Virginie Goepp
email: virginie.goepp@insa-strasbourg.fr

Nada Matta
email: nada.matta@utt.fr

Emmanuel Caillaud
email: emmanuel.caillaud@unistra.fr

Françoise Feugeas
email: francoise.feugeas@insa-strasbourg.fr

Systematic community of Practice activities evaluation through Natural Language Processing: application to research projects

Keywords: Community of practice, Performance Evaluation, Pragmatics, Natural Language Processing, Research Project

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Introduction

Knowledge is one of the most valuable resources for modern organizations [START_REF] Zack | Developing a knowledge strategy[END_REF]. The efficiency of organizations is strongly linked to the way the knowledge is created, shared and managed [START_REF] Chu | Index evaluations and business strategies on communities of practice[END_REF][START_REF] Nonaka | The Knowledge-Creating Company: How Japanese Companies Create the Dynamics of Innovation[END_REF]. After [START_REF] Guptill | Knowledge management in health care[END_REF] and [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF], Communities of Practice (CoPs) are particularly effective to consider the whole knowledge lifecycle. CoPs are "groups of people who share a concern, a set of problems, or a passion about a topic, and who deepen their knowledge and expertise in this area by interacting on an ongoing basis." [START_REF] Wenger | Cultivating Communities of Practice[END_REF].

In this boarder, the efficiency evaluation of these groups becomes crucial. Several propositions are worked out in the literature generally focused on the knowledge created and exchanged between the CoPs members. These approaches, as stated in [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF], can be grouped into: (i) subjective methods; (ii) objective methods. Generally, these are difficult and time consuming to apply on real CoPs. For example, the interaction matrix required for SNA (Social Network Analysis) as proposed in [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF] takes a lot of time to be built. In this paper, we exploit the analysis of electronic messages exchanged between the members of a CoP to refine the CoPs activities performance evaluation by going beyond the classical evaluation of knowledge sharing level largely studied in knowledge management [START_REF] Zack | Developing a knowledge strategy[END_REF]. More precisely, we look for speech acts [START_REF] Austin | How to do things with words[END_REF] in the message content to identify, among other, the role of the people involved in the CoP, the knowledge shared and the learning processes that take place between the CoP members. Pragma-linguistics techniques are then applied for this purpose [START_REF] Levinson | Pragmatics[END_REF]. Another advantage of our approach is that it is systematic and semi-automated.

The paper is structured as follows. The second section deals with the state of the art, describing the current approaches for CoPs performance evaluation. The third section presents the text analysis approach we propose for evaluating CoPs activities. In section four the approach we propose is applied on a project based CoP the SEPOLBE scientific project dedicated to develop bioadmixtures for concrete. Section five concludes and gives further research directions.

State of the Art

In this state of the art, we will analyse the different definitions of the CoPs and how the efficiency of CoPs is evaluated.

2.1.CoPs definition

In [START_REF] Wenger | Communities of Practice: Learning, Meaning and Identity[END_REF] CoPs are treated as the informal relations and understandings developed in mutual engagement on an appropriated joint enterprise. In other words, a community of practice is defined as a group that coheres through "mutual engagement" on an "appropriated enterprise", and creates a common "repertoire".

In [START_REF] Wenger | Cultivating Communities of Practice[END_REF] the concept is redefined towards a more managerial stance, making the concept more popular and simple. Here CoPs are "groups of people who share a concern, a set of problems, or a passion about a topic, and who deepen their knowledge and expertise in this area by interacting on an ongoing basis." According to [START_REF] Cox | What are communities of practice? A comparative review of four seminal works[END_REF], this definition is much vaguer than the previous one. The definition is of a group that is somehow interested in the same thing, not closely tied together in accomplishing a common enterprise. The purpose is specifically to learn and share knowledge, not to get the job done. From this point of view a CoP has three structural features:

(i) Domain: it "… creates common ground and a sense of common identity. A well-defined domain legitimises the community by affirming its purpose and value to members and other stakeholders. The domain inspires members to contribute and participate, guides their learning, and gives meaning to their actions" [START_REF] Wenger | Cultivating Communities of Practice[END_REF].

(ii) Community: it "…creates the social fabric of learning. A strong community fosters interactions and relationships based on mutual respect and trust. It encourages a willingness to share ideas, expose one's ignorance, ask difficult questions, and listen carefully. Community is an important element because learning is a matter of belonging as well as an intellectual process." [START_REF] Wenger | Cultivating Communities of Practice[END_REF].

(iii) Practice: it "…is the specific knowledge the community develops, shares and maintains'' [START_REF] Wenger | Cultivating Communities of Practice[END_REF].

Considering our objective of a systematic approach based on the e-mail exchanged, we are interested in the practice feature of a CoP that is to say the way knowledge is created, shared and managed.

