

Sulfur and nitrogen centers are isoelectronic, it is nevertheless appropriate to demonstrate that racemization of enantiopure sulfur operate only under specific conditions compared to nitrogen. Khan et al. have published in 1964 a study to show that thermal racemization of sulfoxide appears only at high temperature, approximatively 200 °C. 134 The others condition to racemize a enantiopure sulfoxide are concentrate acidic media, 135 irradiation, 136,137 and finally electron transfer (Scheme 59). 138 Scheme 59: Experimental conditions to racemize chiral sulfoxide Nowadays, numerous examples of sulfoxide ligands are reported with different application in catalysis. 139 The first example of enantioselective catalysis with ruthenium and chiral sulfoxide ligands was published by James et al. in 1976, with a poor enantioselectivity obtained of 12 % ee in catalytic hydrogenation of olefinic carboxylic acids under H 2 (Scheme 60). 140

R S R' O * 200 °C hν H + conc e - R S R' O * R S R' O * + R S R' O * R S R' O * + R S R' O * R S R' O * + R S R' O * R S R'
O * + Scheme 60: First example of enantioselective catalysis using chiral sulfoxide ligand Since then a large variety of examples were developed, reported and applied in enantioselective catalysis (Scheme 61). 139 For example, Dorta et al. have reported in 2008 the 1,4-addition of arylboronic acids to cyclic a,b-unsaturated ketones and esters with a bissulfoxide rhodium complex in 99% yield with 98% ee. 141 Later, Liao et al. have published, in 2012, the asymmetric addition of arylboronic acids to NH isatins with Rh(I) sulfoxide complex in a good yield of 95% and a 92% ee. 142 Finally, Xiao et al have reported, in 2014, the asymmetric Tsuji-Trost reaction in presence of an amine-sulfoxide-phosphine ligand with yields superior to 86% and ee superior to 97%. 143

Scheme 61: Selected examples of chiral sulfoxide ligands applied in catalysis

In parallel, several groups have reported the synthesis of others hemilabile ligands with a sulfoxide function and presenting a NHC as the strong σ-donor moiety (Scheme 62). The first example was reported by Huynh et al. in 2009. 144,145 The novel sulfoxide ligand present two benzimidazole arms. However, the corresponding palladium complex obtained showed no coordination of the sulfoxide moiety. Later, Cardenas et al. have published in 2013 the synthesis of an imidazolium-sulfoxide ligand in a good 76 % yield. 146 The same behavior was observed with the palladium complexes, sulfoxide has a weak interaction with the transition metal without showing any coordination. Finally, Chen et al. have reported in 2014 another imidazolium-sulfoxide ligand. 147 Coordination of oxygen and sulfur was obtained by chlorine removal of the bis-NHC dichloropalladium complex with AgPF 6 , which was confirmed by Xray analysis. The formation of sulfoxide bidentate hemilabile complex was essentially achieved with phosphine and some examples are now available with stronger σ-donor ligand. All these results led us to the possibility of synthesizing a bidentate ligand presenting a chiral center as a useful demonstration and tool for group 14 heavier analogues in order to obtain an active catalyst, which can present asymmetric induction.

II. Conclusion

Germylenes, heavier analogues of carbenes, have attracted considerable interest the last decades since the breakthrough of NHC. Their kinetic and thermodynamic stabilization was first studied with the development of new substituents to afford novel steric and electronic properties. Thus, a large variety of ligands has been described for the synthesis of heteroleptic or homoleptic germylenes through the development of aryl, alkyl, nitrogen, oxygen, sulfur, phosphorus or even 4p, 6p, 10p delocalized substituents.

The synthesis of stable germylene complexes successfully applied in catalytic reactions was a breakthrough achieve in recent years. Interestingly, the architecture of these complexes was monodentate, bis-monodentate or pincer with any stereogenic information. That is why the lack of information about asymmetric bidentate hemilabile complexes pushed us to investigate the formation, characterization and properties of a germylene combined with a sulfoxide moiety.

First, the formation of germylene-a-sulfoxide ligands was investigated and their properties in coordination chemistry studied with several transition metals. The design of the ligands was then rationalized to prepare germylene-b-sulfoxide.

Then, the formation of a novel family of metallylenes with sulfonimidamide substituents was envisioned in order to incorporate an asymmetric sulfur (VI) directly on the skeleton of the group 14 stabilizing group.

Finally, the catalytic activity of several complexes was tested in hydrogen transfer reaction. The scope of the catalysis was investigated as well as the influence of the stereogenic center on the substrates. Polymerization was also investigated with the novel stannylene sulfonimidamide.

O Chapter II:

Germylene -a-Sulfoxide Ligands: Synthesis, Characterization and Coordination of a Novel Hemilabile Metallylene Ligand

Chapter II:

Germylene -a-Sulfoxide Ligands: Synthesis, Characterization and Coordination of a Novel

Hemilabile Metallylene Ligand

Abstract

Hemilabile amidinate germylene -sulfur (II, IV, VI) ligands have been synthesized in two steps in good yield from the readily available GeCl 2 •dioxane and commercially available sulfoxides.

These ligands were easily converted into tungsten, molybdenum, ruthenium phosphine and ruthenium p-cymene complexes. NMR spectroscopy, X-ray diffraction and IR studies reveal that different types of coordination are possible with the amidinate germylenes -a-sulfur (II, IV, VI), thus confirming the hemilabile character of these ligands. Formation of monodentate, bi-dentate and bis-germylene complexes were observed through the utilization of different transition metals or metal precursors.

I. Introduction

Stabilization of germylenes is now well known. 1 Nevertheless, germylenes are mainly studied in coordination chemistry with carbonyl complexes, confining their use in catalysis.

The last chapter demonstrates that the lack of stability of germylenes is one of the reason of their scarcity in catalytic reactions and that thermodynamic stabilization appears as an evident choice for the stabilization of germylenes, Therefore, amidinate groups have been widely explored to stabilize metallylenes thanks to their easiness of preparation and the possibility of functionalization on three different positions (Scheme 1). 2 Scheme 1: Synthetic pathway of amidinatogermylenes Amidinate group is an impressive versatile tool to stabilize germylenes with a unique opportunity to modulate it on various positions, to change the electronic and/or the steric hindrance properties. That is why amidinate groups are extensively studied and used in metallylene chemistry, numerous amidinatogermylenes being reported to date (Scheme 2). [3][4][5][6][7] Scheme 2: Examples of amidinatogermylenes Nevertheless, coordination chemistry of germylenes is in the early beginning in comparison to carbenes, and again the scarce examples reported in catalysis are generally based on the amidinate skeleton (Scheme 3). [8][9][10][11] Scheme 3: Germylene complexes applied in catalysis

R 2 N N R 1 R 2 Ge Cl 1) R 1 Li N C N R 2 R 2 2) GeCl 2 .dioxane R 3 Li R 2 N N R 1 R 2 Ge R 3 N N t Bu Ge Cl i Pr i Pr i Pr i Pr N N t Bu Ge Cl N N Ph Ge Ph N N N N ( i Pr) 2
Our research project consists in the development of new bi-dentate hemilabile mixed metallylene-sulfoxide ligands for their application in coordination chemistry and catalysis. 12 The following part will discuss about the design, the synthesis and the properties of the ligands (Figure 1). Synthesis of germylenes combined with a sulfoxide group is challenging and attractive for multiple reasons: (i) formation of a new type of tetrylenes, (ii) possible effect of sulfoxide as intramolecular Lewis base and (iii) elaboration of bi-dentate ligands for coordination chemistry. Then, application of the bi-dentate ligands to form complexes will be discussed latter in the chapter. Several complexes with different properties and a hemilabile character is expected with the germylene and the sulfoxide toward transition metals (Figure 2).

Investigation in the formation of a germylene-sulfoxide

In early exploration of the subject, the first question was: is it possible to stabilize a germylene center with a sulfoxide function, intra or inter molecularly? The question is particularly relevant to the reactivity of sulfoxide, known as oxidant for several reactions like Swern oxidation, oxidation of alkynes to a-dicarbonyl and oxidation of thiols to disulfides. 13- 15 Certainly, the most known reaction using sulfoxide as oxidant is Swern oxidation that permits to obtained ketones from the corresponding alcohols with equimolar amounts of sulfoxide and oxalyl chloride (Scheme 4).

Scheme 4: Swern oxidation reaction

In 1987, Satgé et al. reported the use of DMSO as an oxidant to obtain a germanonechromium complex. 16 Even though DMS was identified as resulting of the reduction of DMSO and confirmed that sulfoxide oxidized the germylene center, the germanone-chromium complex has not been isolated and only the products of further reactions were obtained. To elucidate the question of our model, reaction of GeCl 2 •dioxane with one equivalent of sulfinyl carbanion was carried out (Scheme 5).

Scheme 5: Reaction of sulfinyl anion with GeCl 2 •dioxane

The only product identified at the end of the reaction was the protonated sulfoxide.

This result can be explained according to two hypotheses: the first one was the protonation of the nucleophile due to the absence of reaction with GeCl 2 •dioxane and protonation of the

R 2 OH R 1 Cl O Cl O 1) DMSO, 2) NR' 3 R 2 O R 1 + DMS + CO + CO 2 1) LDA, -80 °C, 1h 2) GeCl 2 •dioxane S O THF S O Ge Cl
carbanion by the solvent. The other possibility was the reaction with GeCl 2 •dioxane occurred with formation of an unstable product that caught proton during its degradation. As a mean to go further, we tried the same reaction with 0.5 equivalent of GeCl 2 •dioxane to obtain the homoleptic germylene (Scheme 6). However, the same result was observed and the protonated sulfoxide was recovered at the end of the reaction. Variation of temperature and order of addition were also investigated to obtain the product, but the same results were observed.

Scheme 6: Reaction of two equivalents of sulfinyl carbanion with GeCl 2 •dioxane Therefore, the pre-stabilization of the germylene appears necessary to perform any nucleophilic substitution with sulfinyl carbanion because alkylarylsulfoxide seems not able to stabilize enough the germylene center. The role of the pre-stabilization is also to allow the sulfoxide to coordinate transition metal without destabilization of the metallylene.

II.2. Synthesis of amidinatochlorogermylene (II) precursor

Amidinatochlorogermylenes are excellent precursors that combine both stabilization of metallylene and a good leaving group for nucleophilic substitution. 17 Indeed, chlorine atom is easily accessible and has been already substituted by several strong nucleophiles. 5,18,19 The amidinatochlorogermylene selected is one recently reported by our laboratory. 18 It shows a modest steric hindrance and a simple skeleton that should allow a convenient nucleophilic substitution and an easy structural analysis of the future ligands.

The precursor was formed in a one-pot reaction from the di-isopropylcarbodiimide (DIC) (Scheme 7). The first step is a nucleophilic addition of t-BuLi on the DIC, followed by transmetalation with GeCl 2 •dioxane to obtain the amidinatochlorogermylene as a pale yellow solid in a good 97% yield.

Synthesis of amidinatogermylene (II) -a-sulfur (II, IV, VI)

The mixed germylene-sulfoxide ligand was obtained through a synthetic pathway that included a conventional nucleophilic substitution of halide. The sulfinyl carbanion was formed by deprotonation with a non-nucleophilic base to prevent any nucleophilic substitution of alkyl on the sulfur atom. 20 Also, the deprotonation was selectively done in a position and the regioselectivity was explained by electrostatic effect. 21,22 Racemic methylphenylsulfoxide was used first to determine the reaction conditions.

Sulfinyl carbanion was formed by addition of LDA on the sulfoxide at -80 °C. After 1h at -80 °C and 1h at room temperature, the mixture was added to the amidinatochlorogermylene at -80 °C (Scheme 8).

Scheme 8: Synthetic pathway of 1a

1 H NMR analysis showed the formation of a complex mixture with total consumption of the starting material and none signal corresponding to 1a. This result can be rationalized by the concomitant formation of di-iso-propylamine during the deprotonation that reacts with 1a 23 Di-iso-propylamine has been removed to determine its influence. Evaporation under reduced pressure of the preformed sulfinyl carbanion was selected as the easier method to eliminate the amine. Besides, the stability of the carbanion after elimination of the amine was ascertained by a trap step with iodomethane (Scheme 9). 1 H NMR analysis of the obtained product shown clean formation of methylated product, proving the viability of the method without decomposition of the carbanion during the process.

Scheme 9: Methylation of dry sulfinyl anion

From this result, the reaction of condensation with amidinatochlorogermylene was performed in the same conditions (Scheme 14). After extraction with pentane, NMR spectroscopy analysis undoubtedly shown the formation of a clean product assimilated to 1a.

Removal of di-iso-propylamine was the key step to avoid the formation of side products in the synthesis.

The 1 H NMR spectrum exhibits an AB system at 2.74 ppm for the Ge-CH 2 -SO, in THF-d 8 , which is a characteristic signal for a -CH 2 -in a position of a chiral center (Figure 3). The signal (2.74 ppm) is in the same range of the starting material (2.68 ppm), it may be explained by the close electronegativity between germanium and hydrogen. The chiral center has also a noticeable influence on the amidinate iso-propyl groups, even if the -N-CH-(CH 3 ) 2 (4.31 ppm) shows no difference compared to the starting material (4.31 ppm), the major difference observed concerns the -N-CH-(CH 3 ) 2 . Indeed, the starting material showed two doublets, due to planar symmetry, contrary to four doublets in the product. The four signals for CH 3 -groups appear as the result of the loss of symmetry in the molecule brought by the sulfoxide moiety (Figure 3). In addition, 13 C NMR has also evidenced a solid proof on the formation of 1a (Figure 4). A secondary carbon (61.5 ppm) was identified as the -CH 2 -between the sulfoxide group and the germylene moiety, the corresponding carbon being primary in the starting sulfoxide, which undoubtedly shows the formation of 1a. Again, the chiral center has a noticeable influence on the amidinate iso-propyl groups, each carbon was found non-equivalent due to a loss of symmetry in the product. The tertiary carbons (-N-CH-(CH 3 ) 2 ) appear as two peaks with almost the same chemical shift (47.7 and 47.6 ppm) and the primary carbons (-N-CH-(CH 3 ) 2 )

appear as three peaks with two carbon overlapping (26.9, 24.5 and 24.5 ppm). Study of stability was realized at room temperature on a dry sample and a sample in a solution of THF-d 8 with a 10-hour stirring. Same results were obtained and showed no particular effect of the solvent on the stability of 1a (Figure 5). The mechanism of degradation was not studied as well as the resulting products. However, it was determined that the compound 1a was stable at -24 °C and no degradation was observed at this temperature after a week. This observation led to try low temperature crystallization without any success. Mass spectroscopy analysis have been performed to validate the formation of 1a with another analytical method. However, only peaks corresponding to amidinatogermylene and methylphenylsulfoxide fragments were observed by electronic impact and MALDI-TOF analysis.

Figure 5: 1 H NMR of 1a after 10 hours in THF-d 8 1b, analogue of 1a from methyl-p-tolylsulfoxide (Scheme 9), was also synthesized through the same synthetic pathway. The formation of 1b was also confirmed by 1 H and 13 C NMR analysis. 1b was synthetized in order to envision an asymmetric version of our ligand. Indeed, enantiopure methyl-p-tolylsulfoxide was readily accessible from usual chemical company, or could be obtained easily from (-)-menthyl-p-toluenesulfinate. 24,25 Although unstable at room temperature, 1a and 1b have been characterized by 1 H and 13 C NMR spectroscopy analysis. These results lead us to envisage the modulation of the two moieties to expand the synthetic strategy to a large variety of substituents.

The goal was to determine the limit of the synthetic pathway to obtain a mixed germylene-sulfoxide ligand. As well as the impact of the design on the thermal stability was studied to determine the role of the steric hindrance on the ligand. First, steric hindrance was increased successively on both moieties. To increase bulkiness on the amidinatogermylene moiety, N-i-Pr group was replaced by a larger substituent. Cyclohexyl (Cy) group was chosen as an available and versatile group that can protect and remain the germylene center accessible for nucleophilic substitution (Scheme 10). Moreover, Cy-AmGeCl have been synthetized through similar procedure described for i-Pr-AmGeCl derivative. 3 Tipp (tri-i-propylphenyl) and t-Bu were chosen as larger substituents to increase steric hindrance and change nature of the sulfoxide moiety (Scheme 10).

Scheme 10: Different germylene-sulfoxide ligands with various substituents

Starting with the corresponding sulfoxides and amidinatochlorogermylenes, 1c -1f were obtained through the same synthetic pathway used for 1a and 1b (Scheme 10). 1 H and 13 C NMR have exhibited similar observations (AB system, secondary carbon, loss of symmetry...) than 1a and 1b. The compounds were obtained as oils with the same rate of degradation at room temperature and same stability at -24 °C. Although, steric hindrance was increased on both moieties, the bulkiness was not large enough to have any effect on the thermal stability of mixed germylene-sulfoxide system. However, the synthetic pathway allowed a simple method for the modification of the skeleton to obtain a large variety of ligands.

Finally, the influence of sulfoxide moiety on the germylene was also investigated. Sulfur (II) (thioether) and sulfur (VI) (sulfone) were chosen to replace the sulfoxide as readily available derivatives of lowest and highest oxidation state of sulfur. Moreover, thioether and sulfone can be seen as "extreme interacting form of sulfoxide" by the only possibility of interaction with sulfur, in the case of thioether, or with oxygen in the case of sulfone.

The synthetic pathway remains unchanged (Scheme 11). Indeed, n-BuLi can be used with thioether or sulfone to obtain the corresponding carbanion. It is important to note, in the case of thioether, that a-lithiation is preferred to ortho-lithiation. 26 Scheme 11: Synthesis of thioether (1g) and sulfone (1h) derivative 1g and 1h were obtained in the same conditions and were characterized in 1 H and 13 C NMR analysis. The loss of asymmetric center had a predictable impact on the NMR which was to keep the same symmetry in the molecule and so the same multiplicity of peaks. The chemical shift corresponding to -CH 2 -spacer of 1g and 1h appeared as a singlet in the similar area as the starting materials. This observation was unsurprising because germanium and hydrogen have a close electronegativity. Still, integration of this singlet in 1 H NMR undoubtedly proved the formation of a -CH 2 -spacer. In addition, a secondary carbon was observed for the spacer and confirmed the formation of 1g and 1h. The properties of these two news ligands were particularly different to the previous germylene-sulfoxide ligands and each other. Indeed, 1g was obtained as a very sensitive oil at room temperature which appears to degrade faster than all the sulfoxides, and with a slowly degradation at -24 °C where 1a-1f were stable at this temperature. In contrary, 1h was isolated as a stable solid at room temperature and was characterized by X-ray crystallography. Crystals have been obtained from a saturated solution of pentane (Figure 6). Moreover, even if sulfones are known as poor ligands in coordination chemistry, 27 some examples have already been published by our group for the stabilization of metallylenes with sulfones. 28,29 However, the oxygen-germanium distance (3.48 Å) is too far in solid state to demonstrate any stabilization interaction, the formation of a four-members ring being too strained to observe an interaction between an oxygen atom of the sulfone and the germanium.

Finally, the distance germanium-carbon (2.066(3) Å) is considered as long for a Ge-C bond (1.90-2.10 Å) but not unusual. 30

II.4. Investigation with heavier analogue

Heavier analogue, i-e stannylene, was next studied to determine if the mixed sulfoxidestannylene could be synthetized in the same synthetic pathway as 1a-1h. However, the corresponding AmSnCl, heavier analogue of AmGeCl, has not been reported yet in the literature.

AmSnCl was obtained through a similar procedure as AmGeCl (Scheme 12). The nucleophile, formed by addition of t-BuLi on DIC, was added on two equivalents of SnCl 2 to obtain 2b with a reasonable yield (78 %). The excess of SnCl 2 was found necessary to obtain clean heteroleptic stannylene, when less amount conducted to form a product identified as the homoleptic stannylene.

Scheme 12: Synthesis of AmSnCl 2b was characterized by multinuclear NMR spectroscopy and mass spectroscopy. The 1 H and 13 C NMR did not exhibit unusual signal or chemical shift and shown a derivative with a C 2 symmetry similar to AmGeCl. 119 Sn NMR exhibited only one signal (55 ppm) which was in accordance with previous analogues of AmSnCl (30-69 ppm). 31,32 However, crystallization in a saturated solution of pentane gave the product of oxidation 2d (Figure 7). The product of oxidation was determined as the reaction of 2b with serendipitous oxygen, similar reaction being reported by Ruzicka in 2012. 32 The structure exhibits two different tin atoms with two different oxidation states (+II and +IV). Moreover, the crystals were insoluble in usual solvents as reported by Ruzicka, which characterized a similar structure by solid state NMR.

The condensation reaction of the sulfinyl carbanion with AmSnCl was tested (Scheme 13).

Scheme 13: Synthetic pathway of 2c

1 H NMR analysis showed the formation of a complex mixture with total consumption of the starting AmSnCl and recovering of starting sulfoxide.

II.5. Coordination chemistry of amidinatogermylene (II) -a-sulfur (II, IV, VI) ligands

The first target in coordination chemistry was formation of a carbonyl complex to get information concerning the donation properties of the germylene and the sulfoxide to a transition metal. In the literature, several bi-dentate germylene carbonyl complexes have already been explored with tungsten, ruthenium and cobalt. 33,34 Castel et al., in 2012, reported in our laboratory the formation of phosphaalkenyl germylene that reacts with W(cod)(CO) 4 to give the corresponding bi-dentate complex. Starting with an equimolar amount of tungsten precursor, a solution of 1b in THF was added at room temperature and stirred overnight (Scheme 14). Surprisingly, the reaction led to the formation of a bis-germylene tungsten complex, 3b. Castel et al. reported, in 2010, the formation of a bis-germylene tungsten complex starting with the same tungsten precursor and amidinatochlorogermylene. 35 Structure of bis-germylene tungsten complex 3b was determined through multiple analysis. First in 1 H NMR, half an equivalent of tungsten precursor was remaining in solution with total consumption of 1b (coordinated cod, HC=CH at 3.8 ppm in C 6 D 6 ). Besides, 13 C NMR and IR spectroscopy confirmed a free sulfoxide function. In 13 C NMR, carbon monoxide ligands of 3b have one unique signal at 208 ppm, which show their electronic and magnetic equivalence. In IR spectroscopy, peak at 1021 cm -1 was characteristic of a non-coordinated sulfoxide close to 1b at 1015 cm -1 . Finally, X-ray structure of 3b was obtained from crystals grown in a THF solution at 6 °C (Figure 8). The structure of 3b shows a usual distance between the germylene and the tungsten of 2.5195(2) Å (2.50-2.65 Å). 5,33,35,36 Unsurprisingly, Ge1-N1 and Ge1-N2 bond lengths of 1.9506(18) and 1.9609 (17) Å are equal and shorter than in the free AmGeCl (1.98 Å), which can explain by the coordination of the germylene lone pair to the transition metal. Ge1-C4 bond distance was also in the range of carbon-germanium single bonds with a length of 2.002(2) Å. S1-O1 shows also usual bond length of 1.481(6) Å. The other bonds length and angles were also in the normal range of a germylene-tungsten complex.

1b was used as a racemic ligand, and the formation of one or two diastereomers was investigated. Even if 3b R,S was formed and determined by X-ray analysis, the other diastereomer could have not crystallized due to differences of physical properties. 1 H NMR of 3b was studied at low temperature (-80 °C) in order to obtain different signals of both diastereomer without any success. Enantiopure 3b R,R was synthetized from enantiopure 1b R and 1 H and 13 C NMR analysis shown the exact same chemical shifts in that those obtained from crystals of 3b R,S . We suppose that any diastereomeric differentiation can be observed by 1 H and 13 C NMR spectroscopy, probably due to the wide distance separating the two sulfinyl stereogenic centers.

In order to modulate the coordination properties of the ligand and to synthesize a bidentate complex, the conditions of reaction were changed. Three parameters: (i) temperature, (ii) dilution and (iii) equivalent of W(cod)(CO) 4 , were tested to study their influence on the reaction. Temperature (i) was cooled at -80 °C and dilution (ii) was increased by a factor 10.

However, the results showed in both case any influence on the formation of the product. The third reaction (iii) was carried out with 10 equivalents of W(cod)(CO) 4 and led to formation of a new product. 13 C NMR exhibited four news signals for the carbon monoxide and let hope the formation of a bi-dentate complex (Figure 9). Nevertheless, the product could not be isolated because of the excess of W(cod)(CO) 4 but this observation showed that coordination with sulfoxide, strained 4-member ring with sulfur and /or weak coordination with oxygen, was unfavorable compare to the coordination of a second germylene. The coordination was also tested with 1g and 1h with the same metallic precursor, and, unsurprisingly, these ligands gave analog results with the formation of the corresponding bisgermylene tungsten complexes (Scheme 15). Scheme 15: Formation of 3g and 3h 3g and 3h were crystalized in a THF solution at 6 °C (Figure 10). The X-ray structure shows a usual distance between the germylene and the tungsten of 2.5163(6) and 2.5206(2) Å (2.50-2.65 Å). The other bonds length and angles are also in usual range with Ge1-N1 and Ge1-N2 being shorter than AmGeCl or 1h due to a better donation of nitrogen atom to the germylene center. Scheme 16: Bis-germylene molybdenum complex X-ray structure of 4b was obtained from crystals grown in a saturated THF solution at 6 °C (Figure 11). The structure shows an usual distance between the germylene and the molybdenum of 2.561(4) Å (2.50 Å). 35,[37][38][39] As seen before, 1b was used as a racemic ligand and the formation of one or two diastereomers was investigated in NMR without any success. The formation of bis-germylene group VI transition metal complexes was a milestone to choose another metal precursor. Indeed, tungsten (0) and molybdenum (0) were certainly a good choice for a coordination with sulfur, nevertheless, this coordination seems to be unfavourable with oxygen due to the size of the 4-member ring. That is why ruthenium was preferred in the continuity of the study for its ability to be coordinated either by sulfur or oxygen. 40 Equimolar amount of Ru(PPh 3 ) 3 Cl 2 and 1b was stirred overnight in a solution of THF at room temperature (Scheme 17).

