To appear in Glosema. Revista Asturiana de Llingüística 1, March 2019

The Story of Zero by T. Givón, Amsterdam/Philadelphia: John Benjamins Publishing Company. ISBN: 978 90 272 1239 9, v-xv and 414 pp. This is a massive work, dealing with a variety of constructions systematically comparing English, Spanish, (Biblical) Hebrew, German, Ute and Japanese, with data also presented from certain other languages from the Indian sub-continent, Africa and the Americas. But curiously, there is no presentation or discussion of examples from Arabic. It is largely based around already published work by the author, and focuses on the structural contexts in which zeros occur. There is very little on the wider discourse contexts in which zero forms function (but see below for a qualification of this point). Furthermore, there is an unusually high number (and variety!) of typographical errors and even of spellings, suggesting that the proof-reading stage of the production process was not carried out optimally. Moreover, given that the majority of chapters are adapted from existing publications by the author, there is no cross-referencing between the chapters, and also some degree of redundancy.

There are 13 chapters, arranged in two overall parts. Part I comprises chapters dealing with Givón's theoretical framework, which is essentially functional and cognitive in orientation. Chapter 1 deals with the communicative framework in which zero and overt anaphoric markers are used, while chapter 2 details Givón's broader conception of "referential coherence" in terms of a "grammar" of markers viewed as "mental processing instructions". Chapters 3 and 4 focus on the close relationship between zero forms and "pronominal agreement" (both tightly bound up with the expression of continuity in a discourse). Chapter 5 asks whether zero anaphora is a "typological exotica", answering the question in the negative, while chapter 6 is devoted to a discussion of zero forms in "verbless clauses", drawing evidence from spoken Ute narratives, spoken English, early child language, second language pidgins and Broca's aphasic speech. Chapter 7 deals with so-called "cataphoric zero", and adduces in this respect examples of the passive and antipassive voices (see below for more on this issue).

Part II then discusses coreference in relative clauses, with data from Japanese, Bambara, Hittite, Hebrew, Ute and German (chapter 8), in clausal verb complements (chapter 9), in adverbial clauses (chapter 10), and how zero forms and 3 rd person pronouns function in the context of clause chaining (chapter 11). Chapters 12 and 13 then set the focus more broadly, asking whether there are "promiscuous ill-governed zeros" (chapter 12) and showing that there are only relatively few such instances. Finally, chapter 13 demonstrates that the phenomenon of "stranded adpositions" is not some quirk of language, but is in fact functionally and communicatively motivated.

The book is completed by an extensive 18-page bibliography, a general and a language index. However, there is no overall conclusion to the work, drawing together the various strands of the argument and descriptions and pinpointing avenues for future research on zero forms; but only a short section 7 ("Closure") to the final chapter (chap. 13, pp. 387-8) on the communicative function of stranded case-marking adpositions and their correlation with ellipsed nominal arguments in the languages that permit it.

As a whole, this work is impressive: in its coverage of languages, from a variety of types, taking account also of certain forms of language use (early child language, secondlanguage pidgins, Broca's aphasic speech), its wide-ranging and effective references to the literature on the topics covered (already very extensive), and its handling of the structural features of the phenomena under discussion. However, apart from the preliminary chapters devoted to the communicative functions of indexical markers, viewed as "processing instructions" (chapters 1 and 2), the bulk of the work focuses on what we might call the "microlinguistic" aspects of zero forms. These are approached indirectly, via their roles in the setting up of various structural relations within constructions (the passive and antipassive, left-dislocation, so-called "Y-movement", complement, adverbial and nominal clauses and so on). The broad focus of the work is on these, rather than on zero forms per se in fact, thus belying the emphasis of the title to an extent.

Yet Givón does recognize (chap. 1) what we might call "meso-textual" structures, in the shape of "clause-chaining". Here, structured groupings of clauses in a text constitute a unit of discourse (see below),1 introduced by a "reorientation device", separating off the unit in question from the clauses upstream, then a "chain-initial" clause, followed by one or more "chain-medial" ones, a "chain-boundary" clause and finally a "chain boundary". The discourse to which these clause-chainings may give rise would then be internally coherent semanticopragmatically. Above this "intermediate" level, Givón also recognizes the dimensions of "paragraph", "episode" and "story" (in the case of narrative discourse): see in this respect the Hierarchy represented in (5) in Chapter 1 (p. 5). But apart from a very few allusions to the status of a zero-containing clause within this meso-textual structure, it is to all intents and purposes abandoned as a framing device for the study of these forms.

I will end this review by highlighting certain key issues raised by this work. First, in Givón's (largely successful) attempt to undermine the claimed distinction within Generative Grammar between "configurational" and "non-configurational" languages in chapter 5, he attempts to show that zero gaps in both subject and non-subject positions are widespread in spoken English (contrary to what is claimed by this conception, English being said to be a prototypical "configurational" language). To test this claim, he had pairs of subjects watch a short (presumably silent) video, having been told in advance that the one each saw was slightly different. Each member then had to try to establish via discussion the similarities and differences between the two viewings. But in analyzing the data this experiment yielded, no account seems to have taken to distinguish between the genuine occurrence of zero forms, and simply hesitations followed by repairs. An example comes from section 3.4.1.5.4 in chap. 5, on "zero-anaphora objects":

(1) "The guy in my story picked [Ø]…got [Ø]…and picked up all those tools [CAT]" (Ex. (34a), p. 150)

But this isn't a finished, "final" clause structure at all (as the analysis provided suggests): we are dealing here surely with a series of hesitations on the speaker's part in terms of the optimal verb to choose, where he or she plumps eventually for the same verb as used initially, but followed by a particle (i.e. a "phrasal" verb). There is no instance of "cataphora" here (a highly marked referential device, as Givón in fact notes elsewhere in the book, e.g. on p. 183), as indicated by the abbreviation "(CAT)". The speaker keeps in short-term memory for the duration of the utterance the full object NP all those tools and simply spends processing time searching for the optimal verb to use in governing it. Note that "reinstating" an unstressed overt pronoun for the "gaps" as indicated here would result in clear ungrammaticality:

(1) a. *The guy in my story picked them…got them…and picked up all those tools. This is a case therefore of over-analysis, the analyst reading into a user's textual productions more than can reasonably be supposed to be present. There are a number of other examples like this in this chapter. This problem also has implications for the many relative textual frequency tables throughout chapters 5 and 6 (such as Table VI "Distribution of zero-object categories", on p. 153) that are based on these supposed "data", thereby largely affecting the overall conclusions drawn on their basis.

A second major issue has to do with Givón's conception of text. As in a great many works on anaphora and indexical reference generally, the textual dimension of language use is made to do duty for aspects of the latter for which it is not strictly relevant. For Givón, a given indexical-anaphoric marker (he recognizes in this category zero forms, unaccented 3 rd person pronouns, accented pronouns and definite NPs) has to be justified by an appropriate textual antecedent, co-occurring in its vicinity in a given text for it to be considered as anaphoric (Givón frequently uses the term "text-based antecedent" in this respect, e.g. on p. 61).

However, the author does recognize (p. 43) the limitations of purely text-based accounts of indexical reference, which tend not to take into consideration "the mind that produces and interprets the text" (p. 43: Givón's own emphasis). Hence the author's insistence that the search for referents of given indexical forms takes place "in mentally-stored text" (pp. 27, 37), and not in text itself per se. Yet this cannot literally be the case, since working memory is finite and limited. Indeed, the textual trace of a communicative event is short-lived, disappearing from short-term memory once that discourse is constructed -or very soon thereafter (see, e.g., Jarvella, 1979, and indeed Givón himself, on p. 66). What is stored in memory is discourse, not text as such, that is, a mental representation of the speaker and addressee's interpretation of the ongoing communicative event, subject to continuous revision as a function of the ever-changing context of that event. It is discourse which is hierarchically structured, while text is essentially linear (notwithstanding Givón's characterization of text as both hierarchical and linear). Text, then, would be the connected sequence of perceptible cues (i.e. the physical product of an act of utterance) provided by the speaker/writer for their addressee/reader to infer the discourse (the negotiated meaning) that may be associated with a given stretch of text in conjunction with a relevant context. However, Givón does not make this distinction explicit (though it appears often to be implicit to varying extents, notably in chapter 2) in his analyses and presentations.

Yet all the many tables of data presented all through the book are in terms of relative textual frequencies of occurrence of the forms at issue, so the textual dimension looms large at every turn. This is especially apparent in Givón's heuristic of "anaphoric distance"2 in terms of degree of anaphoricity, and of "referential persistence" in terms of "cataphoricity". Here, an essentially discourse phenomenon is being characterized in purely textual terms. For it is quite possible, for example, that a macro-topical discourse entity may not be mentioned textually for a large stretch of text, yet remain topical and activated, and will be treated as such in terms of the use of highly continuous markers at a later stage (I have found several instances of this in my French-and English-language collected corpora of utterances). This phenomenon surely invalidates to some degree, at least, the "anaphoric distance" criterion.

Finally, Givón's conception of the "anaphoric"/ "cataphoric" distinction, which looms large in the work as a whole, is somewhat problematic. He uses the concept of anaphora in the accepted sense of the "referential dependency" of a highly attenuated indexical form upon the existence of a given topical referent in memory, depending on the level of attention or saliency which it enjoys at the point of retrieval. However, his use of the term in general tends to be rather broader than this (cf. the issue of "zero anaphora" in unplanned spoken language discussed in chapter 5), and so is not always appropriate. As far as his conception of "cataphora" is concerned, however, his usage is so broad that it loses all specificity, in opposition to "anaphora" (in the strict sense of the term). To all intents and purposes, "cataphora" is tantamount in the author's usage to "referent locatable textually downstream", while "anaphora" is "referent textually locatable upstream". In addition, "cataphora" (or textual "downstreamness") is associated by Givón with the relative "importance" of the referent at issue in the discourse -though the notion of "importance" is not defined. But of course this leads to an inevitable contradiction: "cataphora" signals both unimportant information to come, and important information to come. As far as zero forms are concerned, the author characterizes as "the communicative logic of zero" the notion that "Unimportant information need not be mentioned" (item (1b), p. 3). He illustrates this on p. 4 with examples of the English short passive and "antipassive" constructions: But these zero forms are simply interpretable as generic or indeterminate references (if indeed they count as "references" at all, which is doubtful): see the three-way distinction amongst nonreferential (generic or indeterminate), referential-(in)definite (discourse-new) and anaphoric (contextually definite) internal implicit arguments which the reviewer draws in Cornish (2007:193). The passive voice in (2a) has intransitivized the basic accomplishment predicate 'fire', to create a state one (fired in the short passive in (2a) being a quasi-adjective). The zero realization of the second semantic argument corresponds to a variable, whose value is determined via the lexical-semantics of the predicate (i.e. a potential 'firer'). And in (2b), the zero realization of the second argument has similarly converted 'eat' from an accomplishment to an activity predicate, the variable determined again via the lexical semantics of 'eat' ('something edible'). So neither "anaphora" nor "cataphora" in the strict sense is involved in examples (2a) and (2b) at all. Finally, let us look briefly at Givón's characterization of zero forms, the purported major topic of the book as a whole. Close examination of his examples suggests there are three subtypes. First, a "discourse" use, initially illustrated in comparison to that of unstressed pronouns by the English examples in (8) (p. 7: an invented dialogue), (11) (p. 38: an invented narrative), ( 14) (p. 78: an identical dialogue example to that given earlier in (8) on p. 7), and (6) (p. 284: the very same invented dialogue as in ( 8) and ( 14) listed above). Second, the one mainly illustrated in the chapters dealing with various types of clause, mainly non-finite ones, but also finite relative clauses. Apart from the relative clause zeros (which may be subject or non-subject in status), all these involve subject zeros. We may call these "micro-textual" instances, since their occurrence and interpretation are more or less completely determined by the grammatical contexts in which they appear. And third, the variable, non-anaphoric occurrences of zero as illustrated in (2a) and (2b) above, which Givón (wrongly) classifies under the general heading of "Cataphora", as we have seen.