Different types of CoPs are identified in the literature. [START_REF] Mcdermott | Critical success factors in building communities of practice[END_REF] indicates four types of community:

(i) Communities which are linked to a strategic objective;

(ii) Communities which focus on tactical processes, process optimisation and sharing of best practice;

(iii)Project-based communities (iv) Communities developing a particular body of knowledge.

We are interested in project based communities. This kind of CoP has several interesting features. First of all, it is confined in time with fix start and end, enabling to study all its lifecycle phases as detailed in [START_REF] Lee | A maturity model based CoP evaluation framework: A case study of strategic CoPs in a Korean company[END_REF] from the building stage corresponding to the initial state of a CoP, where people come together and develop a detailed plan of structure of community to the close stage, during which a CoP declines or transforms into several other communities.

Secondly the people involved in the CoP are project members and therefore act actively in the achievement of the project. Their participation degree, as described in [START_REF] Wenger | Cultivating Communities of Practice[END_REF], is as core group. A core group is the group of people that carries out the work in the community. It actively participates in discussions and identifies the topics to be addressed within the community. The coordinator takes place in this group. He is the one who organises events, connects communities and generally keeps the community alive.

Moreover, project members are known at the outset enabling to study their mutual interactions easily.

2.2.CoP performance evaluation

A CoP is defined as successful when its members exchange specific knowledge, practices and/or experiences that contribute to developing a practice (know-how) in a specific field [START_REF] Mcdermott | How to avoid a mid-life crisis in your COPs: Uncovering six keys to sustaining communities[END_REF]. The research around the performance evaluation and management of CoPs gains gradually importance. Indeed, in the nineties CoPs were presented as spontaneous, self-organizing, and fluid processes that management cannot intentionally establish [START_REF] Brown | Organizational leraning and communities of practice: Toward a unified view of working[END_REF][START_REF] Lave | Situated learning. Legitimate Peripheral Participation[END_REF]. In other words, at that time it was considered that the performance of a CoP cannot be measured and managed to improve its efficiency. Later some works suggest that CoPs are amenable to manipulation and can be managed [START_REF] Lesser | Using communities of parctice to manage intellectual capital[END_REF][START_REF] Wenger | Communities of practice and social leraning systems[END_REF][START_REF] Wenger | Communities of practice: The organizational frontier[END_REF]. In turn as a result of these works diagnosis frameworks for CoP efficiency management were proposed. These aim at assessing the knowledge creation or sharing level inside a given CoP. To do so, as stated in [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF], these frameworks are either based on subjective methods or on objective one. Subjective methods are methods that use qualitative constructs to assess the performance level whereas objective one assess this performance level through a quantitiative indicators. In the next sub-sections we detail two diagnosis frameworks one based on a subjective method [START_REF] Borzillo | Unravelling the dynamics of knowledge creation in communities of practice though complexity theory lenses[END_REF] and the second on an objective one [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF]. For each category we analyze its advantages and drawbacks in order to set our research objectives.

In [START_REF] Borzillo | Unravelling the dynamics of knowledge creation in communities of practice though complexity theory lenses[END_REF] the underlying hypothesis of diagnosis is that organizations need to guide CoPs to generate usable knowledge sustainability. As a result, the authors aim to elucidate the related knowledge creation dymanics. Therefore, they go beyond the mere evaluation of the four factors -knowledge objectives, leadership, collaboration and boundary spanning -that are generally associated with knowledge creation in CoPs. Contrary to this "fragmented" approach, they propose an "integrated" one enabling to understand how the interactions between these factors lead to dynamic knowledge creation processes. To do so, they exploit the complex adaptative system (CAS) theory that provides an integrative and dynamic framework to understand the interaction patterns in networks of interdependent agents who interact and are bound by their common needs or objectives.As a consequence, the four factors of knowledge creation are translated according to the CAS theory lenses into four constructs.

First, the knowledge objectives factor becomes adaptative tension that drives selforganization and emergence. It emerges from external constraints and corresponds to the energy diffrential between the system and its environment. The focus is therefore on the definition of the upper and lower bounds of adaptative tension that will define the "region of complexity" inside which a system is able to create new order (self-organization) and producing new knowledge (emergence). Second, the leadership factor becomes enabling leadership. In this perspective, the managers' role is to design systems in which distributed intelligence can easily emerge. For CoPs, enabling leadership means enhancing the socialization between individuals. Third, collaboration becomes enhanced cooperation.

Indeed, CAS theory emphasizes that knowledge creation depends on the nature of the interactions or connections between agents implying for CoPs regular meetings, workshops and the enabling information technology for interaction. Fourth, the boundary spanning factor remains unchanged. It highlights cognitive diversity for knowledge creation by interacting with actors external to a given CoP.