Scheme 17: Germylene ruthenium phosphine complex 31 P NMR showed a clean formation of 5b with two broaden signals at 55 and 24 ppm with a signal corresponding to free PPh 3 at -5 ppm. However, purification of 5b to remove free PPh 3 was not possible with usual solvent like pentane, which was unusual since PPh 3 is soluble in pentane contrary to 5b. Presence of free PPh 3 in a ruthenium complex was reported in the literature by the group of Grushin in 2014 with an X-Ray structure of (Ru(PPh 3 ) 3 Cl 2 .PPh 3 ) where one PPh 3 was found in the lattice without hydrogen bond, p-stacking or coordination to the metal center. 41 Nevertheless, bi-dentate germylene sulfoxide ruthenium complex was formed unambiguously with an oxygen coordination of the sulfoxide, which was characterized in IR analysis with a strong band at 945 cm -1 . 5a, phenyl derivative of 5b and less soluble in usual solvent, was obtained in a moderate yield of 56 % after washing with diethyl ether to remove free PPh 3 . 31 P NMR showed a same chemical shift and broaden signals at 55 and 24 ppm as 5b. Suitable crystals of 5b were obtained from a saturated solution of THF at -24 °C (Figure 12). [47][48][49] Finally, exchange of ligand of 5b was envisaged. One equivalent of Dppp (diphenylphosphinopropane) was added at room temperature and the reaction was stirred one hour at room temperature in THF (Scheme 18). Scheme 18: germylene ruthenium diphosphine complex 5c 31 P NMR showed a clean formation of 5c with two doublet signals at 47 and 26 ppm with a notable coupling constant of 47.1 Hz shoving two different phosphorus coupling with each other. However, the reaction needed 1.2 equivalent of DPPP to consume all the starting material due to the formation of a side product identified as RuCl 2 Dppp 2 which could not be eliminated at the end of the reaction. Suitable crystals were obtained from a saturated solution of THF at -24 °C (Figure 13). X-ray structure shows a distorted octahedral complex with an interatomic Ru-Ge distance comparable to 5a of 2.4413(3) Å (2.28-2.50 Å). 10,[42][43][44][45] Phosphine and ruthenium also have an usual distance of P1-Ru1 of 2.2440(6) Å and P1-Ru2 of 2.3119(6) Å. 41 The formation of a mono-dentate complex was also investigated with numerous transition metals. In the first exploration, (RuCl 2 (p-cymene)) 2 was selected. Indeed, Alvarez et al. published a ruthenium amidinatogermylene complex starting with the same precursor in 2016. 10 1b in a solution of THF was added to half an equivalent of (RuCl 2 (p-cymene)) 2 at room temperature and the reaction was stirred overnight (Scheme 19). Scheme 19: mono-dentate germylene ruthenium 6b complex 6b was obtained with a good 80% yield after washing with diethyl ether. Suitable crystals for X-ray crystallography were obtained from a saturated solution of THF at -24 °C (Figure 14). The X-ray structure shows usual interatomic Ru-Ge distance of 2.4056(5) Å (2.28-2.49 Å). 10,[42][43][44] It is important to note that Ge1-N1 and Ge1-N2 had bond lengths of 1.942(3) and 1.956(2) Å which are slightly shorter than AmGeCl (1.98 Å) or 5b (1.95 and 1.98 Å), which can be explained by a stronger donating germylene due to a poor donating ligand in trans position compare to phosphine in 5b. The loss of symmetry due to the presence of the stereogenic sulfoxide was exhibited in 1 H NMR and 13 C NMR analysis for the p-cymene group, where 4 doublets with 6 different carbons (2 quaternary and 4 tertiary) were assigned to each Formation of a bi-dentate complex by chlorine abstraction was also investigated from 6b in usual conditions described in the literature (Scheme 20). 50 Scheme 20: reaction of 6b with chlorine abstractor 6b was rapidly consumed after addition of AgPF 6 in dichloromethane at room temperature and a new product assimilated to 6b' was identified and characterized in 1 H and 13 C NMR (Figure 15). 6b' appears as two diastereoisomers in the form of two A-B systems with a 77/23 ratio calculated in 1 H NMR. Moreover 6b' exhibits different chemical shifts for the p-cymene group and the methylene bridge due to the chlorine abstraction and possible coordination of the sulfoxide. However, 6b' has not been fully characterized because of its Coordination with [RuCl 2 (p-cymene)] 2 was extended to 1a-1c-1d-1f-1g and 1h. In each case, ruthenium complex was obtained in good yield and suitable crystals for X-ray diffraction crystallography were obtained from saturated solutions of THF at -24 °C (Figure 16). Similar observations, as seen for 6b, were realized by 1 H and 13 C NMR analysis with all the germylene ruthenium complexes. As expected for 6g and 6h, corresponding to the thioether and sulfone analogues, two doublets by 1 H NMR and four different aromatic carbons by 13 C NMR (2 quaternary and 2 tertiary) were observed for the p-cymene group due to the loss of the asymmetric center. The second transition metal used to form a mono-dentate complex was Fe 2 (CO) 9 .

Ru
Coordination chemistry with this precursor was already known in our group and was carried out with 1b in THF at room temperature (Scheme 21). 18 Scheme 21: reaction of 1b with Fe 2 (CO) 9 The reaction was complete after 16h and an orange-brown solid was obtained, 1 H and 13 C NMR analysis exhibit the formation of a clean new product assimilated to 7b (Figure 17). Formation of 7b was also confirmed by mass-spectroscopy (m/z = 578.046). However, suitable crystals for X-ray diffraction were not obtained. The reaction was monitored by 1 H NMR and showed a total consumption of 1b after 30 min in both cases. The new clean products were assimilated to 8b and 9b (Figure 17).

However, these new complexes appeared very unstable, 8b being totally degraded in a mixture of green products after 2 hours at room temperature or at -24 °C, 9b leading to the formation of a gold mirror and a complex mixture of products in solution.

III. Conclusion

In conclusion, amidinatosulfoxide germylenes 1a-b were synthetized and characterized undoubtedly by 1 H and 13 C NMR analysis. The study of the modification of steric hindrance on both moieties by the preparation of 1c-f shows any effect on the thermal stability of these new mixed ligands. However, the synthetic appears as a simple method for the modification of the skeleton to obtain a large variety of ligands and to obtain different oxidation states on the sulfur atom by the preparation of thioether and sulfone analogues 1g and 1h.

Tungsten (0) derivatives 2b, 2g, 2h were prepared and surprisingly showed the formation of bis-germylene complexes 3b, 3g, 3h. Coordination of tungsten with sulfur atom would formed an unfavorable strained 4-member ring for 3b and 3g, or a week coordination with oxygen for 3b and 3h, which can explain the coordination of the tungsten by a second germylene.

Ruthenium complex 5a was obtained as a bidentate hemilabile complex with germanium and oxygen atoms coordinated to the ruthenium center through a 5-member ring.

X-ray structure showed a highly distorted octahedral structure with the coordination of oxygen that seems to be a result of an important steric hindrance around the metallic center, generated by PPh 3 and germanium ligand, and shows the hemilability of the ligand.

Mono-dentate coordination with (RuCl 2 (p-cymene)) 2 for the preparation of 5a-d, f-h was studied. The versatility of the synthetic pathway demonstrates that the skeleton can be easily modified to obtain a large variety of steric hindrance and sulfur (II, IV, VI) derivatives with a good yield of 72-84 %.

IV. Experimental section

Amidinate(dicyclohexyl t-butyl) chloro germylene : t-BuLi (2 mL, 3.4 mmol, 1.7 M in pentane, 1 eq) was added to a solution of CyN=C=NCy (701 mg, 3.4 mmol, 1 eq) in diethyl ether (10 mL) at -78 °C. The solution was raised to room temperature and stirred for 4 h. Then, GeCl 2 •dioxane (0.788 g, 3.4 mmol, 1 eq) was added to the solution at 0 °C, the mixture was stirred for 15 h at room temperature. Finally, the solvent was removed under reduced pressure and extracted with pentane (3x5 mL), to give, after removing all solvents, a white solid (1.111 Amidinate (di-iso-propyl-t-butyl) methyl-p-tolylsulfoxide germylene (1b): LDA (77 mg, 0.72 mmol, 1.1 eq) in diethyl ether (2.5 mL) was added dropwise to a solution of methyl-ptolylsulfoxide (110 mg, 0.72 mmol, 1.1 eq) in diethyl ether (2.5 mL) at -78 °C. The solution was stirred during 1 hour at the same temperature (-78 °C). Then, the solution was allowed to warm up at room temperature and stirred an additional period of 45 min. Finally, the solvent was removed under reduced pressure in order to obtain a white solid. The resulting solid was dissolved in diethyl ether (5 mL) and added dropwise to a solution of chlorogermylene (189 mg, 0.65 mmol, 1 eq) in diethyl ether (5 mL) at -78 °C. The mixture was stirred during 2.5 hours at -78 °C. Then, the solution was filtered at the same temperature (-78 °C) and concentrated until it remains 1 mL of solution.

The product was extracted with pentane (2x5 mL) and the solvents were removed in order to afford an oil (220 mg) in 82% yield. The compound is stable and storable at -24 °C in an inert (2 mL) at -78 °C. The solution was stirred during 1 hour at the same temperature (-78 °C). Then, the solution was allowed to warm up at room temperature and stirred an additional period of 45 min. Finally, the solvent was removed under reduced pressure in order to obtain a white solid. The resulting solid was dissolved in diethyl ether (2 mL) and added dropwise to a solution of chlorogermylene (156 mg, 0.42 mmol, 1 eq) in diethyl ether (2.5 mL) at -78 °C. The mixture was stirred during 2.5 hours at -78 °C. Then, the solution was filtered at the same temperature (-78 °C). Finally, the solvent was removed under reduced pressure to afford an oil (132 mg) in 66% yield. 1 at -78 °C. The solution was stirred during 1 hour at the same temperature (-78 °C). Then, the solution was allowed to warm up at room temperature and stirred an additional period of 45 min. Finally, the solvent was removed under reduced pressure in order to obtain a white solid.

The resulting solid was dissolved in diethyl ether (5 mL) and added dropwise to a solution of chlorogermylene (189 mg, 0.65 mmol, 1 eq) in diethyl ether (5 mL) at -78 °C. The mixture was stirred during 2.5 hours at -78 °C. Then, the solution was filtered at the same temperature (-78 °C) and concentrated until it remains 1 mL of solution. Pentane (5 mL) was then added to the solution and the solution was finally filtered. The solvents were removed under reduced pressure to afford an oil (220 mg) in 82% yield. 1f is stable and storable at -24 °C in an inert atmosphere of argon. Amidinate (di-iso-propyle-t-butyl) chloro stannylene (2a): t-BuLi (0.8 mL, 1.28 mmol, 1.6 M in diethyl ether, 1 eq) was added to a solution of i-PrN=C=N-i-Pr (0.2 mL, 1.28 mmol, 1 eq) in diethyl ether (5 mL) at -78 °C.

The solution was raised to room temperature and stirred for 4 h. Then, the solution was added dropwise to SnCl 2 (349 mg, 2.56 mmol, 2 eq) in diethyl ether (5 mL) at -78 °C, the mixture was stirred for 2 h at the same temperature (-78 °C) and 2 h at room temperature. Finally, the solvent was removed under reduced pressure and extracted with pentane (2x3 mL). The filtrate was concentrated under reduced pressure to give a white solid (342 mg) in 79 % yield. M.p. : 67 °C; 1 H NMR (300.18 MHz, C 6 D 6 , 25 °C): δ 0.87 (d, 3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 1.01 (s, 9H, C(CH 3 ) 3 ); 1.18 (d, 3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 4.16 (sept., 3 J HH = 6.3 Hz, 2H, CH(CH 3 ) 2 ). 13

Amidinate(di-iso-propyle-t-butyl) germylene methyl-ptolylsulfoxide tungsten tetracarbonyl complex (3b):

Amidinate (di-iso-propyle-t-butyl) germylene methyl-ptolylsulfoxyde 1b (135 mg, 0.330 mmol, 1 eq) was dissolved in tetrahydrofran (5 mL). The solution was then added to tetracarbonyl(1,5-cyclooctadiene)tungsten(0) (101 mg, 0.165 mmol, 0.5 eq) in THF (2 mL). The mixture was stirred during 15 hours at room temperature, then filtered and the solvent removed under reduced pressure. Finally, the solid was washed with pentane (2x3 mL) to obtain a pale yellow solid (143 mg) in 78% yield. Crystallization from THF at 6 °C gave pale yellow crystals suitable for X-ray study. M.p. : 117 °C (decomposition); 1 H NMR (300.18 MHz, C 6 D 6 , 25 °C): δ 1.29 (s, 18H, C(CH 3 ) 3 ); 1.45 (d, 3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 1.48 (d, 3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 1.57 (d, 3 J HH = 6.3 Hz, 12H, CH(CH 3 ) 2 ); 1.99 (s, 6H, p-CH 3 ); 2.94 (d, 2H, 2 J HH = 13.8 Hz, GeCH 2 SO); 3.35 (d, 2H, 2 J HH = 13.8 Hz, GeCH 2 SO); 4.34 (sept., 3

Amidinate

(di-iso-propyle-t-butyl) germylene methylphenylthioether tungsten tetracarbonyl complex (3g): Amidinate (di-iso-propyle-t-butyl) germylene methylphenylthioether 1g (100 mg, 0.26 mmol, 1 eq) was dissolved in tetrahydrofran (5 mL) and tetracarbonyl(1,5cyclooctadiene)tungsten(0) (53 mg, 0.13 mmol, 0.5 eq) was added to the solution. The mixture was stirred during 15 hours at room temperature, then filtered and the solvent removed under reduced pressure.

Finally, the solid was washed with pentane (2x3 mL) to obtain a pale yellow solid ( C(CH 3 ) 3 ); 1.33 (d, 3 J HH = 6.3 Hz, 12H, CH(CH 3 ) 2 ); 1.49 (d, 3 J HH = 6.3 Hz, 12H, CH(CH 3 ) 2 ); 3.23 (s, 4H, GeCH 2 SPh); 4.19 (sept., 3 J HH = 6.3 Hz, 4H, CH(CH 3 ) 2 ); 6.90 (m, 2H, CH Ar ); 7.04 (m, 4H, CH Ar ); 7.35 (m, 4H, CH Ar ). 13

Amidinate

(di-iso-propyle-t-butyl) germylene methylphenylsulfone tungsten tetracarbonyl complex (3h): Amidinate (di-iso-propyle-t-butyl) germylene methylphenylsulfone 1h (100 mg, 0.24 mmol, 1 eq) was dissolved in tetrahydrofran (5 mL). The solution was then added to tetracarbonyl(1,5-cyclooctadiene)tungsten(0) (98 mg, 0.12 mmol, 0.5 eq) in THF (2 mL). The mixture was stirred during 15 hours at room temperature, then filtered and the solvent removed under reduced pressure. Finally, the solid was washed with pentane (2x3 mL) to obtain a pale yellow solid (115 mg) in 86% yield. Crystallization from THF at 6 °C gave pale yellow crystals suitable

W CO OC CO OC N N Ge S(O) 2 N N Ge S(O) 2
for X-ray study. M.p. : 124 °C (decomposition); 1 H NMR (300.18 MHz, C 6 D 6 , 25 °C): δ 1.29 (s, 18H, C(CH 3 ) 3 ); 1.49 (d, 3 J HH = 6.3 Hz, 12H, CH(CH 3 ) 2 ); 1.64 (d, 3 J HH = 6.3 Hz, 12H, CH(CH 3 ) 2 ); 3.55 (s, 4H, GeCH 2 SO); 4.44 (sept., 3 J HH = 6.3 Hz, 4H, CH(CH 3 ) 2 ); 6.91 (m, 6H, CH Ar ); 7.80 (m, 4H, CH Ar ). 13

Amidinate (di-iso-propyle-t-butyl) germylene methyl-ptolylsulfoxide molybdenum tetracarbonyl complex (4b):

Amidinate (di-iso-propyle-t-butyl) germylene methyl-ptolylsulfoxyde 1b (150 mg, 0.367 mmol, 1 eq) was dissolved in tetrahydrofran (5 mL). The solution was then added to (bicyclo[2.2.1]hepta-2,5diene)tetracarbonylmolybdenum(0) (55 mg, 0.184 mmol, 0.5 eq) in THF (2 mL) at room temperature. The mixture was stirred during 15 hours at room temperature, then filtered and the solvent removed under reduced pressure. Finally, the solid was washed with pentane (2x3 mL) to obtain a pale yellow solid (159 mg) in 84% yield.

Crystallization from THF at 6 °C gave yellow crystals suitable for X-ray study. M.p. : 103 °C; 1 H NMR (300.18 MHz, C 6 D 6 , 25 °C): δ 1.28 (s, 18H, C(CH 3 ) 3 ); 1.46 (d, 3 J HH = 6.3 Hz, 12H, CH(CH 3 ) 2 ); 1.56 (d, 3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 1.58 (d, 3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 1.99 (s, 6H, p-CH 3 ); 2.90 (d, 2H, 2 J HH = 13.8 Hz, GeCH 2 SO); 3.35 (d, 2H, 2 J HH = 13.8 Hz, GeCH 2 SO); 4.27 (sept., 3 J HH = 6.3 Hz, 2H, CH(CH 3 ) 2 ); 4.37 (sept., 3 J HH = 6.3 Hz, 2H, CH(CH 3 ) 2 ); 6.88 (d, 4H, 3 J HH = 8.2 Hz, CH Ar ); 7.53 (d, 4H, 3 J HH = 8.2 Hz, CH Ar ). 13

I. Introduction

The previous chapter showed that germylene -a-sulfoxide can act as a hemilabile ligand of ruthenium (II) complex via coordination by oxygen and germylene atoms (Scheme 1). On the other hand, bis-germylene complexes were obtained with group VI transition metals (molybdenum and tungsten). The formation of bis-monodentate complexes instead of a bidentate one can be explained by favorable interaction of group VI transition metals at the (0) oxidation state with soft center like sulfur. However, coordination with sulfur of germylene -asulfoxide would imply the formation of an unfavorable strained 4-member ring that would be a transient intermediate to react further with another equivalent of ligand to form a more stable bis-germylene complex.

Scheme 1: Carbene and heavier analogues in ground state

The design of a 2 nd generation of germylene-sulfoxide ligand was considered by increasing the distance between both moieties.

The modification of the distance between the two entities could provide a variety of coordination to transition metals with germylene and sulfur or oxygen atoms of the sulfoxide group (Figure 1). 2,3 In the first case, oxygen and phosphorus were coordinated to rhodium through a 5-member ring. The coordination by sulfur atom appears unfavorable due to the formation of a strained 4-member ring. Nevertheless, it was confirmed latter, by Liao et al., that increasing the distance between phosphorus and sulfoxide allowed to form a more favorable 5-member ring with sulfur in comparison of a 6-member ring with oxygen. Scheme 2: Phosphinosulfoxide-rhodium complexes Thereby, synthesis of a 2 nd generation of hemilabile bi-dentate ligands will be described in this chapter. Several complexes of transition metals with different properties of coordination will be characterized and compared to the 1 st generation of ligands.

T.M.

II. Results and discussion

II.1. Synthesis of amidinatogermylene -b-sulfoxide

Synthetic pathway to obtain the 2 nd generation of ligands remains the same as previously described, exploiting the nucleophilic substitution of the chlorine atom of AmGeCl precursor. The choice of the sulfoxide moiety for this second generation was focused on the aryl-tert-butylsulfoxide. Indeed ortho-deprotonation of the aromatic ring will take place since sulfoxide acts as an ortho-directing group when a-position is saturated (Scheme 3). 4,5 Scheme 3: ortho-versus a-deprotonation of alkyl-arylsulfoxides tert-Butyl-p-tolyl-sulfoxide has been obtained in two steps from the corresponding thiocresol. The first reaction consists of the formation of the corresponding thioether in acidic conditions followed by an oxidation of thioether into sulfoxide according to the report of Grela in 2009 (Scheme 4). 6,7 Scheme 4: Synthesis of tert-butyl-p-tolyl-sulfoxide

Finally, the first b-sulfoxide amidinatogermylene has been synthetized according to the method used for the 1 st generation. tert-butyl-p-tolyl-sulfoxide was deprotonated with n BuLi at -80 °C for 1h and then was added to AmGeCl at the same temperature. After 2h, the solvent was removed under reduced pressure at room temperature and extraction afforded 7a in a good 82%yield (Scheme 5). It was not possible to obtain crystals of 7a, due to its degradation at room temperature in solid state or in solution. The mechanism of degradation has not been studied as well as the resulting by-products. However, it has been determined 7a was stable at -24 °C and no degradation was observed at this temperature after a week. This observation led to try crystallization at low temperature without any success.

Li-Base

S O R R R S O Li R R Li-Base R = H R = alkyl, aryl S O R R R Li m-cpba S S O CH 2 Cl 2 t BuOH SH H 2 SO 4
Mass spectroscopy analysis have been performed to validate the formation of 7a with another analytical method. However, amidinatogermylene and tert-butyl-p-tolyl-sulfoxide fragment were the only peaks to appear in electronic impact and MALDI-TOF analysis.

Finally, the synthesis was extended to the corresponding sulfone, exploiting the orthodirecting effect of the sulfone group. tert-Butyl-p-tolyl-sulfone was obtained in two steps from the corresponding thiocresol as previously described, via the oxidation of thioether into sulfone according to the report of Paolini in 1995 and Grela in 2009 (Scheme 6). 8,9 Scheme 6: Formation of tert-butyl-p-tolyl-sulfone tert-Butyl-p-tolyl-sulfone was deprotonated with n BuLi at -80 °C for 1h and then was added to AmGeCl at the same temperature. After 2h, the solvent was removed under reduced pressure at room temperature and extraction afforded 7b in a good 82% yield (Scheme 7). 1 H NMR of 7b showed the same characteristic signal as 7a with a singlet for aromatic hydrogen in ortho-position of germylene at 8.08 ppm. 13 C NMR spectrum has also evidenced a solid proof on the formation of 7b. Indeed, all the aromatic carbons had different chemical shifts, which demonstrated the loss of symmetry induced by the germylene group in orthoposition compared to the starting material that showed only four signals for the aromatic carbons due to the planar symmetry.

II.2. Coordination properties of amidinatogermylene -b-sulfoxide ligand

First, coordination chemistry was studied with tungsten (0), tested in the previous chapter and 7a. Indeed, 1 st generation ligand gave a bis-germylene complex in place of a bidentate one. The hypothesis was a weak or impossible coordination of sulfur through the strained 4-member ring led to the coordination of a second germylene to the tungsten. Starting with an equimolar amount of [W(cod)(CO) 4 ] precursor, a solution of 7a in THF was added at room temperature and stirred overnight (Scheme 8). Complex 8 was obtained with a good 89% yield. Interestingly, formation of a bidentate complex was observed with sulfur and germanium atoms coordinated to tungsten center.

Coordination was determined by IR spectroscopy with a band at 1067 cm -1 characteristic of a sulfur bonded to the transition metal. 10,11 Another indication was observed in 13 The structure of 8 shows an octahedral geometry with an usual bond distance between the germylene and the tungsten of 2.5661( 5) Å (2.50-2.65 Å), which is slightly longer than the distance observed for the 1 st generation bis-germylene complex (2.52 Å). [12][13][14][15] Unsurprisingly, Ge1-N1 and Ge1-N2 bond lengths of 1.951(3) and 1.952(3) Å are equal and shorter than the The other bond lengths and angles are in the normal range of a germylene-tungsten complex. It is important to note, to the best of our knowledge, that complex 8 is the first crystallized example of a tungsten complex coordinated by a sulfur atom of a sulfoxide function.

Then, coordination has been extended to determine if the same reactivity would be observed with molybdenum (0), lighter analogue of tungsten (0). Starting with the same ligand 7a and an equimolar amount of Mo(nbd)(CO) 4 , 9 was obtained after stirring overnight the mixture at room temperature in THF (Scheme 9).

Scheme 9: Synthesis of molybdenum complex 9

Again, a bidentate complex was obtained with sulfur and germanium atoms coordinated to molybdenum center. Coordination was confirmed by IR spectroscopy (1089 cm - 1 ) and 13 C NMR analysis (209.3, 214.0, 216.9 and 220.8 ppm). X-ray structure of 9 was obtained from crystals grown in a saturated solution of THF at 6 °C (Figure 4). The structure shows an octahedral geometry with a germylene-molybdenum distance slightly longer of 2.5758(6) Å, but still in the range of complexes previously reported (2.50-2.54 Å). 13,[16][17][18] Ge1-N1 and Ge1-N2 bond lengths of 1.955(2) and 1.969(2) Å are equal and shorter than in the free AmGeCl (1.98 Å) due to coordination of the germylene lone pair to the transition metal. Again, to the best of our knowledge, this structure is the first crystallized example of a molybdenum complex coordinated by a sulfur atom of a sulfoxide function. Then ruthenium(II) was investigated in the continuity of our study for its ability to be coordinated either by sulfur or oxygen atom, as previously observed in the previous chapter with bidentate coordination by oxygen and germanium. 19 An equimolar amount of Ru(PPh 3 ) 3 Cl 2 and 7a were stirred overnight in a solution of THF at room temperature (Scheme 10).

Scheme 10: synthesis of germylene -b-sulfoxide ruthenium complex 10a 31 P NMR of the crude product showed a clean formation of 10a as a 16-electron complex with one singlet signal at 38 ppm and a singlet for two equivalents of free PPh 3 at -5 ppm. Moreover, coordination with sulfur was determined by IR spectroscopy with a characteristic band at 1095 cm -1 . However, even if 10a was unambiguously characterized by -174-mass spectroscopy (809.1114 ([M -Cli-Pr] + )), crystallization afforded systematically bisruthenium complex 10b (Scheme 11). µ-SO bridged binuclear transition metal complexes were already observed in the literature with ruthenium and rhodium. [20][21][22][23][24] Nevertheless, it is important to note that all the complexes characterized were obtained with DMSO and 10b is therefore the first example of µ-SO bridged ruthenium complex with an asymmetric sulfoxide. It is also the first example characterized with two additional chlorine atoms participating at the bridge.

Scheme 11: germylene bis-ruthenium phosphine complex 10b X-ray structure exhibits two distorted octahedral ruthenium atoms with chlorine and sulfoxide bridges (Figure 5). Germanium-ruthenium bond distance of 2.3669(5) Å is in the range of already reported complexes (2.28-2.50 Å). [25][26][27][28][29] Phosphine and ruthenium have usual 2.24 Å), [30][31][32] but the distance is slightly longer than in the µ-SO bridge of complexes already reported (2.06-2.16 Å). [20][21][22][23] Finally, ruthenium-sulfur bond length of 2.3374 (10) Å is in the top range of bridge µ-SO complexes already described (2.19-2.34 Å). [20][21][22][23] This result can be explained by a high donation of the phosphine located in trans-position that can weaken the bond and increase the length between ruthenium and sulfur. Nevertheless, it is to the best of our knowledge the first example of a trans-phosphine-sulfoxide complex fully characterized. Interestingly, when crystals of 10b were analyzed by 31 P NMR in CD 2 Cl 2 , we observed the presence of three isomers in a 68 / 18 / 14 ratio. Chemical shifts for the three isomers were observed at 28.7, 39.9 and 29.5 respectively for singlet phosphorus in trans position of sulfur atom. The two-other phosphorus located on the second ruthenium appeared as six doublets for the three isomers. Analysis at variable temperature was carried out to determine if temperature could have an influence on the ratio of the three isomers. However, any change of the ration was observed by varying the temperature on the range of +35 to -70 °C (Figure 6). was positions isomers resulting of the interconversion of phosphine with non-bridging chlorine (Figure 7). The second hypothesis was decoordination of a bridging atom and coordination of a solvent molecule or formation of an empty site (Figure 7). The second hypothesis, relying on decoordination, should depend on the solvent.

Indeed, the ratio between the three isomers should change with a coordinating solvent compare to a non-coordinating solvent. However, 31 P NMR of 10b in CD 2 Cl 2 and fluorobenzene shows the exact same ratio between the three isomers which prove that the solvent is not coordinating (Figure 8). Still, an empty site formed by decoordination is possible. The result on the potential-energy surface (PES) showed that decoordination, with formation of an empty site, of the sulfoxide or a bridging chloride is not occurring. This result may indicate that the three molecules are position isomers. However, the size of the molecule did not allow to obtain results to conclude yet on the structure of the three isomers with calculations.

Finally, coordination chemistry was studied with group 10 transition metal. Ni(cod) 2 was used as precursor in presence of an equimolar amount of 7a in toluene at room temperature (Scheme 12).

Scheme 12: synthesis of germylene nickel(cod) complex 11a

Nickel complex 11a was obtained after 20 min as a very unstable yellow solid. X-ray structure of 11a exhibits a distorted tetrahedral geometry with an usual Ge1-Ni1 bond length of 2.2625(3) Å in the range of already reported for germylene-nickel complexes (2.09 -2.30 Å). 18,[34][35][36][37][38] The Ni1-S1 bond distance, 2.1591(4) Å, is slightly longer in comparison of the results already published by Peters in 2012 (2.10-2.13 Å). 39 Ge1-Ni1-S1angle is 90.025 (14)° which lie in 5-member ring angles. It is important to note that Ge1-N1 and Ge1-N2 bond lengths of 1.9893( 14) and 1.9913 (13) Å are in the same range than the free AmGeCl (1.98 Å). Indeed, Ge-N bond length usually decreases due to the higher donation of nitrogen to germanium when the latest is coordinated to a transition metal. In our case, this After 1h Cristals result can be explained by the electron rich nickel (0) center that should perform p-back donation to the germylene center.

Finally, we have evaluated the reactivity of 11a in a pressure of carbon monoxide to give 11b as a stable nickel complex at room temperature in toluene (Scheme 13).

Scheme 13: synthesis of germylene nickel tricarbonyl complex 11b

The very fast ligand exchange at room temperature led to the formation of the tricarbonyl nickel complex, demonstrating the hemilabile character of the ligand by replacing the weak s-donor by another ligand. The structure of 11b has been determined by 13 C NMR analysis, with only one signal for the carbonyl ligands at 199 ppm, and by IR spectroscopy with a band at 1027 cm -1 , confirming no coordination of sulfoxide to the nickel and finally by X-ray diffraction analysis of crystals obtained from a saturated solution of toluene at -24 °C (Figure 12). CO gas X-ray structure of 11b exhibits a nickel center with a tetrahedral geometry with a slightly longer Ge--Ni1 bond length of 2.3202(4) Å, but still in the range of already reported germylene-nickel complexes (2.09 -2.30 Å). 18,[34][35][36][37][38] Ge1-N1 and Ge1-N2 bond lengths of 1.9598(18) and 1.971(2) Å are equal and shorter than in the free AmGeCl (1.98 Å), which can be explained by a better donation of the germanium to the nickel and a smaller p-back donation than for 5a.