To these, we may add an additional "discourse" use of zero forms in English, namely a referential hearer-old, but discourse-new type, which is responsible for actually introducing a new entity into a discourse (cf. [START_REF] Cornish | Implicit internal arguments, event structure, predication and anaphoric reference[END_REF]. So its status cannot therefore be characterized in terms of that of a very high continuity marker, as in the case of the anaphoric subtype. One example is the deictic use, as in imperative constructions (cf. ex. (8) in Cornish, 2007: 198: Eat ø!/ Watch ø!/Mind ø!/Smell!/Taste ø!, or Break ø in an emergency, as in the familiar instruction placed on a glass panel behind which is an alarm). And the variable use as illustrated in (2a,b) above needs to be subdivided into an "indeterminate" subtype (as illustrated in (2a)), and a "generic" one (as in (2b)). Both have in common the fact that their interpretations are bound up with the predicating ability of the verb, adjective or proposition which governs them.

Moreover, regarding the two referential subtypes identified above, the distinction with respect to the use of unstressed 3 rd person pronouns is not only a matter of degree of attention focus or continuity, as Givón claims, but is a function also of the inherent referring properties of the two indexical marker types. Zero markers have a more diffuse, global referential value in context, whereas overt 3 rd person pronouns tend to refer more specifically and concretely (cf. Cornish, 2007: 213). Examples are (3a,b)):

(3) a. [Context: article about a 1.3 kg meteorite which crashed into a New Zealand couple's living room shortly before breakfast (The Guardian, 14.06.04, p. 2)] "...and the Archers' one-year-old grandson had been playing in the room moments before it hit ø." (extract from ex. (1c´´) in Cornish, 2007, p. 191) b. [At the theatre: A is seated next to B, who is placed right behind a tall spectator in the seat in front] A to B: Can you see ø? (ex. (22d) in Cornish, 2007, p. 211) In (3a), replacing the zero by the pronoun it would have induced a more local interpretation, whereby it was the 'NZ couple's living room' which was hit by the meteorite. In contrast, the zero form as used here refers more diffusely to the house as a whole. And in (3b), the same overt pronoun it would tend to refer specifically to the stage qua stage, while the zero form targets the ambient scene more globally as a whole (including the décor, the actors and so on).

There are several avenues for future research on zeros deriving from this exceptional piece of scholarly linguistic work. The most basic one would be to answer the question as to how actually to recognize a zero marker, given that by definition these are inaudible in the stream of spoken text, and invisible in that of written. The question is not moot, as we saw earlier in this review in discussing Givón's notion of supposed "zero anaphoric" or "cataphoric" constituents in unplanned spoken English. Next is the issue of the different subtypes of zero, over and above the purely referential, anaphoric subtype, which is the one the author is principally concerned with in this book. Another important issue is the comparison between the functioning of zeros and 3 rd person pronouns, which as we have seen is not exhausted by the criterion of the degree of saliency of their respective intended referents at the point of use. Finally, there is the question of the strategic use of zeros (where these are permitted in distributional terms) by speakers or writers instead of that of 3 rd person pronouns: see [START_REF] Oh | English zero anaphora as an interactional resource II[END_REF] for some very interesting data and analyses based on a spoken English corpus.

  (2) a. Passive: Two months later, she was fired [by Ø]. (Givón's ex. (2a), ch. 1, p. 4) b. Antipassive (sic): He eats [Ø] regularly. (Givón's ex. (2b), ch. 1, p. 4)

Though the author does not explicitly recognize any clear distinction between the dimensions of text and discourse (cf.Cornish,

2009).

This is defined (p.

39) as "The number of clauses (or elapsed time) from the last occurrence of the referent in the preceding discourse." However, "referents" do not "occur" as such: it is rather the textual expression targeting that referent which occurs in a given text (i.e. here, certainly, the "antecedent" in traditional accounts).


Imen Ben Saad

Najeh Hannachi

Thierry Roisnel

Faouzi Hlel

Ionic organic-inorganic (C 6 H 10 N 2 ) (Hg 2 Cl 5 ) 2 .3H 2 O compound: Structural study, Hirshfeld surface, thermal behavior and spectroscopic studies

Keywords: Organic-inorganic hybrid, X-ray diffraction, Hirshfild surface, FT-IR, FT-Raman spectroscopy and NMR

A novel organic-inorganic hybrid material (C 6 H 10 N 2 )(Hg 2 Cl 5 ) 2 .3H 2 O has been prepared under hydrothermal conditions. It is characterized by single crystal X-ray diffraction, thermal analysis and spectroscopy measurements (IR, Raman and NMR). The structural analysis revealed that this material crystallizes in the monoclinic system (C 2/c space group) with the following unit cell parameters a = 19.6830(15) Å, b =18.1870(15) Å, c = 6.8567(6) Å, β = 93.224(3) ° and Z=4. According to the data collected at 150(2) K, the refinement converged to R= 0.0296. The atomic arrangement can be described as an alternation of cationic [C 6 H 10 N 2 ] 2+ .H 2 O and anionic [Hg 2 Cl 5 ] -layers along the c axis. In fact, a three-dimensional cohesion, which leads to these peridinium complexes, involves (N-H***Cl) (N-H***O) (O-H***O) and π-π interactions. Furthermore the FT-IR, Raman and NMR-MAS confirm the presence of organic and inorganic entities. Finally, the differential scanning calorimetry revealed several endothermic peaks.

Introduction

The advancement of recent technology and the need for new functions are generating a huge demand for new materials and new applications [1][2][3][4][5][6][7]. For this reason, organic-inorganic hybrid materials are receiving attention because they can help combine the specific properties of inorganic frameworks and futures of organic molecules [START_REF] Laine | Organic/Inorganic Hybrid Materials[END_REF][START_REF] Sanchez | [END_REF]. Recently, much attention has

M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT

2 been paid to organic-inorganic hybrid materials based on metal-halide units. Indeed, the synthesis of low-dimensional inorganic-organic materials enables both inorganic and organic components at the molecular level to be optimized. The organic cations, which are characterized by a special kind of π-π interaction in aromatic ring compounds, have attracted attention NLO materials; there are many typical aromatic that shows interesting photochemical properties [10][11][12].

In particular, hybrid materials based on ammonium and metal divalent (Cd, Zn, Hg ...) halides used a solvent in the synthesis of a large number of chemicals in various classes. The In this context, we are going to report in the present paper the synthesis of (C 6 H 10 N 2 ) (Hg 2 Cl 5 ) 2 .3H 2 O through a hydrothermal method. We have performed X-ray diffraction measurements which provided us with information about the complete crystal structure at 150(2) K of the new compound. The Hirshfeld surface analysis is introduced in order to evaluate the interactions within the crystal structure. This structural study is accompanied by thermal analyses and spectroscopic study (RAMAN; IR; NMR-MAS) measurements. The single crystal of the title compound (C 6 H 10 N 2 )(Hg 2 Cl 5 ) 2 .3H 2 O was prepared by hydrothermal methods as follows: 1, 2-benzen diammonium C 6 H 8 N 2 (0.0905 g; 0.836 mmoles;67.5%) and mercury chloride HgCl 2 (0.9094 g;3.349 mmoles;32.5%) were dissolved in aqueous solution of HCl ( 2M; 37%) for a few minutes with agitation successive to ensure complete dissolution of the compound. Second, such solutions were slowly combined in an autoclave and kept at 85 °C under auto-genous pressure for 24 h. After cooling these solutions for five days at room temperature, colourless single crystals suitable for an X-ray structure determination were obtained. Schematically the reaction is shown in the following equation:

C 6 H 8 N 2 +4 HgCl 2 (C 6 H 10 N 2 )(Hg 2 Cl 5 ) 2 .3H 2 O

Crystal structure determination

The X-ray diffraction data collection was performed using a single crystal (0.150 x 0.120 x 0.090 mm) selected through an optical examination. Intensity data were obtained on a D8

M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT

Hishfeld surfaces

The inter contacts observed in the crystal structure are quantified and graphically visualized using Hishfeld surface computational method. Here, we estimate the intermolecular interactions through inter contacts and then, we discuss the results.

Spectroscopy measurements (IR, Raman and NMR-MAS)

The infrared spectrum was recorded in the 400-4000 cm -1 range with a Nicolet IR 200 FT 1000 spectrometer using a sample pressed in spectroscopically pure KBr pellets.

Back scattering Raman spectra were obtained under microscope with a HR 800 Raman spectrometer (Horiba Jobin-Yvon) with nitrogen cooled CCD detector. The spectra were registered in two acquisitions from 50 to 3500 cm -1 .

The NMR-MAS experiments were performed at room temperature on a Bruker WB 300.

Then, the powdered sample was packed in a 4 mm diameter rotor and set to rotate at a speed of 8 kHz in a Doty MAS probehead. The 13 C spectrum was collected through a crosspolarization of proton with 5 ms contact time.

Thermal behavior

A thermogravimetric analysis (TGA) was carried out using an ATG PYRIS 6 instrument at the temperature range from 303 to 773 K with a heating rate of 10°C/min under a nitrogen atmosphere. The Differential Scanning Calorimeter (DSC 400) was used to examine the phase behavior of the (C 6 H 10 N 2 )(Hg 2 Cl 5 ) 2 .3H 2 O salt. The spectrum was obtained from temperature sweep experiments by heating the mixed system 303-443 K at the rate of 10°C/ min. The sample was weighed into aluminum pans, and the covers were crimped into place. Prior to the sample analysis, the baseline was obtained with an empty, hermetically-sealed aluminum pan.

Results and discussion

Structural analysis and Geometry optimization

The asymmetric unit of the title compound (Fig. 1) is made up of one inorganic (Hg 2 Cl 5 ) - anion, a half (C 6 H 10 N 2 ) 2+ cation and two water molecules (H 2 O). In fact, the projection along the c axis of the atomic arrangement can be described by the alternation of cationic and As far as the geometry of the dimeric of (Hg 2 Cl 5 ) -anions (Fig . 4) is concerned, (Hg 2 Cl 5 ) -is an assembly of two in-equivalent triangles determined by the association of two monomercury chloride HgCl 3 -units which carry a chlorine atom-common Cl (3) . Hg atoms are three coordinated as to built two triangles linked via Cl (3) chlorines atoms. The linkage (L) (Hg-Cl L ) bonds Hg-Cl (3) , 2.7985(17) Å to 2.856(2) Å are greater than the external (E) (Hg-Cl E ) ones. The last distances are around 2.335(2) Å (table 4). In both triangles, Cl E -Hg-Cl E are greater than the ideal values (120°), as they are 163.22 (7) ° in Cl (2) -Hg (1) -Cl (1) and 161.93 (7) ° for Cl (5) -Hg (2) -Cl (4) . The Cl L -Hg-Cl E angles are smaller than the ideal values (120°) as they vary between 90.07 (6) ° and 99.85 (6) °.

The Hg (1) Cl 3 triangle is planar and <Cl-Hg-Cl> is close to 120°. However, the Hg (2) Cl 3 triangle is pseudo-planar and <Cl-Hg-Cl> equal to 117° and Hg atom is looked out chlorine atoms plane. Booth HgCl 3 triangles are not coplanar but they show a decaled representation.

The Hg (2) -Cl (3) -Hg (1) , which is equal to 132. [START_REF] Wolff | Crystal Explorer 3.0[END_REF]

Study of intermolecular interactions through Hirshfeld surface analysis

The identification and the visualization of the intermolecular short/long contacts are determined in the reported structure by means of the powerful Hirshfeld surface analysis technique. This method is constructed based on the electron distribution calculated as the sum 6). The 2D fingerprint plots presented in this paper were generated using the reported equation ( 1) in

[46-47].
Eq.1:

݀ = ௗ ି ೡೢ ೡೢ + ௗ ି ೡೢ ೡೢ
The 2D fingerprint maps of (C 6 H 10 N 2 ) (Hg 2 Cl 5 ) 2 .3H 2 O provide some quantitative information about the individual contribution of the intermolecular interaction in the asymmetric unit Fig6, and some distinct spikes appearing in the 2D fingerprint plot which estimate the different interaction motifs in the crystal lattice Fig. 7 The major contribution is from Cl-H (11.8%), H-Cl (8.7%) (e). This is evidence that van der (0.9%)/(0.7%) (h) respectively interactions are recorded in the molecule.