Then, during 4 years, 5 CoPs from an international-operating industrial group were studied via a longitudinal exploratory study (six series of interviews) in order to uncover if the four constructs of CAS theory impact positively or negatively the dynamics of knowledge creation. The data gathered was analysed qualitatively (preliminary analysis for data categorization, within-in community analyses to search linkages between first order concepts, croos-community analysis to reveal consistencies and contradictions between the CoPs) and quantitatively (average ranking caculation of each constructs). As a result, two modes of CoPs are proposed. Each mode couples two of the four studied constructs (see Figure 1). When adaptive tension and enabling leadership are prevalent, the CoP is in a "guided" mode. When enhancing cooperation with boundary spanning are prevalent the CoP is in a "self-directed" mode.

---Insert the Figure 1 here---These modes are then coupled with knowledge creation processes. The authors argue that a "guided-mode" supports knowledge expansion, while a "self-directed mode" simulates knowledge probing. The guided mode is used to improve the existing product offerings, which requires creating improved knowledge. During the "self-directed" mode, communities explore radically new knowledge.

This study is interesting as it exploits complexity theory to focus on the interaction of the factors leading to knowledge creation in CoP. Even if this link is not formally described, there is generally acknowledged that there is a positive correlation between performance and knowledge creation. However, it seems difficult, on a given CoP, to evaluate the four constructs: adaptive tension, enabling leadership, enhanced cooperation and boundary spanning. It requires time-consuming data collection (interviews from different informants (community sponsors, leaders and members); attending to CoP workshops) and data exploitation. Moreover, only two modes are described in this paper the other possible configurations of the constructs are not considered. That is why another research stream explores the use of objective methods.

CoP diagnosis framework based on objective methods

In [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF] ---Insert the Figure 2 here---The diagnosis methodology proposed by [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF] is the following (see Figure 3):

1.

Pre-process: this step enables to understand the methodology of knowledge sharing and to build the knowledge sharing matrix. This matrix records the knowledge propagators in columns, and knowledge receivers in rows. It will be the input for the SNA;

2. Analysis: SNA and development of new indexes for CoP diagnosis;

3.

Strategy: suggestion of a strategy for future knowledge sharing activities.

---Insert the Figure 3 here---

The SNA is based on the knowledge sharing matrix set up during the pre-process step.

If the CoP has n members the matrix will be an n*n size one with each cell filled. The input data are generally retrieved from questionnaires, interviews and data log, even if other transaction data could be used (online messenger tools, e-mails, etc.). The data processed have to define if two members exchange data or not. For e-mails it requires to identify the sender and the recipients of a given message. It is stated that the working out of this matrix spends tremendous time. Moreover, the kind of questionnaires to use is not detailed.

By using a knowledge sharing matrix for input data, basic indexes can be generated by SNA. Some of the basic indexes are:

• Node type (transmitter or out-flow only node, receiver or in-flow only node, carrier or node with only one connected in-flow and only one out-flow except from the in-flow node, ordinary or node with a mixed in-and out-flow, isolate or node that is not connected to others);

• Network density that is an indicator for the general level of connectedness of the graph;

• Betweeness centrality: it is the share of times that a node i needs a node k (whose centrality is being measured) in order to reach a node j via the shortest path;

• In and out degree of centrality: it is the proportion of a connected edge to the maximum possible connections.

Based on these indexes the analysis step can be carried out. To do so, the authors provide a member and a CoPs typology. Both typologies are based on knowledge propagating and receiving abilities. There are four kinds of members (see Figure 4):

• Balanced player: a member who propagates knowledge to and receives knowledge from other members. This kind of member corresponds to the ordinary or carrier nodes;

• Egoistic propagator: a member who propagates knowledge to other members, but does not receive knowledge from other members. Such a member corresponds to the transmitter nodes;

• Egoistic receiver: a member who receives knowledge from other members, but does not propagate knowledge to other members. Such a member corresponds to the egoistic receiver nodes;

• Knowledge isolator: a member who does not propagate knowledge to or receive knowledge from other members. These members are the isolator nodes.

---Insert the Figure 4 here---Based on the member typology the CoP typology is set up (see Figure 5). It is based on the knowledge receiving and knowledge propagating core group ratio that is to say the ratio between the propagators or the receivers and the total number of member in the core group. The core group is identified thank to in-and out-degree centrality. Four communities' types are proposed:

• Active community: the core group has a high ratio of knowledge propagation and receiving;

• Spreading community: the core group has a high ratio of knowledge propagation but a low ratio of knowledge receiving;

• Learning community: the core group has a low ratio of knowledge propagation but a high ratio of knowledge receiving;

• Inactive community: this community has low ratios of knowledge propagation and receiving within the core group.