The specific structure of 11b as LNi(CO) 3 allows a TEP (Tolman Electronic Parameter) comparison with other well-known ligands as phosphines or NHCs. The goal of TEP comparison consists in the correlation of the value of IR band stretching frequency of the carbon monoxyde ligands with the electron density of the transition metal (Figure 13). 40 In the case of an electron rich ligand , the metal-carbon bond is shorter and strengthen due to pbackbonding of the metal to the ligands that will decrease carbonyl band shift due to weaken carbon-oxygen triple bond. In the other case of an electron poor ligand, the p-backbonding is lower and will increase carbonyl band shift due to stronger carbon-oxygen triple bond.

Figure 13: Carbonyl complex to determine TEP IR spectroscopy of 11b shows in dichloromethane a carbonyl band at 2058 cm -1 , which prove a better s-donor strength than most of the phosphines like P(OMe) 3 (2080 cm -1 ), PMe 3 (2066 cm -1 ) or PCy 3 (2060 cm -1 ), 41 but the result showed poorest s-donor strength than NHCs like IMes (2052 cm -1 ), i-Pr (2051 cm -1 ) or Me (2058 cm -1 ), or silylene (2046 cm -1 ) (Figure 14). 42,43 TEP comparison of tricarbonyl nickel complexes shows that 11b stand between the s-donation strength of trialkylphosphines and common NHCs. However, the complex can be assigned as a better s-donor than the germylene nickel complex published by Hoge et al. in 2016 with a band at 2067 cm -1 , 44

Less donating ligands

More donating ligands 2050 2060 2070

PMe 3 PCy 3 N N N N Ge C 2 F 5 C 2 F 5 PMe 3 PR 2 B Si N Ar O Ge O Ge O t Bu O t Bu O t Bu t BuO N Ge O O t Bu S O N N Ge

III. Conclusion

A 2 nd generation of germylene-sulfoxide ligand has been obtained by metal metathesis of AmGeCl chlorine atom with ortho-lithiated aromatic sulfoxide in a good 82% yield. This novel b-sulfoxide germylene ligand presents a stability comparable to that of the 1 st generation.

Its design presents a larger distance between sulfoxide and germylene moieties, allowing to modulate its coordination properties.

Thereby, germylene -b-sulfoxide ligand reacts with W(cod)(CO) 4 or Mo(nbd)(CO) 4

precursors to form the corresponding complexes in a good yield of 89 %. Bidentate coordination has been observed with germanium and sulfur atoms coordinated to the metal center. The characterization of bidentate germylene complexes confirmed that the formation of bisgermylene complexes obtained during the use of 1 st generation a-sulfoxide germylene ligands is due to a less stable coordination of sulfur through a strained 4-member ring.

Coordination was also investigated with Ru(PPh 3 ) 3 Cl 2 to give a novel 16 electron complex. Surprisingly, an unprecedented bis-ruthenium complex with sulfoxide and chlorine bridges has been obtained by crystallization. 31 P NMR analysis show the formation of three isomers in solution whereas only one is observed in X-ray diffraction analysis.

Group 10 transition metal was also investigated with Ni(cod) 2 precursor. The corresponding complex is highly unstable. Nevertheless, its structure has been determined by X-ray diffraction analysis to show a bidentate complex with germanium and sulfur atoms coordinated to nickel (0). Reaction with carbon monoxide affords a stable tricarbonyl nickel (0) complex, confirming the hemilabile character of this ligand by exchange of the sulfoxide for a stronger s-donating ligand. Finally, TEP comparison of carbonyl bands by IR spectroscopy shows that the s-donor strength of germylene ligand is between the s-donor strength of phosphines and NHCs.

IV. Experimental section

Amidinate (diisopropyle-t-butyl) t-butyl-p-tolylsulfoxide

germylene (7a): n-BuLi (0.72 mmol, 0.48 mL, C = 1.6 mol/L in hexane, 1.1 eq) was added dropwise to a solution of t-butyl-ptolylsulfoxide (141.1 mg, 0.72 mmol, 1.1 eq) in toluene (3 mL) at -78 °C. The solution was stirred during 1 hour at the same temperature (-78 °C). Then the mixture was added dropwise to a solution of AmGeCl (189 mg, 0.65 mmol, 1 eq) in toluene (3 mL) at -78 °C. The mixture was stirred during 2 hours at -78 °C and then warmed up to room temperature slowly. The solvent was evaporated under reduced pressure, the crude was then extracted with toluene (2x 2mL) and concentrated in order to afford a yellow oil (241 mg) in 82% yield. The compound is stable and storable at -24 °C in an inert atmosphere of argon. 1 H NMR (300.18 MHz, C 6 D 6 , 25 °C): δ 0.66 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 0.92 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.09 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.14 (s, 9H, C(CH 3 ) 3 ); 1.23 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.29 (s, 9H, C(CH 3 ) 3 ); 2.20 (s, 3H, p-CH 3 ); 3,97 (sept., 3 J HH = 6.3 Hz, 1H, CH(CH 3 ) 2 ); 4.10 (sept., 3 C(CH 3 ) 3 ); 125.9 (C Ar ); 128.8 (C Ar ); 132.6 (C Ar ); 138.8 (C Ar/q ); 145.8 (C Ar/q ); 159.5 (C Ar/q ); 171.9 (N-C-N).

Amidinate (diisopropyle-t-butyl) t-butyl-p-tolylsulfone

germylene (7b): n-BuLi (0.60 mmol, 0.38 mL, C = 1.6 mol/L in hexane, 1.1 eq) was added dropwise to a solution of t-butyl-ptolylsulfone (127 mg, 0.60 mmol, 1.1 eq) in toluene (3 mL) at -78 °C. The solution was stirred during 1 hour at the same temperature (-78 °C). Then the solution was added dropwise to a solution of AmGeCl (189 mg, 0.55 mmol, 1 eq) in toluene (2 mL) at -78 °C. The mixture was stirred during 1 hour at -78 °C and 1 hour at room temperature. The solvent was evaporated under reduced pressure, the crude was then extracted with toluene (2x 2mL) and concentrated in order to afford a light yellow solid (211 mg) in 82% yield. 1 H NMR (300.18 MHz, C 6 D 6 , 25 °C): δ 0.93 (d, 3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 1.11 (s, 9H, C(CH 3 ) 3 ); 1.34 (d, 3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 1.36 (s, 9H, C(CH 3 ) 3 ); 2.18 (s, 3H, p-CH 3 ); 4.10 (sept., 3 J HH = 6.3 Hz, 2H, CH(CH 3 ) 2 ); 6.93 (d, 1H, 3 J HH = 8.0 Hz, CH Ar ); 7.93 (d, 1H, 3 J HH = 8.0 Hz, CH Ar ); 8.08 (s, 1H, CH Ar ). 13 C(CH 3 ) 3 ); 127.9 (C Ar ); 131.4 (C Ar ); 134.8 (C Ar ); 139.0 (C Ar/q ); 141.9 (C Ar/q ); 164.7 (C Ar/q ); 172.2 (N-C-N).

Amidinate

(diisopropyle-t-butyl) germylene t-butyl-ptolylsulfoxide tungsten tetracarbonyl complex (8): Amidinate (diisopropyle t-butyl) t-butyl-p-tolylsulfoxide germylene (7a) (140 mg, 0.31 mmol, 1 eq) was dissolved in THF (3 mL) and added to tetracarbonyl(1,5-cyclooctadiene) tungsten (0) (125 mg, 0.31 mmol, 1 eq) in THF (1 mL). The mixture was stirred during 15 hours at room temperature, then filtered and the solvent removed under reduced pressure. Finally, the solid was washed with pentane (2 x 3 mL) to obtain a pale yellow solid (206 mg) in 89% yield. Crystallization from a solution of THF at 6 °C gave pale yellow crystals suitable for X-ray diffraction analysis. M.p. : 117 °C (decomposition); 1 H NMR (300.18 MHz, C 6 D 6 , 25 °C): δ 0.54 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 0.81 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.06 (s, 9H, C(CH 3 ) 3 ); 1.20 (s, 9H, C(CH 3 ) 3 ); 1.23 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.29 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 2.13 (s, 3H, p-CH 3 ); 3.98 (sept., 3 J HH = 6.3

Hz, 1H, CH(CH 3 ) 2 ); 4.08 (sept., 3

Amidinate (diisopropyle-t-butyl) germylene t-butyl-p-tolyl

sulfoxide molybdenum tetracarbonyl complex (9): Amidinate (diisopropyle t-butyl) t-butyl-p-tolylsulfoxide germylene (7a) (100 mg, 0.22 mmol, 1 eq) was dissolved in THF (3 mL) and added to tetracarbonyl(bicyclo[2.2.1]hepta-2,5-diene) molybdenum (0) (66 mg, 0.22 mmol, 1 eq) in THF (1 mL). The mixture was stirred during 15 hours at room temperature, then filtered and the solvent removed under reduced pressure. Finally, the solid was washed with pentane (2 x 3 mL) to obtain a pale yellow solid (113 mg) in 78% yield. Crystallization from a solution of THF at 6 °C gave pale yellow crystals suitable for X-ray diffraction analysis. M.p. : 98 °C (decomposition); 1 H NMR (300.18 MHz, C 6 D 6 , 25 °C): δ 0.54 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 0.80 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.05 (s, 9H, C(CH 3 ) 3 ); 1.20 (s, 9H, C(CH 3 ) 3 ); 1.22 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.29 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 2.11 (s, 3H, p-CH 3 ); 3.91 (sept., 3 J HH = 6.3

Hz, 1H, CH(CH 3 ) 2 ); 4.03 (sept., 3

Formula

C28H44Cl2GeN2O2RuS dcalc (g/cm 3 )

Amidinate (diisopropyle-t-butyl) germylene t-butyl-p-tolyl

sulfoxide ruthenium phosphine complex (10a): Amidinate (diisopropyle t-butyl) t-butyl-p-tolylsulfoxide germylene (7a) (100 mg, 0.22 mmol, 1 eq) was dissolved in THF (3 mL) and added to tris(triphenylphosphine) ruthenium dichloride (211 mg, 0.22 mmol, 1 eq). The mixture was stirred during 15 hours at room temperature, then filtered and the solvent removed under reduced pressure.

Finally, the crude was dissolved in THF (2 mL) and pentane (8 mL) was added slowly to precipite 10a. After filtration and evaporation, a red solid (135 mg) in 69% yield was obtained with 15% of the starting PPh 3 remaining. 31 (d, 3 J HH = 6.6 Hz, 3H, CH(CH 3 ) 2 ); 0.06 (d, 3 J HH = 6.6 Hz, 3H, CH(CH 3 ) 2 ); 0.23 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 0.69 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.56 (s, 9H, C(CH 3 ) 3 ); 1.63 (s, 9H, C(CH 3 ) 3 ); 2.45 (s, 3H, p-CH 3 ); 3.77 (sept., 3 J HH = 6.3 Hz, 1H, CH(CH 3 ) 2 ); 3.96 (sept., 3 J HH = 6.3 Hz, 1H, CH(CH 3 ) 2 ); 6.72-7.43 (m, 50H, CH Ar ). 13 Ru-PPh 3 ). Isomer C : 1 H NMR (500 MHz, CDCl 3 , 25 °C): δ 0.00 (d, 3 J HH = 6.6 Hz, 3H, CH(CH 3 ) 2 ); 0.16 (d, 3 J HH = 6.6 Hz, 3H, CH(CH 3 ) 2 ); 0.39 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 0.98 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.52 (s, 9H, C(CH 3 ) 3 ); 1.59 (s, 9H, C(CH 3 ) 3 ); 2.46 (s, 3H, p-CH 3 ); 3.79 (sept., 3 J HH = 6.3

Hz, 1H, CH(CH 3 ) 2 ); 4.04 (sept., 3 J HH = 6.3 Hz, 1H, CH(CH 3 ) 2 ); 6.72-7.43 (m, 49H, CH Ar ); 8.44 (d, 1H, 3 J HH = 8.2 Hz, CH Ar ). 13

Formula

C28H44Cl2GeN2O2RuS dcalc (g/cm 3 )

CO gas

Formula

C28H44Cl2GeN2O2RuS dcalc (g/cm 3 )

Formula

C28H44Cl2GeN2O2RuS dcalc (g/cm 3 )

I. Introduction

The synthesis of new metallylenes was extensively studied the past decades and allowed to develop a large panel of electronic and steric properties [1][2][3] in order to obtain novel properties. 4,5 Nevertheless, insertion of chirality in the design of the stabilizing substituents was only studied over few publications compared to the overall study of carbene analogues (Figure 1). Nevertheless, no applications of asymmetric germylenes and stannylenes were reported yet. This observation led us to consider the synthesis of a new tetrylene family with a chiral center directly included into the design of the stabilizing substituent. On this path, sulfonimidamide group was selected as a valuable alternative of amidinate group (Figure 3). 13 The report showed that tautomerism undergoes through a fast proton transfer between the imine and amine atoms. It is also mentioned that the proton transfer rate depends on the substituents of both nitrogen (aryl, alkyl, dissymmetric...). It is important to note that the tetrahedral sulfur atom can exhibit a configurationally stable chiral center when substituents on the nitrogen atoms were different, 14,15 which lead Reek et al. to report in 2012 the synthesis of a sulfonimidamide based ligand employed successfully in iridium asymmetric catalysis. 16 Figure 3: Sulfonimidamide properties

The utilization of sulfonimidamide was also interestingly employed with bis[bis(trimethylsilyl)amido]zinc to obtained a novel homoleptic tetracoordinated zinc published in 2006 by Guzyr et al. 17 The four nitrogen atoms are located at a distance from 2.00 to 2.03 Å of the zinc center, which indicates a 4p delocalized system between both nitrogen comparable to the amidinate substituent (Scheme 1). for the stabilization of germylenes and stannylenes (Scheme 2). 18 The heteroleptic group 14 compounds were obtained by nucleophilic substitution of the corresponding dihalogenometallylene and characterized by X-ray crystallography. Nitrogen were located, in

R 1 S NH N O R 2 R 3 R 1 S N NH O R 2 R 3 R 1 S NH N O R 2 R 3 * R 2 ≠ R 3 H-exchange R 1 , R 2 , R 3 = Alkyl or Aryl S N Zn S N R 1 N R 1 N R 3 R 3 R 2 R 2 O O S N R 1 NH R 3 R 2 O Zn(HMDS) 2 R 1 = Tolyl, R 2 = n Bu, R 3 = Ph R 1 = Ph, R 2 = SO 2 Ph, R 3 = Ph R 1 = Tolyl, R 2 = t Bu, R 3 = t Bu
both case, at the same distance of the metallylene, which indicates a 4p delocalized system comparable and in accordance with the results reported by Guzyr et al. The authors have designed the ligand to introduce a free phosphine arm that could be used for a potential bidentate coordination with the metallylene lone pair. However, no report about coordination nor application has been published yet to the best of our knowledge even if the perspectives implied an active interest.

Scheme 2: Triimidosulfur (VI) phosphanyl metallylenes

In this chapter, synthesis of sulfonimidamides will be discussed first with the challenge of the design and the choice of the substituents. In the second part, application of sulfonimidamides for stabilization of heavier analogues of carbenes will be discussed as well as the specific properties observed.

II. Results and discussion

II.1. Synthesis and characterization of sulfonimidamides

Since the first description of sulfonimidamides by Levchenko in 1960, numerous methods were developed to synthesize these S(VI) derivatives and the most common synthetic pathways use a nucleophilic substitution of a sulfonimidoyl chloride prepared by oxidative imidation of sulfinyl chlorides, oxidative chlorination of sulfonamides or deoxychlorination of secondary sulfonamides. [19][20][21][22][23] However, most of the synthesis are difficult to perform, with the use of highly reactive and toxic reagents. That is the reason we relied on the method reported by Chen in 2015 to obtain symmetric and racemic asymmetric sulfonimidamides in two steps from sulfonyl chloride derivatives (Scheme 3). 24 The first step consists in a simple nucleophilic substitution of chlorine atom with a primary amine in presence of triethylamine. Then, the sulfamide reacts with a chlorinating agent to form a sulfonimidoyl chloride, which is substituted by the addition of a second amine.

Scheme 3: Synthetic pathway to obtain Sulfonimidamide

The efficiency of the strategy allowed us to obtain sulfonimidamides 12a-c, in moderate yield of 38% up to 53% (Scheme 4). 12a was synthetized as an equivalent of AmGeCl, used previously, with a symmetric sulfur and i-Pr substituent on each nitrogen.

Asymmetric S(VI) was introduced with 12b that exhibits two different substituents on nitrogen, i-Pr and Mes. Finally, 12c is obtained as an ammonium chloride salt certainly formed by intra or intermolecular deprotonation. The aim of 12c is to include a weak s-donor ligand arm in order to use it for hemilabile coordination after formation of the corresponding metallylene.

Unfortunately, the lack of time did not allow us to use 12c to form the corresponding metallylene nor to study its application in coordination chemistry.

S Cl R 1 O O R 2 NH 2 Et 3 N S NH R 1 O O R 2 Chlorine agent S Cl R 1 N O R 2 R 3 NH 2 Et 3 N S NH R 1 N R 3 R 2 O
Scheme 4: Synthesis of 12a-c 12a-c were fully characterized by NMR, mass spectroscopy and X-ray diffraction. 1 NMR spectra of 12a and 12b were similar with slight differences. N-H proton was found with a chemical shift of 5.10 ppm and aromatic protons were assigned as two multiplets at 8.08 and 7.03 ppm respectively. Slight differences were found in the chemical shift of the i-Pr group, C-H has a chemical shift of 3.62 ppm in 12a when it was found shielded in 12b with a chemical shift of 3.41 ppm. The same observation was observed for CH 3 with a chemical shift of 1.12 and 1.07 in 12a and an upfield of 0.84 and 0.59 ppm in 12b. On the other hand, 12c was not compared due to the use of another deuterated solvent, essentially for solubility reason. Again, 1 H NMR spectrum of 12c exhibits a very particular signal for the -N-CH 2 -CH 2 -N-group that appear as particularly complex multiplets. The multiplicity observed can be explained by the loss of symmetry due to the chiral S(VI) atom that makes each hydrogen different.

Crystals of 12a were obtained by slow evaporation of ethyl acetate and X-ray structure exhibits an unsurprising sulfur-nitrogen bond distance different for each nitrogen (Figure 4).

The difference in the distance can be easily explained by the multiplicity of sulfur-nitrogen bond, one is a single bond of 1.628(2) Å and the other one is a double bond of 1.501(2) Å. 12b

shows the same behavior with sulfur nitrogen bond length of 1.5343 (10) and 1.6032(10) Å. It is important to note that the nitrogen bearing a mesityl group forms a double bond rather than the nitrogen with an alkyl substituent. The observation can be rationalized by the presence of an aromatic group that promotes a sp2 configuration and a better delocalization of the nitrogen free doublet. In both case, the structure was obtained in a dimeric form with H-bond between tertiary and secondary amine function of two molecules. Finally, 12c was obtained by slow evaporation of dichloromethane and exhibits also H-bond between chloride and hydrogen bound to the nitrogen. The structure also follows the same rule with sulfur-nitrogen bond

II.2. Synthesis and characterization of germylenes and stannylenes stabilized by sulfonimidamides

The next step was to study the stabilization of metallylenes by sulfonimidamides. First, nucleophilic substitution was investigated by deprotonation of sulfonimidamide 12a with n BuLi (Scheme 5). However, only protonated sulfonimidamide was recovered at the end of the reaction even by using a 2:1 ratio to form the homoleptic metallylene. In order to investigate the formation of the lithiated sulfonimidamide and if the base had an influence, 12a was subsequently deprotonated with n BuLi and quenched with TMSCl in the exact same experimental conditions. The product was obtained in quantitative yield, which means that lithiated sulfonimidamide was not a strong enough nucleophile to perform the nucleophilic substitution.

Scheme 5: Formation of lithiated sulfonimidamide and reactivity with dichlorometallylenes Homoleptic metallylenes 13a and 14a were obtained cleanly after a night at room temperature. 13a and 14a were unambiguously characterized by X-ray crystallography of crystals obtained from a saturated solution of pentane at -25 °C (Figure 5). 13a shows a nitrogen-germanium bond distance of 2.008(12) and 2.3241(12) Å, which demonstrates that two nitrogen are s-bonded and the two-remaining nitrogen are acting as a Lewis base. It is important to note that the s-bond is in the usual range for a Ge-N bond length reported to date for a 4p delocalized system (1.95 -2.07 Å). 18,[29][30][31][32][33][34] S-N bond lengths are also in agreement with one single bond and one double bond with a distance of 1.5757 (12) 13b and 14b were also characterized by X-ray crystallography (Figure 7). 13b shows a nitrogen-germanium bond distance of 2.0269(13) -2.0318(13) Å and 2.2257(15) -2.2633 (14) Å, which demonstrates that two nitrogen are s-bonded and the two-remaining nitrogen were acting as a Lewis base. It is important to note that the s-bond is in the usual range for a Ge-N bond length reported to date for a 4p delocalized system (1.95 -2.07 Å). shows than the double bond is exchanged between the nitrogen. Indeed, S=N double bond is located on the nitrogen with a mesityl group in 12b when S=N double bond is located on the nitrogen with a i-Pr group in 13b. The same observations are observed on the structure of 14b.

Nitrogen-tin bond distances are in the usual range of 2.229(2) and 2.342(2) Å, also S-N bond lengths of 1.5554(2) and 1.576(2) Å are in agreement with 13b. Finally, the same double bond exchange is observed between both nitrogen as previously observed with 13b.

III. Conclusion

Sulfonimidamides have been synthesized in moderate 38-53% yields. The synthetic pathway allows to integrate various subsituents on the nitrogen atoms with a combination of i-Pr and mesityl groups. This design also allows the formation of symmetric and asymmetric center on the central sulfur atom.

Homoleptic germylenes and stannylenes have been obtained by protonolysis reaction with Ge(HMDS) 2 or Sn(HMDS) 2 . These new metallylenes have been characterized by NMR spectroscopy and X-ray diffraction analysis. X-ray structures show different bond lengths for germanium-nitrogen or tin-nitrogen interatomic distances. However, fast exchange is observed by 1 H NMR spectroscopy at room temperature. These results lead to classify these new metallylenes as 4p delocalized stabilized systems.

Finally, DFT calculations have been performed to understand the electronic properties brought by the sulfonimidamide on the metallylene and how the design can influence its stabilization. Calculations indicate that tin is much more electronically stabilized than germanium. Comparison of the structures with mesityl substituent show a small effect on the molecular orbitals of the germylene when the stannylene remains in the same range.

Surprisingly, strong stabilizing interactions were found with nNàs*SO and nNàs*CC. N-iso-propyl-N'-mesitylbenzenesulfonimidamide (12b): Hexachloroethane (264 mg, 1.11 mmol, 1.1 eq) was added to a solution of triphenylphosphine (293 mg, 1.11 mmol, 1.1 eq) in CHCl 3 (10 mL) at room temperature. The solution was heated at reflux for 6 h. Then, the mixture was allowed to return at room temperature and trimethylamine (210 µL, 1.52 mmol, 1.5 eq) was added, the mixture was stirred for 30 min at room temperature. N-iso-propylbenzenesulfonamide (200 mg, 1.01 mmol, 1 eq) was dissolved in CHCl 3 and added on the mixture. Finally, after stirring the mixture for 30 min at room temperature 2,4,6-Trimethylaniline (426 µL, 410 mg, 3.03 mmol, 3 eq) was added and the solution stirred overnight at room temperature. The solvent was removed under reduced pressure and the crude product was purified by flash column chromatography (Eluent: Petroleum Ether / Ethyl Acetate : 4 / 6, Rf = 0.80) to give a white solid (157 mg) in 49 % yield.

IV. Experimental section

Crystals were obtained by slow evaporation in ethyl acetate. M.p. : 93 °C; 1 H NMR (300.18 MHz, C 6 D 6 , 25 °C): δ 0.61 (d, 3 J HH = 6.5 Hz, 3H, CH(CH 3 ) 2 ); 0.84 (d, 3 J HH = 6.5 Hz, 3H, CH(CH 3 ) 2 ); 2.15 (s, 3H, CH 3 ); 2.53 (s, 6H, CH 3 ); 3.41 (sept., 3 The mixture was stirred 20 min at room temperature and the solvent was removed under reduced pressure. The solid was extracted with pentane (3x3 mL) to give a white solid in 96 % yield (72 mg). Crystallization from benzene at room temperature gave colourless crystals suitable for X-ray study. M.p. : 117 °C (decomposition); 1 H NMR (300.18 MHz, C 6 D 6 , 25 °C): δ 1.26 (d, 3 J HH = 6.6 Hz, 12H, CH(CH 3 ) 2 ); 1.46 (d, 3 J HH = 6.6 Hz, 12H, CH(CH 3 ) 2 ); 3.61 (sept., 3 J HH = 6.6 Hz, 4H, N-CH(CH 2 ) 2 ), 6.96-7.10 (m, 6H, CH Ar ), 7.90-7.93 (m, 4H, CH Ar ). 13 135.0 (C Ar/q ); 136.7 (C Ar/q ); 141.0 (C Ar/q ); 141.5 (C Ar/q ). MS m/z (%): 750 (M + ).

Formula

C36H46GeN4O2S2, C6H6 dcalc (g/cm 3 ) Finally, hydrogen transfer reaction was investigated with asymmetric ruthenium complexes. The best conditions of catalysis were also applied to reduce various ketones and aldehyde at room temperature.

A second catalysis will be considered by using sulfonimidamide metallylenes described in chapter IV. These new metallylenes were applied in polymerization of ecaprolactone.

I. Introduction

The transition metal chemistry of germylenes has experienced an important interest the last decade that led to the application of germylenes in different catalytic processes.

Nevertheless, these applications remain sporadic compared to the use of lighter analogues such as silylenes or carbenes. However, the proof of the catalytic activity of germylene-complexes was an important milestone to their development and their activity, which allowed them to leave the field of theoretical tools. 1,2 Applications of germylenes-complexes can be overviewed in four different publications reported during the past decade. [3][4][5][6] The different complexes were applied in C-H borylation of benzene, Sonogashira-Hagihara cross-coupling, hydrogen transfer reaction and cyanosilylation of aldehydes and ketones. Our interest on hydrogen transfer reaction was immediate due the large application of ruthenium complexes in this field and the possibility to generate chiral alcohol during the reaction. An excellent review on hydrogen transfer reaction was published by Wang and Astruc in 2015. 7 Thus, Cabeza et al. have reported the coordination of iridium and ruthenium complexes by amidinato-tert-butyl germylenes in 2015 (Scheme 1). 5 Scheme 1: Germylene-iridium I and -ruthenium II complexes applied in hydrogen transfer reaction Iridium (I) and ruthenium (II) complexes were applied in hydrogen transfer reaction of cyclohexanone with iso-propyl alcohol. Both complexes were active and reduced cyclohexanone with 55% of conversion after 24h at 50 °C for ruthenium complex, whereas iridium complex fully converted the ketone into the alcohol after 1.5h at the same temperature. Surprisingly, the catalysis does not require any base as additive to form the active catalyst. Typically, active catalysts without any addition of an external base present a free Lewis base substituent on the ligand which acts as the external base. 8 Moreover, only one substrate, the cyclohexanone, was used for the catalysis. The reaction was unfortunately not extended to other carbonyl substrates to determine the scope and the activity of the catalyst. Addition of chloride abstractor by using AgOTf resulted in a total deactivation of the iridium (I) and ruthenium (II) catalysts (Table 1).