Infrared and Raman spectroscopy

In order to identify the results obtained by means of the crystal structure description of the cationic-anionic layers of the functional groups were studied the vibrational spectroscopy.

Therefore, we have investigated the vibrational properties of the organic and inorganic groups using the Raman scattering and infrared absorption at room temperature. It should be noted that the region high-frequencies 3400 cm -1 and 3350 cm -1 in IR are related to the symmetric and asymmetric stretching of (OH). Furthermore, the bands observed at 3235 cm -1 and 3280 cm -1 in IR are ascribed to symmetric and asymmetric stretching of NH.

Those observed at 3157 cm -1 and 2360 cm -1 in IR are assigned to the symmetric and asymmetric stretching of CH. The band located around 1670 cm -1 in IR is attributed to the stretching of C=C. The bands observed at 1369 cm -1 and 1473 cm -1 in infrared correspond to scissoring of CH + NH as well as to the stretching of CN. However, the bands located at 1257 and 1290 cm -1 in FT-IR and at 1070 cm -1 in Raman are assigned to the stretching vibration of C=N. Nevertheless, the (C-C) bending out-of-plane wavenumbers are assigned at 1112 cm -1 in infrared, while the NH wagging mode observed at 689 cm -1 in IR and at 601 cm -1 in Raman. In fact, the C-C-N in the plane-bending vibration is observed at 591 cm -1 in infrared and in Raman at 567 cm -1 . Finally, the C=C bands show a scissoring vibration at 429 cm -1 and at 432 cm -1 . The wavenumbers observed with precision of the Raman lines are determined by using the LabSpec5 program with a combined Lorentzian-Gaussian band (fig. 8.b). The error range for the determination of the peak position is ±0.5 cm -1 after the accumulation of the data and fitting procedure.

This study is limited to the low-frequency range (50 to 450 cm -1 ), because it includes some lattice and internal modes which are very sensitive to crystal changes and phase transitions

[14]. The Raman lines observed at 55 cm -1 are associated with the anionic (Hg 2 Cl 5 ) -layers.

The shoulder at 100 cm -1 and the band at 110 cm -1 correspond to the HgCl 2 libration of the layers. A well resolved band at 237 and 250 cm -1 corresponds to υ Hg-Cl [52].

CP/MAS-NMR spectroscopy

The NMR spectrum 13 C CP-MAS of the title compound rotating at magic angle and set to rotate at a speed of up to 8 kHz is shown in Fig. 9.

The simulation of these NMR-MAS spectrum isotropic bands is carried out using the Dmfit NMR-MAS measurements permit to localize six in-equivalent carbon sites. However, the NMR technique is more sensible to electronic density neceilies which is influenced by H bonding in this case.

3.5.Thermal analysis

The resultats of the calorimetric (DSC) and the thermogravimetric (TGA) measurement for (C 6 H 10 N 2 )(Hg 2 Cl 5 ) 2 .3H 2 O are illustrated in Fig. 10. The endothermic peak, observed on the DSC curve at 336 K, is accompanied by weight loss equal to 2.835% (weight loss calculated 2.725%) on the TGA curve. This corresponds to the departure of two molecules of water.

After that, the monohydrate compound (C 6 H 10 N 2 )(Hg 2 Cl 5 ) 2 .1H 2 O appears to be stable up to about 355K. Above this temperature several endothermic peaks found by DSC accompanied with a major loss weight indicating the decomposition of the material.

4-Conclusion

This manuscript reports a new mercury (II) hybrid which is a new compound that has been synthesized under hydrothermal conditions and characterized by a single-crystal X-ray diffraction, Hirshfeld surface analysis, spectroscopic study and thermal behavior. Their structure contains a half [C 6 H 10 N 2 ] 2+ cation and inorganic [Hg 2 Cl 5 ] -anion. The crystal crystallizes in the monoclinic system with C 2/c space group at 150 K, besides, its structural arrangement can be described as an alternation of organic-inorganic layers, which is

Structural data

a R int = ∑ |F o 2 -< F o 2 >| / ∑[F o 2 ] / b S = {∑ [w(F o 2 -F c 2 ) 2 ] / (n -p)} 1/2 / c R1 = ∑ | |F o | -|F c | | / ∑ |F o | M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT d wR2 = {∑ [w(F o 2 -F c 2 ) 2 ] / ∑ [w(F o 2 ) 2 ]} 1/2 / w = 1/[σ(F o 2 ) + aP 2 + bP] where P = [2F c 2 + MAX(F o 2 , 0)] /3

  structural chemistry of Cd (II), Zn (II), Hg (II) or Cu (II) halides in the solid state is exceptionally diverse, which can provide electrical mobility [13-15]. Among the systems that are currently receiving a limited attention are the Hg-based halides. Since the states around the Fermi level in organic-inorganic halide hybrid materials (HOIMs) are dominated by metal and the halogenated states, the Hg-based compounds should have band gaps compared to Cd and Zn hybrids due to the difference in electro negativity of Hg halide metal [16-17]. Mercury (II) is the most volatile material. The flexibility of mercury (II) makes it possible to form octahedral and tetrahedral complexes. All the properties are related to the structural changes of these compounds, depending on the effects of different factors, such as temperature and composition. The mercury complex shows a wide range of coordination numbers and geometries (tetrahedral, trigonal, bipyramidal and octahedral), because of the relatively closed shell of the large coordination distances of Hg (II) in the compounds. For this reason, the crystal structure arrangement is appreciably different [18-20]. All the properties are related to the structural change of this compound, depending of the effects of the different factors, such as temperature and composition [21-24].

  layers. The cohesion of compound entities is ensured by hydrogen bonding (N-H***Cl), (N-H***O), (O-H***O) and π-π interactions (Fig .2).The cationic layer (Fig .3) is formed by (C 6 H 10 N 2 ) 2+ groups observed at z/b = 1/3. Between organic entities, two water molecules are intercalated. Each two cations are antiparallel, managed by inversion center while orienting their groups (NH 2 ) towards the inside and outside layers to establish weak hydrogen bonds N-H***Cl with adjacent anionic layers and N-H***O with water molecules. The value of the centroid-to-centroid distances between the two (C 6 H 10 N 2 ) 2+ rings averaging 4.3 Å, This value indicates a rather weak π-π interaction [27]. The atoms of all the organic cations will be differentiated by their position in the plan as well as their directions of the ammonium groups. The C-C bond lengths vary from 1.378 (10) Å to 1.402(13) Å and the C-N bond length value is equal to 1.467(9) Ǻ. On the other hand, the coordination around (C 6 H 10 N 2 ) 2+ cation is characterized by two different sets of N-H***O cohesion with two short N-H bonds (≈ 0.910 Ǻ). However, the C-C-C, C-C-N angles are in the range of 119.80(4) ° to 120.50(7) ° and 119.20(6) ° to 120.90(4) °, respectively (table. 3). The Bond length and angle values are in good agreement with the bond lengths of the other aromatic salts [28-31].

of spherical atom electron densities [ 42 - 43 ]. 1 software [ 44 ].

 4243144 Hirshfeld surfaces and their associated twodimensional fingerprint plots (2D) are calculated using CRYSTAL EXPLORER 3.The breakdown of the two-dimensional fingerprint plots was used for identification of the regions of particular importance to intermolecular interactions by colorcoding having short or long contacts [45]. In this study, the Hirshfeld surfaces treat molecular interactions in cells and it's defined by points where the contribution to the electron density from the molecule of interest is equal to the contribution from all the other molecules. For a given crystal structure and set of spherical atomic electron densities, the combination of d e (the nearest nucleus outside the surface) and d i (the nearest nucleus inside the surface) in the form of a 2D fingerprint plot provides a summary of intermolecular contacts in the crystal. M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT The dnorm (normalized contact distance) is a symmetric function of distances from the Hirshfeld surface (di) and (de) were the first functions of distance explored for mapping on the surfaces, relative to their respective Van Der Waals radii of the atoms internal or external to the surface ( ݎ ௩ௗ௪ / ݎ ௩ௗ௪ ) which identifies the regions of particular importance to the intermolecular interactions. Complementary regions are also visible in the fingerprint plots where one molecule acts as a donor (d e > d i ) and the other as a recipient (d e < d i ) (table

  Waals forces exert an important influence on the stabilization of the packing in the crystal structure, while other intercontacts contribute less to the Hirshfeld surfaces: C-C (5.4%) (b), H-C/C-H 1.4%/2.4% (f); H-O (4.5%) (j) H-H -3.3 % (i) and O-O 3.5%(k). However, the Cl-Cl (d) and Hg-Cl (g) contacts have significant contributions, 11.3 %, and 11.7% % respectively. Again, very low percentages of Hg-Hg and Cl-C/C-Cl (0.4%) (a) and

Fig. 8 .

 8 (a), presents the IR and Raman spectra of the reported compound at room temperature. The assignments of the observed bands, which are based on a comparison of the modes and frequencies observed in similar compounds [14, 31, 48-51], are listed in table 7.

5 [ 54 ].

 554 solid-state NMR spectroscopy program [53]. The spectrum is composed of three isotropic bands b 1 , b 2 and b 3 with different ppm. The simulation of the isotropic band permits to identify six peaks using Gaussian and Lorentzian functions (table 8). The deconvolution of signal b 3 shows the presence of two resonances observed at 121, 123 ppm correspond C 3 and C 4 carbon atoms. Signal b 2 shows the existence of two resonance at around 128, 129 ppm which can be attributed to C 2 and C The most shielded signal b 1, which is located at 131, 133 ppm, corresponds to the carbon M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT atoms C 1 and C 6 linked to the nitrogen atoms [55, 56]. The remainder chemical shift, the values of which are commonly observed in similar compounds [57], corresponds to the aromatic carbon atoms of the phenyl ring. In an X-ray single crystal study, the cation present C v poncutel symmetry and carbon atoms occupy three in-equivalent sites. Inversely, the

Fig. 1 .

 1 Figures caption:

Fig. 2 .

 2 Fig.2. Projection of crystal of (C 6 H 10 N 2 ) (Hg 2 Cl 5 ) 2 .3H 2 O on ab plane.

Fig. 3 .

 3 Fig.3. The cationic layer on bc plane.

Fig. 4 .

 4 Fig.4. The anionic layer on bc plane.

Fig. 5 .

 5 Fig.5. Intermolecular hydrogen bonds of (C 6 H 10 N 2 )(Hg 2 Cl 5 ) 2 .3H 2 O compound.

Fig . 6 .

 6 Fig .6.Hirshfeld surface mapped with d e d norm and d i of the title compound : d norm mapped on Hirshfeld surface for visualizing the intercontacts.

Fig. 7 .

 7 Fig.7. full fingerprint ((a) --(l)) of the title compound : di is the closest internal distance from a given point on the Hirshfeld surface and de is the closest external contacts.

Fig. 8 .Fig. 8 .Fig. 9 .

 889 Fig.8. a. Infrared and Raman spectrum of (C 6 H 10 N 2 )(Hg 2 Cl 5 ) 2 .3H 2 O Fig. 8.b.Deconvulution of the Raman spectrum by using the LabSpec5 program of title compound (C 6 H 10 N 2 )(Hg 2 Cl 5 ) 2 .3H 2 O Fig.9. Experimental and fitted curves of b 1 ; b 2 and b 3 bands.

Fig. 10 .

 10 Fig.10. DSC and TGA curves for the (C 6 H 10 N 2 )(Hg 2 Cl 5 ) 2 .3H 2 O

  0.0296, wR2 d = 0.0710 R1 c = 0.0318, wR2 d = 0.0733 1.469 and -1.860 e -.Å -3

Fig. 5 .Fig . 6 .Fig. 8 .Fig. 8 .Fig. 9 .