---Insert the Figure 5 here---Then, diagnosis of the CoP under study (thrid step of the framework) is made according the CoP typology. For each community type improving strategies like, for example, "create more practical knowledge" or "redefine the knowledge domain" are proposed.

This diagnosis framework is complete as it observes a CoP according knowledge propagating and receiving actions and proposes improving strategies. However, this approach has two main drawbacks. First, the setting up of the knowledge sharing matrix is complex and time consuming, even if e-mails could be exploited to retrieve the required data automatically. Secondly the diagnosis focuses only on the knowledge exchanges on a binary mode (knowledge receiving yes/no and knowledge propagating yes/no). There is no in-deep analysis of the quality and the type of exchanges that would be interesting to better highlight the CoP performance.

Synthesis

Existing diagnosis methods for CoPs rely efficiency evaluation on the ability of a CoP to exchange and sustain knowledge over time. However, these are difficult and timeconsuming to put into action on real CoPs. They require either to assess subjective constructs, either to work out a matrix of knowledge interaction. In both cases the input data required for evaluation stem from questionnaires and interviews of the members of the CoP.

In [START_REF] Borzillo | Unravelling the dynamics of knowledge creation in communities of practice though complexity theory lenses[END_REF] four subjective constructs (adaptative tension, enabling leadership, enhanced cooperation and boundary spanning) are evaluated and their interactions studied. This enables to reflect the way knowledge is created inside a given CoP in a "guided" or "self-directed" mode.

In [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF] the members who propagate knowledge and these who receive knowledge are identified and their interactions are analysed. This enables to evaluate the level of knowledge sharing in a binary manner "Is knowledge exchanged or not between two members ?", then to characterize the CoP members and the CoPs according their role in knowledge sharing (propagator and receiver) and to last to provide improving strategies for each kind of CoP identified.

The main advantage of the approach of [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF] is to evaluate the CoP efficiency in an objective manner, even if the indicators proposed are binary and do not reflect as it is the case for [START_REF] Borzillo | Unravelling the dynamics of knowledge creation in communities of practice though complexity theory lenses[END_REF] the complexity of knowledge sustainability. In our view, the objective method option such as proposed in [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF] is the most promising because it ensures the reliability of the evaluation.

However, it could be improved and completed with a semi-automated analysis of the content of the knowledge shared as well as the related intentions of the actors. In this way, the nature of the knowledge shared can be identified so as the contribution of this sharing to organizational learning by indentification of the leraning processes involved and the role of the actors in the CoP. For this purpose, our approach looks for the impacts of interactions on the CoP users and their organization by analysing communication.

There are different kinds of techniques to analyse communication (as TextMining, Natural Language Processing (NLP), etc.). On the one hand, TextMining groups a set of techniques enabling to extract information from documents. On the other hand, NLP is the field of study that focuses on the interactions between human language and computers.

Both approaches do not enable to emphasize the interactions between actors that is the main feature of knowledge sharing and learning evaluation in CoPs. Therefore, we use Pragmatics approach because that helps to analyse the content of communication and to identify intention of interactions between participants. We present in the next section this type of analysis.

Text analysis for CoP performance evaluation

3.1.Communication analysis

Several approaches study how to analyze communication as a specific discourse. We note for instance, tagging work in [START_REF] Yelati | Novel Approach for Tagging of Discourse Segments in Help-Desk E-Mails[END_REF], in which the authors present techniques that help to identify topics in e-mails. We also note NLP (Natural Language Processing) community on automated speech act identification in emails [START_REF] Baron | Letters by phone or speech by other means: The linguistics of email[END_REF][START_REF] Carvalho | Improving email speech acts analysis via ngram selection[END_REF][START_REF] Corney | Gender preferential text mining of e-mail discourse, 18th Computer Security Applications Conference[END_REF]. For instance, [START_REF] Kalia | Identifying business tasks and commitments from email and chat conversations[END_REF] use NLP in order to identify messages concerning tasks and commitment. They parse verbs and sentences in order to identify tasks and track messages between senders and receivers. Pragmatics, the study of language in use, is concerned with the intended meaning of speakers beyond what is explicitly stated. It is a branch of linguistics concerned with the use of language in social contexts and the ways in which participants produce and comprehend meanings through language. Pragmatics focuses on aspects of signification that are not only predicted by linguistics knowledge. It is concerned with the analysis of the speaker's meaning rather than on the meaning of words and utterances (semantic or linguistic meaning). Thus

Pragmatics takes into account the role of physical and social context [START_REF] Austin | How to do things with words[END_REF].