Entry Catalyst (2 mol%) AgOTf (X eq) Reaction time Conversion (%) the mechanism of Sn(oct) 2 in polymerization of L-lactide. 11 Then, several stannylenes were developed and used successfully in polymerization (Scheme 3). [12][13][14] Scheme 3: Stannylenes applied in polymerization (e-caprolactone and lactide)

The germylene-a-sulfoxide ruthenium complexes described in chapter II will be investigated as catalyst in hydrogen transfer catalysis of acetophenone. Then, the influence of the design of the catalyst and the catalysis parameters will be studied. Finally, the new metallylenes described in chapter IV will be investigated as catalysts of polymerization of ecaprolactone and the influence of the sulfonimidamide design on the catalysis will also be studied. A slight effect of the counter-cation can be observed by using sodium hydroxide (70%) in place of potassium hydroxide (76 %) (Table 2, entry 1 and 2). Replacement of KOH or NaOH by potassium or cesium carbonate lead to decrease the conversion (Table 2, entries 3 and 4). A similar result has been observed during the use of t-BuOK (Table 2, entry 5). The nature of the base can influence the stability of the complex or the formation of the ruthenium-hydride active species.

We next studied the influence of the quantity of base (Table 3). Surprisingly, the catalyst was still active in hydrogen transfer reaction without any addition of base with the full reduction of acetophenone after a long reaction time of 18 hours (Table 3, entries 1 and 2). This result was already observed by the group of Cabeza in 2016. 5 Moreover, modification of the quantity of base showed that 20 mol% was the ideal amount of KOH for a reaction time of 2h, the addition of a larger or a lower quantity resulting in a negative impact on the catalysis (Table a The reactions were carried out in dry and degassed isopropyl alcohol (2 mL) under argon in presence of acetophenone (0.9 mmol) b Determined by 1 H NMR analysis by using tetramethylbenzene (0.45 mmol) as internal standard.

Table 3: Influence of the quantity of base in hydrogen transfer reaction with complex 6b

The next parameter studied was the quantity of i-PrOH, i-e the concentration of the reaction (Table 4). Increasing the volume of i-PrOH to 3 mL induces a slight decrease of the catalytic activity (59 %), that can be explained by a dilution of the catalytic system (Table 4, entries 1 and 2). On the opposite, decreasing the volume of i-PrOH to 1 mL gives rise to a slight enhance of activity (88 %) after 2h, leading to a full conversion (>97 %) after 2.5 hours (Table 4, entries 3 and 4). Finally, the use of 0.5 mL of i-PrOH induces a slight drop of activity (73 %) that can be explained by the poor solubility of the base in these conditions, or the decrease of i- a The reactions were carried out in dry and degassed isopropyl alcohol (X mL) under argon in presence of acetophenone (0.9 mmol) b Determined by 1 H NMR analysis by using tetramethylbenzene (0.45 mmol) as internal standard.

PrOH
Table 4: Influence of the concentration in hydrogen transfer reaction with complex 6b

Then, catalyst 6b was compared to all the other p-cymene ruthenium-based complexes in order to study the influence (i) of the steric hindrance of the amidinate group, (ii) of the substituent of the sulfoxide, (iii) of the oxidation state of the sulfur atom, (iv) of the substituent of the germylene (Scheme 5).

Scheme 5: Germylene-ruthenium complexes 6b-d-f-g-h-i

The different ruthenium complexes (2 mol%) were used in the same conditions with i-PrOH (2 mL) and KOH (20 mol%) at 80 °C. The conversion was monitored after 2 hours of reaction time (Table 5). Modification of the steric hindrance on the amidinate group shows an influence on the activity of the catalyst which decreases by replacing i-Pr (76 %) group on complex 6b by a bulkier cyclohexyl (57 %) group on complex 6d (Table 5, entries 1 and 2).

The activity also decreases after replacing the aryl substituent on the sulfoxide (76 %) by an alkyl group (43 %) for the complex 6f (Table 5, entries 1 and 3). This result can be explained by the poor stability of complex 6f at 80°C. Indeed, a t-Bu group bonded to a sulfoxide function can undergo, by heating, the elimination of iso-butene and the concomitant formation of the corresponding sulfinic acid, which is known as an unstable group. 15 The influence of the oxidation state of the sulfur atom can be observed comparing the corresponding thioether and sulfone complexes, 6g and 6h, that both induce an impressive drop of the catalytic activity with 29% and 23% of conversion respectively after 2 hours (Table 5, entries 4 and 5). Complex 6i has been synthesized in order to study the influence of the alkyl aryl sulfur (II/IV/VI) groups on the germanium center during the catalysis. The result shows again a decrease of the catalytic activity (39 %) in comparison with complex 6b, but this result cannot be attributed formally to complex 6i (Table 5, entry 6). Indeed, the substitution of the chlorine atom by the base during a The reactions were carried out in dry and degassed isopropyl alcohol (2 mL) under argon in presence of acetophenone (0.9 mmol) b Determined by 1 H NMR analysis by using tetramethylbenzene (0.45 mmol) as internal standard.

Table 5: Catalytic activity of different ruthenium complexes 6b-d-f-g-h-i in hydrogen transfer reaction Finally, complex 5a was used in hydrogen transfer reaction in order to study the influence of the coordination of the ruthenium center by the sulfoxide group and by the triphenylphosphine (Scheme 6).

Scheme 6: Germylene-ruthenium complexes 5a, 5a.PPh 3 and 5b.PPh 3 5a was used in the same conditions in i-PrOH (2 mL) at 80 °C. The conversion was monitored after 2 hours of reaction time (Table 6). A full conversion is obtained after 2 hours with 20 mol% of KOH (Table 6, entry 4). Surprisingly, the catalyst is totally inactive in absence of external base (Table 6, entry 3). a The reactions were carried out in dry and degassed isopropyl alcohol (2 mL) under argon in presence of acetophenone (0.9 mmol) b Determined by 1 H NMR analysis by using tetramethylbenzene (0.45 mmol) as internal standard.

Table 6: Catalytic activity of complex 5a in hydrogen transfer reaction

The effect of the temperature was next investigated with complexes 6b, 5a, 5a.PPh 3 and 5b.PPh 3 in presence of the same amount of base KOH (20 mol%) (Table 7). At 50 °C, during the use of complex 6b, a 61 % maximum conversion is obtained after 17 hours (Table 7, entry 1) while a fully conversion is obtained after 4 hours with complexes 5a, 5a.PPh 3 and 5b.PPh 3 (Table 7, entries 3, 5 and 6). The comparison of 5a and 5a.PPh 3 allows to determine if the presence of residual PPh 3 might have an influence on the catalytic activity for a potential application of 5b.PPh 3 in asymmetric catalysis, 5b.PPh 3 cannot be obtained pure without residual PPh 3 . After 2 hours, the conversion is similar, 68 % compared to 74 % (Table 7, entries 2 and 4). However, the conversion is complete after 4 hours with the three different catalysts (Table 7, entries 3, 5 and 6). Finally, we observe that 5b.PPh 3 is active at 25 °C with a conversion of 26 % after 2 hours and a full conversion after three days (Table 7, entries 7-10).

Finally, the positive effect of the ligand can be validated by comparing the use of Ru(PPh 3 ) 3 Cl 2 in the same conditions ( a The reactions were carried out in dry and degassed isopropyl alcohol (X mL) under argon in presence of acetophenone (0.9 mmol) b Determined by 1 H NMR analysis by using tetramethylbenzene (0.45 mmol) as internal standard.

Table 7: Catalytic activity of complexes 5a, 5a.PPh 3 and 5b.PPh 3 in hydrogen transfer reaction Enantiopure complexes 6b, 6d and 5b.PPh 3 , synthetized by using (R)-(+)-methyl-ptolyl sulfoxide as precursor, have been tested in asymmetric hydrogen transfer of acetophenone (Table 8). The ee have been determined by HPLC analysis using a chiral OD column with an UV detector. At 50 °C, 7-8 % poor ee are obtained (Table 8, entries 1, 2 and 3). However, a moderate 21 % ee is obtained by decreasing the temperature at 25°C ( a The reactions were carried out in dry and degassed isopropyl alcohol (X mL) under argon in presence of acetophenone (0.9 mmol) b Determined by 1 H NMR analysis by using tetramethylbenzene (0.45 mmol) as internal standard. c ee were determined by HPLC with a chiracel OD column 9). First, some para-substituted acetophenones have been used and reduced successfully after 3 days with different substituents such as bromo, methoxy or trifluoromethane groups (Table 9, entries 2-4). Interestingly, benzophenone was reduced in the same conditions and proved that steric hindrance can be increased on both sides of the ketone (Table 9, entry 5). However, steric hindrance on the substrate can also have a dramatic influence, adamantyl-methyl ketone being unchanged even after 4 days at room temperature (Table 9, entry 7). Finally, benzaldehyde has been also reduced successfully after 4 hours (Table 9, entry 6).

5b.PPh 3 was successfully employed in hydrogen transfer catalysis for the reduction of several ketones and aldehyde. The enantioselective catalysis showed a moderate ee of 21% that proved the influence of the enantioselective ligand on the active catalyst species.

II.2. Catalytic activity of sulfonimidamide metallylenes in polymerization catalysis

Polycaprolactone is a polymer of great interest because of the numerous applications as biodegradable and biocompatible polymer. The polymer can be formed by catalysis with tin (II) which is a well-known catalyst to start living polymerization. Thereby, the sulfonimidamide metallylenes described in the chapter IV were envisaged in polymerization catalysis (Scheme 7).

Scheme 7: Sulfonimidamide metallylenes used in polymerization catalysis

Polymerization of e-caprolactone was envisaged by using 14a as catalyst in toluene at 100 °C (Scheme 8). The reaction was monitored by 1 H NMR analysis.

Scheme 8: Polymerization catalysis using 14a

After 1 hour at 100 °C, the polymerization took place with a conversion of 29 % and an interesting PDI of 1.09 (Table 10, entry 1). The conversion can reach 77 % after 7 hours with a higher PDI of 1.40, showing thus a larger polydispersity of the polymer that can be explained by trans-esterification reactions. Moreover, a deactivation of the catalyst has been observed after 7h, not allowing a full conversion (Table 10, entry 2). The results are promising and show a better activity of 14a than other tin (II) derivatives in the absence of initiator such as primary alcohols or amines. Table 10: Catalytic activity of complex 14a in polymerization of e-caprolactone

Then, the investigations of the activity of 14b, was considered due to the steric and electronic differences of the tin (II) center (Table 11). In the same conditions as previously described, a conversion of 89% after 1 hour was obtained (Table 11, entry 1). However, moderate PDI of 1.66 showed again a larger polydispersity of the polymer due to the formation of a gel that blocked the stirring bar and increase the trans-esterification of the polymer. This problem was solved by lowering the temperature to 80 °C, which decreased significantly the activity of the catalyst without stopping the reaction. After 1h, the conversion of 11% was obtained with a better PDI of 1.18 ( The structure of the polymer was also investigated to determine if the mechanism was a ROP or a REP to give a linear or a cyclic polycaprolactones. 16 Linear polycaprolactone and ROP mechanism was determined due to end group signal found in 1 H NMR corresponding to a sulfonimidamide and a -CH 2 -OH end group (Figure 1). -CH 2 -OH end group was observed as a triplet at 3.63 ppm, moreover, aromatic signals of the sulfonimidamide group were also found in the pure polymer.

III. Conclusion

Ruthenium complexes 6b-i have been described as active catalysts in hydrogen transfer reaction of acetophenone in iso-propanol. Optimization of the reaction conditions during the use of 6b as catalyst has shown the importance of the base on the catalytic activity.

Comparison of the different ligands has demonstrated the influence of the steric hindrance on the ligand. Finally, the corresponding thioether and sulfone derivatives induced a significant decrease of the activity compared to 6b. This latter result demonstrates clearly that the sulfoxide moiety has an important impact on the catalysis by a greater activity or by a better stability. Finally, 5a and 5b appeared much more active than all the other ruthenium complexes allowing to reduce acetophenone at room temperature.

Hydrogen transfer reaction was finally investigated with enantiopure ruthenium complexes 6b, 6d and 5b. The enantiomeric excess of the reaction at 50 °C was low. However, a moderate 21% ee was obtained at room temperature with 5b. The same complex has also allowed the reduction of various ketones and aldehyde at room temperature.

In a second part, sulfonimidamide stannylenes 14a and 14b were successfully applied in polymerization of e-caprolactone. 14a has shown a catalytic activity with moderate to good PDI (1.09 to 1.40) for a benchmark reaction, comparable to already reported and known tin (II) catalysts. Surprisingly, 14b appeared much more active, with high potential for polymerization catalysis. Moreover, 14b exhibits a stereogenic center to consider its use in stereoselective polymerization.

IV. Experimental section

Amidinate (di-iso-propyle-t-butyl) chloro germylene ruthenium complex (6i): amidinatochlorogermylene (100 mg, 0.34 mmol, 1 eq) was dissolved in tetrahydrofuran (5 mL) and dichloro(pcymene)ruthenium dimer (104 mg, 0.17 mmol, 0.5 eq) was added to the solution. The mixture was stirred during 15 hours at room temperature, then filtered and the solvent removed under reduced pressure. Finally, the red solid was washed with Et 2 O (2x3 mL) in order to obtain a pale red solid (175 mg) in 86% yield. Crystallization from THF at 6 °C gave red crystals suitable for Xray study. M.p. : 173 °C (decomposition); 1 H NMR (300.18 MHz, C 6 D 6 , 25 °C): δ 0.97 (s, 9H, C(CH 3 ) 3 ); 1.17 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.41 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.45 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.95 (s, 3H, p-CH 3 ); 3.02 (sept., 3 J HH = 6.3 Hz, 1H, CH(CH 3 ) 2 ); 3.92 (sept., 3 J HH = 6.3 Hz, 2H, CH(CH 3 ) 2 ); 5.06 (d, 2H, 3 J HH = 8.2 Hz, CH Ar ); 5.31 (d, 2H, 3 J HH = 8.2 Hz, CH Ar ). 13 Then, the formation of germylene -b-sulfoxide ligand has been investigated with a larger spacer between the metallylene and the sulfoxide moieties. The influence of the spacer showed different properties on the coordination chemistry of the ligand. Indeed, the complexation behavior toward group IV and nickel (0) was surprisingly different and resulted in the formation of bidentate complexes with germanium and sulfur coordinated to the metal center. The formation of a nickel (0) complex allowed to obtain another nickel (0) tricarbonyl complex, by addition of carbon monoxide, which was used for a TEP comparison. The result showed that the s-donation strength of the germylene was between the s-donation strength of phosphines and NHCs. Surprisingly, the formation of a new bis-ruthenium complex has been observed with a µ-SO bridge.

Conclusion

-258-

The synthesis of several symmetric and dissymmetric sulfonimidamides has been performed. They were used for the stabilization of germylenes and stannylenes. Homoleptic metallylenes were obtained after protonolysis reaction of the sulfonimidamides and the bis(HMDS) metallylene. Their electronic properties have been investigated by DFT calculations. Finally, stannylenes have been applied in the polymerization of e-caprolactone,

showing an interesting activity, especially for the dissymmetric sulfonimidamide stannylene.

Chapter II:

  Je tiens tout d'abord à remercier chaleureusement Madame Emmanuelle Schulz, directrice de recherche C.N.R.S. au laboratoire ICMMO à Paris et Monsieur Jean-Philippe Goddard, professeur à l'Université de Haute Alsace au laboratoire LIMA, pour avoir accepté de juger ce travail de thèse en la qualité de rapporteurs. Je remercie également Monsieur Éric Manoury, directeur de recherche C.N.R.S. au LCC à Toulouse pour avoir présidé le jury. Je souhaite également remercier le professeur Jean-Marc Sotiropoulos qui a effectué les différents calculs théoriques présents dans ce manuscrit. Ces travaux de recherche ont été réalisés au sein du Laboratoire d'Hétérochimie Fondamentale et Appliquée (LHFA) à l'Université Paul Sabatier de Toulouse sous la direction de David Madec entre octobre 2015 et novembre 2018. Je souhaite spécialement te remercier, David pour m'avoir encadré au long de cette thèse. Tu m'as toujours encouragé à suivre mes nouvelles idées, à explorer de nouvelles voies et à les exploiter même si cela menait rarement au résultat escompté. Ce qui va me manquer le plus, c'est assurément les discussions scientifiques et ta disponibilité pour regarder les derniers spectres RMN pour déterminer les produits formés.

Schéma 2 :(

 2 Si, Ge, Sn...) coordination et en catalyse. Un état de l'art sur les complexes présentant un ligand du groupe 14 et une fonction sulfoxyde est présenté ainsi que leur proportion à être décrits comme des ligands hémilabiles (Schéma 2). Hémilabilité d'un ligand bidente par addition de CO Le deuxième chapitre se concentre sur la synthèse et la chimie de coordination de ligands germylène-a-sulfoxyde avec des complexes des groupes 6 et 8. L'approche synthétique des composés germylène-a-sulfoxyde a été envisagée par réaction de substitution nucléophile d'un atome de chlore lié au germanium avec un carbanion sulfinylé. Le synthon germylène de départ sélectionné est l'amidinatochlorogermylène AmGeCl publié par notre groupe en 2015 et obtenu par condensation d'un lithien sur un carbodiimide puis transmétallation par le GeCl 2 •dioxane. L'atome de chlore du composé AmGeCl est facilement substituable par différents nucléophiles afin d'obtenir des architectures complexes qui ont données lieu à plusieurs publications dans la littérature. Cette stratégie a notamment été utilisée pour la synthèse de ligands de type pince publiée par le groupe de Driess en 2012. La déprotonation en a du sulfoxyde est facilement réalisable avec une base faiblement nucléophile comme le LDA bon σ-donneur H = ligand mauvais σ-donneur Schéma 3: Synthèse de 1a

Schéma 4 :

 4 Différent germylene-sulfoxyde synthétisé 1b-f 1b-f ont été obtenus selon la même méthode de synthèse que 1a. Cette large gamme de ligands permet d'étudier l'influence de l'encombrement stérique sur le germylène, grâce aux groupements iso-propyle (1a-b) ou cyclohexyle (1c-d), mais aussi sur le sulfoxyde, grâce aux groupements aryle (1a-b-e) ou alkyle (1f). Finalement, la réaction a été étendue aux autres états d'oxydations du soufre, le S(II) et le S(VI) (Schéma 5). Schéma 5: Synthèse du ligand S(II) 1g et du ligand S(VI) 1h

Schéma 6 :+

 6 Formation du complexe bis-germylene tungstène 3b

Schéma 8 :Schéma 9 :( 2 Schéma 10 :

 89210 Formation du complexe bidente germylene ruthénium 5a Le complexe 5a a été entièrement caractérisé par plusieurs méthodes d'analyses comme la RMN, la spectroscopie IR et la diffraction des RX, démontrant ainsi une coordination bidente du germanium et de l'oxygène du sulfoxyde au ruthénium. Ce complexe est parfaitement stable à température ambiante dans des conditions inertes et nous a amenés à sélectionner un autre précurseur de ruthénium, (RuCl 2 (p-cymène)) 2 , pour obtenir une série de complexes monodentes. Dans un premier temps, la réaction a été effectuée avec 1b pour obtenir 6b avec un bon rendement de 80% (Schéma 9). Formation du complexe monodente germylene ruthénium 6b Le complexe 6b a été entièrement caractérisé par plusieurs méthodes d'analyses comme la RMN, la spectroscopie IR et la diffraction des RX. La réaction de coordination a ensuite été étendue à tous les ligands (Schéma 10). A nouveau, tous les complexes de ruthénium obtenus ont été entièrement caractérisés et sont stables à température ambiante sous atmosphère inerte. RuCl 2 (p-cymene)) Formation des complexes monodente germylene ruthénium 6b-d-f-g-h

Schéma 13 :

 13 Formation du complexe germylene molybdène 9Le changement du groupement espaçant le germylene et le sulfoxyde a définitivement impacté la coordination du sulfoxyde afin d'obtenir des complexes bidentes avec les métaux de transition du groupe 6 contrairement à des complexes bis-monodentes avec la première génération.

XTableau 1 :

 1 de ce complexe n'a pas permis de caractériser le complexe 10a car un nouveau complexe de bis-ruthénium 10b a été obtenu systématiquement au cours des cristallisations réalisées (Schéma 15). Schéma 15: Formation du complexe 10b lors de la cristallisation Le complexe 10b montre des déplacements chimiques différents en RMN du31 P avec un singulet à 29 ppm et deux doublets à 44 et 52 ppm. La particularité de ce nouveau complexe est d'avoir deux atomes de chlore et la fonction sulfoxyde qui joue le rôle de pont entre les deux atomes de ruthénium. Il s'agit du premier exemple où un atome de soufre et un atome d'oxygène d'un même sulfoxyde coordinent deux centres métalliques différents avec une fonction sulfoxyde asymétrique. Finalement, la chimie de coordination de 7 a été étudiée avec le groupe 10. Ni(cod) 2 a été utilisé comme précurseur métallique pour conduire à la formation du complexe 11a (). La synthèse des différents sulfonimidamides a été réalisée avec plusieurs groupements i-Pr ou mésityle, permettant d'obtenir un soufre symétrique ou asymétrique de façon racémique (Schéma 18). Schéma 18: Formation des sulfonimidamides 12a et 12b Les sulfonimidamides 12a et 12b ont été entièrement caractérisés par RMN et diffraction des rayons X. Ces ligands ont ensuite permis d'obtenir les germylènes homoleptiques correspondants par protonolyse avec le réactif Ge(HMDS) 2 (Schéma 19). L'élimination de l'amine formée après une nuit de réaction permet d'obtenir les germylènes 13a et 13b avec de bons rendements selon une méthode efficace. Schéma 19: Formation par protonolyse des germylènes 13a et 13b Les germylènes 13a et 13b ont pu être entièrement caractérisés par RMN et diffraction des rayons X et comparés au ligand de départ. Cette réaction a ensuite été étendue aux dérivés lourds des germylènes, les stannylènes. En suivant le même protocole expérimental, les Pr 12b, R = Mes 12c, R = -CH 2 CH 2 NH(Me) 2 Cl Pr 12b, R = Mes 13a, R = i Pr 13b, R = Mes stannylènes homoleptiques correspondants ont pu être obtenus par protonolyse avec Sn(HMDS) 2 et ont été entièrement caractérisés (Schéma 20). Schéma 20: Formation par protonolyse des stannylènes 14a et 14b Finalement, des calculs DFT ont été réalisés pour déterminer la stabilisation électronique du ligand en fonction du métallylène et l'influence apportée par les différents substituants présents sur l'azote sur cette stabilisation. Finalement, le cinquième et dernier chapitre est consacré à l'application des différents complexes et métallylènes en catalyse. Les différents complexes de ruthénium de première génération et le complexe à 16 électrons de deuxième génération ont été testés en catalyse et leur activité a été comparée. La catalyse sélectionnée est la réaction de transfert d'hydrogène qui consiste en la réduction d'un composé carbonylé en son alcool correspondant en milieu protique (Schéma 21). Schéma 21: Réaction de transfert d'hydrogène Dans un premier temps, les complexes p-cymène 6b-d-f-g-h ont été utilisés pour la réduction de l'acétophénone dans l'iso-propanol avec une base (KOH) et 2 mol% de catalyseur (Schéma 22). Schéma 22: Réduction de l'acétophénone en son alcool correspondant La conversion de l'alcool a été vérifiée après deux heures de réaction par RMN du 1 H avec un étalon interne, le 1,2,4,5-tétramethylbenzène (Tableau 1). Réduction de l'acétophénone en son alcool correspondant par 6b-d-f-g-h Après 2 heures de réactions à 80 °C, l'alcool correspondant a été obtenu avec un rendement de 76% en utilisant le complexe de ruthénium 6b comme catalyseur. L'augmentation de l'encombrement stérique avec un groupe cyclohexyle sur l'amidinate entraîne une baisse de l'activité et la conversion avec 6d est de 57%. 6f montre l'importance du groupement aryle car une chute de la conversion à 43% est observée, cette baisse peut être expliquée par l'instabilité du complexe et la formation d'iso-butène et d'un acide sulfinique lors du chauffage. Finalement l'influence du groupe sulfoxyde est notable car les dérivés thioéther et sulfone présentent des activités bien moindres de 29 et 23% respectivement pour 6g et 6h. Finalement, le complexe 5a a été utilisé pour la réaction de transfert d'hydrogène avec le même substrat et dans les mêmes conditions en faisant varier la température et le temps de réaction.

Tableau 3 :

 3 Réduction de plusieurs cétones et aldéhyde en alcool correspondant par 5a L'extension à plusieurs cétones para-substituées a permis d'obtenir les alcools correspondants chimio-sélectivement. En effet, 5a peut réduire une cétone en présence d'un groupement bromé, méthoxylé ou trifluorométhane sélectivement en 72 heures à 25 °C. La réduction dans les mêmes conditions a aussi permis de réduire la benzophénone et finalement le benzaldéhyde en 4 heures. Un essai avec une cétone plus encombrée, l'adamantyl-méthylcétone, a montré aucune réactivité et cela même après 96 heures de réaction. Finalement, les stannylènes 16a et 16b ont été utilisés en catalyse de polymérisation de la e-caprolactone. Les tests ont été réalisés dans le toluène à 100 °C (Schéma 23).

  ) and molar mass distributions (Đ) of the polymer samples were determined by size exclusion chromatography (SEC) at 35 °C with a Waters 712 WISP high-speed liquid chromatograph equipped with a R410 refractometer detector. Tetrahydrofuran (THF) was used as the eluent, and the flow rate was set up at 1.0 mL/min. A SHODEX precolumn (polystyrene AT806M/S Mw = 50000000 g/mol) and two STYRAGEL columns (HR1, 100-5000 g/mol, and HR 4E, 50-100000 g/mol) were used. Calibrations were performed using polystyrene standards (400-= Hydrogen transfer i-Pr = iso-propyl IR = Infra-red L.B. = Lewis base LDA = Lithium di-iso-propylamine MALDI-TOF = Matrix Assisted Laser Desorption Ionisation -Time of Flight

  Scheme 2: Degenerate energy levels of triplet and singlet state

4 Scheme 5 :

 45 Scheme 5: Synthesis of Ge(II) by cyclo-elimination reaction and reactivity towards alkenes and tin derivatives

Scheme 7 :I. 3 .

 73 Scheme 7: Synthesis of Ge(II) via photolysis reaction

Scheme 42 :

 42 Scheme 42: Coordination or oxidative addition of pincer germylene-phosphine ligands

Scheme 46 :

 46 Scheme 46: Coordination of substituted amidinatogermylenes with group 8 and 9 complexes

Scheme 50 :

 50 Scheme 50: Germylene pincer complex of cobalt

Scheme 53 :

 53 Scheme 53: Bis-germylene complex of platinum

126- 128 Scheme 56 :Scheme 57 :

 1285657 Scheme 56: Sulfoxide and their coordination ability

Scheme 62 :

 62 Scheme 62: Sulfoxide-NHC complexes reported

Figure 1 :

 1 Figure 1: Combination of germylene stabilized with intramolecular Lewis base and sulfoxide

Figure 2 :

 2 Figure 2: Different possibilities of coordination of hemilabile germylene-sulfoxide ligand to a transition metal

Figure 3 : 1 H

 31 Figure 3: 1 H NMR spectrum of 1a in THF-d 8

Figure 4 : 8 2

 48 Figure 4: 13 C NMR spectrum of 1a in THF-d 8

Figure 6 :

 6 Figure 6: Molecular structure of 1h (hydrogens are omitted for clarity)

  The formation of 2d could be seen as the reaction of four molecules of 2b with a molecule of oxygen. Two tin (II) atoms were oxidized to tin (IV) and the amidinates group of the two-remaining tin (II) have migrated to tin (IV) with the formation of the central 1,3-Sn 2 O 2 ring.

Figure 7 :

 7 Figure 7: Molecular structure of oxidation product 2d (hydrogens are omitted for clarity)

X

  Scheme 14: Bis-germylene tungsten complex

Figure 8 :

 8 Figure 8: Molecular structure of 3b (hydrogens are omitted for clarity)

Figure 9 :

 9 Figure 9: 13 C NMR (190-220 ppm) of 3b and reaction with 10 equivalents of tungsten in C 6 D 6

Figure 10 :

 10 Figure 10: Molecular structure of 3g and 3h (hydrogens are omitted for clarity)

Figure 11 :

 11 Figure 11: Molecular structure of 4b (hydrogens are omitted for clarity)

Figure 12 :

 12 Figure 12: Molecular structure of 5a (hydrogens are omitted for clarity)

Figure 13 :

 13 Figure 13: Molecular structure of 5c (hydrogens are omitted for clarity)

(

  RuCl 2 (p-cymene)) 2 aromatic hydrogen and carbon atoms respectively. The -CH 2 -linker between germylene and sulfoxide was the only one to show a specific shift in NMR. Indeed, in1 H NMR an A-B system appeared clearly in C 6 D 6 at 3.56 and 3.72 ppm compared to a singlet at 2.93 ppm for the starting material in the solvent. In 13 C NMR, the signal was upfield at 50.6 ppm compared to 61.7 ppm.