 56889 Fig.5. Intermolecular hydrogen bonds of (C 6 H 10 N 2 )(Hg 2 Cl 5 ) 2 .3H 2 O compound.

10 Fig. 10 .

 1010 Fig.10. DSC and TGA curves for the (C 6 H 10 N 2 )(Hg 2 Cl 5 ) 2 .3H 2 O

  (6) °, is significantly characterized by the presence of two types of (Hg 2 Cl 5 ) -. The great value bond length of Hg -Hg found for the distance between the two mercury atoms is considerably larger than the expected Van Der Cl hydrogen bonds from nitrogen or oxygen atoms on the chlorine atoms in the anions.In fact, there are several types of hydrogen bonding interactions present in the crystal structure. These interactions provide a linkage between the cationic (C 6 H 10 N 2 ) + entities and (Hg 2 Cl 5 ) 2-anions. The bonding between inorganic and organic entities in the compounds is

	ACCEPTED MANUSCRIPT
	and N(O)-H***realized by two types of hydrogen bonding N-H***Cl and N-H***O reported in (table.5) and
	M showed in (fig.5). The N-Cl distances vary between 3.134(4) Å and 3.691(4) Å. In this compound, the H-Cl and H-O distances are in the range of 1.91 Å to 2.87 Å and 2.76(1) Å to 3.390(8) Å, respectively. However, the N-H***Cl and N-H***O angle values vary from A N U S C R I P T 117.5°-177.6° to 140.5°-160.7°, respectively.
	A C C E P T E D

Waals contacts. This result is comparable to the reported compounds. The (Hg 2 Cl 5 ) -anionic species has been frequently observed in mercury halide chemistry [29, 32-39]. The (Hg 2 Cl 5 ) --(C 6 H 10 N 2 ) 2+ -H 2 O -(Hg 2 Cl 5 ) -molecular unit is built through the formation of N(O)-H***O The type and the number of hydrogen bonds around each (Hg 2 Cl 5 ) -anion are strongly influenced by the position of the aromatic ring. In fact, two different types of hydrogen bond are found. The aromatic cation inherently possesses the ability to approach the anion without steric hindrance and can therefore share its N-H proton with the chlorine atom commun acceptors. The chlorine atom is involved in hydrogen bond interactions with cation. The N-H distances are approximately equal to 0.910 Å, suggesting that the (C 6 H 10 N 2 ) 2+ cations have established two nearly symmetric hydrogen bonds. The material cohesion is assured by two different interactions, which may indicate a reasonably low interaction [40-41].

Table . 1

 . : Summary of crystal data, X-rays diffraction intensity measurements and refinement parameters (C 6 H 10 N 2 ) (Hg 2 Cl 5 ) 2 . 3H 2 O.

Table 2 :

 2 Fractional atomic coordinates, site occupancy (%) and equivalent isotropic displacement parameters (Å 2 ).

Table 3 :

 3 Main distances (Å) and bond angles (°) for the organic entities of (C 6 H 10 N 2 ) (Hg 2 Cl 5 ) 2 .3H 2 O ; (e.s.d. are given in parentheses).

Table 4 :

 4 Main distances (Å) and bond angles (°) for the inorganic entities of (C 6 H 10 N 2 ) (Hg 2 Cl 5 ) 2 .3H 2 O ; (e.s.d. are given in parentheses).

Table 5 :

 5 Main inter -atomic distances (Å) and bond angles (°) involved in the hydrogen bonds of (C 6 H 10 N 2 )(Hg 2 Cl 5 ) 2 .3H 2 O.

Table 6 :

 6 The combinaison d e and d i obtained by the 2-D fingerprint plots.

Table 7 :

 7 Assignments of the observed infrared and Raman spectra of (C 6 H 10 N 2 ) 2 (Hg 2 Cl 5 ) 3H 2 O (J. in this work) .

Table 8 :

 8 13 C cross-polarization NMR MAS of (C 6 H 10 N 2 ) (Hg 2 Cl 5 ) 2 . 3H 2 O at 8kHz.

Table . 1

 . : Summary of crystal data, X-rays diffraction intensity measurements and refinement parameters (C 6 H 10 N 2 ) (Hg 2 Cl 5 ) 2 . 3H 2 O.

Table 2 :

 2 Fractional atomic coordinates, site occupancy (%) and equivalent isotropic displacement parameters (Å 2 ).

	Atom	X	Y	Z	U(eq)
	Hg1	0.30045(2)	0.55231(2)	0.32962(4)	0.01309(11)
	Hg2
	Cl1	0.27697(2)	0.83275(2)	0.21764(5)	0.01720(11)
	Cl2
		0.20975(9)	0.50255(11)	0.4897(3)	0.0138(3)
		0.40494(9)	0.56962(10)	0.1997(3)	0.0151(4)
	Cl3	0.23528(8)	0.68232(9)	0.2061(3)	0.0125(3)
	Cl4	0.16611(8)	0.86841(10)	0.2779(3)	0.0142(4)
	Cl5	0.39414(9)	0.81733(11)	0.2488(3)	0.0185(4)
	N1	0.0728(3)	0.7161(3)	0.2229(9)	0.0107(12)
	C2	0.0351(3)	0.6469(4)	0.2374(10)	0.0096(13)
	C4	0.0348(4)	0.5148(4)	0.2373(12)	0.0159(15)
	C3	0.0693(4)	0.5812(4)	0.2233(11)	0.0129(14)
	O1W	0.4816(3)	0.6934(3)	0.4978(8)	0.0194(12)
	O2W	0.500000	0.5758(5)	0.750000	0.026(2)

Table 3 :

 3 Main distances (Å) and bond angles (°) for the organic entities of (C 6 H 10 N 2 ) (Hg 2 Cl 5 ) 2 .3H 2 O ; (e.s.d. are given in parentheses).

	Symmetry transformations used to generate equivalent atoms: i -x, y, -z+1/2

Table 4 :

 4 Main distances (Å) and bond angles (°) for the inorganic entities of (C 6 H 10 N 2 ) (Hg 2 Cl 5 ) 2 .3H 2 O ; (e.s.d. are given in parentheses).

	Distances (Å)		Angles (°)
	N1 -C2	1.467(9)	C3-C2-C2 i	119.80(4)
	C2 -C3	1.378(10)	C3 -C2 -N1	119.20(6)
	C2 -C2 i	1.402(13)	C2 i -C2 -N1	120.90(4)
	C4 -C3	1.391(11)	C3 -C4-C4 i	119.70(4)
	C4 -C4 i	1.392(16)	C2 -C3 -C4	120.50(7)

Table 5 :

 5 Main inter -atomic distances (Å) and bond angles (°) involved in the hydrogen bonds of (C 6 H 10 N 2 )(Hg 2 Cl 5 ) 2 .3H 2 O

	D-H***A	D-H (Å)	H...A (Å)	D...A (Å)	<(DHA) (°)
	N1-H1A***Cl3	0.91	2.36	3.265(6)	175.6
	N1-H1B***O1W i	0.91	1.94	2.784(9)	154.3
	N1-H1C***Cl5 i	0.91	2.94	3.390(7)	112.1
	N1-H1C***O1W ii	0.91	2.02	2.829(8)	147.1
	Symmetry transformations used to generate equivalent atoms:
	i -x +1/2, -y+1/2, -z	T= [0, 0, 0]
	ii x +1/2, -y+1/2, z-1/2	T= [-1, 0, 0]

Table 6 :

 6 The combinaison d e and d i obtained by the 2-D fingerprint plots.

		min	max mean Mean+ Mean-	Pi	Sigma+ Sigma-SigmaT nu
	D( norm ) -1.1791 1.0493 0.3060 0.3832 -0.2951 0.2194 0.039703 0.0845450.1242490.2174
	Di	0.6973 2.7738 1.8176 1.8176 nan	0.2620 0.110412 nan	nan	nan
	De	0.6981 2.7692 1.8539 1.8539 nan	0.2618 0.113041 nan	nan	nan

Table 7 :

 7 Assignments of the observed infrared and Raman spectra of (C 6 H 10 N 2 ) 2 (Hg 2 Cl 5 ) 3H 2 O (J. in this work) .

		IR wavenumbers (cm _ 1)		Raman wavenumbers (cm _ 1)	Assignments
	[48]	[31] [49] [ 50]	J	[48] [14]	[31] [49] [50] J
				56		55 , 3
				92	81	100,2
				99		110,1
				115
				125	135	138,7
				158		155,9	Inorganic entities
				172
						208,3
					223	237,3
						250,8
				322		335,1

Supplementary material

Crystal data for a new complex containing: (C 6 H 10 N 2 ) (Hg 2 Cl 5 ) 2 3H 2 O, has been deposited at the Cambridge Crystallographic Data Center as supplementary publications (CCDC -1836685). The data can be obtained free of charge at http://www.ccdc.cam.ac. uk/conts/retrieving.html or from the Cambridge Crystallographic Data Center, 12 Union Road, Cambridge CB2 1EZ, UK; fax: 44 1223 336 033; E-mail: deposit@ccda.cam.ac.uk. The atomic arrangement shows alternation of cationic and anionic layers.

X-ray diffraction, DSC, TGA, IR, Raman and NMR studies were reported.

The intermolecular interactions have also been analyzed by the Hirshfled surfaces analysis.


Dorcet

William Erb

Jean-Pierre Hurvois

Thierry Roisnel

Vincent Dorcet

Ferroceneboronic acid and derivatives: synthesis, structure, electronic properties and reactivity in directed C-H bond activation

Keywords:

INTRODUCTION

The discovery of ferrocene 65 years ago rejuvenated the area of organometallic chemistry and the 1973 Nobel Prize for Chemistry was therefore awarded to Fischer and Wilkinson for their work. This organometallic scaffold fastly imposed itself as one of the most used sensor due to its reversible redox properties and has found numerous applications as ligand in organometallic chemistry. [START_REF]Ferrocenes: Homogeneous Catalysis, Organic Synthesis, Materials Science[END_REF] Recent years have witnessed the emergence of ferrocene-based material chemistry and various applications of this organometallic compound in medicinal chemistry. [START_REF]Ferrocenes: Ligands, Materials and Biomolecules, Štěpnička[END_REF] Unsubstituted ferrocenium salts can be obtained from ferrocene by oxidation and their use in synthesis was recently reviewed. 3 Similarly, substituted ferroceniums salts can also behave as one-electron oxidant or Lewis acids as exemplified by the work of Jahn and Hall, respectively. [START_REF] Khobragade | Acceptor-Substituted Ferrocenium Salts as Strong, Single-Electron Oxidants: Synthesis, Electrochemistry, Theoretical Investigations, and Initial Synthetic Application[END_REF] In the course of carbon-heteroatom bond formation studies in the ferrocene series, [START_REF] Tazi | From 2-to 3-Substituted Ferrocene Carboxamides or How to Apply Halogen "Dance" to the Ferrocene Series[END_REF] we became interested in the synthesis and use of ferroceneboronic acid and its derivatives (Figure 1). However, a literature survey revealed striking differences in the analytical descriptions of such compounds. The case of ferroceneboronic acid (FcB(OH)2, 1) is highly relevant: initially prepared by Nesmejanov in 1959 from ferrocenyllithium and tributylborate, it was characterized by its melting point and elemental analysis. 6 Later prepared by Helling 7 (1961) and Pauson 8 (1967), it is only in 1970 that Post described its mass spectrometry analysis. [START_REF] Post | II. Ferrocenyl boric acids and related compounds. Mass spectral and hydrogen-bonding studies[END_REF] Interestingly, he noticed the tendency of FcB(OH)2 to dehydration, leading to variable amounts of the corresponding boroxine (4), which complicates its analysis. In 1978, Illuminati measured the pKa of FcB(OH)2 and reported its [START_REF]Ferrocenes: Homogeneous Catalysis, Organic Synthesis, Materials Science[END_REF] H NMR spectra in deuterated acetone. [START_REF] Floris | The kinetics and mechanism of the protodeboronation of ferroceneboronic acid in moderately concentrated sulfuric acid[END_REF] However, only the 1 H signal of the boronic acid group was attributed by deuterium exchange. Christensen later described a similar [START_REF]Ferrocenes: Homogeneous Catalysis, Organic Synthesis, Materials Science[END_REF] H NMR spectrum in deuterated chloroform. [START_REF] Kamounah | A New Preparation of Iodoferrocene[END_REF] However, to the best of our knowledge, the only copy of 1 H NMR spectrum available could be found in the work of Lacina who followed FcB(OH)2 titration with diols by NMR. [START_REF] Lacina | Interaction of ferroceneboronic acid with diols at aqueous and non-aqueous conditions -signalling and binding abilities of an electrochemical probe for saccharides[END_REF] In 2004 Aldridge reported the X-ray diffraction analysis of 1 and the hydrogen bonding network developed at the solid state. [START_REF] Bresner | Hydrogenbonding motifs in the solid-state structure of ferroceneboronic acid[END_REF] Finally, Voloshin reported the UV-spectrum of FcB(OH)2 in 2008. [START_REF] Voloshin | Template synthesis and structures of bis-ferrocenylboronate macrobicyclic iron(II) tris-dioximates[END_REF] The case of the trifluoroborate salts, relevant ferroceneboronic acid derivatives, [START_REF] Darses | Potassium Organotrifluoroborates: New Perspectives in Organic Synthesis[END_REF] is also interesting. Tetra-n-butylammonium ferrocenyltrifluoroborate (2) was initially prepared by Lough in 2001. [START_REF] Quach | Tetra-nbutylammonium ferrocenyltrifluoroborate[END_REF] The identity of the compound was clearly established by X-ray diffraction analysis and no other analyses were performed. Two years later, Bats reported the synthesis and crystal structure of ferricenyltrifluoroborate. [START_REF] Bats | The twinned structure of ferricenyltrifluoroborate[END_REF] Although the C-B bond length was little affected upon oxidation of Fe 2+ to Fe 3+ , he noticed a slight elongation (0.04 Å) of the Fe-C bond. In 2005, Aldridge reported for the first time the full characterization of ferrocenyltrifluoroborate with an ammonium counter anion (3). [START_REF] Bresner | Selective Electrochemical Detection of Hydrogen Fluoride by Ambiphilic Ferrocene Derivatives[END_REF] Although unattributed 1 H, [START_REF] Bresner | Hydrogenbonding motifs in the solid-state structure of ferroceneboronic acid[END_REF] C, [START_REF] Kamounah | A New Preparation of Iodoferrocene[END_REF] B and [START_REF] Smith | Reaction of boronic acids with tetrafluoroborate? It depends on the acidity[END_REF] F NMR spectra were described. The structure of the product was further supported by IR spectroscopy, mass spectrometry R e v i s e d m a n u s c r i t p t and X-ray diffraction analysis. Finally, Grzybowski reported in 2014 the formation of ferricenyltrifluoroborate, and its characterization by IR spectroscopy, elemental analysis and electrochemical measurements. [START_REF] Smith | Reaction of boronic acids with tetrafluoroborate? It depends on the acidity[END_REF] On the other hand, triferrocenylboroxine (4) and the related triferrocenylborazine (5) and triferrocenyltrithiaborine (6) have been more studied. Originally reported by Post in 1970, [START_REF] Post | II. Ferrocenyl boric acids and related compounds. Mass spectral and hydrogen-bonding studies[END_REF] various analytical data can be found in the literature ( 1 H, [START_REF] Bresner | Hydrogenbonding motifs in the solid-state structure of ferroceneboronic acid[END_REF] C, [START_REF] Kamounah | A New Preparation of Iodoferrocene[END_REF] B, [START_REF] Paul | Ir-Catalyzed Functionalization of 2-Substituted Indoles at the 7-Position: Nitrogen-Directed Aromatic Borylation[END_REF] Fe NMR data, IR and mass spectra, elemental analysis) [START_REF] Bats | Isomorphism and phase transition in triferrocenylboroxine and triferrocenylborazine[END_REF] and it should be noted that, in the solid state, the three ferrocenyl groups are generally arranged on the same side of the central six-membered ring. [START_REF] Makarov | Synthesis and structure of tris(4-ferrocenylphenyl)boroxine and its utility in cross-coupling reaction[END_REF] Boronic esters and diaminoboryl derivatives are also well represented in the literature, the former notably due to the ability of ferroceneboronic acid to react with diols and sugars. [START_REF] Lacina | Interaction of ferroceneboronic acid with diols at aqueous and non-aqueous conditions -signalling and binding abilities of an electrochemical probe for saccharides[END_REF][START_REF] Ori | Electrochemical detection of saccharides by the redox cycle of a chiral ferrocenylboronic acid derivative: a novel method for sugar sensing[END_REF] Various 5-membered boronic esters such as pinacol (7), ethyleneglycol (8), hydrobenzoin (9) or catechol (10) derivatives have also been prepared and characterized. [START_REF] Tlili | Synergistic effects in ambiphilic phosphino-borane catalysts for the hydroboration of CO2[END_REF] Finally, full analytical data could be found for the various diaminoborylferrocenes 11-14. [START_REF] Kotz | Preparation and properties of ferrocenyldichloroborane[END_REF] Therefore, it appears that ferroceneboronic acid (1) and potassium trifluoroborate (19) remain to be fully characterized. Furthermore, to the best of our knowledge, recently developed boron-protecting groups such as 1,8-diaminonaphthalene (dan), [START_REF] Noguchi | Boron-Masking Strategy for the Selective Synthesis of Oligoarenes via Iterative Suzuki-Miyaura Coupling[END_REF] anthranilamide (aam), [START_REF] Ihara | A Simple, Removable ortho-Directing Modifier for Arylboronic Acids Serving also as a Protecting Group in Cross-Coupling Reactions[END_REF] cyclic triolborates [START_REF] Yamamoto | Cyclic Triolborates: Air-and Water-Stable Ate Complexes of Organoboronic Acids[END_REF] and N-methyliminodiacetic acid (MIDA) [START_REF] Gillis | A Simple and Modular Strategy for Small Molecule Synthesis: Iterative Suzuki-Miyaura Coupling of B-Protected Haloboronic Acid Building Blocks[END_REF] have never been introduced onto FcB(OH)2, although their utility in cross-coupling reactions has been fully demonstrated. [START_REF] Lennox | Selection of boron reagents for Suzuki-Miyaura coupling[END_REF] Finally, owing to the growing importance of azaborine chemistry, [START_REF] Bélanger-Chabot | Recent Developments in Azaborinine Chemistry[END_REF] it would be of high interest to be able to access the ferrocenic analog of known compounds to elucidate their specific properties.

Here, we report our study of the known FcB(OH)2 (1, Figure 2) and its original diaminonaphthalene (FcB(dan), 15), boronanthranilamides (FcB(aam), 16; FcB(Me-aam), 17 and 18), potassium trifluoroborate (FcBF3K, 19), triolborate (FcB(triolborate), 20) and N-methyliminodiacetic acid (FcB(MIDA), 21) derivatives. NMR, X-ray diffraction and electrochemical analysis were performed to classify these borylated groups in terms of electron-donating and -withdrawing capacity. Finally, ferrocene catalytic silylation and borylation by C-H activation, directed by the boron anthranilamide group, is described.

Results and discussion

Synthesis of ferroceneboronic acid and its derivatives. Historically, ferroceneboronic acid (1) was prepared by deprotometalation of ferrocene using butyllithium before interception of the resulting lithioferrocene with tributylborate. 6b, 7 However, mixtures of ferroceneboronic acid (1) and 1,1'-ferrocenylenediboronic acid were invariably obtained. Pauson later described the reaction of ferrocenyl dihaloborane with water to generate FcB(OH)2 in yields up to 55%. [START_REF] Mcvey | Part XVII. The aminomethylation of methoxy-and dimethoxyferrocene[END_REF] Here, we report a modification of the Nesmeyanov procedure based on the use of tBuLi in presence of catalytic tBuOK 31 . Employing the phase-switch purification developed by Hall, [START_REF] Mothana | Multistep Phase-Switch Synthesis by Using Liquid-Liquid Partitioning of Boronic Acids: Productive Tags with an Expanded Repertoire of Compatible Reactions[END_REF] ferroceneboronic acid (1) was obtained on a multigram scale in 85% yield, pure enough for most applications without the requirement of chromatographic purification (Scheme 1). Scheme 1. Synthesis of ferroceneboronic acid (1).

Boron naphthalene-1,8-diamido derivatives are obtained by the reaction of boronic acids with 1,8-diaminonaphthalene under azeotropic removal of water. In our hands, the procedure developed by Suginome [START_REF] Noguchi | Boron-Masking Strategy for the Selective Synthesis of Oligoarenes via Iterative Suzuki-Miyaura Coupling[END_REF] afforded FcB(dan) (15) in a surprisingly low yield (Table 1, entry 1). Concerned by the potential presence of anhydrides, a hydrolysis step was added, but with minor success (entry 2). Although still moderate, best results were finally obtained using the FeCl3/imidazole catalytic system developed by Pucheault (entry 3). 33 Likewise, the formation of the boron-anthranilamide group relies on the esterification of the boronic acid with anthranilamide. Following the procedure described by Suginome, [START_REF] Ihara | A Simple, Removable ortho-Directing Modifier for Arylboronic Acids Serving also as a Protecting Group in Cross-Coupling Reactions[END_REF] FcB(amm) (16) was isolated in a moderate yield after column chromatography (Table 2, entry 1). Better results were noticed when adding an initial hydrolysis step (entry 2), whereas the FeCl3/imidazole catalytic system always afforded 16 in moderate yields, probably due to the lower nucleophilicity of anthranilamide when compared to 1,8-diaminonapthalene (entries 3 and 4). The formation of the methylated anthranilamide derivatives 17 and 18 was more difficult. Indeed, heating at toluene reflux 1 with either 22 or 23 only afforded traces of products, whereas the FeCl3/imidazole system was unable to catalyze the reaction, even with prolonged reaction time (Scheme 2). It was finally found that complete conversion could be reached by heating at toluene reflux 1 and 22 or 23 in the presence of FeCl3 and im-R e v i s e d m a n u s c r i t p t idazole under azeotropic removal of water. However, the instability of 17 and 18 led to major degradation during the purifications. As the introduction of the methyl groups does not significantly affect the structures of the anthranilamides, as judged by NMR and X-ray diffraction analysis, the origin of this instability remains unclear. Hydrolysis, protodeboronation or oxidation appears as possible decomposition pathways, although none of them could currently be preferred.

Scheme 2. Formation of FcB(Me-aam) (17 and 18).

Potassium trifluoroborate salts are usually prepared by reacting boronic acids with KHF2 according to Vedejs. [START_REF] Vedejs | Conversion of Arylboronic Acids into Potassium Aryltrifluoroborates: Convenient Precursors of Arylboron Difluoride Lewis Acids[END_REF] Even if the generality of this method remains incontestable, corrosive KHF2 causes etching of glassware and Soxhlet extraction is often required to get pure compounds. The simplified procedure developed by Lloyd-Jones 35 using potassium fluoride and tartaric acid was here followed to access analytically pure potassium ferrocenyltrifluoroborate (19) in 47% yield without purification (Scheme 3).

Scheme 3. Synthesis of potassium ferrocenyltrifluoroborate (19).

Triolborates are easily accessible by following Yamamoto and Miyaura's protocol. [START_REF] Yamamoto | Cyclic Triolborates: Air-and Water-Stable Ate Complexes of Organoboronic Acids[END_REF] Here, the reaction between 1 and 1,1,1-tris(hydroxymethyl)ethane under azeotropic removal of water afforded the ester 24, which was directly converted into the triolborate 20 in the presence of potassium hydroxide in 70% yield over two steps (Scheme 4, top).

MIDA boronates, introduced by Mancilla [START_REF] Mancilla | New bicyclic organylboronic esters derived from iminodiacetic acids[END_REF] and nicely exploited in iterative cross-couplings by Burke, are prepared by reacting boronic acids and N-methyliminodiacetic acid. According to a literature procedure, 28a the new N-methyliminodiacetic acid boronate FcB(MIDA) (21) was obtained in 65% yield (Scheme 4, bottom). Scheme 4. Synthesis of FcB(triolborate) (20) and FcB(MIDA) (21).

NMR spectroscopic characterization.