Pragmatics analysis of communication using e-mails uses only some of these methods like ngrams analysis by [START_REF] Carvalho | Improving email speech acts analysis via ngram selection[END_REF], Verbal Response Mode scheme by Lampert in [START_REF] Lampert | Detecting emails containing requests for action[END_REF] or a custom coding scheme like in [START_REF] Felice | Identifying speech acts in emails: Toward automated scoring of the TOEIC® Email task[END_REF].

As cited above, we use Pragmatics in order to study communication in community of practices and topic identification. Our aim is first to identify if contributors learns from each other's and on which topics. So, we apply the CaMCa "Context aware Mediated Communication analysis" approach [START_REF] Rauscher | KTR: an approach that supports Knowledge extraction from design interactions[END_REF], we develop for this aim. CaMCa is based on Pragmatics analysis and context awareness. So, it helps to identify, from one side, intention of communications and from another side, links interactions to the activity context. CoPs activity evaluation needs these dimensions because participants activities and roles are important. As the analysis is context dependent, it makes no sense to study big volume of interactions such as in SNA. The objective differs from SNA for e-mails and that could be used to improve the CoP diagnosis framework of [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF]. Indeed, as detailed in [START_REF] Tang | Email mining: tasks, common techniques, and tools[END_REF] SNA for e-mails is generally used for contact identification focusing on the structure of the network built from the email corpus and paying less attention to email contents.

3.2.CaMCa approach

Pragmatics puts on the fact that a dialogue is context and time dependent. Identifying the sense of interaction is related to the conditions, environment and situation of communication. We develop the Context aware Mediated Communication analysis (CaMca) approach that considers from one side the context and the domain of the activity and from the other side the speech acts in mediated communication.

The different phases of this approach are [START_REF] Rauscher | KTR: an approach that supports Knowledge extraction from design interactions[END_REF] (see Figure 5): o Main Speech Acts.

•
---Insert the Figure 6 here---Each phase of CaMCa will bring a piece of information about CoP activity. Indeed, the context identification is useful to underline the actors' skills and collaboration roles corresponding to the "Community" feature of a CoP as described in section 2.1.

Thisenables to identify the core group and the coordinator of the CoP under study. The domain identification will be used to identify the topics on which the CoP exchanges, enabling to define the nature of knowledge shared. That is the "Domain" feature of a CoP.

Last but not least the Mediated Communication Analysis focuses on the e-mail exchanged enabling to assess the degree of knowledge sharing and interactions between CoP participants ("Practice" feature) and the related knowledge processes that take place.

In fact, in context we try to identify the organization of the communication. It mainly concerns actors and their collaboration goals. The domain analysis puts on, the nature of the activity subject of interactions, on which practices participants discuss. Finally, the analysis of communication helps to emphasis the real effects of interactions: what is happened when actors received and post messages? Is there any learning, coordination, conflict, alliances, etc? and how it is done? CaMCa is used in order to identify the nature of interactions in CoPs. Then the results obtained can be compared to the CoP typology depicted in Figure 4. In this way, performance and diagnosis of studied CoPs can be put on in a systematic way.

So, we propose to apply CaMCa to a project based CoP. Interaction around a project is analysed and first principles of systematic CoPs diagnosis approach is determined. These principles are identified by analysing the communication of the real SEPOLBE project, presented in the next section.

Case study

In this section, we will illustrate the use of CaMCa on a project-based CoP. We will analyse the exchanges between the members of the Cop. The roles of the actors, particularly the coordination, will be analysed. The knowledge exchanged and created will also be studied.

4.1.Study context: the SEPOLBE Project

We apply the CaMca approach to the SEPOLBE research project in order to identify the knowledge shared and the learning processes that take place between the members and to analyse how the CoP is coordinated (Who is the coordinator?; Level of coordination). The SEPOLBE project is dedicated to develop bioadmixtures for concrete [START_REF] Goepp | Community of Practice Theory and Process Modelling: Two Tools for Better Collaboration in Research Projects, Advances in Production management systems : Innovative and knowledge-based production management in a global-local world[END_REF]. These substances are conscientious of the environment and should limit the bio contamination of the concrete surface and improve the resistance to corrosion of its metallic reinforcement. This project implies four research teams and a company. The research teams have different complementary areas of competency: concrete surface analysis, physical chemistry analysis of films on steel and concrete, electro chemistry for steel corrosion inhibition, petro physics for concrete physical chemistry characterization.

Competences in micro biology, chemistry and microscopy are also required to develop the substances and to analyse the surface bio contamination. The industrial partner manufactures and markets concrete products such as admixtures. Its product mix already includes protection products but none of them is dedicated to biological contamination.

The duration of this project is about four years. Actors are coming from three main domains: Microbiology, Electrochemistry and Civil engineering. To show the applicability of our approach, we focus on two tasks of the project: (i) Project coordination and (ii)

Assessment of the cleaning ability of the mortar base surfaces. Here, objective is to evaluate the ability of the bioadmixtures to limit the development of biofilms on the concrete surface and its impact on the cleaning concrete surface (biofilm dropping out).