Figure 14 :

 14 Figure 14: Molecular structure of 6b (hydrogens are omitted for clarity)

  degradation leading to the formation of amidinatohexafluorophosphate salt characterized by X-Ray diffraction as by-product.

Figure 15 : 1 H

 151 Figure 15: 1 H NMR of 6b and 6b' after 1 hour in CD 2 Cl 2

Figure 16 :

 16 Figure 16: Molecular structures of 6a-6c-6d-6f-6g and 6h (hydrogens are omitted for clarity)

  Scheme 22: reaction of 1b with CuCl and [AuCl.SMe 2 ] in THF-d 8

Figure 17 : 1 H 8 +

 1718 Figure 17: 1 H NMR of 1b, 7b, 8b and 9b in THF-d 8

4 (

 4 CH 3 ) 2 ); 26.8 (CH(CH 3 ) 2 ); 29.0 (C(CH 3 ) 3 ); 40.0 (C(CH 3 ) 3 ); 47.4 (CH(CH 3 ) 2 ); 61.GeCH 2 SO); 127.1 (C Ar ); 129.0 (C Ar ); 131.8 (C Ar ); 146.1 (C Ar/q ); 172.7 (N-C-N). MS (EI: 70 eV) m/z (%): 413.2 ([M + 1, 8 %] + ). IR (Nujol, cm -1 ): 1493 (med) (C=C arene ), 1305 (med) (SO),

  C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 26.4 (CH(CH 3 ) 2 ); 29.4 (C(CH 3 ) 3 ); 42.4 (C(CH 3 ) 3 ); 46.9 (CH(CH 3 ) 2 ); 179.7 (N-C-N). 119 Sn NMR (167.88 Hz, C 6 D 6 , 25 °C): δ = 55.5 ppm.

  2 (C Ar/q ); 175.2 (N-C-N); 208.0 (CO). MS (Maldi-TOF) m/z (%): 1002 ([M -(CO) 4 ] + ). IR (Nujol, cm -1 ): 2035 (s) (CO), 1996 (s) (CO), 1938 (s) (CO), 1021 (med) (SO).

3 ( 7 (

 37 C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 22.CH(CH 3 ) 2 ); 25.9 (CH(CH 3 ) 2 ); 29.5 (C(CH 3 ) 3 ); 32.6 (GeCH 2 SPh); 39.7 (C(CH 3 ) 3 ); 47.CH(CH 3 ) 2 ); 124.6 (C Ar ); 126.9 (C Ar ); 129.0 (C Ar ); 142.0 (C Ar/q ); 173.6 (N-C-N); 208.3 (CO). MS (Maldi-TOF) m/z (%): 1026 ([M -CO] + ). IR (Nujol, cm -1 ): 2036 (s) (CO), 1947 (s) (CO),

4 (

 4 C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 21.9 (CH(CH 3 ) 2 ); 26.CH(CH 3 ) 2 ); 29.3 (C(CH 3 ) 3 ); 39.7 (C(CH 3 ) 3 ); 48.1 (CH(CH 3 ) 2 ); 58.3 (GeCH 2 SO); 126.8 (C Ar ); 129.1 (C Ar ); 131.8 (C Ar ); 146.3 (C Ar/q ); 176.7 (N-C-N); 207.3 (CO). IR (Nujol, cm -1 ): 2035 (s) (CO), 1999 (s) (CO), 1877 (br) (CO), 1376 (med) (SO 2 ), 1107 (med) (SO 2 ). MS (Maldi-TOF) m/z (%): 1090 ([M -CO] + ).

2 (

 2 C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 21.1 (p-CH 3 ); 23.2 (CH(CH 3 ) 2 ); 23.4 (CH(CH 3 ) 2 ); 26.CH(CH 3 ) 2 ); 26.4 (CH(CH 3 ) 2 ); 29.3 (C(CH 3 ) 3 ); 39.8 (C(CH 3 ) 3 ); 47.9 (CH(CH 3 ) 2 ); 50.0 (CH(CH 3 ) 2 ); 59.8 (GeCH 2 SO); 123.7 (C Ar ); 129.9 (C Ar ); 139.7 (C Ar/q ); 148.4 (C Ar/q ); 174.8 (N-C-N); 216.5 (CO). IR (Nujol, cm -1 ): 2021 (s) (CO), 1999 (s) (CO), 1905 (s) (CO), 1015 (med) (SO). MS (Maldi-TOF) m/z (%): 1026 ([M + ).

Figure 1 :

 1 Figure 1: Different possibilities of coordination of hemilabile germylene sulfoxide ligand to a transition metal

Scheme 5 :

 5 Scheme 5: Synthesis of 2 nd generation ligand 7a

Figure 2 : 1 H

 21 Figure 2: 1 H NMR spectrum of 7a

4 O 7 :

 47 Scheme 7: Synthesis of 2 nd generation germylene -b-sulfone ligand 7b

Scheme 8 :

 8 Scheme 8: Synthesis of tungsten complex 8

  C NMR spectrum with four signals at 202.1, 206.7, 208.3 and 210.2 ppm corresponding to the carbonyls ligands of the tungsten having different chemical shifts due to the loss of symmetry brought by the bidentate coordination and the asymmetric sulfoxide center. 1 H and13 C NMR spectra exhibit no others special chemical shifts. Finally, X-ray structure of 2 was obtained from crystals from a THF solution at 6 °C (Figure3).

Figure 3 :

 3 Figure 3: Molecular structure of 8 (hydrogens are omitted for clarity)

  1.98 Å) due to the coordination of the germylene lone pair to the transition metal.

Figure 4 :

 4 Figure 4: Molecular structure of 9 (hydrogens are omitted for clarity)

distance of 2 .

 2 2737(11), 2.3072(12) and 2.3673(11) Å. The chlorine atoms in axial position have very particular angles, Cl1-Ru1-Cl2 of 170.43(4)° and Cl4-Ru1-Cl2 of 159.53(4)° explained by the bridge between the two ruthenium atoms. Ge1-Ru1-S1 and Ge1-Ru1-P1 angles of the 5-member ring are 84.33(3)° and 96.51(3)° respectively. The ruthenium-oxygen distance, 2.197(3) Å, is in the range of reported complexes bearing a phosphine in trans position(2.15-

Figure 5 :

 5 Figure 5: Molecular structure of 10b (hydrogens are omitted for clarity)

Figure 6 :

 6 Figure 6: 31 P NMR analysis of 10b at variable temperature

Figure 7 :

 7 Figure 7: Possible formation of three molecules in solution

Figure 8 :

 8 Figure 8: 31 P of 10b in CD 2 Cl 2 and fluorobenzene

Figure 9 :

 9 Figure 9: Optimized molecule of 10b used for calculations

1 HFigure 10 :

 110 Figure 10: 11a 1 H NMR spectrum in cod area of some crystals in young tube and monitored after 1 hour in solution at room temperature

Figure 11 :

 11 Figure 11: Molecular structure of 11a (hydrogens are omitted for clarity)

Figure 12 :

 12 Figure 12: Molecular structure of 11b (hydrogens are omitted for clarity)

Figure 14 :

 14 Figure 14: TEP comparison of several Ni(CO) 3 complexes

7 (

 7 J HH = 6.3 Hz, 1H, CH(CH 3 ) 2 ); 7.04 (d, 1H, 3 J HH = 8.2 Hz, CH Ar ); 7.64 (s, 1H, CH Ar ); 7.97 (d, 1H, 3 J HH = 8.2 Hz, CH Ar ). 13 C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 21.5 (p-CH 3 ); 23.8 (O=SC(CH 3 ) 3 ); 24.2 (CH(CH 3 ) 2 ); 24.4 (CH(CH 3 ) 2 ); 27.5 (CH(CH 3 ) 2 ); 27.CH(CH 3 ) 2 ); 29.3 (C(CH 3 ) 3 ); 40.2 (C(CH 3 ) 3 ); 47.3 (CH(CH 3 ) 2 ); 47.4 (CH(CH 3 ) 2 ); 56.5 (O=S-

6 (

 6 C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 21.6 (p-CH 3 ); 23.6 (CH(CH 3 ) 2 ); 24.0 (CH(CH 3 ) 2 ); 27.4 (CH(CH 3 ) 2 ); 27.CH(CH 3 ) 2 ); 29.3 (C(CH 3 ) 3 ); 29.4 (S(O) 2 C(CH 3 ) 3 ); 40.1 (C(CH 3 ) 3 ); 47.8 (CH(CH 3 ) 2 ); 58.9 (S-

31 P{ 1

 1 H} NMR (200 MHz, C 6 D 6 ): δ 28.7 (s, Ru-PPh 3 ), 44.8 (d, 2 J PP = 42.0 Hz, Ru-PPh 3 ), 53.6 (d, 2 J PP = 42.0 Hz, Ru-PPh 3 ). Isomer B : 1 H NMR (500 MHz, CDCl 3 , 25 °C): δ -0.24

  C{ 1 H} NMR (125 MHz, CDCl 3 , 25 °C): δ 21.5 (p-CH 3 ); 23.5 (CH(CH 3 ) 2 ); 23.8 (CH(CH 3 ) 2 ); 25.0 (CH(CH 3 ) 2 ); 26.1 (O=SC(CH 3 ) 3 ); 26.7 (CH(CH 3 ) 2 ); 30.3 (C(CH 3 ) 3 ); 39.9 (C(CH 3 ) 3 ); 47.0 (CH(CH 3 ) 2 ); 48.6 (CH(CH 3 ) 2 ); 71.9 (O=S-C(CH 3 ) 3 ); 178.0 (N-C-N). 31 P{ 1 H} NMR (200 MHz, C 6 D 6 ): δ 39.9 (s, Ru-PPh 3 ), 41.6 (d, 2 J PP = 37.3 Hz, Ru-PPh 3 ), 44.1 (d, 2 J PP = 37.3 Hz,

3 (

 3 C{ 1 H} NMR (125 MHz, CDCl 3 , 25 °C): δ 21.7 (p-CH 3 ); 23.2 (CH(CH 3 ) 2 ); 24.CH(CH 3 ) 2 ); 24.5 (CH(CH 3 ) 2 ; 26.1 (O=SC(CH 3 ) 3 ); 27.7 (CH(CH 3 ) 2 ); 30.2 (C(CH 3 ) 3 ); 40.1 (C(CH 3 ) 3 ); 46.5 (CH(CH 3 ) 2 ); 48.6 (CH(CH 3 ) 2 ); 69.7 (O=S-C(CH 3 ) 3 ); 178.4 (N-C-N). 31 P{ 1 H} NMR (200 MHz, C 6 D 6 ): δ 29.5 (s, Ru-PPh 3 ), 47.6 (d, 2 J PP = 40.9 Hz, Ru-PPh 3 ), 48.3 (d, 2 J PP = 40.9 Hz, Ru-PPh 3 ). IR (Nujol, cm -1 ): 1162 (s) (SO). HRMS m/z (%): 1547.1821 ([M -Cl] + ) calcd for C 76 H 84 Cl 3 GeN 2 OP 3 Ru 2 S ([M -Cl] + ) 1547.1829.

  CH 3 ) 3 ); 48.0 (CH(CH 3 ) 2 ); 48.2 (CH(CH 3 ) 2 ); 56.8 (O=S-C(CH 3 ) 3 ); 126.6 (C Ar ); 130.0 (C Ar ); 133.0 (C Ar ); 139.6 (C Ar/q ); 145.7 (C Ar/q ); 151.2 (C Ar/q ); 173.6 (N-C-N); 199.0 (CO). IR (cm -1 ): 2059 (CO), 1982 (CO), 1027 (SO). HRMS m/z (%): 567.1246 ([M + 1 -CO] + ) calcd for C 24 H 38 GeN 2 O 4 NiS ([M + 1] + ) 567.1241.

Figure 1 :

 1 Figure 1: Examples of germylenes with chiral substituents

Figure 2 :

 2 Figure 2: Example of stannylene with chiral substituent

12

 12

  S(VI) atom in central position with two double bonds with oxygen and nitrogen, and two single bonds with carbon and nitrogen. Delocalization of electrons was determined with identical substituents on the nitrogen atoms byJohnson et al. in 1979.

Scheme 1 :

 1 Scheme 1: Stabilization of Zn(II) with sulfonimidamide

  Pr 12b, R = Mes 12c, R = -CH 2 CH 2 NH(Me) 2 Cldistance of 1.6188(9) and 1.5154(9) Å, the single bond being located on the nitrogen with an alkyl substituent.

Figure 4 :

 4 Figure 4: Molecular structures of 12a (left) and 12b (right) (hydrogens are omitted for clarity)

2 X

 2 Scheme 6: Reactivity of 12a with M(HMDS) 2 (M = Ge or Sn) to obtain 13a and 14a

  and 1.5445(13) Å corresponding to a S-N bond with a better p character than the second one. Comparison with 12a shows than the double bond is longer (D = +0.05 Å) and the single bond is shorter (D = -0.05 Å), it can be explained by the delocalization of electrons between both nitrogen. 14ashows the same observations with a nitrogen-tin s-bond of 2.180(4) and 2.233(4) Å and a dative bond of 2.392(5) and 2.427(5) Å. S-N bond lengths are also in the same range as 13a with single bonds of 1.580(5) and 1.573(5) Å and double bonds of 1.529(5) and 1.568(5) Å.

Figure 5 :Scheme 7 : 2 Scheme 8 :

 5728 Figure 5: Molecular structures of 13a (left) and 14a (right) (hydrogens are omitted for clarity)

Figure 6 : 1 H 1 H

 611 Figure 6: 1 H NMR variable temperature of 13b from 25 °C to 70 °C

Figure 7 :

 7 Figure 7: Molecular structures of 13b (left) and 14b (right) (hydrogens are omitted for clarity)

Figure 8 :Figure 9 :

 89 Figure 8: Optimized structures of 13b and 14b for PES calculations

1 (

 1 J HH = 6.5 Hz, 1H, N-CH(CH 2 ) 2 ), 5.11 (s, 1H, NH), 6.84 (s, 2H, CH Ar ), 6.98-7.02 (m, 3H, CH Ar ), 8.04-8.07 (m, 2H, CH Ar ). 13 C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 20.6 (CH 3 ); 20.9 (CH 3 ); 23.0 (CH(CH 3 ) 2 ); 24.CH(CH 3 ) 2 ); 46.0 (CH(CH 3 ) 2 ); 128.0 (C Ar ); 128.6 (C Ar ); 131.3 (C Ar ); 143.3 (C Ar/q ). HRMS m/z (%): 317.1697 ([M + 1] + ) calcd for C 18 H 25 N 2 OS ([M + 1] + ) 317.1688.

  ,N'-di-iso-propylbenzenesulfonimidamide) stannylene (14a): N,N'-di-iso-propylbenzenesulfonimidamide (12a) (60 mg, 0.25 mmol, 2 eq) was dissolved in C 6 D 6 (0.4 mL) and added to Sn(HMDS) 2 (55 mg, 0.125 mmol, 1 eq) at room temperature.

  C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 25.1 (CH(CH 3 ) 2 ); 25.9 (CH(CH 3 ) 2 ); 47.0 (CH(CH 3 ) 2 ); 129.0 (C Ar ); 129.1 (C Ar ); 131.2 (C Ar ); 142.4 (C Ar/q ). MS m/z (%): 598 (M + ).

  )

  Transfer and Polymerization CatalysisAbstractRuthenium complexes synthesized in previous chapter II were used in hydrogen transfer reaction for the reduction of acetophenone into the corresponding alcohol in i-PrOH as a solvent and a reactant. Comparison of the different ligands was investigated to determine the influence of various parameters, such as the steric hindrance on sulfoxide or on the amidinate group, or the oxidation state of the sulfur atom.

12

 12

40 a

 40 The reactions were carried out in dry and degassed toluene (3 mL) under argon in presence of e-caprolactone (8.7 mmol) b Determined by1 H NMR analysis by comparing the integration of the signal of the polymer with the monomer.

Figure 1 :

 1 Figure 1: Polymerization catalysis using 14a

6 (

 6 C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 18.2 (p-CH 3 ); 22.CH(CH 3 ) 2 ); 24.3 (CH(CH 3 ) 2 ); 25.1 (CH(CH 3 ) 2 ); 28.7 (C(CH 3 ) 3 ); 30.9 (CH(CH 3 ) 2 ); 38.9 (C(CH 3 ) 3 ); 48.7 (CH(CH 3 ) 2 ); 85.3 (C Ar ); 85.7 (C Ar ); 98.3 (C Ar/q ); 105.1 (C Ar/q ); 179.5 (N-C-N).

  , we have developed: (i) the synthesis of two-generations of hemilabile germylene-sulfoxide ligands and their corresponding transition metal complexes, (ii) the elaboration of new homoleptic metallylenes stabilized by sulfonimidamides and (iii) the application of the previous complexes and metallylenes in hydrogen transfer or polymerization catalysis.A novel germylene -a-sulfoxide ligand has been investigated in the first place and successfully obtained even if sulfoxides are well known oxidant. The versatility of the methodology has been extended to a wide range of (i) structural architectures, by modification of the amidinate or the sulfoxide group, and (ii) oxidation state of sulfur with the introduction of thioether or sulfone. These ligands have been used in coordination chemistry with group IV and two different ruthenium (II) precursors to obtain several monodentate, bis-monodentate and bidentate complexes. The formation of a bidentate ruthenium (II) complex with a coordination through germanium and oxygen atoms showed a potential hemilability of the sulfoxide ligand. The ruthenium complexes have been applied in hydrogen transfer reaction of acetophenone in i PrOH to form the corresponding alcohol. The optimal conditions at 25 °C allowed to fully reduce various carbonyl compounds such as arylmethylketones, bis(aryl)ketone and arylaldehyde in a reaction time of 4 to 72 hours. The asymmetric reduction of acetophenone has been also investigated starting with enantiopure ligands to obtain a moderate ee of 21 %.

Table 1 :

 1 The gap increases in favor of singlet state with the size of the group 14 elements. The difference Energy gap between singlet and triplet states

	remains the same even with the cyclic derivative (C 4 H 4 M:)
	H 2 M:	H 2 C:	H 2 Si:	H 2 Ge:	H 2 Sn:	H 2 Pb:
	∆E S-T (Kcal/mol)	-9	16.7	21.8	24.8	34.8
	C 4 H 4 M:	C 4 H 4 C:	C 4 H 4 Si: C 4 H 4 Ge: C 4 H 4 Sn: C 4 H 4 Pb:
	∆E S-T (Kcal/mol)	-9.6	14.8	22.8	26.2	27.3

  Scheme 10: Different pathways for the synthesis of NHGe Nevertheless, the first thermodynamically stabilized germylene was published by Lappert et al. in 1974.35 Chlorine atoms of GeCl 2 •dioxane were easily substituted by HMDS lithium salt in diethyl ether to afford (HMDS) 2 Ge: as a stable oil in 67% yield. This precursor

	Me 3 Si	SiMe 3	Cl	Ge	Eind		Et	Et	Et	Et
		Ge	Ar	Ar	Eind	Ge	Et Eind =			Et
	Me 3 Si	SiMe 3	Ar = C 6 H 3 -2,6-trip 2				Et	Et
	Kira, 1999	Power, 1997	Matsuo, 2012
	1985 with yields of 27% (R = CH 3 ) and 67% (R = C 6 H 5 ) respectively 41 and the benzimidazole
	ring published by Meller in 1989 with 87% yield (Scheme 12

was then used to obtain several substituted germylenes by protonolysis. The first example was also introduced by Lappert and Atwood in 1980 for the synthesis of the first bis-alkoxide germylene in 66% yield (Scheme 11). 36 X-ray structure showed a V-shaped geometry with a Ge-O s-bond length of 1.81 Å. Since, the method was applied in many reactions, as example, in the use of sensitive ligands in basic conditions or for the easiness of removing H-HMDS as by-product under reduced pressure.

37,38

Scheme 11: Formation of alkoxy-germylene by protonolysis Interestingly, different NHGe were reported before the group of Herrmann with a similar strategy consisting to substitute the chlorine atoms of GeCl 2 •dioxane with the corresponding lithium amide salt. The different NHGe reported are the 4-member ring published by Veith in 1982 with a 91% yield

39,40

the 5-membered ring published by

Meller in

  the one reported by Meller above,42 and one nitrogen is dative bonded with a larger distance of 2.05 Å. Scheme 14: Example of donation of a Lewis base In 1997, Lappert et al., Leung et al. and Meller et al. have reported the same year the first diaryl and dialkyl germylenes stabilized with a Lewis base following the same

	t Bu	N	Si	Si N	N	N t Bu Li	Li	GeCl 2 .dioxane	t Bu	N	Si	Si N	N	N	Ge	1/8 S 8	t Bu	N	Si	N Si	N	N	Ge	S
																	L.B.
								Ge									Ge
																		L.B.
		N				Ge		N		N		Ge		N			N		Ge		N
				N			N		Me 3 Si	SiMe 3	Me 3 Si	SiMe 3	Me 3 Si	Ph			Ph	SiMe 3
			Lappert, 1997			Meller, 1997			Leung, 1997

to experimental procedure, i-e nucleophilic substitution of GeCl 2 •dioxane with the corresponding aryl or alkyl lithium salts (Scheme 15).

[49][50][START_REF] Ossig | Bis[(2-pyridyl)bis(trimethylsilyl)methyl-C, N]germanium(II): A Base-Stabilized Germylene and the Corresponding Germanethione, Germaneselenone, and Germanetellurone[END_REF]

The homoleptic diarylgermylene synthesized by Lappert was obtained in 65% yield.

1

H NMR spectrum showed only one singlet for the -2,6-NMe 2 substituents at room temperature, while two separate signals at 178 K were observed. This result indicates a fast exchange, at room temperature, between the -2,6-NMe 2 substituents for the stabilization of the germylene. This exchange is slowed down with the temperature and gets closer to the X-ray structure with only one nitrogen donating to the germanium center. The homoleptic dialkylgermylene, synthesized by Meller and Leung independently, was obtained in 53% or 67% yield. X-ray structure showed a square-pyramidal geometry with Ge-C s-bond length of 2.13 and 2.14 Å, and Ge-N dative bond distance of 2.27 and 2.31 Å respectively. The difference in Ge-N dative bond distance compare to the structure obtained by Veith can be explained by variation of nitrogen donation to the germanium center. Scheme 15: Lewis base stabilization of some selected germylene Then several heteroleptic germylenes were reported with only one substituent bearing the Lewis base (Scheme 16). Jutzi et al. reported in 1998 the synthesis of the arylchlorogermylene with only one nitrogen as Lewis base in 72% yield.

[START_REF] Schmidt | Germylenes and Germyl Cations with the 2,4-Di-tert-butyl-6-(N, Ndimethylaminomethyl)phenyl Ligand[END_REF]

Later in 2002, Couret et al. published an arylchlorogermylene with two nitrogen as Lewis base in a good 90% yield. 53 t Bu t Bu t Bu t Bu t Bu t Bu t Bu t Bu

  The utilization of intermolecular Lewis base to stabilize germylenes was introduced by Jones et al. in 2006 (Scheme 17).

																						t Bu
	i Pr i Pr	N	Ge	Cl	t Bu	i Pr i Pr	N	Ge	Cl	N	i Pr i Pr	t Bu	O	Ge	Cl	t Bu	t Bu t Bu	O	O	Ge	t Bu t Bu
			t Bu												t Bu
																					t Bu
			Jutzi, 1998				Couret, 2002								Jutzi, 2001
																		Cl
									Cl						O		Ge	O
							O	Ge		O			O	S			S	O
													Tolyl						Tolyl
																	t Bu
							Yamamoto, 2005					Madec, 2015

  -W bond length of 2.56 Å. Since then more than a hundred of complexes based on amidinate metallylenes are reported to date. As examples, Castel et al. have reported a bis-germylene tungsten and molybdenum Starting from the same AmGe-t-Bu precursor, Cabeza et al. have published the coordination with iridium and ruthenium in 2015 (Scheme 46). 114 Complexes were obtained in excellent yield of 98%. X-ray structure showed, for ruthenium, a Ge-Ru bond length of 2.43 Å which relies in the longest distance reported. Besides, Ge-Ir bond length is also the longest reported to date with 2.42 Å.

	t Bu complexes in 2010, Cabeza et al. have reported a germylene manganese complex in 2014 and t Bu t Bu t Bu t Bu t Bu t Bu t Bu
	N Madec et al. have reported a germylene iron complex in 2015. 71,112,113 P Cl N P Cl N P Cl CO	N	P	CO
	Ge		Ni	Cl		Ge	Pt	Cl	Ge	Ir	Ge	Ru	Cl
	N						N			N		CO	N	H
	t Bu	P	t Bu		t Bu	P	t Bu	t Bu	P	t Bu	2 t BuP	3 i PrP
	Cabeza, 2017				Cabeza, 2017		Cabeza, 2018	Cabeza, 2018
	Scheme 44: Selected examples of amidinategermylene complexes
	An interesting observation was reported by Cabeza et al. in 2015 (Scheme 45). 75 They
	evidenced the need to tuned the chloroamidinatogermylene published by Roesky, 73 in 2008, to
	have access to coordination chemistry of group 11 transition metals. Indeed, the synthesis of
	AmGe-t-Bu derivative by nucleophilic substitution of AmGeCl with t-BuLi can be applied in
	coordination chemistry of copper, silver and gold complexes in good yields going from 61% to
	95%.
	N Scheme 45: Importance of substituted amidinategermylene for synthesis of group 11 Ph N Ph Me 3 P PMe 3 N Ph N Ph OC CO
	N	Ge		Fe	Ge	N		CO atm complexes		N	Ge	Fe	Ge	N
			N		N	N						N	N	N

  or the amidinatochlorogermylene. Indeed, Power et al. reported in 2009 that germylene in presence of ammonia led to the insertion product.