All the new compounds were characterized by [START_REF] Kamounah | A New Preparation of Iodoferrocene[END_REF] B, 1 H and [START_REF] Bresner | Hydrogenbonding motifs in the solid-state structure of ferroceneboronic acid[END_REF] C NMR spectroscopy and, when possible, spectra were attributed on the basis of short and long range correlations (Figure 3). 11 B NMR is a powerful tool to investigate the geometry and electronic environment around the heteroatom. As expected, upon quaternarization to the potassium trifluoroborate and triolborate, the [START_REF] Kamounah | A New Preparation of Iodoferrocene[END_REF] B NMR resonance is shifted to higher fields (19: δ( 11 B) = 3.0 ppm, 20: δ( 11 B) = 2.4 ppm). The MIDA boronate 21 is characterized by a chemical shift of 13.9 ppm, consistent with the presence of a dative N-B bond at the pyramidalized boronate ester. 28a The chemical shifts of FcB(dan) and the three FcB(aam) are slightly shifted downfield (15: δ( 11 B) = 32.4 ppm, 16: δ( 11 B) = 31.7 ppm, 17: δ( 11 B) = 31.9 ppm, 18: δ( 11 B) = 31.7 ppm) when compared to 1. If the downfield shift from boronic acid to aminoboranes is known in the literature, [START_REF] Nöth | Nuclear Magnetic Resonance Spectroscopy of Boron Compounds[END_REF] the difference between 15 and 16 is counterintuitive. Indeed, Nöth has reported that high δ( 14 N) results in high δ( 11 B) on boronamides. [START_REF] Nöth | Kernresonanzspektroskopische Untersuchungen an Borverbindungen, VII. 11 B-und 14 N-Kernresonanzstudien an tetrakoordinierten Bor-Stickstoff-Verbindungen[END_REF] With higher 14 N chemical shifts observed for the anthranilamide when compared to the diaminonaphthalene, [START_REF] Sibi | Nitrogen-15 NMR spectroscopy: Nitrogen-15 chemical shifts of 1,2-diaminobenzenes and 1,8diaminonaphthalenes[END_REF] one might have expected higher δ( 11 B) in 16. However, as revealed by X-ray diffraction analysis, the B(dan) substituent is titled relative to the substituted cyclopentadienyl (Cp) ring (Figure 4) whereas boron anthranilamide is almost coplanar (Figure 5). Therefore, although weak, interaction between the vacant boron p-orbital and the ferrocenyl core could exist at a higher level in 16 than for 15, leading to this unexpected [START_REF] Kamounah | A New Preparation of Iodoferrocene[END_REF] B chemical shifts reverse order. Very small differences in δ( 11 B) are observed between 16, 17 and 18 although the B(Me-aam) substituents are titled in the two latter (Figures 6 and7). Therefore, the electron-rich methyl groups seems to counterbalance the reduced filling of boron p-orbital by the ferrocenyl group.

The 1 H and [START_REF] Bresner | Hydrogenbonding motifs in the solid-state structure of ferroceneboronic acid[END_REF] C spectra can help classify the borylated substituents in terms of electron-donating and -withdrawing properties when compared to reference compounds (Table 3). [START_REF] Nesmeyanov | The 13 C NMR and electronic effects in the pie-cyclopentadienyl derivatives of iron[END_REF] Indeed, on monosubstituted ferrocenes, electron-withdrawing groups have a higher downshifting effect on Hα (adjacent to the substituent) than on Hβ (remote to the substituent).

From ferrocene (FcH) to ferroceneboronic acid (1), both Hα and slightly shift downfield (about 0.1 ppm), indicating weak electron-withdrawing properties for the B(OH)2 substituent.

The electron-withdrawing properties of B(dan) and B(aam) groups are clearly established by the large chemical shifts observed (15: + 0.55, 16: + 0.69 ppm for Hα and 15: + 0.23, 16: + 0.28 ppm for Hβ), very similar to those of ketones (FcCOMe: + 0.61 ppm for Hα and + 0.28 ppm for Hβ). Furthermore, the electron-withdrawing ability of the anthranilamide moiety can be modulated by the addition of methyl groups (16: + 0.69 17: + 0.53, 18: + 0.55 ppm for Hα), opening possibilities for the tuning of boron Lewis acidic character. The B(MIDA) group ( 21) is closer to the weak electron-withdrawing group SiMe3. [START_REF] Brown | Ferrocenyl ligands-III. Bulky ferrocenyl derivatives. 1,1'-Bis(diphenylphosphino)-3,3'bis(trimethylsilyl)ferrocene. Synthesis, metal complexation and the crystal and molecular structure[END_REF] It is known that functional groups have little effect onto the unsubstituted Cp ring. 40d However, small to moderate downfield shifts are generally observed for electron-withdrawing groups whereas small upfield shifts take place with electrondonating groups. The effect of the borylated groups used in this study are therefore difficult to rationalize. Indeed, B(OH)2, B(dan) and B(aam) groups, classified as electron-withdrawing based on [START_REF] Kamounah | A New Preparation of Iodoferrocene[END_REF] B NMR, all shift upfield the 1 H NMR signal of the Cp ring. Furthermore, their effect is more pronounced than an amino and close to that of a phosphino substituent. The remaining boron-anthranilamides (17, 18) have very little upfield shifting effect. Although the origin of these results remains unclear, this might results from the variable degree of interaction between the ferrocenyl core and the boron vacant p-orbital. On the other hand, the trifluoroborate (19) and triolborate (20) both act as strong electron-donating as judged by the high upfield shifts of the Cp ring whereas the MIDA boronate (21) group has no effect.

R e v i s e d m a n u s c r i t p t

Concerning [START_REF] Bresner | Hydrogenbonding motifs in the solid-state structure of ferroceneboronic acid[END_REF] C NMR spectroscopy, Cβ are known to be more sensitive to strong electron-withdrawing group whereas Cα are more influenced by strong electron-donating substituents. 40a, 40c For medium electron-donating and -withdrawing groups, chemical shifts are more difficult to classify. Indeed, although [START_REF] Bresner | Hydrogenbonding motifs in the solid-state structure of ferroceneboronic acid[END_REF] C chemical shifts observed for B(OH)2 suggest an electron-donating group, this might not be representative as we previously classified this group as a weak electron-withdrawing group. A similar contradiction is noted for B(MIDA) (21): 1 H chemical shifts suggest an electron-withdrawing group whereas [START_REF] Bresner | Hydrogenbonding motifs in the solid-state structure of ferroceneboronic acid[END_REF] C chemical shifts are closer to an electron-donating group behavior. Therefore, the unambiguous classification of these groups cannot be done only with 1 H and [START_REF] Bresner | Hydrogenbonding motifs in the solid-state structure of ferroceneboronic acid[END_REF] C spectroscopy.

Results were more intriguing for B(dan) (15) and B(aam) (16-18), all classified as electron-withdrawing groups from 1 H NMR data. Therefore, their shifting effect on the Cβ should be higher than on Cα. However, the opposite effect was recorded. A surprising slight increase in the short-range acidifying effect is also noted on Cα from 16 to 18. A similar effect was also noted by Wrackmeyer and Herberhold on bis(diisopropylamino)boryl ferrocene and remains unexplained. [START_REF] Wrackmeyer | Metal-boron interactions in boron-substituted ferrocenes, ruthenocenes and osmocenes[END_REF] On the contrary, the higher shifts observed for Cα compared to Cβ on trifluoroborate (19), triolborate (20) are in agreement with the literature.

Minor variations of the unsubstituted Cp ring were also noted. Its [START_REF] Bresner | Hydrogenbonding motifs in the solid-state structure of ferroceneboronic acid[END_REF] C resonance is shifted upfield for the two borates (19: δ( 13 C) = -0.5 ppm, 20: δ( 13 C) = -0.4 ppm). On the contrary, the [START_REF] Bresner | Hydrogenbonding motifs in the solid-state structure of ferroceneboronic acid[END_REF] C resonance of the Cp is shifted downfield for FcB(OH)2 (1), FcB(aam) (16), FcB(dan) (15) and FcB(MIDA) (21) (δ( 13 C) = + 1.50, + 1.20, + 0.60, + 0.50 ppm, respectively). Interestingly, this order correlates with the boron chemical shifts for the trivalent derivatives (1: δ( 11 B) = 31.0 ppm, 16: δ( 11 B) = 31.7 ppm, 15: δ( 11 B) = 32.4 ppm). Therefore, as the donation of the boron substituents into the boron vacant p orbital increases, boron Lewis acidity decreases and the unsubstituted Cp ring is less electron-depleted. This suggests interactions between boron, Cipso and iron atoms or through-space interactions between boron and the unsubstituted Cp, as proposed by Holthausen and Wagner. [START_REF] Scheibitz | 5H4.BR2 Bending in Ferrocenylboranes: A Delocalized Through-Space Interaction Between Iron and Boron[END_REF] As variations of interatomic distances and bending angles are characteristic of such interactions, we next study the structure of the borylated ferrocenes by X-ray crystallography.

X-ray crystal structure determination. Crystals of 15, 16, 17, 18, 19 and 21 were obtained by evaporation of their corresponding solutions.

In 15, the planar diaminonaphthalene group is tilted relative to the substituted Cp ring (Figure 4, C6-C10-B11-N22 = 16.5(3)°), whereas the Cp and anthranilamide rings are almost coplanar in 16 (Figure 5, C6-C10-B11-N12 = 0.9(3)°). However, the introduction of the methyl group in 17 and 18 forces the borylated substituent to rotate and release the steric pressure generated by this additional substituent (Figures 6 and7 in these compounds is highly significant and is evaluated by the angle α* between the center of gravity of the substituted Cp ring, the Cipso and the boron atom. According to the crystallographic data, it is the highest in 16 and decreases upon introduction of the methyl groups, whereas they are similar for 15 and 17 (15: 5.53°, 16: 7.97°, 17: 5.50°, 18: 1.08°). These data suggest less interactions between the ferrocenyl group and boron in 15 compared to 16, resulting from the higher filling of the boron empty orbital by the nitrogen lone pairs in 15. This might reflect the intrinsic electronic differences between the aniline and the amide. The methyl group has a similar donating effect in 17 and 18, although clearly higher for the latter, probably for similar reasons. This is in agreement with the work of Wagner [START_REF] Scheibitz | 5H4.BR2 Bending in Ferrocenylboranes: A Delocalized Through-Space Interaction Between Iron and Boron[END_REF] The crystal structure of 19 reveals the longest bond between boron and cyclopentadienyl ring (Figure 8, C10-B11 1.588(4) Å), as well as the smallest bending angle (α* 0.98°). These values are in good agreement with the reported X-ray crystal structures of the FcBF3 -anion and are characteristic of quaternarized boron atom. [START_REF] Quach | Tetra-nbutylammonium ferrocenyltrifluoroborate[END_REF][START_REF] Bresner | Selective Electrochemical Detection of Hydrogen Fluoride by Ambiphilic Ferrocene Derivatives[END_REF] However, unlike the reported structures of ferrocenyltrifluoroborate anions, the role of the potassium cation in the crystal packing should be pointed out (Figure 8). Indeed, each potassium ion is shared between three BF3 groups and therefore participates to the formation of an inner cationic layer while the ferrocene parts are pointing outward, as observed for unsubstituted potassium phenyltrifluoroborate. [START_REF] Kamiński | Finding Rules Governing Layered Architectures of Trifluoroborate Potassium Salts in the Solid State[END_REF] FcB(MIDA) ( 21) has its iron-boron distance (Fe1-B11: 3.1695(19) Å), Cipso-B bond (C10-B11: 1.568(2) Å) and bend angle (α* 3.17°) between those of FcB(OH)2 (1) and FcBF3K (19), which confirm the moderate electron-donating properties of this substituent. The single-crystal X-ray diffraction data also confirm the presence of a dative nitrogen-boron bond (B11-N12 1.664(2) Å). When compared to other heterocyclic B(MIDA) derivatives such as the 2-pyridine, [START_REF] Dick | A General Solution for the 2-Pyridyl Problem[END_REF] 2-pyrazine and 5-thiazole ones, [START_REF] Dick | General Method for Synthesis of 2-Heterocyclic N-Methyliminodiacetic Acid Boronates[END_REF] it appears that the Cipso-B bond is shorter (from -0.016 to -0.021 Å) while the B-N dative bond is longer (from +0.016 to +0.030 Å) in 21. This longer dative bond results from the better electronic donation of the ferrocenyl core to boron.