The ICube and B2HM teams are in charge of this task. The ICube team has to provide to the B2HM team "adequate" concrete samples. The B2HM is in charge of the contamination and cleaning tests.

For these tasks we analyze the e-mail exchanges between the people involved in the task. The people involved provided us the e-mails they received and sent to complete a given task (coordination or cleaning ability evaluation). So, we had access to the e-mails as a whole (sender, recipients, date, content, etc.)

4.2.Learning evaluation using E-mail analysis

The main topics of the task dealing with the assessment of the cleaning ability of the mortar base surfaces concern: Concrete, Mortar, Sample, Bioadmixtures (or BA), Molecular, Bacteria, Essay, Experiment, Polishing, Sample, Ultrasonic, …

Actors communicate together using mainly e-mails but if the content of message is available other sources of electronic messages could be exploited such as forums could be exploited. So, we analyze their communication in order to understand if there was any learning of procedures or concepts. First of all, our expert on Pragmatics identifies a grid of main speech act types concerning learning (see Table 1).

---Insert here the Table 1---Then, based on different synonyms and sentence forms given by the pragmatics expert and the list of project topics, the NLP algorithm (Lucen) has been used in order to retrieve the corresponding messages. Figure 7 illustrates the global results obtained. The inside wheel shows the topics identified and the outside wheel the corresponding speech acts.

---Insert the Figure 7 here---

In our analysis, we try to identify if there is learning of concepts or procedures. So, we look for some specific speech acts like proposition, explanation, request, verification and information. Then we study this type of interaction among time: at the beginning, on the middle and at the end of task and project. For instance, at 20/12/12 Charlotte "civil engineer" asks about the Bioadmixtures experiment conditions needed. Thierry "Microbiologist" answers her by explaining a procedure (see Table 2).

---Insert here the Table 2 ---At 21/03/13, some months after this interaction, Charlotte "civil engineer" presents some modification on the procedure (see Table 3).

---Insert here the Table 3 ---

We suppose then that Charlotte learns the procedure, uses it and tries to adapt it to specific conditions.

At 10/04/13, Charlotte asks for more verification about the samples conservation and

Bioadmixtures test conditions of sample treatment. Chao and Thierry define more specifications about these conditions (see Table 4).

---Insert here the Table 4---Charlotte asks then more verification about the procedure she applies (see Table 5).

---Insert here the Table 5---

We suppose that among these interactions, actors learned from each other about bioreceptivity mixture experiment and sample treatment and conservation. Other analysis of messages show also interactions about samples' name coding and sending modes.

The chronology of interactions proves their dynamicity especially if actors have a timeline to respect, they communicate about the project phases.

4.3.Coordination analysis

Using CaMca approach, e-mails are also analysed in order to analyse how the CoP is coordinated. For this purpose, our analysis is based on coordination intentions [START_REF] Matta | Coordination interactions analysis in design projects[END_REF]. A specific grid was defined containing speech acts related to coordination and topics concerning the coordination (see Table 6). The main coordination speech acts are about information, proposition and request. Topics are around: meetings, documents and reports. A statistical analysis is also done in order to identify the engagement of actors in interactions. This type of analysis can complete those done by SNA in [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF], especially the CoPs users behaviors studied. Adding to statistical studies of exchanges, the identification of the interaction roles as used in our study help to emphasis the dynamic organization movements.

---Insert here the Table 6---42 messages have been analysed using this grid and based on the CaMCa approach.

These messages correspond to four milestones of the projects: Kick off, 12th, 18th and 30th month. Message date, Senders, Receivers, speech acts, topics are identified. 101 important sentences are identified from these messages. Table 7 illustrates a part of the analysis for the Kick off milestone.

---Insert here the Table 7 ---First statistics analysis syntheseized in Table 8 shows that Francoise is the main animator of the group. She takes the role of animator of coordination. She is the author of 22 messages. In these messages, Françoise informs about project documents, meeting reports and meetings logistics (19 speech acts), proposes meetings schedules and project presentations (17 speech acts) and asks for modification on Meetings Reports, logistics and project documents. We observe also the dynamic participation of other actors like Bernard

(2 speech acts on Information and 1 on Request about Meeting logistics) and Anouk (1 speech act on Information and 1 Request about Meeting logistics) in the organization of meetings.

---Insert here the Table 8 ---Finally, even messages are addressed to all participants of projects (16 participants), only 7 participate in the discussions. Time interaction analysis shows that messages are close to meetings dates.