			1) t-BuLi					GeCl 2 •dioxane
		N C	Et 2 O, -80 °C, 15 min		N	Li	Et 2 O, 15 h, R.T.			N	Ge
		N	2) 25 °C, 4 h			N					N	Cl
								97 %
							N
								Ge
							N	Cl
	Ph	S O	2) R.T., 1h 1) LDA Et 2 O, -80 °C, 1 h	Ph	S O	Li	Et 2 O, -80 °C, 2.5 h	N N	Ge		S O	Ph
										H	H
											1a

  g) in 88 % yield. M.p. : 74 °C; 1 H NMR (300.18 MHz, THF-d 8 , 25 °C): δ 0.85-1.95 (m, 20H, CH(CH 3 ) 2 ); 1.39 (s, 9H, C(CH 3 ) 3 ); 3.83 (m, 2H, N-CH(CH 2 ) 2 ). 13 C{ 1 H} NMR (75.48 MHz, THF-d 8 , 25 °C): δ 26.0 (CH 2 ); 26.1 (CH 2 ); 26.2 (CH 2 ); 29.0 (C(CH 3 ) 3 ); 35.7 (CH 2 ); 37.9 (CH 2 ); 40.8 (C(CH 3 ) 3 ); 56.1 (N-CH(CH 2 ) LDA (53.4 mg, 0.5 mmol, 1.04 eq) in diethylether (2 mL) was added dropwise to a solution of methylphenylsulfoxide (70 mg, 0.5 mmol, 1.04 eq) in diethyl ether (2 mL) at -78 °C. The solution was stirred during 1 hour at the same temperature (-78 °C). Then, the solution was allowed to warm up at room temperature and stirred an additional period of 45 min. Finally, the solvent was removed under reduced pressure in order to obtain a white solid. The resulting solid was dissolved in diethyl ether (2 mL) and added dropwise to a solution of chlorogermylene (138.7 mg, 0.48 mmol, 1 eq) in diethyl ether (2.5 mL) at -78 °C. The mixture was stirred during 2.5 hours at -78 °C. Then, the solution was filtered at the same temperature (-78 °C). Finally, the solvent was removed under reduced pressure to afford an oil (102 mg) in 72% yield.1 H NMR (300.18 MHz, THF-d 8 , 25 °C): δ 1.11 (d,3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.14 (d,3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.16 (d,3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.18 (d,3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.38 (s, 9H, C(CH 3 )

			Amidinate (di-iso-propyl-t-butyl) methylphenylsulfoxide
			germylene (1a):
	N
	Ge
	N	Cl
	Formula		C17 H31 Ge N2 Cl	dcalc (g/cm 3 )	1.300
	Mol wt		371.50	µ (mm -1 )	1.751
	Temp. (K)		193(2)	F(000)	784
	Cryst syst		Monoclinic	cryst size (mm)	0.10 x 0.10 x 0.02
	Space group	P21/c	θ range (deg.)	2.07 to 26.44°
	a (Å)		9.9516(6)	index range h k l	-12<=h<=12, -13<=k<=21,
					-14<=l<=14
	b (Å)		16.9688(9)	no of reflns collected /	9937
	c (Å)		11.3866(6)	unique	3884 [R(int) = 0.0464]
	a (deg.)		90	Completeness to θmax(%)	99.2 %
	b (deg.)		99.127(3)	data/restraints/params	3884 / 27 / 213
	g (deg.)		90	goodness-of-fit	1.115
	V (Å3)		1898.47(18)	R1, wR2 (I > 2σ(I))	0.0569, 0.1705
	Z		4	R1, wR2 (all data)	0.1104, 0.2340

2 ); 177.9 (N-C-N). MS (EI : 70 eV) m/z (%): 373.1 ([M + 1, 20 %] + ). 3 ); 2.69 (d, 1H, 2 J HH = 13.8 Hz, GeCH 2 SO); 2.76 (d, 1H, 2 J HH = 13.8 Hz, GeCH 2 SO); 4.31 (sept., 3 J HH = 6.3 Hz, 2H, CH(CH 3 ) 2 ); 7.36-7.47 (m, 3H, CH Ar ); 7.65-7.70 (m, 2H, CH Ar ). 13 C{ 1 H} NMR (75.48 MHz, THF-d 8 , 25 °C): δ 24.3 (CH(CH 3 ) 2 ); 24.5 (CH(CH 3 ) 2 ); 26.9 (CH(CH 3 ) 2 ); 29.3 (C(CH 3 ) 3 ); 40.7 (C(CH 3 ) 3 ); 47.6 (CH(CH 3 ) 2 ); 47.7 (CH(CH 3 ) 2 ); 61.5 (GeCH 2 SO); 124.4 (C Ar ); 129.2 (C Ar ); 129.9 (C Ar ); 151.5 (C Ar/q ); 171.9 (N-C-N).

  atmosphere of argon.1 H NMR (300.18 MHz, THF-d 8 , 25 °C): δ 1.11 (d,3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.15 (d,3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 1.16 (d,3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.38 (s, 9H, C(CH 3 ) 3 ); 2.36 (s, 3H, p-CH 3 ); 2.69 (d, 1H, 2 J HH = 13.8 Hz, GeCH 2 SO); 2.76 (d, 1H, 2 J HH = 13.8 Hz, GeCH 2 SO); 4.31 (sept., 3 J HH = 6.3 Hz, 2H, CH(CH 3 ) 2 ); 7.26 (d, 2H, 3 J HH = 8.2 Hz, CH Ar ); 7.54 (m, 2H, 3 J HH = 8.2 Hz, CH Ar ). 13 C{ 1 H} NMR (75.48 MHz, THF-d 8 , 25 °C):

	N	O
	Ge
	N	S
	δ 21.1 (p-CH 3 ); 24.3 (CH(CH 3 ) 2 ); 24.5 (CH(CH 3 ) 2 ); 26.9 (CH(CH 3 ) 2 ); 27.0 (CH(CH 3 ) 2 ); 29.4
	(C(CH 3 ) 3 ); 40.7 (C(CH 3 ) 3 ); 47.6 (CH(CH 3 ) 2 ); 47.7 (CH(CH 3 ) 2 ); 61.9 (GeCH 2 SO); 124.3 (C Ar );
	129.8 (C Ar ); 139.8 (C Ar/q ); 148.6 (C Ar/q ); 171.8 (N-C-N). IR (Nujol, cm -1 ) : 1493 (med)
	(C=C arene ), 1017 (med) (SO).
		Amidinate	(dicyclohexyl-t-butyl)	germylene
		methylphenylsulfoxide (1c): LDA (49 mg, 0.46 mmol, 1.1 eq) in
		diethyl ether (2 mL) was added dropwise to a solution of
		methylphenylsulfoxide (65 mg, 0.46 mmol, 1.1 eq) in diethyl ether
	N	O
	Ge
	N	S

  ar ); 7.66-7.70 (m, 2H, C-H ar ).13 C{1 H} NMR(75.48 MHz, THF-d 8 , 25 °C): δ 25.3 LDA (49 mg, 0.46 mmol, 1.1 eq) in diethyl ether (2 mL) was added dropwise to a solution of methyl-ptolylsulfoxide (65 mg, 0.46 mmol, 1.1 eq) in diethyl ether (2 mL) at -78 °C. The solution was stirred during 1 hour at the same temperature (-78 °C). Then, the solution was allowed to warm up at room temperature and stirred an additional period of 45 min. Finally, the solvent was removed under reduced pressure in order to obtain a white solid. The resulting solid was dissolved in diethyl ether (2 mL) and added dropwise to a solution of chlorogermylene (156 mg, 0.42 mmol, 1 eq) in diethyl ether (2.5 mL) at -78 °C. The mixture was stirred during 2.5 hours at -78 °C. Then, the solution was filtered at the same temperature (-78 °C). Finally, the solvent was removed under reduced pressure to afford an oil (132 mg) in 66% yield.1 H NMR (300.18 MHz, THF-D 8 , 25 °C): δ 1.20-1.82 (m, 20H, CH(CH 3 ) 2 ); 1.37 (s, 9H, C(CH 3 ) 3 ); 2.36 (s, 3H, p-CH 3 ); 2.70 (s, 2H, Ge-CH 2 -SO); 3.80 (m, 2H, N-CH(CH 2 ) 2 ); 7.26 (d, 2H, 3 J HH = 8.2 Hz, CH Ar ); 7.55 (m, 2H, 3 J HH = 8.2 Hz, CH Ar ).

				Amidinate (dicyclohexyl-t-butyl) germylene methyl-p-
	N N	Ge	S O	tolylsulfoxide (1d): Amidinate (di-iso-propyle-t-butyl)	germylene	methyl-t-
	(CH 2 ); 25.5 (CH 2 ); 25.7 (CH 2 ); 28.7 (C(CH 3 ) 3 ); 34.5 (CH 2 ); 34.7 (CH 2 ); 40.7 (C(CH 3 ) 3 ); 55.2
	(CH(CH 2 ) 2 ); 60.8 (GeCH 2 SO); 123.7 (C Ar ); 128.5 (C Ar ); 129.2 (C Ar ); 150.7 (C Ar/q ); 171.1
	(N-C-N).

H NMR (300.18 MHz, THF-d 8 , 25 °C): δ 1.07-1.33 (m, 10H, CH(CH 3 ) 2 ); 1.36 (s, 9H, C(CH 3 ) 3 ); 1.53-1.93 (m, 10H, CH(CH 3 ) 2 ); 2.73 (s, 2H, Ge-CH 2 -SO); 3.80 (m, 2H, N-CH(CH 2 ) 2 ); 7.34-7.52 (m, 3H, C-H 13 C{ 1 H} NMR (75.48 MHz, THF-D 8 , 25 °C): δ 20.5 (p-CH 3 ); 25.2 (CH 2 ); 25.3 (CH 2 ); 25.5 (CH 2 ); 25.5 (CH 2 ); 25.6 (CH 2 ); 25.7 (CH 2 ); 28.7 (C(CH 3 ) 3 ); 34.7 (CH 2 ); 34.5 (CH 2 ); 37.6 (CH 2 ); 37.7 (CH 2 ); 40.1 (C(CH 3 ) 3 ); 55.2 (CH(CH 2 ) 2 ); 55.3 (CH(CH 2 ) 2 ); 61.0 (GeCH 2 SO); 123.7 (C Ar ); 129.1 (C Ar ); 139.1 (C Ar/q ); 147.7 (C Ar/q ); 170.9 (N-C-N). IR (Nujol, cm -1 ) : 1464 (med) (C=C arene ), 1027 (med) (SO).

butylsulfoxide (1f): LDA (77 mg, 0.72 mmol, 1.1 eq) in diethyl ether (2.5 mL) was added dropwise to a solution of methyl-tbutylsulfoxide (110 mg, 0.72 mmol, 1.1 eq) in diethyl ether

(2.5 mL)

  3H, CH(CH 3 ) 2 ); 1.39 (s, 9H, C(CH 3 ) 3 ); 2.09 (d, 2H, 2 J HH = 11.8 Hz, GeCH 2 SO); 2.45 (d, 2H, 2 J HH = 11.8 Hz, GeCH 2 SO); 4.32 (sept.,3 J HH = 6.3 Hz, 2H, CH(CH 3 ) 2 ). at the same temperature (0 °C). Then, the solution was cooled at -78 °C and added dropwise to a solution of chlorogermylene (194 mg, 0.67 mmol, 1 eq) in THF (2.5 mL) at -78 °C. The mixture was stirred during 1.5 hours at -78 °C. Then, the solution was evaporated by vacuum and the mixture was extracted with pentane (8 mL). Finally, the filtrate was evaporated under reduced pressure to afford an oil (180 mg) in 71% yield.1 H NMR (300.18 MHz, THFd 8 , 25 °C): δ 1.13 (d,3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 1.20 (d,3 J HH = 6.3 Hz, 6H, CH(CH 3 )

	N	O
	Ge
	N	S
		Amidinate	(di-iso-propyle-t-butyl)	germylene
		methylphenylthioether (1g): n-BuLi (540 µL, 0.87 mmol, 1.3 eq, C =
		1.6 M in hexane) was added dropwise to a solution of thioanisole (108
		mg, 0.87 mmol, 1.3 eq) in THF (2 mL) at 0 °C. The solution was stirred
	N N during 2 hour The resulting Ge S O
	mixture was added dropwise to a solution of chlorogermylene (218 mg, 0.75 mmol, 1 eq) in
	THF (2 mL) at -78 °C. The mixture was stirred during 1 hours at -78 °C. The solvent was
	evaporated under reduced pressure and the resulting solid was extracted with toluene (2x3 mL)
	at room temperature. Finally, the solvent was removed under reduced pressure to afford a pale
	white solid (268 mg) in 87% yield. Suitable crystals for X-ray cristallography were obtained
	from a saturated solution of pentane. M.p. : 112 °C. 1 H NMR (300.18 MHz, C 6 D 6 , 25 °C): δ
	0.99 (s, 9H, C(CH 3 ) 3 ); 1.05 (d, 3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 1.10 (d, 3 J HH = 6.3 Hz, 6H,
	CH(CH 3 )

1

H NMR (300.

18

MHz, THF-d 8 , 25 °C): δ 1.14 (s, 9H, C(CH 3 ) 3 ); 1.11 (d, 2 ); 1.42 (s, 9H, C(CH 3 ) 3 ); 2.35 (s, 2H, GeCH 2 SPh); 4.32 (sept.,

3

J HH = 6.3 Hz, 2H, CH(CH 3 ) 2 ); 7.10-7.25 (m, 5H, CH Ar ).

13

C{ 1 H} NMR (75.48 MHz, THF-d 8 , 25 °C): δ 23.8 (CH(CH 3 ) 2 ); 27.4 (CH(CH 3 ) 2 ); 29.4 (C(CH 3 ) 3 ); 31.9 (GeCH 2 SPh); 40.8 (C(CH 3 ) 3 ); 47.5 (CH(CH 3 ) 2 ); 123.9 (C Ar ); 126.2 (C Ar ); 128.7 (C Ar ); 144.4 (C Ar/q ); 171.7 (N-C-N).

Amidinate

(di-iso-propyle-t-butyl) germylene methylphenylsulfone (1h): n-BuLi (510 µL, 0.82 mmol, 1.1 eq, C =

1.6 M in hexane) was added dropwise to a solution of methylphenylsulfone (129 mg, 0.82 mmol, 1.1 eq) in THF (5 mL) at -40 °C. The solution was stirred during 1 hour at the same temperature (-40 °C). 2 ); 3.18 (s, 2H, GeCH 2 SO 2 ); 3.94 (sept., 3 J HH = 6.3 Hz, 2H, CH(CH 3 ) 2 ); 7.01-7.07 (m, 3H, CH Ar ); 8.04-8.09 (m, 2H, CH Ar ). 13 C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 24.1

  J HH = 6.3 Hz, 2H, CH(CH 3 ) 2 ); 4.43 (sept.,3 J HH = 6.3 Hz, 2H, CH(CH 3 ) 2 ); 6.88 (d, 4H, 3 J HH = 8.2 Hz, CH Ar ); 7.51 (d, 4H, 3 J HH = 8.2 Hz, CH Ar ).13 C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 21.1 (p-CH 3 ); 23.2 (CH(CH 3 ) 2 ); 23.3 (CH(CH 3 ) 2 ); 26.0 (CH(CH 3 ) 2 ); 26.2 (CH(CH 3 ) 2 ); 29.3 (C(CH 3 ) 3 ); 39.8 (C(CH 3 ) 3 ); 47.8 (CH(CH 3 ) 2 ); 47.9 (CH(CH 3 ) 2 ); 59.6 (GeCH 2 SO); 123.7 (C Ar ); 129.9 (C Ar );

		Cl
			Sn
	ClL 2 Sn	O	O SnL 2 Cl
			Sn
			Cl
	L = Amidinate di-iso-propyl-t-butyl
	139.7 (C Ar/q ); 148.
					O
						S
		N	OC CO
	N	Ge	W	Ge	N
			OC	CO	N
		S	O

  Hz, CH Ar ); 5.38 (dd, 1H,3 J HH = 5.8 Hz,4 J HH = 1.3 Hz, CH Ar ); 6.86-6.96 (m, 2H, CH Ar ); 7.52-7.55 (m, 2H, CH Ar ).13 C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 18.6 (p-CH 3 ); 22.9 NMR (300.18 MHz, C 6 D 6 , 25 °C): δ 0.95 (s, 9H, SO-C(CH 3 ) 3 ); 1.23 -1.31 (m, 12H, CH(CH 3 ) 2 ); 1.28 (s, 9H, C(CH 3 ) 3 ); 1.49 (d,3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.56 (d,3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.94 (s, 3H, p-CH 3 ); 2.98 (sept.,3 J HH = 6.3 Hz, 1H, CH(CH 3 ) 2 ); 3.24 (d, 1H, 2 J HH = 13.8 Hz, GeCH 2 SO); 3.32 (d, 1H, 2 J HH = 13.8 Hz, GeCH 2 SO); ) and dichloro(p-cymene)ruthenium dimer (68 mg, 0.11 mmol, 0.5 eq) was added to the solution. The mixture was stirred during 15 hours at room temperature, then filtered and the solvent removed under reduced pressure. Finally, the red solid was washed with Et 2 O