Electrochemistry.

The electrochemical behavior of ferroceneboronic acid and its derivatives was next studied by cyclic voltammetry (Table 4). Due to the low solubility of these complexes in acetonitrile,

R e v i s e d m a n u s c r i t p t

the measurements were performed in dry, oxygen-free dimethylformamide (DMF) at a concentration of 3 mM with nBu4NPF6 (0.1 M) as supporting electrolyte. For comparison, the cyclic voltammogram of ferrocene (Fc) was recorded in the same solvent and displayed a reversible mono-electronic system with a peak separation of 80 mV. a Scan rate = 0.1 V/s. Bu4NPF6 (0.1 M) in DMF; working electrode: glassy carbon; reference electrode: Ag/AgCl. b An additional oxidation peak was observed at 0.16 V. nr: not reversible. Potential differences, E (defined as Epa Fc -Epa boronic ).

Compounds 1, 16, 17, 19 and 21 exhibited typical one-electron and reversible processes at a scan rate of 0.1 V/s with the ipc/ipa ratios of unity and the peak separation in the 80-90 mV range. As a result, the corresponding ferricinium species appeared stable at the time scale of cyclic voltammetry.

The easier oxidation peak for compound 19 was easily attributed to the presence of the trifluoroborate substituent. Obviously, quaternarization of the boron substituent provided a significant cathodic shift (Epa Fc -Epa 19 = 310 mV) and this observation is in agreement with that of Grzybowski. [START_REF] Smith | Reaction of boronic acids with tetrafluoroborate? It depends on the acidity[END_REF] One might expect a similar observation for the triolborate 20. Unfortunately, the voltammogram of 20 displayed a first irreversible oxidation peak (Epa1 = 0.16), which may be attributed to a chemical reaction giving rise to a new reversible oxidation system at Epa1 = 0.60 V. The origin of this chemical process remains unclear even if the second system could be related to the reversible Fe 2+ /Fe 3+ process. The exact nature of this follow-up chemical reaction would require further investigation.

We also reasoned that introduction of the B(MIDA) moiety onto ferrocene would increase significantly its oxidation potential due to the ester functionalities. However, for compound 21, a fully reversible couple (ipa/ipa = 0.97) was observed, indicating that the nitrogen donation into the vacant boron p-orbital can counterbalance the electron-withdrawing properties of the carbonyl function. Finally, from boronic acid (1) to boron complexes 16, 17 and 18, the potential at which oxidation occurs results from the moderate electron-withdrawing properties of the anthranilamide group. Conversely, the cyclic voltammogram of complex 18 exhibited an ipa/ipa value of 1.20, which is in agreement with a partial loss of reversibility. This phenomenon could be attributed to a slow electron exchange between the ferricinium moiety and the N-methyl group of the anthranilamide substituent. Hence, the presence of an alkyl substituted nitrogen atom may be detrimental to the stability of the ferrocenium species.

The electrochemical behavior of complex 15 is worthy of an additional comment. Indeed, its cyclic voltammogram exhibits an irreversible oxidation peak at Epa = 0.58 V, whose height is twice than that recorded for the vast majority of the substrates. This abnormal result may be attributed to the oxidation of both the ferrocene and 1,8-diaminonaphtalene core, which occurs at a very similar potential. To confirm this hypothesis, the anodic electrochemistry of 1,8-diaminonaphtalene displayed an irreversible single system at Epa = 0.6 V vs Ag/AgCl (see SI). Therefore, the oxidation potential of 1,8-diaminonaphtalene is approximately the same than that recorded for the ferrocene itself.

Catalytic C-H activation.

In recent years, the silylation of unactivated C-H bond has enormously grown with the development of efficient catalytic systems. [START_REF] Cheng | Catalytic Silylation of Unactivated C-H Bonds[END_REF] Nowadays, the directed intermolecular silylation is an appealing way to access silylated aromatics in a site-selective fashion. Various directing groups can be used and, in 2009 and 2011, Suginome reported the ability of borylated 2-(5-pyrazolyl)aniline (pza) and anthranilamide (aam) to direct the ortho-silylation of substituted benzenes. [START_REF] Ihara | A Simple, Removable ortho-Directing Modifier for Arylboronic Acids Serving also as a Protecting Group in Cross-Coupling Reactions[END_REF][START_REF] Ihara | Easily Attachable and Detachable ortho-Directing Agent for Arylboronic Acids in Ruthenium-Catalyzed Aromatic C-H Silylation[END_REF] However, to the best of our knowledge, silylated ferrocenes have only been prepared by interception of lithiated ferrocenes and the catalytic silylation of ferrocenes has never been reported. [START_REF] Zhao | Rhodium-Catalyzed 2-Arylphenol-Derived Six-Membered Silacyclization: Straightforward Access toward Dibenzooxasilines and Silicon-Containing Planar Chiral Metallocenes[END_REF] Here, we present preliminary results on the use of B(aam) to direct ferrocene C-H bonds activation. We initially surveyed the reaction of 16 with HSiMe2Ph in the presence of norbornene as hydrogen acceptor and [Ir(OMe)(COD)]2/4,4'-di-tert-butyl-[2,2']bipyridinyl (dtbpy) as catalytic system. [START_REF] Cheng | Iridium-Catalyzed, Diastereoselective Dehydrogenative Silylation of Terminal Alkenes with (TMSO)2MeSiH[END_REF] To our delight, the product 25 was formed, albeit in very low yield (Table 5, entry 1). We therefore switched to Suginome's conditions [START_REF] Ihara | A Simple, Removable ortho-Directing Modifier for Arylboronic Acids Serving also as a Protecting Group in Cross-Coupling Reactions[END_REF] and isolated the title product in a better yield (entry 2). By doubling the catalyst loading, we obtained 25 in a moderate yield, together with a small amount of the bis-silylated derivative 26 (entry 3). Interestingly, when the reaction time was extended, the mono-/bisfunctionalized products ratio changed and 26 was isolated in 48% yield (entry 4). Silylation was also attempted from the methylated anthranilamides 17 and 18; however, their instability during both reaction and purification steps led to multiple products.

The conformation of the two substituents in 25 was elucidated by 2-dimensional NMR experiments and X-ray diffraction analysis (Figure 10). From NOESY experiments, the correlations seen between the amide proton and the unsubstituted Cp ring suggest that the amide is pointing down. Correlations observed between the aniline NH and one of the methyl of the SiMe2Ph group also support this orientation. Interestingly, the correlations observed between the dimethylsilyl group and both the NH and the ferrocenyl proton suggests some degree of free rotation between the Cipso-B and Cipso-Si bounds. The structure at the solid state confirms the NMR analysis (Figure 9, right).

R e v i s e d m a n u s c r i t p t

The amide proton is clearly oriented toward the unsubstituted Cp ring while the phenyl ring of the silylated substituent is pointing up, explaining the absence of correlation of any NH and phenyl protons. It is noteworthy that the introduction of the dimethylphenylsilyl group has a clear effect on the borylated substituent. From 16 to 25, both the C6-B11 and Fe1-B11 distances increase (+0.016 Å and +0.184 Å, respectively), while the bending angle α* decreases (-4.83°). This indicates lower interactions between boron, Cipso and iron atoms, resulting from the steric repulsion generated by the silylated group. Due to the steric hindrance resulting from the two silylated groups, the borylated substituent in 26 should be almost perpendicular to the Cp ring. However, despite all our efforts, crystals suitable for X-ray diffraction analysis were never obtained. However, NOESY experiment revealed correlations of both NH with the unsubstituted Cp ring, thus suggesting two conformers, one with the amide pointing toward the unsubstituted Cp ring and one with the amide pointing up.

Encouraged by these promising results in silylation, we finally turned our attention to the borylation of ferrocene C-H bond, directed by the boron-anthranilamide group. If successful, this would constitute the first ortho-directed C-H borylation of ferrocene C-H bonds. Indeed, to the best of our knowledge, the catalytic ferrocene borylation has only been reported twice, one by Plenio, 51 affording 1,3-disubstituted derivatives, and the second by Li, [START_REF] Wang | B-Type Bidentate Boryl Ligands Enabling a Highly Active Iridium Catalyst for C-H Borylation[END_REF] only dedicated to the formation of monosubstituted products. Rhodium-catalyzed borylation was first evaluated. However, despite all our efforts, multiple products were invariably formed (Table 6, entries 1 and 2). Surprisingly, the use of Plenio's conditions afforded 28 as the main product, resulting from the directing group functionalization (entries 3 and 4). Such a regioselectivity switch between catalytic rhodiumcatalyzed silylation and iridium-catalyzed borylation is known, [START_REF] Cheng | Rhodium-Catalyzed Intermolecular C-H Silylation of Arenes with High Steric Regiocontrol[END_REF] and was also recently documented in the benzene series using the same boron anthranilamide directing group. [START_REF] Yamamoto | Regioselective Synthesis of o-Benzenediboronic Acids via Ir-Catalyzed o-C-H Borylation Directed by a Pyrazolylaniline-Modified Boronyl Group[END_REF] However, even if it is known that borylation is sensitive to ortho substituents, the exact origin of this reversal is not totally understood. [START_REF] Cheng | Rhodium-Catalyzed Intermolecular C-H Silylation of Arenes with High Steric Regiocontrol[END_REF] Taking into account the generally accepted mechanism of iridium-catalyzed borylation, [START_REF] Mkhalid | C-H Activation for the Construction of C-B Bonds[END_REF] this might indicate that the directing group would not be effective to coordinate the iridium catalyst surrounded by three pinacol residues and the bipyridine ligand. To open a coordination site onto the metal, we therefore tested the hemilabile ligand designed by Lassaletta. [START_REF] Ros | Use of Hemilabile N,N Ligands in Nitrogen-Directed Iridium-Catalyzed Borylations of Arenes[END_REF] However, whatever the conditions used, 28 was always isolated as the main product, although in considerably lower yield (entry 5). Taking into account the low yield of silylated product 25 formed and the absence of ferrocene borylation, both under iridium catalysis, it can be advanced that the boron-anthranilamide group has poor ortho-directing ability for this metal. The borylation site is also interesting as one could expect a reaction either at the most acidic (next to the carbonyl) or at the less hindered positions. However, extensive NMR and X-ray diffraction analysis proved without any doubt the structure (Figure 11), which features both intra-and intermolecular hydrogen bonds. The directing group functionalization gave clues about the different mechanisms operating for rhodium-catalyzed silylation and iridium-catalyzed borylation. Indeed, from the work of Suginome, [START_REF] Ihara | A Simple, Removable ortho-Directing Modifier for Arylboronic Acids Serving also as a Protecting Group in Cross-Coupling Reactions[END_REF] free amide NH is required to direct the rhodiumcatalyzed silylation whereas the aniline does not appear to participate. However, the regioselectivity here observed for the iridium-catalyzed borylation is closer to the work of Maleczka and Smith on the borylation of indoles in which the direct interaction of the indole nitrogen and iridium center, as well as an outer-sphere mechanism involving the nitrogen and the vacant p-orbital of a boryl ligand, have been proposed. [START_REF] Mkhalid | C-H Activation for the Construction of C-B Bonds[END_REF][START_REF] Paul | Ir-Catalyzed Functionalization of 2-Substituted Indoles at the 7-Position: Nitrogen-Directed Aromatic Borylation[END_REF] In an attempt to rationalize our results, the sterically accessible (especially bearing labile monophosphine) rhodium catalytic active R e v i s e d m a n u s c r i t p t species might interact with the amide to perform the ferrocene C-H bond activation as planned. However, the iridium catalyst might not be able to interact with this boronamide, for electronic or steric reasons, and an outer-sphere mechanism would therefore become preferable as depicted in Scheme 5. The better lone-pair donating properties of anilines, when compared to amides, could explain this site of functionalization, whereas the interaction between the aniline nitrogen and the vacant p-orbital of the boron, decreasing the stability of such intermediate, would explain why our regiocontrol and yield are lower than those observed by Maleckza and Smith.