As showed in this analysis, CaMca can be used to identify the nature of animation of CoPs and the core group. In SEPOLBE, we can see that some actors are engaged in the animation of CoPs and form the core group that is essential for a successful CoP. The animation is dynamic around meetings and tasks deadline. Beside that, interactions concern explanations of procedures and precision of techniques.

4.4.Discussion

We focus on this paper on a systematic and semi-automated analysis of CoPs that goes beyong knowledge sharing level assessment. Our analysis technique is based from one side on interaction content analysis and from other side on participants' competencies. This technique is summarized in Table 9.

---Insert here the Table 9---

The analysis of the SEPOLBE project interactions shows that we can answer to some characteristics of CoPs using CaMCa approach especially (see Table 10). So, in the SEPOLBE project there are two interaction sequences about Bioreceptivity Experiment and Samples Conservation that show learning between Charlotte and Thierry. The close dates of interactions can emphasize an active community but only 40% of participants send messages and only 18% are involved on coordination. So, we can note that only 40% of the community are active. The 50% of coordination messages emphasize the cooperation dimension of the CoPs.

Francoise can be identified as the coordinator because she is implied in 22 messages using propose and request speech acts. Finally, we can note that the effective participants are balanced player; all participants are in copy of messages or as receivers, even when there is some dialogue between Charlotte and Thierry (see Table 10).

---Insert here the Table 10 ---As showed in this paper, combining messages analysis and context awareness can give a technique to go beyong the classical knowledge sharing level assessment of CoPs. We tend in our analysis to identify a systematic methodology that help to diagnosis CoPs. This methodology is based on intention identification principle [START_REF] Richard | Mental activities, Understand, Reason, Find solutions (in French) Les activites mentales, Comprendre, raisonner, trouver des solutions[END_REF], which shows that a sense interpretation is linked to an action and environment. We used an approach mixing statistics and content analysis. We succeeded in identifying the real coordinator of the CoP and how the actors learn from each other thanks to the emails exchanges.

Conclusion

CoP efficiency evaluation is a great deal in research. Indeed, having the possibility to know if a given CoP is successful or not is essential to better manage it over time. The existing approaches for efficiency evaluation are difficult and time-consuming to put into action on real CoPs. They require either to evaluate subjective constructs making the analysis unreliable, either to work out a knowledge interaction matrix that is timeconsuming to set up.

These approaches build their evaluation on the fact that a CoP is successful if knowledge is exchanged between the members but they focus evaluation on the level of knowledge shared and created. This is a useful but partial. Indeed, when knowledge is shared there is some interactions between the actors involved in the CoP. Therefore, we propose to analyse in detail these interactions through the exchanges of emails thanks to NLP. Our approach is easy to put in action as it is systematic and semi-automated. It requires the e-mails exchanged and the definition of the speech-acts that will be retrieved.

Our approach allowed us to identify one of the key role of a project-based CoP: the leader of the core group. We also succeeded in identifying the learning process during the project between stakeholders from different domains: civil engineering and biochemistry. These first promising results must be confirmed on other project-based CoPs but also on other types of CoPs for instance to study problem solving exchanges, experts identification, etc.

Last but not least it would be interesting to couple the proposed approach general guidelines of CoP management as they are proposed in [START_REF] Probst | Why communities of practice succeed and why they fail[END_REF] or [START_REF] Jeon | Individual, social, and organizational contexts for active knowledge sharing in communities of practice[END_REF]. Indeed, in [START_REF] Probst | Why communities of practice succeed and why they fail[END_REF] [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF] Figure 3: Diagnosis process of CoPs based on Social Network Analysis (SNA) [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF] Figure 4: CoP member typology according to [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF] Figure 5: CoP typology according to [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF] Figure 6: CaMCa basic approach [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF] Figure 3: Diagnosis process of CoPs based on Social Network Analysis (SNA) [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF] Figure 4: CoP member typology according to [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF] Figure 5: CoP typology according to [START_REF] Kim | A diagnosis framework for identifying the current knowledge sharing activity status in a community of practice[END_REF] Figure 6: CaMCa basic approach

  a framework diagnosis for CoPs is proposed based on SNA (Social Network Analysis). SNA is a scientific method to analyze a social network by focusing on patterns of relationships between actors and examining the availability of resources and their exchange between actors. Here, performance evaluation of CoPs focuses on knowledge sharing activity by providing a view of the relationship network between the members o f the CoP that is to say of the knowledge receivers and the knowledge knowledge propagators and the related amount of knowledge exchanged as shown in the conceptual framework of Figure 2.

o

  Thread of communication: Reply, comments;

For

  presentation, linking message to main topics Identification of Senders/Receivers Linking Topic-speech act-competences -Date Linking sender to Speech Acts and object Count messages related to Senders/Speech acts and objects Analysis of sequences is important then the Sender play animator role for the object -If Answer-sender-date is close to animator messages then the animation is dynamic -Compare senders and message Recievers : -Messages Recievers do not interact then related CoPs participants are not engaged