	11.7085(8) 13.3702(10) 79.929(3) 77.221(2) 70.656(2) 3136.1(2) 1 Amidinate methylphenylsulfoxide Ruthenium complex (5a): A solution of no of reflns collected / 21442 unique 5306 [R(int) = 0.0717] Completeness to θmax(%) 98.6 data/restraints/params 5306 / 37 / 332 goodness-of-fit 1.123 R1, wR2 (I > 2σ(I)) 0.0658, 0.0867 R1, wR2 (all data) 0.0947, 0.0939 (di-iso-propyle-t-butyl) germylene amidinate (di-iso-propyle-t-butyl) germylene methylphenylsulfoxyde 1a (151 mg, 0.38 mmol, 1eq) with tris(triphenylphosphine)ruthenium(II) dichloride (364mg, 0.38 mmol, 1eq) in tetrahydrofran (5 mL) was stirred during 15 hour at room temperature. Then, the mixture was filtered and the solvent was removed under reduced c (Å) a (deg.) b (deg.) g (deg.) V (Å3) Z pressure in order to obtain a red solid. Finally, the resulting solid was washed with diethyl ether (3x5 mL) to afford a red solid (240 mg) in 58% yield. M.p. : 145 °C (decomposition); 1 H NMR (300.18 MHz, C 6 D 6 ): δ 0.78 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 0.88 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 0.94 (s, 9H, C(CH 3 ) 3 ); 1.09 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.35 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 2.86 (d, 1H, 2 J HH = 13.8 Hz, GeCH 2 SO); 3.61 (d, 1H, 2 J HH = 13.8 Hz, GeCH 2 SO); 3.69 (sept., 3 J HH = 6.3 Hz, 2H, CH(CH 3 ) 2 ); 6.90 (m, 3H, CH Ar(sulfoxide) ); 7.09 (m, 19H, CH Ar(phosphine) ); 7.45 (m, 2H, CH Ar(sulfoxide) ); 7.93 (m, 11H, CH Ar(phosphine) ). 13 C{ 1 H} NMR (75.48 MHz, C 6 D Formula C54H60Cl2GeN2OP2RuS dcalc (g/cm 3 ) 1.417 Mol wt 1091.62 µ (mm -1 ) 1.130 Temp. (K) 193(2) F(000) 2248 Cryst syst Monoclinic cryst size (mm) 0.04 x 0.04 x 0.02 Space group P2 1 /c θ range (deg.) 3.45 to 25.35 a (Å) 12.5612(6) index range h k l -15<=h<=14, -29<=k<=29, -20<=l<=19 b (Å) 24.1634(10) no of reflns collected / 58061 c (Å) 16.9752(9) unique 9335 [R(int) = 0.1056] a (deg.) 90 Completeness to θmax(%) 99.6 N N Ge S O Ru Cl Cl Ph 3 P Ph 3 P b (deg.) 96.627(2) data/restraints/params 9335 / 0 / 584 g (deg.) 90 goodness-of-fit 1.032 V (Å3) 5117.9(4) R1, wR2 (I > 2σ(I)) 0.0446, 0.0996 Z 4 R1, wR2 (all data) 0.0866, 0.1195 Amidinate (di-iso-propyle-t-butyl) germylene methyl-p-tolylsulfoxide Ruthenium complex (5c): A solution of amidinate (di-iso-propyle-t-butyl) germylene methyl-p-tolylsulfoxyde 1b (151 mg, 0.38 mmol, 1eq) with tris(triphenylphosphine)ruthenium(II) dichloride (364mg, 0.38 mmol, 1eq) in tetrahydrofran (5 mL) was stirred during 15 hour at Formula C46H58Cl2GeN2OP2 RuS, 1.5(C4H10O) dcalc (g/cm 3 ) 1.375 Mol wt 1104.68 µ (mm -1 ) 1.086 Temp. (K) 193(2) F(000) 1150 Cryst syst Triclinic cryst size (mm) 0.180 x 0.080 x 0.080 Space group P-1 θ range (deg.) 5.100 to 30.508 a (Å) 9.6109(7) index range h k l -13<=h<=13, -19<=k<=19, -30<=l<=30 b (Å) 13.8981(11) no of reflns collected / 100922 c (Å) 21.5911(16) unique 16207 [R(int) = 0.0637] a (deg.) 101.572(3) Completeness to θmax(%) 99.1 b (deg.) 95.184(3) data/restraints/params 16207 / 87 / 632 g (deg.) 106.959(3) goodness-of-fit 1.024 V (Å3) 2668.2(4) R1, wR2 (I > 2σ(I)) 0.0355, 0.0762 Z 2 R1, wR2 (all data) 0.0555, 0.0845 N N Ge S O Ru Cl Cl P P Ph Ph Ph Ph Amidinate (di-iso-propyle-t-butyl) germylene methylphenylsulfoxide Ruthenium complex (6a): Amidinate (di-iso-propyle-t-butyl) germylene methylphenylsulfoxide 1a (170 mg, 0.43 mmol, 1 eq) was dissolved in tetrahydrofran (5 mL) and dichloro(p-cymene)ruthenium dimer (132 mg, 0.215 mmol, 0.5 eq) was added to the solution. The mixture was stirred during 15 hours at room temperature, then, filtered and the solvent removed under reduced pressure. Finally, the red solid was washed with Et 2 O (2x3 mL) in order to obtain a pale red solid (247 mg) in 82% yield. M.p. : 164 °C (decomposition); 1 H NMR (300.18 MHz, CD 2 Cl 2 , 25 °C): δ 1.29-1.37 (m, 9H, CH(CH 3 ) 2 ); 1.38-1.44 (d, 3 J HH = 6.3 Hz, 9H, CH(CH 3 ) 2 ); 1.59 (s, 9H, C(CH 3 ) 3 ); 2.21 (s, 3H, p-CH 3 ); 2.86 (sept., 3 J HH = 6.3 Hz, 1H, CH(CH 3 ) 2 ); 2.85 (d, 1H, 2 J HH = 13.8 Hz, GeCH 2 SO); 3.12 (d, 1H, 2 J HH = 13.8 Hz, GeCH 2 SO); 4.42 (sept., 3 J HH = 6.3 Hz, 2H, CH(CH 3 ) 2 ); 5.08 (m, 2H, CH Ar ); 5.41 (dd, 1H, 3 J HH = 5.8 Hz, 4 J HH = 1.3 Hz, CH Ar ); 5.53 (dd, 1H, 3 J HH = 5.8 Hz, 4 J HH = 1.3 Hz, CH Ar ); 7.39-7.45 (m, 3H, CH Ar ); 7.51-7.55 (m, 2H, CH Ar ). Formula C28H44Cl2GeN2ORuS dcalc (g/cm 3 ) 1.493 Mol wt 701.29 µ (mm -1 ) 1.708 Temp. (K) 193(2) F(000) 1440 Cryst syst Monoclinic cryst size (mm) 0.48 x 0.34 x 0.28 Space group P2 1 /n θ range (deg.) 2.99 to 31.00 a (Å) 9.1389(14) index range h k l -13<=h<=13, -29<=k<=29, -24<=l<=24 b (Å) 20.527(3) no of reflns collected / 117282 c (Å) 16.685(3) unique 9912 [R(int) = 0.0353] a (deg.) 90 Completeness to θmax(%) 99.6 b (deg.) 94.363(7) data/restraints/params 99.12 / 511 / 501 g (deg.) 90 goodness-of-fit methylphenylthioether 1g (85 mg, 0.22 mmol, 1 eq) was dissolved in 1.145 N N Ge S Ru Cl Cl O V (Å3) 3120.9(8) R1, wR2 (I > 2σ(I)) 0.0465, 0.0963 Z 4 R1, wR2 (all data) 0.0524, 0.1004 Amidinate(di-iso-propyle-t-butyl) germylene methyl-p-tolylsulfoxide Ruthenium complex (6b): Amidinate (di-iso-propyle-t-butyl) germylene methyl-p-tolylsulfoxide 1b (135 mg, 0.330 mmol, 1 eq) was dissolved in tetrahydrofran (5 mL) and dichloro(p-cymene)ruthenium dimer (101 mg, 0.165 mmol, 0.5 eq) was added to the solution. The mixture was stirred during 15 hours at room temperature, then filtered and the solvent removed under reduced pressure. Finally, the red solid was washed with Et 2 O (2x3 mL) in order to obtain a pale red solid (189 mg) in 80% yield. Suitable crystals for x-ray crystallography were obtained from a saturated solution of THF at -24 °C. M.p. : 169 °C (decomposition); 1 H NMR (300.18 MHz, C 6 D 6 , 25 °C): δ 1.23 (d, 3 J HH = 6.8 Hz, 3H, CH(CH 3 ) 2 ); 1.24 (d, 3 J HH = 6.8 Hz, 3H, CH(CH 3 ) 2 ); 1.27 (d, 3 J HH = 6.8 Hz, 3H, CH(CH 3 ) 3.72 (d, 1H, 2 J HH = 13.8 Hz, GeCH 2 SO); 4.14 (sept., 3 J HH = 6.3 Hz, 1H, CH(CH 3 ) 2 ); 4.28 (sept., 3 J HH = 6.3 Hz, 1H, CH(CH 3 ) 2 ); 4.78 (dd, 1H, 3 J HH = 5.8 Hz, 4 J HH = 1.3 Hz, CH Ar ); 4.82 (dd, 1H, 3 J HH = 5.8 Hz, 4 J HH = 1.3 Hz, CH Ar ); 5.25 (dd, 1H, 3 J HH = 5.8 Hz, 4 J HH = 1.3 Hz, CH Ar ); 5.33 (dd, 1H, 3 J HH = 5.8 Hz, 4 J HH = 1.3 Hz, CH Ar ); 6.77 (d, 2H, 3 J HH = 8.2 Hz, CH Ar ); 7.45 (d, 2H, 3 J HH = 8.2 Hz, CH Ar ). 13 C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 18.8 (p-CH 3 ); 21.1 (p-CH 3 ); 22.8 (CH(CH 3 ) 2 ); 23.2 (CH(CH 3 ) 2 ); 24.4 (CH(CH 3 ) 2 ); 25.0 (CH(CH 3 ) 2 ); 25.9 (CH(CH 3 ) 2 ); 26.7 (CH(CH 3 ) 2 ); 29.0 (C(CH 3 ) 3 ); 31.2 (CH(CH 3 ) 2 ); 39.4(C(CH 3 ) 3 ); 48.0 (CH(CH 3 ) 2 ); 48.1 (CH(CH 3 ) 2 ); 50.6 (GeCH 2 SO); 80.8 (C Ar ); 81.5 (C Ar ); 86.8 (C Ar ); 88.1 (C Ar ); 94.0 (C Ar/q ); 108.2 (C Ar/q ); 123.6 (C Ar ); 129.9 (C Ar ); 139.6 (C Ar/q ); 147.4 (C Ar/q ); 176.9 (N-C-N). MS m/z (anthracene matrix) : 681 ([M -Cl] + ), 547 ([M -Cl -p-Cymene] + ). HRMS (ESI) m/z (%): 717.1054 ([M + 1] + ) calcd for C 29 H 46 GeCl 2 N 2 ORuS ([M + 1] + ) 717.1046. IR (Nujol, cm -1 ): 1462 (med) (C=C arene ), 1017 (med) (SO). Formula C29H46Cl2GeN2ORuS dcalc (g/cm 3 ) 1.515 Mol wt 715.30 µ (mm -1 ) 1.702 Temp. (K) 193(2) F(000) 1472 N N Ge S Ru Cl c (Å) 15.4835(6) unique 7729 [R(int) = 0.0799] a (deg.) 90 Completeness to θmax(%) 99.1 b (deg.) 107.5740(16) data/restraints/params 7729 / 542 / 500 g (deg.) 90 goodness-of-fit V (Å3) 3136.1(2) R1, wR2 (I > 2σ(I)) 0.0364, 0.0624 Z 4 R1, wR2 (all data) 0.0748, 0.0728 Amidinate (dicyclohexyl-t-butyl) germylene C 6 D 6 , 25 °C): δ 1.08-1.21 (m, 4H, 4H, (CH 2 ) cy ); 1.24 (d, 3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 1.27 (d, 3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 1.40 (s, 9H, C(CH 3 ) 3 ); 1.43-1.94 (m, 12H, (CH 2 ) cy ); 1.97 (s, 3H, p-CH 3 ); 2.01-2.22 (m, 2H, (CH 2 ) cy ); 2.36 (m, 1H, (CH 2 ) cy ); 2.67 (m, 1H, (CH 2 ) cy ); 2.94 (sept., 3 J HH = 6.3 Hz, 1H, CH(CH 3 ) 2 ); 3.60 (d, 1H, 2 J HH = 13.8 Hz, GeCH 2 SO); 3.76 (d, 1H, 2 J HH = 13.8 Hz, GeCH 2 SO); 3.87 (m, 1H, CH(CH 2 ) 2 ); 3.97 (m, 1H, CH(CH 2 ) 2 ); 4.87 (dd, 1H, 3 J HH = 5.8 Hz, 4 J HH = 1.3 Hz, CH Ar ); 4.94 (dd, 1H, 3 J HH = 5.8 Hz, 4 J HH = 1.3 Hz, CH Ar ); 5.31 (dd, 1H, 3 J HH = 5.8 Hz, 4 J HH = 1.3 Hz, CH Ar ); 5.38 (dd, 1H, 3 J HH = 5.8 Hz, 4 J HH = 1.3 Hz, CH Ar ); 6.86-6.96 (m, 2H, CH Ar ); 7.52-7.55 (m, 2H, CH Ar ). 13 C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 18.6 (p-CH 3 ); 22.9 (CH(CH 3 ) 2 ); 23.2 (CH(CH 3 ) 2 ); 25.3 (CH 2 ); 25.7 (CH 2 ); 25.9 (CH 2 ); 26.0 N N Ge S Ru Cl Cl O 29<=l<=29 b (Å) 9.3573(3) no of reflns collected / c (Å) 20.8554(7) unique 10806 [R(int) = 0.0560] a (deg.) 90 Completeness to θmax(%) 99.8 b (deg.) 90 data/restraints/params 10806 / 1 / 386 g (deg.) 90 goodness-of-fit 1.074 V (Å3) 3529.3(2) R1, wR2 (I > 2σ(I)) 0.0325, 0.0597 Z 4 R1, wR2 (all data) 0.0446, 0.0652 Amidinate(dicyclohexyl-t-butyl) germylene methyl-p-tolylsulfoxyde 1d (110 mg, 0.22 mmol, 1 eq) was dissolved in tetrahydrofran (5 mL) and dichloro(p-cymene)ruthenium dimer (69 mg, 0.11 mmol, 0.5 eq) was added to the solution. The mixture was stirred during 15 hours at room temperature, then, filtered and the solvent removed under reduced pressure. Finally, the red solid was washed with Et 2 O (2x2 mL) in order to obtain a pale red solid (138 mg) in 79% yield. M.p.: 175°C (decomposition); 1 H NMR (300.18 MHz, C 6 D 6 , 25 °C): δ 1.08-1.21 (m, 4H, 4H, (CH 2 ) cy ); 1.24 (d, 3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 1.27 (d, 3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 1.40 (s, 9H, C(CH 3 ) 3 ); 1.43-1.94 (m, 12H, (CH 2 ) cy ); 1.97 (s, 3H, p-CH 3 ); 2.01-2.22 (m, 2H, (CH 2 ) cy ); 2.36 (m, 1H, (CH 2 ) cy ); 2.67 (m, 1H, (CH 2 ) cy ); 2.94 (sept., 3 J HH = 6.3 Hz, 1H, Amidinate (di-iso-propyle-t-butyl) germylene methyl-t-butylsulfoxide Ruthenium dichloro p-cymene complex (6f): Amidinate (di-iso-propyl-t-butyl) germylene methyl-t-butylsulfoxide 1f (110 mg, 0.29 mmol, 1 eq) was dissolved in tetrahydrofran (5 mL) and dichloro(p-cymene)ruthenium dimer (89 mg, 0.145 mmol, 0.5 eq) was added to the solution. The mixture was stirred during 15 hours at N N Ge S Ru Cl Cl O b (deg.) 95.520(2) data/restraints/params 12768 / 81 / 350 g (deg.) 90 goodness-of-fit 1.037 V (Å3) 1530.76(13) R1, wR2 (I > 2σ(I)) 0.0186, 0.0470 Z 2 R1, wR2 (all data) 0.0207, 0.0480 Amidinate (di-iso-propyle-t-butyl) germylene methylphenylthioether Ruthenium dichloro p-cymene complex (6g): Amidinate (di-iso-propyl-t-butyl) germylene N N Ge S Ru Cl Cl c (Å) 18.5286(10) unique 12937 [R(int) = 0.0456] a (deg.) 90 Completeness to θmax(%) 99.5 b (deg.) 98.650(3) data/restraints/params 12937 / 78 / 353 g (deg.) 90 goodness-of-fit 1.014 V (Å3) 3007.3(3) R1, wR2 (I > 2σ(I)) 0.0360, 0.0714 Z 4 R1, wR2 (all data) 0.0675, 0.0812 Temp. (K) 193(2) F(000) 2944 Cryst syst Monoclinic cryst size (mm) 0.16 x 0.15 x 0.07 Space group P2 1 /n θ range (deg.) 2.94 to 25.68 a (Å) 18.7846(10) index range h k l -22<=h<=22, -21<=k<=21, -25<=l<=25 b (Å) 17.6499(8) no of reflns collected / 249295 c (Å) 20.9404(11) unique 12278 [R(int) = 0.0753] 90 θmax(%) 99.8 a (deg.) Completeness to CH(CH 3 ) N N Ge S Ru Cl Cl O Temp. (K) 193(2) F(000) Cryst syst Monoclinic cryst size (mm) Space group P2 1 /n 3.49 to 27.48 a (Å) 9.5361(14) index range h k l -12<=h<=12, -20<=k<=20, -32<=l<=32 b (Å) 15.417(2) no of reflns collected / 58979 c (Å) 24.820(5) unique 8267 [R(int) = 0.0507] a (deg.) 90 Completeness to θmax(%) 99.8 b (deg.) 97.325(7) data/restraints/params 8267 / 72 / 422 g (deg.) 90 goodness-of-fit 1.145 V (Å3) 3619.2(10) R1, wR2 (I > 2σ(I)) 0.0326, 0.0887 Z 4 R1, wR2 (all data) 0.0470, 0.0965 Formula C26H48Cl2GeN2ORuS dcalc (g/cm 3 ) 1.478 Mol wt 681.30 µ (mm -1 ) 1.739 Temp. (K) 193(2) F(000) 704 Cryst syst Monoclinic cryst size (mm) 0.200 x 0.180 x 0.140 Space group P2 1 θ range (deg.) 4.104 to 34.337 a (Å) 10.3057(5) index range h k l -16<=h<=16, -18<=k<=18, -18<=l<=20 b (Å) 11.3503(6) no of reflns collected / c (Å) 13.1474(6) unique a (deg.) 90 Completeness to θmax(%) 99.5 29<=l<=29 b (Å) 14.4680(7) no of reflns collected / 43298 Mol wt 717.29 1.652 µ (mm -1 ) 12768 [R(int) = 0.0234] a (Å) 11.3474(6) index range h k l -17<=h<=18, -23<=k<=22, -Formula 1.472 C28H44Cl2GeN2O2RuS dcalc (g/cm 3 ) 44633 C28H44Cl2GeN2RuS dcalc (g/cm 3 ) 1.514 Mol wt 685.29 µ (mm -1 ) 1.769 Temp. (K) 193(2) F(000) 1408 Cryst syst Monoclinic cryst size (mm) 0.140 x 0.060 x 0.010 Space group P2 1 /n 4.200 to 34.750 1305 (med) (SO), 1140 (med) (SO). θ range (deg.) 7.68-7.77 (m, 2H, CH Ar ). 719.0850 ([M + 1] + ) calcd for C 28 H 44 Cl 2 GeN 2 O 2 RuS ([M -Cl] + ) 719.0838. IR (Nujol, cm -1 ): 129.0 (C Formula 4.75 (d, 2H, 3 J HH = 5.8 Hz, CH Ar ); 5.24 (d, 2H, 3 J HH = 5.8 Hz, CH Ar ); 6.73-6.84 (m, 3H, CH Ar ); θ range (deg.) 1] + ) 683.1201. (CH(CH 3 ) 2 ); 80.4 (C Ar ); 87.9 (C Ar ); 94.2 (C Ar/q ); 108.7 (C Ar/q ); 124.5 (C Ar ); 126.8 (C Ar ); 6.3 Hz, 1H, CH(CH 3 ) 2 ); 4.15 (s, 2H, GeCH 2 SO 2 ); 4.22 (sept., 3 J HH = 6.3 Hz, 2H, CH(CH 3 ) 2 ); 0.08 x 0.08 x 0.02 1017 (med). HRMS (ESI) m/z (%): 683.1205 ([M + 1] + ) calcd for C 26 H 48 GeCl 2 N 2 ORuS ([M + 23.8 (CH(CH 3 ) 2 ); 25.9 (CH(CH 3 ) 2 ); 29.3 (C(CH 3 ) 3 ); 31.2 (CH(CH 3 ) 2 ); 39.2 (C(CH 3 ) 3 ); 48.0 9H, C(CH 3 ) 3 ); 1.67 (d, 3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 1.91 (s, 3H, p-CH 3 ); 2.95 (sept., 3 J HH = 1648 (C Ar/q ); 87.2 (C Ar/q ); 88.2 (C Ar ); 93.9 (C Ar/q ); 108.3 (C Ar/q ); 176.7 (N-C-N). IR (Nujol, cm -1 ): 13 C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 18.9 (p-CH 3 ); 22.8 (GeCH 2 SPh); 23.0 (CH(CH 3 ) 2 ); °C): δ 1.23 (d, 3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 1.29 (d, 3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 1.32 (s, 10.5479 Mol wt 795.44 µ (mm -1 ) 1.483 39.3 (C(CH 3 ) 3 ); 47.9 (CH(CH 3 ) 2 ); 48.0 (CH(CH 3 ) 2 ); 54.3 (GeCH 2 SO); 80.6 (C Ar/q ); 81.4 2H, CH Ar ); 6.80-6.85 (m, 1H, CH Ar ); 6.92-6.97 (m, 2H, CH Ar ); 7.24-7.27 (m, 2H, CH Ar ). solution of THF at -24 °C. M.p.: 178 °C (decomposition); 1 H NMR (300.18 MHz, C 6 D 6 , 25 1.017 Cryst syst Orthorhombic cryst size (mm) Space group Pca2 1 θ range (deg.) a (Å) 18.0845(6) index range h k l 13<=k<=13, -Formula C35H54Cl2GeN2ORuS dcalc (g/cm 3 ) 1.460 26.0 (CH(CH 3 ) 2 ); 26.6 (CH(CH 3 ) 2 ); 28.9 (C(CH 3 ) 3 ); 31.2 (CH(CH 3 ) 2 ); 36.8 (SO-C(CH 3 ) 3 ); (sept., 3 J HH = 6.3 Hz, 2H, CH(CH 3 ) 2 ); 4.68 (d, 3 J HH = 5.7 Hz, 2H, CH Ar ); 5.27 (d, 3 J HH = 5.7 Hz, mg) in 84% yield. Suitable crystals for X-ray crystallography were obtained from a saturated -25<=h<=23, -C 35 H 54 GeCl 2 N 2 ORuS ([M + 1] + ) 797.1674. 22.6 (SOC(CH 3 ) 3 ); 22.8 (CH(CH 3 ) 2 ); 23.1 (CH(CH 3 ) 2 ); 24.3 (CH(CH 3 ) 2 ); 24.9 (CH(CH 3 ) 2 ); 1.93 (s, 3H, p-CH 3 ); 3.02 (sept., 3 J HH = 6.3 Hz, 1H, CH(CH 3 ) 2 ); 3.65 (s, 2H, GeCH 2 SPh); 3.96 Finally, the red solid was washed with Et 2 O (2x3 mL) in order to obtain a pale red solid (293 2.925 to 30.559 150.3 (C Ar/q ); 176.8 (N-C-N). HRMS (ESI) m/z (%): 797.1659 ([M + 1] + ) calcd for 5.31 (d, 1H, 3 J HH = 5.8 Hz, CH Ar ). 13 C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 18.8 (p-CH 3 ); hours at room temperature, then filtered and the solvent removed under reduced pressure. CH(CH 3 ) 2 ); 1.28 (d, 3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 1.33 (d, 3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 0.500 x 0.160 x 0.050 (C Ar/q ); 86.1 (C Ar/q ); 87.9 (C Ar ); 93.8 (C Ar/q ); 106.7 (C Ar/q ); 123.7 (C Ar ); 129.2 (C Ar ); 129.6 (C Ar ); 1H, 3 J HH = 5.8 Hz, CH Ar ); 4.75 (d, 1H, 3 J HH = 5.8 Hz, CH Ar ); 5.25 (d, 1H, 3 J HH = 5.8 Hz, CH Ar ); (149 mg, 0.243 mmol, 0.5 eq) was added to the solution. The mixture was stirred during 15 NMR (300.18 MHz, C 6 D 6 , 25 °C): δ 1.20 (s, 9H, C(CH 3 ) 3 ); 1.21 (d, 3 J HH = 6.3 Hz, 6H, Cl O Cryst syst Monoclinic cryst size (mm) 0.040 x 0.040 x 0.020 Space group P2 1 /n θ range (deg.) 5.104 to 28.282 a (Å) 15.0511(6) index range h k l -20<=h<=20, -18<=k<=18, -19<=l<=20 b (Å) 14.1158(6) no of reflns collected / 75426 (C Ar/q ); 82.7 (C Ar/q ); 86.1 (C Ar/q ); 87.9 (C Ar ); 93.8 (C Ar/q ); 106.7 (C Ar/q ); 123.7 (C Ar ); 129.2 (C Ar ); 129.6 (C Ar ); 150.3 (C Ar/q ); 176.8 (N-C-N). Formula C34H52Cl2GeN2ORuS dcalc (g/cm 3 ) 1.471 Mol wt 781.39 µ (mm -1 ) 1.519 Temp. (K) 193(2) F(000) 1616 1.3 (CH(CH 3 ) 2 ); 23.2 (CH(CH 3 ) 2 ); 25.3 (CH 2 ); 25.7 (CH 2 ); 25.9 (CH 2 ); 26.0 (CH 2 ); 26.2 (CH 2 ); 26.3 (CH 2 ); 29.1 (C(CH 3 ) 3 ); 31.2 (CH(CH 3 ) 2 ); 34.3 (CH 2 ); 34.8 (CH 2 ); 36.2 (CH 2 ); 37.4 (CH 2 ); 39.5 (C(CH 3 ) 3 ); 50.7 (GeCH 2 SO); 56.2 (CH(CH 2 ) 2 ); 56.5 (CH(CH 2 ) 2 ); 81.7 (C Ar/q ); 82.7 : 84 °C (decomposition); 1 H 4.09 (sept., 3 J HH = 6.3 Hz, 1H, CH(CH 3 ) 2 ); 4.20 (sept., 3 J HH = 6.3 Hz, 1H, CH(CH 3 ) 2 ); 4.73 (d, Amidinate (di-iso-propyle-t-butyl) germylene methylphenylsulfone Ruthenium dichloro p-cymene complex (6h): Amidinate (di-iso-propyl-t-butyl) germylene N N Ge S Ru Cl Cl O O b (deg.) 111.232(2) data/restraints/params 12278 / 452 / 825 g (deg.) 90 goodness-of-fit 1.060 V (Å3) 6471.4(6) R1, wR2 (I > 2σ(I)) 0.0314, 0.0654 tetrahydrofran (5 mL(2x3 mL) to obtain a red solid (104 mg) in 69% yield. Suitable crystals for x-ray crystallography in tetrahydrofran (5 mL) and dichloro(p-cymene)ruthenium dimer were obtained from a saturated solution of THF at -24 °C. M.p.: 158 °C (decomposition); 1 H methylphenylsulfone 1h (200 mg, 0.486 mmol, 1 eq) was dissolved Z 8 R1, wR2 (all data) 0.0475, 0.0738

6

): δ 24.0 (CH(CH 3 ) 2 ); 24.8 (CH(CH 3 ) 2 ); 25.0 (CH(CH 3 ) 2 ); 25.5 (CH(CH 3 ) 2 ); 29.2 (C(CH 3 ) 3 ); 38.9 (C(CH 3 ) 3 ); 47.5 (CH(CH 3 ) 2 ); 47.9 (CH(CH 3 ) 2 ); 49.2 (GeCH 2 SO); 125.8 (C Ar(sulfoxide) ); 127.0 ( 3 J PC = 9.0 Hz, C Ar(phosphine) ); 128.7 (C Ar(phosphine) ); 128.9 (C Ar(sulfoxide) ); 125.8 (C Ar(sulfoxide) ); 134.2 ( 2 J PC = 19.6 Hz, C Ar(phosphine) ); 138.0 ( 1 J PC = 12.2 Hz, C Ar/q(phosphine) ); 144.2 (C Ar/q(sulfoxide) ); 175.5 (N-C-N).

31

P NMR (121.49 MHz, C 6 D 6 ): δ 24.5 (br, Ru-PPh 3 ); 55.5 (br, Ru-PPh 3 ). MS (Maldi-TOF) m/z (%): 830 (M -PPh 3 ), 795 (M -(PPh 3 + Cl)), 760 (M -(PPh 3 + Cl + Cl)). IR (Nujol, cm -1 ): 934 (med) (SO).

room temperature. Then, DPPP (158 mg, O.45 mmol, 1.2 eq) was added to the mixture and stirred 4 hour and the solvent was evaporated under vacuum. Finally, the red solid was washed with pentane (3x5 mL) in order to obtain a pale red solid.

31

P{ 1 H} NMR (121.49 MHz, C 6 D 6 ): δ 26.1 (d, 3 J PP = 47.3 Hz, Ru-PPh 2 ); 47.5 (d, 3 J PP = 47.3 Hz, Ru-PPh 2 ). 13 C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 18.6 (p-CH 3 ); 22.9 (CH(CH 3 ) 2 ); 23.2 (CH(CH 3 ) 2 ); 25.9 (CH(CH 3 ) 2 ); 26.0 (CH(CH 3 ) 2 ); 26.1 (CH(CH 3 ) 2 ); 26.2 (CH(CH 3 ) 2 ); 29.1 (C(CH 3 ) 3 ); 31.2 (CH(CH 3 ) 2 ); 39.5 (C(CH 3 ) 3 ); 50.6 (GeCH 2 SO); 56.2 (CH(CH 3 ) 2 ); 56.5 (CH(CH 3 ) 2 ); 81.7 (C Ar ); 82.7 (C Ar ); 86.1 (C Ar ); 87.9 (C Ar ); 93.8 (C Ar/q ); 106.7 (C Ar/q ); 123.7 (C Ar ); 129.2 (C Ar ); 129.6 (C Ar ); 150.3 (C Ar/q );

176.8 (N-C-N). 2 ); 1.33 (s, 9H, C(CH 3 ) 3 ); 1.35 (d,

3

J HH = 6.8 Hz, 3H, CH(CH 3 ) 2 ); 1.55 (d,

3

J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.57 (d,

3

J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.93 (s, 3H, p-CH 3 ); 1.95 (s, 3H, p-CH 3 ); 2.96 (sept.,

3

J HH = 6.3 Hz, 1H, CH(CH 3 ) 2 ); 3.54 (d, 1H, 2 J HH = 13.8 Hz, GeCH 2 SO); methylphenylsulfoxide Ruthenium dichloro p-cymene complex (6c): Amidinate(dicyclohexyl-t-butyl) germylene methylphenylsulfoxide 1c (65 mg, 0.139 mmol, 1 eq) was dissolved in tetrahydrofran (5 mL) and dichloro(pcymene)ruthenium dimer (42 mg, 0.139 mmol, 0.5 eq) was added to the solution. The mixture was stirred during 15 hours at room temperature, then filtered and the solvent removed under reduced pressure. Finally, the red solid was washed with Et 2 O (2x2 mL) in order to obtain a pale red solid

(84 mg)

in 78% yield. M.p. : 173 °C (decomposition); 1 H NMR (300.18 MHz, (CH 2 ); 26.2 (CH 2 ); 26.3 (CH 2 ); 29.1 (C(CH 3 ) 3 ); 31.2 (CH(CH 3 ) 2 ); 34.3 (CH 2 ); 34.8 (CH 2 ); 36.2 (CH 2 ); 37.4 (CH 2 ); 39.5 (C(CH 3 ) 3 ); 50.7 (GeCH 2 SO); 56.2 (CH(CH 2 ) 2 ); 56.5 (CH(CH 2

) 2 ); 81.7 Amidinate (dicyclohexyl-t-butyl) germylene methyl-ptolylsulfoxide Ruthenium dichloro p-cymene complex (6d): 2 ); 3.60 (d, 1H, 2 J HH = 13.8 Hz, GeCH 2 SO); 3.76 (d, 1H, 2 J HH = 13.8 Hz, GeCH 2 SO); 3.87 (m, 1H, CH(CH 2 ) 2 ); 3.97 (m, 1H, CH(CH 2 ) 2 ); 4.87 (dd, 1H, 3 J HH = 5.8 Hz, 4 J HH = 1.3 Hz, CH Ar ); 4.94 (dd, 1H, 3 J HH = 5.8 Hz, 4 J HH = 1.3 Hz, CH Ar ); 5.31 (dd, 1H, 3 J HH = 5.8 Hz, 4 J HH = room temperature, then filtered and the solvent removed under reduced pressure. Finally, the red solid was washed with Et 2 O (2x3 mL) in order to obtain a pale red solid (132 mg) in 67% yield. Crystallization from THF at -25 °C gave red crystals suitable for X-ray diffraction. M.p. Ar ); 141.2 (C Ar/q ); 175.2 (N-C-N). MS (Maldi-TOF) m/z (anthracene matrix) : 651 ([M -Cl] + ), 515 ([M -Cl -p-Cymene] + ). 13 C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 18.6 (p-CH 3 ); 22.9 (CH(CH 3 ) 2 ); 23.6 (CH(CH 3 ) 2 ); 26.5 (CH(CH 3 ) 2 ); 28.9 (C(CH 3 ) 3 ); 31.1 (CH(CH 3 ) 2 ); 39.3(C(CH 3 ) 3 ); 48.3 (CH(CH 3 ) 2 ); 48.7 (GeCH 2 SO); 81.7 (C Ar ); 87.2 (C Ar ); 94.0 (C Ar/q ); 108.4 (C Ar/q ); 126.5 (C Ar ); 129.0 (C Ar ); 131.9 (C Ar ); 145.7 (C Ar/q ); 177.9 (N-C-N). MS m/z (anthracene matrix) : 683 ([M -Cl] + ), 549 ([M -Cl -p-Cymene] + ). HRMS (ESI) m/z (%):

  and also better that the germylene with alkoxy bridge reported

by Du Mont et al. in 1984 (2070 cm -1 ) or the one reported by Denk et al. in 2011 (2071 cm - 1

).

38,45

  J HH = 6.3 Hz, 1H, CH(CH 3 ) 2 ); 6.87 (d, 1H, 3 J HH = 8.2 Hz, CH Ar ); 7.34 (s, 1H, CH Ar ); 8.17 (d, 1H, 3 J HH = 8.2 Hz, CH Ar ).13 C{ 1 H} NMR (75.48 MHz, C 6 D 6 ,

		Cryst syst				Monoclinic	cryst size (mm)	0.16 x 0.15 x 0.07
		Space group		P2 1 /n	θ range (deg.)	2.94 to 25.68
		a (Å)				18.7846(10)	index range h k l	-22<=h<=22, -21<=k<=21, -
								25<=l<=25
		b (Å)				17.6499(8)	no of reflns collected /	249295
		c (Å)				20.9404(11)	unique	12278 [R(int) = 0.0753]
		a (deg.)				90	Completeness to θmax(%)	99.8
		b (deg.)				111.232(2)	data/restraints/params	12278 / 452 / 825
	W(cod)(CO) 4	OC g (deg.) OC		S	O	90	goodness-of-fit	1.060
	THF vernight / R.T.	W V (Å3) OC CO Z	N	Ge	N	6471.4(6) 8	R1, wR2 (I > 2σ(I)) R1, wR2 (all data)	0.0314, 0.0654 0.0475, 0.0738
		25 °C): δ 20.9 (p-CH 3 ); 22.9 (CH(CH 3 ) 2 ); 24.0 (O=SC(CH 3 ) 3 ); 24.8 (CH(CH 3 ) 2 ); 25.6
		(CH(CH 3 ) 2 ); 25.7 (CH(CH 3 ) 2 ); 29.2 (C(CH 3 ) 3 ); 39.9 (C(CH 3 ) 3 ); 47.3 (CH(CH 3 ) 2 ); 48.1
		(CH(CH 3 ) 2 ); 65.8 (O=S-C(CH 3 ) 3 ); 125.7 (C Ar ); 130.0 (C Ar ); 130.1 (C Ar ); 140.9 (C Ar/q );
		149.4 (C Ar/q ); 153.4 (C Ar/q ); 177.9 (N-C-N); 202.1 (CO); 206.7 (CO); 208.3 (CO); 210.2 (CO).
		IR (Nujol, cm -1 ) : 2012 (s) (CO), 1901 (br) (CO), 1067 (s) (SO). MS m/z (%): 704.1 ([M -
		(CO+CH 3 )] + ). HRMS m/z (%): 747.1320 ([M + 1] + ) calcd for C 26 H 38 GeN 2 O 5 WS ([M + 1] + )
		747.1311.
		Formula				C28H44Cl2GeN2O2RuS dcalc (g/cm 3 )	1.472
		Mol wt				717.29	µ (mm -1 )	1.652
		Temp. (K)			193(2)	F(000)	2944

  J HH = 6.3 Hz, 1H, CH(CH 3 ) 2 ); 6.90 (d, 1H, 3 J HH = 8.2 Hz,

	CH Ar ); 7.32 (s, 1H, CH Ar ); 8.14 (d, 1H, 3 J HH = 8.2 Hz, CH Ar ). 13 C{ 1 H} NMR (75.48 MHz, C 6 D 6 ,
	25 °C): δ 21.0 (p-CH 3 ); 23.0 (CH(CH 3 ) 2 ); 23.9 (O=SC(CH 3 ) 3 ); 24.8 (CH(CH 3 ) 2 ); 25.8
	(CH(CH 3 ) 2 ); 25.9 (CH(CH 3 ) 2 ); 29.2 (C(CH 3 ) 3 ); 39.8 (C(CH 3 ) 3 ); 47.4 (CH(CH 3 ) 2 ); 48.2
	(CH(CH 3 )

2 ); 64.1 (O=S-C(CH 3 ) 3 ); 126.1 (C Ar ); 129.8 (C Ar ); 130.2 (C Ar ); 140.4 (C Ar/q ); 148.6 (C Ar/q ); 152.2 (C Ar/q ); 177.3 (N-C-N); 209.3 (CO); 213.9 (CO); 216.9 (CO); 220.8 (CO). IR (CH 2 Cl 2 , cm -1 ) : 2005 (s) (CO), 1882 (br) (CO), 1089 (s) (SO). MS m/z (%): 659.24 ([M + ).

  P{1 H} NMR (121.49 MHz, C 6 D 6 ): δ 38.0 (s, Ru-J HH = 6.3 Hz, 1H, CH(CH 3 ) 2 ); 4.07 (sept.,3 J HH = 6.3 Hz, 1H, CH(CH 3 ) 2 ); 6.18 (d, 1H,3 J HH = 8.2 Hz, CH Ar ); 6.72-7.43 (m, 45H, CH Ar ); 7.91-7.94 (m, 2H, CH Ar ). 13 C{ 1 H} NMR (125 MHz, CDCl 3 , 25 °C):

					Amidinate (diisopropyle-t-butyl) germylene t-butyl-p-
					tolylsulfoxide bis-Ruthenium phosphine complex
					(10b): 10a (135 mg, 0.15 mmol, 1 eq) was dissolved in
					THF (3 mL) in a vial and pentane was added in another
					vial. After two days of slow diffusion of pentane into THF,
					the crystals were filtered and washed with THF (2x 1mL)
					to obtain a pink solid (42 mg). M.p. : 144 °C
	(decomposition); Isomer A : 1 H NMR (500 MHz, CDCl 3 , 25 °C): δ 0.24 (d, 3 J HH = 6.6 Hz, 3H,
	CH(CH 3 ) 2 ); 0.45 (d, 3 J HH = 6.6 Hz, 3H, CH(CH 3 ) 2 ); 0.51 (d, 3 J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 0.81 (d, 3 J HH
	= 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.52 (s, 9H, C(CH 3 ) 3 ); 1.59 (s, 9H, C(CH 3 ) 3 ); 2.42 (s, 3H, p-CH 3 ); 3.91 (sept.,
	δ 21.5 (p-CH 3 ); 24.4 (CH(CH 3 ) 2 ); 24.8 (CH(CH 3 ) 2 ); 25.6 (CH(CH 3 ) 2 ); 26.1 (O=SC(CH 3 ) 3 ); 27.6
	(CH(CH 3 ) 2 ); 30.4 (C(CH 3 ) 3 ); 40.0 (C(CH 3 ) 3 ); 46.3 (CH(CH 3 ) 2 ); 48.1 (CH(CH 3 ) 2 ); 71.8 (O=S-C(CH 3 ) 3 );
	178.3 (N-C-N).
								Cl	PPh 3
		Cl	S	O	cristallization	S	O Cl	Ru	PPh 3
	Ph 3 P	Ru	Ge		THF	Ge	Ru	Cl
		Cl	N	N	N	N	Cl	PPh 3
			10a					10b
	PPh 3 ). HRMS m/z (%): 850.1379 ([M + ACN -Cl -i-Pr] + ) calcd for C 39 H 49 ClGeN 3 OPRuS ([M + ACN
	-Cl -i-Pr] + ) 850.1368, 809.1114 ([M -Cl -i-Pr] + ), 809.1114 ([M -Cl -i-Pr] + ) calcd for
	C 37 H 47 ClGeN 2 OPRuS ([M + ACN -Cl -i-Pr] + ) 809.1102.