CONCLUSION

In summary, we prepared seven original ferroceneboronic acid derivatives bearing borylated groups relevant in cross-coupling reactions or as ortho-directing groups. NMR, electrochemical and X-ray diffraction analysis helped establish a general overview of the structural and electronic behavior of these derivatives and to classify them in terms of electron-withdrawing or -donating properties. Moreover, preliminary results showed the ability of boron anthranilamide to direct the rhodium-catalyzed ferrocenic C-H bond activation. Studies are at present ongoing to establish the limits of this methodology, especially in its enantioselective version. Finally, we have reported on original regioselectivity switch during an iridium-catalyzed borylation, which resulted in the functionalization of the boron anthranilamide group. A putative outer-sphere mechanism was proposed to account of the experimental results and additional investigations are ongoing to uncover the key parameters controlling this unexpected transformation. Therefore, it should be pointed out the marked differences between ferrocene and benzene, during both the synthesis of these borylated derivatives and their use in catalytic transformation.

Figure 1 .

 1 Figure 1. Ferroceneboronic acid (1) and selected derivatives 2-14. Fc = ferrocenyl, dipp = 2,6-diisopropylphenyl.

Figure 2 .

 2 Figure 2. Ferroceneboronic acid derivatives prepared and characterized in this study.

Figure 3 .

 3 Figure 3. Selected NOESY correlations.

, 17 :

 17 C6-C10-B11-N22 = 30.1(5)°, 18: C6-C10-B11-N22 = 31.7(4)°). The Cipso-B bonds are almost similar in 15 and 16 (15: C10-B11 1.545(3) Å, 16: C10-B11 1.541(2) Å), whereas they appear slightly longer in the methylated derivatives (17 and 18: 1.554(3-5) Å). On the contrary, the Fe-B distance increases from 16 to 15 to 17 and 18 (16: Fe1-B11 3.1074(18) Å, 15: Fe1-B11 3.1695(19) Å, 17: Fe1-B11 3.228(4) Å, 18: Fe1-B11 3.232(3) Å). The bending of the boron substituent toward the iron atom

  in which high angles α* are observed with strong Lewis acidic boron substituents. With angles between BBr2 and B(OH)2, the boron naphthalene-1,8-diamido 15 and the two boron-anthranilamides 16 and 17 show moderate Lewis acidity character. Only 18, as a result of the methylated aniline, features a decrease in its Lewis acidic character.

Figure 4 .

 4 Figure 4. Molecular structure of compound 15; thermal ellipsoids shown at the 30% probability level. Selected bond lengths [Å], and angles [°]: Fe1-B11 3.1695(19), C10-B11 1.545(3), B11-N12 1.423(3), B11-N22 1.423(3), α* = 5.53, C6-C10-B11-N22 = 16.5(3).

Figure 5 .

 5 Figure 5. Molecular structure of compound 16; thermal ellipsoids shown at the 30% probability level. Selected bond lengths [Å] and angles [°]: Fe1-B11 3.1074(18), C10-B11 1.541(2), B11-N12 1.420(2), B11-N21 1.442(2), α* = 7.97, C6-C10-B11-N12 = 0.9(3).

Figure 6 .

 6 Figure 6. Molecular structure of compound 17; thermal ellipsoids shown at the 30% probability level. Selected bond lengths [Å] and angles [°]: Fe1-B11 3.228(4), C10-B11 1.554(5), B11-N12 1.452(5), B11-N22 1.406(5), α* = 5.50, C6-C10-B11-N22 = 30.1(5).

Figure 7 .

 7 Figure 7. Molecular structure of compound 18; thermal ellipsoids shown at the 30% probability level. Selected bond lengths [Å] and

Figure 8 .

 8 Figure 8. Left: molecular structure of compound 19; thermal ellipsoids shown at the 30% probability level. Selected bond lengths [Å] and angles [°]: Fe1-B11 3.272(3), C10-B11 1.588(4), B11-F12 1.417(4), B11-F13 1.420(4), B11-F14 1.440(3), α* = 0.98. Right: Arrangement of the molecules at the solid state (atom color: K, violet; F, green; B, pink; C, grey; Fe, orange). Hydrogen were omitted for clarity.

Figure 9 .

 9 Figure 9. Molecular structure of compound 21; thermal ellipsoids shown at the 30% probability level. Selected bond lengths [Å] and angles [°] and torsion angles [°]: Fe1-B11 3.1695(19), C10-B11 1.568(2), B11-O14 1.476(2), B11-O18 1.490(2), B11-N12 1.664(2), α* = 3.17.

Figure 10 .

 10 Figure 10. Left: selected NOESY correlations seen in 25. Right: molecular structure of compound 25; thermal ellipsoids shown at the 30% probability level. Selected bond lengths [Å] and angles [°]: Fe1-B11 3.292(2), C6-B11 1.557(3), B11-N21 1.416(3), B11-N12 1.441(3), C10-Si1 1.866(2), α*(C10-B11) = 3.14, α*(C10-Si1) = 4.42.

  OMe)(COD)]2 (3 mol%), L1 (6 mol%), B2Pin2 (1.0 equiv), Octane, 126 °C, 20 h nd 7

Figure 11 .

 11 Figure 11. Left: selected NOESY correlations seen in 28. Right: Molecular structure of compound 28; thermal ellipsoids shown at the 30% probability level. Selected bond lengths [Å] and angles [°]: Fe1-B1 3.121(3), C10-B1 1.546(4), B1-N1 1.437(4), B1-N2 1.420(4), O1-H31N 2.1275, O31-H1N 2.1183, O2-H2N 2.1153 O33-H32N 2.1625, Fe31-B31 3.161(4), C40-B31 1.553(5), B31-N31 1.440(4), B31-N32 1.421(4), α*(C10-B1) = 5.84. Hydrogen bonds indicated in doted red lines.

Scheme 5 .

 5 Scheme 5. Putative mechanism of regioselectivity switch during borylation of 16.

  s c r i t p t

Table 1 .

 1 Formation of FcB(dan)(15).

	Entry	Conditions	Yield (%)
	1	Toluene, reflux, 16 h	27
	2	i) Toluene, water, rt, 15 min; ii) Reflux, 16 h	31
	3	FeCl3 (5 mol%), imidazole (3 equiv), MeCN, H2O, rt, 16 h	44

Table 2 .

 2 Formation of FcB(aam)(16).

	Entry	Conditions	Yield (%)
	1	Toluene, reflux, 16 h	58
	2	i) Toluene, water, rt, 15 min; ii) Reflux, 16 h	71
	3	FeCl3 (5 mol%), imidazole (3 equiv), MeCN, H2O, rt, 6 h	33
	4 FeCl3 (5 mol%), imidazole (3 equiv), MeCN, H2O, rt, 120 h	61

Table 3 .

 3 Selected 1 H,[START_REF] Bresner | Hydrogenbonding motifs in the solid-state structure of ferroceneboronic acid[END_REF] C and[START_REF] Kamounah | A New Preparation of Iodoferrocene[END_REF] B NMR spectroscopic data. From ref 40d , spectra recorded in CDCl3.c Tentative assignment based on chemical shifts.d Cipso not seen due to boron quadrupolar coupling. e From ref 40c . nd: not determinated.As expected, the trifluoroborate 19 and triolborate 20 act as electron-donating groups. They appear as powerful as the amino group with an almost similar enrichment of both α and β positions (19: -0.30, 20: -0.32 ppm for Hα and 19: -0.30, 20: -0.38 ppm for Hβ).

	δ (ppm)

b

Table 4 .

 4 Electrochemical Data a

	Compound	Epa (V)	Epc (V)	ipa/ipc	ΔE (mV)
	Fc	0.57	0.49	0.97	-
	1	0.56	0.38	0.97	10
	15	0.58	0.41	nr	-10
	16	0.62	0.54	0.97	-50
	17	0.61	0.53	0.97	-40
	18	0.60	0.51	1.20	-30
	19	0.26	0.18	1.06	310
	20	0.60	0.52 b	nr	-30
	21	0.55	0.47	0.97	20

Table 5 .

 5 Study of FcB(aam) silylation.

		Conditions	25 (%) 26 (%)
	1	Octane, 126 °C, 20 h [Ir(OMe)(COD)]2 (3 mol%), dtbpy (6 mol%),	10	nd
	2	RuH2(CO)(PPh3)3 (6 mol%), Toluene, 135 °C, 21 h	20	nd
	3 RuH2(CO)(PPh3)3 (12 mol%), Toluene, 135 °C, 21 h	50	26
	4 RuH2(CO)(PPh3)3 (12 mol%), Toluene, 135 °C, 44 h	19	48

Table 6 .

 6 Study of FcB(aam) borylation.

ACKNOWLEDGMENTS

This work was supported by the Université de Rennes 1. We acknowledge the Fonds Européen de Développement Régional (FEDER; D8 VENTURE Bruker AXS diffractometer). W.E. would like to thank Dr. B. Carboni for the generous gift of MIDA and Prof. F. Mongin for critically reviewing this document and making valuable suggestions.

ASSOCIATED CONTENT Supporting Information

The Supporting Information is available free of charge on the ACS Publications website at DOI:

AUTHOR INFORMATION

Corresponding Author * E-mail for W.E.: william.erb@univ-rennes1.fr.

ORCID

William Erb: 0000-0002-2906-2091 Thierry Roisnel: 0000-0002-6088-4472 Vincent Dorcet: 0000-0001-9423-995X

Notes

The authors declare no competing financial interest.


Frédéric Grognard
email: frederic.grognard@inria.fr

Ivan Yegorov

Julien Guegan

Ludovic Mailleret

Fabien Halkett

Pierre Bernhard

Uninvadable strategies for

Keywords: Uninvadable strategy, Differential game, Adaptive dynamics, Resource allocation, Biotrophic pathogens

come   L'archive ouverte pluridisciplinaire

Acknowledgements: This work was supported by a grant over-seen by the French National Research Agency (ANR) as part of the "Blanc2013" program (ANR-13-BSV7-0011, FunFit project)

ABSTRACT

In this work, we study the competition of two biotrophic fungal cohorts within a common host plant. Their identical dynamics are described by nonlinear ordinary differential equations representing the evolution of the average mycellium size M i of each, and driven by their potentially differing resource allocation strategy over time u i (t). Indeed, biotrophic pathogens uptake resource from living host plant tissues and opt for its allocation to mycellium growth, spore (S i ) production, or a mix of both:

Each cohort's fitness is then defined as the per capita expected spore production over a season of duration T , J i (u 1 (.), u 2 (.)). In an uninvadability context, both cohorts then stand in a zero-sum game where they try to maximize/minimize J 1 (.)-J 2 (.) [START_REF] Bernhard | ESS for life history of cooperating consumers facing cheating mutants 14th International Symposium on Dynamic Games and Applications[END_REF], in an approach complementary to [START_REF] Dieckmann | The adaptive dynamics of function-valued traits[END_REF]. The related Cauchy problem for the Hamilton-Jacobi-Isaacs equation is investigated through analytical and numerical approaches to obtain the solution of the zero-sum state-feedback game defined above. A first property that we obtained is that, if M 1 (0) = M 2 (0), the Nash equilibrium corresponds to identical strategies for both cohorts. These strategies most classically consist in increasing the mycellium size upto some fixed level (with u i (t) = 0), then keeping the mycellium constant at that level while producing spores (with 0 < u i (t) < 1), and finally only producing spores (with u i (t) = 1) until the end of the season.

The obtained solution was then compared to two complementary approaches: the one obtained from single-cohort optimal resource allocation [START_REF] Yegorov | Optimal resource allocation for biotrophic phatogens[END_REF] and the one stemming from adaptive dynamics. We noted that the solution of the optimal approach gives a similar type of solution, except that the mycellium level at which the solution settles in the intermediate phase is lower.

We then noted from the generic form of the solutions obtained in both the optimal and game solutions that two scalar traits can define these allocation strategies: the level at which the mycellium settles during the intermediate phase, and the time before the end of the season at which the sporulation-only phase starts. Computing the equilibrium, canonical equation and stochastic adaptive dynamics for the latter problem [START_REF] Leimar | Multidimensional convergence stability[END_REF], we obtained results in accordance with what the solution of the game yielded, which validates the approach.