3

  Hahn et al. have reported in 2010 the first germylene with chiral N,N'-substituents,6 followed the next year by the publication of Mochida et al. with a bis(oxazoline) ligand and finally Baceiredo et al. with a P,N-stabilized germylene in 2011.[7][8][9]

  18,[29][30][31][32][33][34] S-N bond lengths are also in agreement with one single bond and one dative bond with a distance of 1.5506(15)

	-1.5523(15) Å and 1.5851(13) -1.5844(13) Å in allowance with 13a. Comparison with 12b

  CHCl 3 and added on the mixture. Finally, after stirring the mixture for 30 min at room temperature iso-propylamine (260 uL, 3.03 mmol, 3 eq) was added and the solution stirred overnight at room temperature. The solvent was removed under reduced pressure and the crude product was purified by flash column chromatography (Eluent: Petroleum Ether / Ethyl Acetate : 4 / 6, Rf = 0.78) to give a white solid (129 mg) in 53 % yield. Crystals were obtained by slow evaporation in ethyl acetate. M.p. : 66 °C; 1 H NMR (300.18 MHz, C 6 D 6 , 25 °C): δ 1.07 (d,3 J HH = 6.5 Hz, 6H, CH(CH 3 ) 2 ); 1.12 (d,3 J HH = 6.5 Hz, 6H, CH(CH 3 ) 2 ); 3.62 (sept.,3 J HH = 6.5 Hz, 2H, N-CH(CH 2 ) 2 ), 5.09 (s, 1H, NH), 6.98-7.08 (m, 3H, CH Ar ), 8.09-8.13 (m, 2H, CH Ar ).13 C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 25.4 (CH(CH 3 ) 2 ); 25.5 (CH(CH 3 ) 2 );

		V (Å3)		1360.18(16)	R1, wR2 (I > 2σ(I))	0.0433, 0.0961
		Z		4	R1, wR2 (all data)	0.0714, 0.1095
				N,N'-di-iso-propylbenzenesulfonimidamide (12a): Hexachloroethane (264
	1) n BuLi 0 °C, 1h, THF	O	N	mg, 1.11 mmol, 1.1 eq) was added to a solution of triphenylphosphine (293
	0 °C, 2h, THF 2) M	S	NH	mg, 1.11 mmol, 1.1 eq) in CHCl 3 (10 mL) at room temperature. The solution
				was heated at reflux for 6 h. Then, the mixture was allowed to return at room
	n = 1 or 2	temperature and trimethylamine (210 µL, 1.52 mmol, 1.5 eq) was added, the mixture was stirred
	Cl 2 .dioxane or SnCl 2	for 30 min at room temperature. N-iso-propylbenzenesulfonamide (200 mg, 1.01 mmol, 1 eq)
		was dissolved in 45.5 (CH(CH 3 ) 2 ); 128.0 (C Ar ); 128.6 (C Ar ); 131.3 (C Ar ); 143.3 (C Ar/q ). HRMS m/z (%): 241.1380
		([M + 1] + ) calcd for C 12 H 20 N 2 OS ([M + 1] + ) 241.1375.
		Formula		C12H20N2OS	dcalc (g/cm 3 )	1.174
		Mol wt		240.36	µ (mm -1 )	0.222
		Temp. (K)	193(2)	F(000)	520
		Cryst syst	Triclinic	cryst size (mm)	0.140 x 0.100 x 0.040
		Space group	P-1	θ range (deg.)	3.017 to 24.763
		a (Å)		10.5404(7)	index range h k l	-12<=h<=12, -12<=k<=12, -
					14<=l<=14
		b (Å)		10.5595(7)	no of reflns collected /	34528
		c (Å)		12.5470(9)	unique	4527 [R(int) = 0.0616]
		a (deg.)		76.985(2)	Completeness to θmax(%)	96.8
		b (deg.)		88.549(2)	data/restraints/params	4527 / 164 / 361
		g (deg.)		89.718(2)	goodness-of-fit	1.028

  Then, the mixture was allowed to return at room temperature and trimethylamine (210 µL, 1.52 mmol, 1.5 eq) was added, the mixture was stirred for 30 min at room temperature. Niso-propylbenzenesulfonamide (200 mg, 1.01 mmol, 1 eq) was dissolved in CHCl 3 and added to the mixture. Finally, after stirring the mixture for 30 min at room temperature N,N-After 16h, the solvent was removed under reduced pressure and the resulting solid was extract with pentane. The solvent was removed under reduced pressure to give a white solid in 92 % yield (70 mg). Crystallization from benzene at room temperature gave colourless crystals suitable for X-ray study. M.p. : 108 °C (decomposition); Isomer A: 1 H NMR (300.18 MHz, C 6 D 6 , 25 °C): δ 0.72 (d,3 J HH = 6.5 Hz, 6H, CH(CH 3 ) 2 ); 0.91 (d,3 J HH = 6.5 Hz, 6H, CH(CH 3 ) 2 ); 2.06 (s, 6H, CH 3 ); 3.23 (sept.,3 J HH = 6.5 Hz, 4H, N-CH(CH 2 ) 2 ), 6.87-6.95 (m, 6H, CH Ar ), 7.70-7.73 (m, 4H, CH Ar ).1 H NMR (300.18 MHz, C 6 D 6 , 70 °C): δ 0.73 (d,3 J HH

	c (Å) b (deg.)			88.604(8) 12.6561(5) 90	data/restraints/params unique data/restraints/params	10619 / 0 / 415 5730 [R(int) = 0.0195] 5530 / 1 / 154
	g (deg.) V (Å3) a (deg.) g (deg.) V (Å3)			83.874(13) 1748.5(8) 94.4110(10) 90 3219.3(2)	goodness-of-fit R1, wR2 (I > 2σ(I)) Completeness to goodness-of-fit θmax(%) R1, wR2 (I > 2σ(I))	1.042 0.0375, 0.0989 1.023 99.2 0.0198, 0.0483
	Z b (deg.) Z			4 93.5030(10) 4	R1, wR2 (all data) data/restraints/params R1, wR2 (all data)	0.0370, 0.1061 5730 / 78 / 211 0.0236, 0.0503
	g (deg.)			101.3740(10)	goodness-of-fit	1.046
	V (Å3)		N	Dimethylammonium ethyl iso-propyl sulfonimidamide chloride 818.68(6) Cl R1, wR2 (I > 2σ(I)) 0.0332, 0.0806 Bis (N-iso-propyl-N'-mesitylbenzenesulfonimidamide)
	Z	O	N	H	2	salt (12c): Hexachloroethane (264 mg, 1.11 mmol, 1.1 eq) was added R1, wR2 (all data) 0.0414, 0.0853 germylene (13b): KHMDS (43 mg, 0.215 mmol, 2 eq) was
		S	NH			to a solution of triphenylphosphine (293 mg, 1.11 mmol, 1.1 eq) in added to GeCl 2 •dioxane (25 mg, 0.108 mmol, 1 eq) in Et 2 O at
						CHCl 3 (10 mL) room temperature. The solution was heated at reflux Bis (N,N'-di-iso-propylbenzenesulfonimidamide) room temperature. The mixture was stirred for 2 hours and N-
	for 6 h. 90 (d, 3 J HH = 6.5 Hz, 3H, CH(CH 3 ) 2 ); 1.20 germylene (13a): KHMDS (85.8 mg, 0.43 mmol, 2 eq) was added to GeCl 2 •dioxane (49.7 mg, 0.215 mmol, 1 eq) in Et 2 O at room temperature. The mixture was stirred for 2 hours and N,N'-di-iso-propylbenzenesulfonimidamide (12a) (154 mg, 0.43 mmol, 2 eq) in Et 2 O was MHz, C 6 D 6 , 25 °C): δ 1.33 (d, 3 J HH = 6.6 Hz, 12H, CH(CH 3 ) 2 ); 1.40 (d, 3 J HH = 6.6 Hz, 12H, S N N O N O iso-propyl-N'-mesitylbenzenesulfonimidamide (12b) (68 mg, 0.215 mmol, 2 eq) in Et 2 O was Ge S N added at the same temperature. = 6.5 Hz, 6H, CH(CH 3 ) 2 ); 0.93 (d, 3 J HH = 6.5 Hz, 6H, CH(CH 3 ) 2 ); 2.06 (s, 6H, CH 3 ); 2.56 (s,
	(d, 3 J HH = 6.5 Hz, 3H, CH(CH 3 ) 2 ); 2.84 (s, 6H, N-(CH 3 ) 2 ), 3.01-3.29 (m, 3H, N-CH 2 CH 2 -N), CH(CH 3 ) 2 ); 3.64 (sept., 3 J HH = 6.6 Hz, 4H, N-CH(CH 2 ) 2 ), 6.96-7.08 (m, 6H, CH Ar ), 7.89-7.91 12H, CH 3 ); 3.25 (sept., 3 J HH = 6.5 Hz, 4H, N-CH(CH 2 ) 2 ), 6.77 (s, 4H, CH Ar ), 6.93-7.01 (m, 6H,
	3.36 (sept., 3 J HH = 6.5 Hz, 1H, N-CH(CH 2 ) 2 ); 3.70-3.79 (m, 1H, N-CH 2 CH 2 -N), 7.45-7.49 (m, (m, 4H, CH Ar ). 13 C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 24.6 (CH(CH 3 ) 2 ); 25.4 (CH(CH 3 ) 2 ); CH Ar ), 7.70-7.73 (m, 4H, CH Ar ). 13 C{ 1 H} NMR (75.48 MHz, C 6 D 6 , 25 °C): δ 20.9 (CH 3 ); 23.9
	3H, CH Ar ), 8.14-8.17 (m, 2H, CH Ar ). 13 C{ 1 H} NMR (75.48 MHz, CDCl 3 , 25 °C): δ 22.9 47.4 (CH(CH 3 ) 2 ); 128.9 (C Ar ); 129.1 (C Ar ); 131.4 (C Ar ); 141.9 (C Ar/q ). MS m/z (%): 552 (M + ). (CH(CH 3 ) 2 ); 25.2 (CH(CH 3 ) 2 ); 46.9 (CH(CH 3 ) 2 ); 128.9 (C Ar ); 131.6 (C Ar ); 134.0 (C Ar ); 135.9
	(CH(CH 3 ) 2 ); 24.6 (CH(CH 3 ) 2 ); 38.3 (CH(CH 3 ) 2 ); 44.4 (N-(CH 3 ) 2 ); 46.6 (N-(CH 3 ) 2 ); 60.3 (N-Formula C24H38GeN4O2S2 dcalc (g/cm 3 ) 1.137 (C Ar/q ); 140.1 (C Ar/q ). Isomer B: 1 H NMR (300.18 MHz, C 6 D 6 , 25 °C): δ 1.16 (d, 3 J HH = 6.5 Hz,
	CH 2 ); 127.5 (C Ar ); 128.8 (C Ar ); 132.0 (C Ar ); 141.6 (C Ar/q ). HRMS m/z (%): 270.1646 ([M -Cl] + ) Mol wt 551.31 µ (mm -1 ) 1.104 6H, CH(CH 3 ) 2 ); 1.35 (d, 3 J HH = 6.5 Hz, 6H, CH(CH 3 ) 2 ); 2.02 (s, 6H, CH 3 ); 3.59 (sept., 3 J HH =
	calcd for C 13 H 24 N 3 OS ([M -Cl] + ) 270.1640. Formula C13H24ClN3OS dcalc (g/cm 3 ) Mol wt 305.86 µ (mm -1 ) Temp. (K) 193(2) F(000) 6.5 Hz, 4H, N-CH(CH 2 ) 2 ), 6.87-6.95 (m, 6H, CH Ar ), 7.70-7.73 (m, 4H, CH Ar ). 1 H NMR (300.18 1.241 1160 Cryst syst Tetragonal MHz, C 6 D 6 , 70 °C): δ 1.18 (d, 3 J HH = 6.5 Hz, 6H, CH(CH 3 ) 2 ); 1.32 (d, 3 J HH = 6.5 Hz, 6H, cryst size (mm) 0.300 x 0.200 x 0.160 CH(CH 3 ) 2 ); 2.03 (s, 6H, CH 3 ); 2.34 (s, 12H, CH 3 ); 3.62 (sept., 3 J HH = 6.5 Hz, 4H, N-CH(CH 2 ) 2 ), 0.358 Temp. (K) 193(2) F(000) Space group I4 1 θ range (deg.) 2.936 to 31.886 6.67 (s, 4H, CH Ar ), 6.93-7.01 (m, 6H, CH Ar ), 7.70-7.73 (m, 4H, CH Ar ). MS m/z (%): 704 (M + ). 328 Cryst syst Triclinic cryst size (mm) a (Å) 21.9417(7) index range h k l -21<=h<=32, Formula C36H46GeN4O2S2,C6H6 dcalc (g/cm 3 ) 1.257 -32<=k<=32, 0.540 x 0.340 x 0.060 Space group P-1 θ range (deg.) 2.986 to 33.198 -9<=l<=9 b (Å) 21.9417(7) no of reflns collected / 38402 Mol wt 781.61 µ (mm -1 ) 0.882
	a (Å) c (Å) Temp. (K) b (Å) Cryst syst a (deg.) Space group		7.5259(3) 6.6868(2) 193(2) 8.8203(4) Monoclinic 90 P21/C	unique F(000) index range h k l no of reflns collected / cryst size (mm) Completeness to θmax(%) θ range (deg.)	-11<=h<=10, -1648 5530 [R(int) = 0.0265] 13<=k<=13, -19<=l<=17 22190 0.160 x 0.140 x 0.080 99.2 3.526 to 29.574

dimethylethylenediamine (330 uL, 3.03 mmol, 3 eq) was added and the solution stirred overnight at room temperature. The solvent was removed under reduced pressure and the crude was purified by flash column chromatography (Eluent: DCM / MeOH : 9 / 1, Rf = 0.57) to give a white solid (129 mg) in 38 % yield. Crystals were obtained by slow evaporation in ethyl acetate.

1

H NMR (300.18 MHz, CDCl 3 , 25 °C): δ 0.added at the same temperature. After 16h, the solvent was removed under reduced pressure and the resulting solid was extract with pentane. The solvent was removed under reduced pressure to give a white solid in 90 % yield (107 mg). Crystallization from pentane at -25 °C gave colourless crystals suitable for X-ray study. M.p. : 105 °C (decomposition); 1 H NMR (300.

18

Table 1 :

 1 Hydrogen transfer reaction and effect of chloride abstractionOn the other hand, application of sulfoxides in asymmetric hydrogen transfer reaction was limited to the best of our knowledge to two publications (Scheme 2). The first one was published by van Leeuwen et al. in 2000 by using an iridium complex.9 The ee from 4-

	1	II	/	90 min	19
	2	II	/	24 h	55
	3	I	/	90 min	>99
	4	II	3 eq	90 min	0
	5	I	3 eq	90 min	0
	methylacetophenone was up to 80%. The second publication was reported by Deng et al. in
	2012 with, again, an iridium catalysis and ee up to 65%. 10
			OH	N H
				N
		S	NH 2	S t Bu
		Ph	O	O
		van Leeuwen, 2000	Deng, 2012
	Scheme 2: Sulfoxide used in iridium-catalyzed hydrogen transfer of acetophenone
	Finally, metallylenes can also be applied as organocatalysts. On this path,
	biodegradable polymers such as polylactide (PLA), poly(e-caprolactone) (PCL), and
	poly(trimethylenecarbonate) (PTMC) are of great interest due to their applications as
	biodegradable and biocompatible polymers. Their formations can be catalyzed with tin (II)

which is a well-known catalyst to start living polymerization of several monomers like ecaprolactone or lactide. The early work of Kricheldorf et al. in 1995 studied the influence and

II. Results and discussion II.1. Application of ruthenium complexes in hydrogen transfer reaction

	Entry a Catalyst (2 mol%) base (20 mol%) T (°C)	Reaction time (h)	Conversion (%) b
	1	6b	KOH			80		2	76
	2	"	NaOH		"		"	70
	3	"	i Pr K 2 CO 3		"	t Bu	"	51
	4 5	N N Hydrogen transfer reaction was first investigated starting from acetophenone in i-t Bu Sn Cl N Sn N N i Pr P Ph N Sn Ph " Cs 2 CO 3 " " 27 N t Bu N(SiMe 3 ) 2 " t-BuOK " " 32
	i Pr a The reactions were carried out in dry and degassed isopropyl alcohol (2 mL) under argon in presence of PrOH by using p-cymene ruthenium complex 6b as catalyst in presence of an external base acetophenone (0.9 mmol)
	Bertrand, 1999 (Scheme 4). It is important to note that 6b appears perfectly stable in dry and degassed i-PrOH Gibson, 1997 Wang, 2006 b Determined by 1 H NMR analysis by using tetramethylbenzene (0.45 mmol) as internal standard.
	for a week at room temperature.
			Cl	Ru	O	S
			Cl	Ge
				N	N
						(2 mol%)
		O			6b			OH
				KOH (20 mol%)
				80 °C, 2h
				OH
					(2 mL)
		Scheme 4: Germylene-complexes tested in hydrogen transfer reaction
		The conversion, determined by 1 H NMR analysis by using tetramethylbenzene as
	internal standard, was up to 76% after 2h at 80 °C. The effect of the base on the catalytic
	reaction was next investigated (Table 2).

i Pr i Pr i Pr

Table 2 :

 2 Influence of the base in hydrogen transfer reaction with complex 6b

  as reactant.

	Entry a Catalyst (2 mol%)	Volume i-PrOH (mL)	T (°C)	Reaction time (h)	Conversion (%) b
	1	6b	2	80	2	76
	2	"	3	"	2	59
	3	"	1	"	2	88
	4	"	1	"	2.5	>97
	5	"	0.5	"	2	73

  the catalytic process might undergo as well, that will influence the steric and electronic properties of the active catalyst.

	Entry a		Catalyst (2 mol%)	T (°C)	Reaction time (h) Conversion (%) b
					O					O					O
	Cl	1	Ru		S	6b	Cl	Ru 80			S	2	Cl	Ru	76	S
	Cl 2	N	Ge	N	6d	Cl	N "	Ge	N		"	Cl	N	Ge	N 57
		3				6f		"				"			43
		4				6g		"				"			29
		5		6b		6h		"	6d			"			6f	23
	Cl	6	Ru		S	6i	Cl	Ru "		O	S O	"	Cl	Ru	39
	Cl		Ge			Cl	Ge				Cl		Ge	Cl
			N		N			N		N				N	N
			6g					6h						6i

Table 7 ,

 7 entry 11), a conversion of only 69% being obtained.Entry a Catalyst (2 mol%) V (mL) T (°C) Reaction time (h) Conversion (%) b

	1	6b	1	50	17	61
	2	5a	2	"	2	68
	3	5a	"	"	4	>97
	4	5a.PPh 3	"	"	2	74
	5	5a.PPh 3	"	"	4	>97
	6	5b.PPh 3	"	"	4	>97
	7	5b.PPh 3	"	25	2	26
	8	5b.PPh 3	"	"	6	50
	9	5b.PPh 3	"	"	28	87
	10	5b.PPh 3	"	"	72	>97
	11	Ru(PPh 3 ) 3 Cl 2	"	"	72	69

Table 8

 8 , entry 4).

	Entry a Catalyst (2 mol%)	V (mL)	T (°C)	t (h) Conversion (%) b	ee c
	1	6b	1	50	17	61	7
	2	6d	1	50	17	57	8
	3	5b.PPh 3	2	50	4	>97	7
	4	5b.PPh 3	2	25	72	>97	21

Table 8 :

 8

Catalytic activity of complexes 6b, 6d and 5b.PPh 3 in asymmetric hydrogen transfer reaction Chapter V:

Applications in Hydrogen Transfer and Polymerization Catalysis

  Finally, 5b.PPh 3 was used at room temperature in presence of 20 mol% of KOH to reduce several carbonyl compounds (Table

	-243-

  Table 11, entry 2). A longer reaction time afforded a conversion of 48% with a moderate PDI of 1.36 (Table 11, entry 3). The reactions were carried out in dry and degassed toluene (3 mL) under argon in presence of e-caprolactone (8.7 mmol) b Determined by 1 H NMR analysis by comparing the integration of the signal of the polymer with the monomer.

	Entry a Catalyst (0.5 mol%)	t (H)	T (° C)	Conversion (%) b	PDI
	1	14b	1	100	89	1.66
	2	14b	1	80	11	1.18
	3	14b	6	80	48	1.36

a

Table 11 :

 11 Catalytic activity of complex 14b in polymerization of e-caprolactoneFinally, germylenes 13a and 13b were used in the same conditions (Table12).However, these two catalysts appeared totally inactive in catalysis. The insertion and formation of a Ge(IV) species might be too stable to allow a catalysis with germanium. The reactions were carried out in dry and degassed toluene (3 mL) under argon in presence of e-caprolactone (8.7 mmol) b Determined by1 H NMR analysis by comparing the integration of the signal of the polymer with the monomer.

	Entry a	Catalyst (0.5 mol%)	t (H)	Conversion (%) b	PDI
	1	13a	10	>5	n.d.
	2	13b	10	>5	n.d.

a

Table 12 :

 12 Activity of complex 13a and 13b in polymerization of e-caprolactone

Résumé de thèse

Schéma 23: Catalyse de polymérisation de la e-caprolactone Dans un premier temps, 16a a été utilisé et a montré une conversion de 29% après une heure de réaction avec un bon PDI de 1.09. En laissant la réaction se dérouler, la conversion monte jusqu'à 77% après 7 heures. Enfin, 16b montre une activité supérieure avec une conversion de 89% après une 1 heure. Cependant, cette activité est associée à une réaction de trans-estérification des chaînes polymériques avec un PDI moyen de 1.66. En conclusion, la formation de ligands a et b sulfoxide-germylène a été réalisée avec une variation du groupement espaçant les deux entités. Les variations ont aussi permis d'obtenir des ligands germylènes avec des encombrements stériques différents et variés, mais aussi avec des degrés d'oxydation de l'atome de soufre différents (thioéther et sulfone). Cette variabilité a permis d'étudier la stabilité, l'influence de l'état d'oxydation du soufre et de l'encombrement stérique sur le germylène. Ces ligands ont ensuite été utilisés en chimie de coordination pour obtenir des complexes avec des métaux de transition des groupes 6, 8 et 10. Ces complexes ont montré différentes propriétés de coordination avec la formation de systèmes monodentes, bismonodentes et bidentes. Les complexes de ruthénium ont aussi été appliqués en catalyse pour la réaction de transfert d'hydrogène afin de réduire l'acétophénone. Les résultats obtenus ont permis une réduction à température ambiante. Une extension à plusieurs cétones substituées ainsi qu'à la benzophénone et au benzaldéhyde dans les mêmes conditions a été réalisée. La catalyse énantiosélective a été testée et les résultats obtenus ont montré une induction asymétrique modeste.

Scheme 7: Synthesis of AmGeCl

J HH = 6.3 Hz, 3H, CH(CH 3 ) 2 ); 1.15 (d,3 J HH = 6.3 Hz, 6H, CH(CH 3 ) 2 ); 1.16 (d,3 J HH = 6.3 Hz,

C NMR spectrum has also evidenced a solid proof on the formation of 7a. Aromatic

Remerciements

Notre plus grande gloire n'est point de tomber, mais de savoir nous relever chaque fois que nous tombons. Confucius

Remerciements Catalyseur (5a)

Abbreviations

Chapter III:

Hemilabile Germylene -b-Sulfoxide

Ligand: Synthesis, Characterization and Coordination Properties toward Group VI, VIII and X Transition Metals

Chapter IV:

Design, Synthesis and Characterization of New

Germylenes and Stannylenes Stabilized by

Sulfonimidamides

Chapter IV: Design, Synthesis and Characterization of New Germylenes and Stannylenes Stabilized by Sulfonimidamides Abstract Sulfonimidamide were synthesized with different substituents. This new design allowed to obtain similar or different groups on the nitrogen atom, with the formation of symmetric and asymmetric center on the sulfur atom. The design also allowed to incorporate a weak Lewis base in vision to form a hemilabile ligand.

Then, formation of homoleptic germylenes were obtained by protonolysis reaction.

The reaction was finally extended to the formation of stannylenes. All the metallylenes were fully characterized by NMR spectroscopy and X-ray diffraction analysis. Electronic properties of these new metallylenes were investigated by DFT calculations.

Entry

General procedure for catalytic polymerization of e-caprolactone:

In a schlenk tube, catalyst (0.04 mmol) was dissolved in toluene (3 mL) and stirred for 10 min.

Then, e-caprolactone (1 g, 8.73 mmol) was added and the mixture stirred at the indicated temperature for the desired time. Aliquots (0.2 mL) were dissolved in CDCl 3 (0.4 mL) with a small amount of benzoic acid and conversions were determined by 1 H NMR analysis. Polymer was treated at the end of reaction by addition of benzoic acid. The mixture was then evaporated and the solid was then dissolved in DCM. The solution was cooled with liquid nitrogen and methanol was added drop to drop to precipitate the polymer.

The number-average and weight-average molar masses (Mn and Mw, respectively) and molar mass distributions (Đ) of the polymer samples were determined by size exclusion chromatography (SEC) at 35 °C with a Waters 712 WISP high-speed liquid chromatograph equipped with a R410 refractometer detector. Tetrahydrofuran was used as the eluent, and the flow rate was set up at 1.0 mL/min. A SHODEX precolumn (polystyrene AT806M/S Mw = 50000000 g/mol) and two STYRAGEL columns (HR1, 100-5000 g/mol, and HR 4E, 50-100000 g/mol) were used. Calibrations were performed using polystyrene standards (400-100000 g/mol).

Chapter V:

Abstract

This work concerns the synthesis of mixed germylene-sulfoxide ligands that were involved in coordination chemistry with several transition metals and finally applied in hydrogen transfer catalysis. In a second part, the synthesis of new metallylenes stabilized by a sulfonimidamide group was develop, which were applied in polymerization catalysis. The first chapter is centered on the state of the art of germylenes with their synthesis, their stabilization and finally their coordination chemistry and applications in catalysis. Sulfoxides will also be described for their potential as hemilabile ligands.

The second chapter describes the synthesis of germylene-a-sulfoxide ligands as structurally tunable structures (cyclohexyl, t Bu, tolyl..) and with different oxidation states of the sulfur atom (thioether, sulfoxide and sulfone). The coordination chemistry led to the formation of bis-germylene group IV complexes, bidentate-ruthenium and monodentate ruthenium complexes.

The third chapter shows the extension of the methodology to the formation of germylene-b-sulfoxide ligands. The influence of the spacer between the two entities on the coordination chemistry was studied and shows the formation of bidentate group IV complexes.

Coordination to ruthenium led to obtain a surprising bis-ruthenium complex characterized by X-ray diffraction analysis. Finally, the novel architecture allowed to obtain two nickel (0) complexes, one of them including carbonyl ligands permitting a TEP comparison.

The fourth chapter is centered on the synthesis of new ligands, analogue of amidinate substituents for metallylene stabilization with a central sulfur atom. The effect brought to the metallylene center by the sulfonimidamide was studied by DFT calculations.

The last chapter concerns the application of several ruthenium complexes in hydrogen transfer reaction with various carbonyl compounds. The use of sulfonimidamide stannylenes was also investigated in polymerization catalysis of e-caprolactone.

Keywords: Germylene, sulfoxide, hemilabile ligand, H-transfer reaction, sulfonimidamide, e-caprolactone polymerization.