Figure 1 :Figure 2 :

 12 Figure 1: Guided and self-directed modes of CoPs[START_REF] Borzillo | Unravelling the dynamics of knowledge creation in communities of practice though complexity theory lenses[END_REF]

Figure 7 :FiguresFigure 1 :

 71 Figure 7: Results of NLP analysis

Figure 7 :

 7 Figure 7: Results of NLP analysis

  the most salient reasons for the success and failure of CoPs are worked out. An investigation on 57 CoPs from major European and US companies led to the discovery of 10 "commandments" that lead to the successful development of CoP. These ten "commandments" describe CoP governance practices and could be linked with CoP diagnosis in order to apply the "commandments" that the best fit to a given CoP context.[START_REF] Jeon | Individual, social, and organizational contexts for active knowledge sharing in communities of practice[END_REF] identify and validate a set of organizational factors that was anticipated to have effects on knowledge sharing by CoP members such as perceived consequences, affect, social factors and facilitating conditions.

	Sender	Skill	Reciever	Subject	Speech Act	Sentence
						I want to be sure about
						the modification of the
						procedure…
						I turned out the samples,
		Civil		Samples	Request	I stored them in filtred
	21/06/13 15:43 Charlotte		Chao
		engineering		treatment	Verification	water
						Tomorrow I will polish
						them, treat them with
	According to a given CoP diagnosis the corresponding organizational factors could be put Uvs and I will send them
						to you.
	into action.

Table 5

 5 Verification of the procedure for sample shipping

	Speech Acts

Table 6

 6 Coordination main speech acts and topics

					Related Verbs from	Related Topics from e-
	Date	Sender	Speech Act	Topic
					e-mails	mails
	Kick off Meeting
					I Inform you that	I Inform you that today I
	13/07/2012
		Françoise	Information	Document	today I will send the	will send the financial
	12:22
					financial document	document
					Could you also give
						Could you also give me a
					me a date between
			Request	Meeting Date		date between 12 and 14
					12 and 14 september
						september for a meeting.
					for a meeting.
					The first meeting
						The first meeting date will
				Meeting Date and	date will be held on
		Bernard	Information			be held on Monday 17
				Place	Monday	17
						september.
					september at LISE.
					Please confirm your	Please	confirm	your
			Request	Participation
					participation	participation
					I	propose	the
						I propose the following
			Proposition	Meeting Schedule	following Meeting
						Meeting Schedule
					Schedule

Table 7

 7 Example of analysis of messages

	Sender	Speech act	Topic	Number
			Project Documents	8
			Meeting Report	5
		Information	Project Presentation	2
			Meeting Date, Place	2
			Meeting logistics	2
		Total		19
			Meeting Date, Place	7
		Proposition	Project Presentation	3
	Francoise		Meeting Scheduling	7
		Total		17
			Meeting Date, Place	6
			Meeting Report	2
			Meeting Scheduling	1
		Request
			Meeting logistics	2
			Project Documents	3
			Project Presentation	3
		Total		17
			Meeting Date, Place	1
		Proposition
			Meeting logistics	1
	Bernard
		Total		2
		Request (Total)	Meeting logistics	3
		Information (Total)	Meeting logistics	1
	Anouk
		Request (Total)	Meeting logistics	2
	Thierry	Request (Total)	Meeting logistics	1
	Thierry, Isabelle, Sandrine,
		Information (Total)	Meeting Participation	7
	Anouk, Sebastien, Virginie
	Table 8 Summary of interaction analysis

Table 9

 9 Our analysis technique

	SEPOLBE analysis
	Subject : bioreceptivity
	Samples' Conservation
	Experiment


Sima Yazdani

Glen P Junor

Jesse L Peltier

Milan Gembicky

Rodolphe Jazzar

Douglas B Grotjahn

Guy Bertrand

Zhang

Lavallo

Michelet César

Influence of Carbene and Phosphine Ligands on the Catalytic Activity of Gold Complexes in the Hydroamination and Hydrohydrazination of Alkynes

Keywords: cyclic (alkyl)(amino) carbene, gold catalysis, hydroamination, hydrohydrazination, mechanistic study

come

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Influence of Carbene and Phosphine Ligands on the Catalytic Activity of Gold Complexes in the Hydroamination and Hydrohydrazination of Alkynes

Sima Yazdani, †, ‡ Glen P. Junor, † Jesse L. Peltier, † Milan Gembicky, † Rodolphe Jazzar,* , † Douglas B. Grotjahn,* , ‡ Guy Bertrand* , †

The hydroamination of carbon-carbon multiple bonds is the most atom-efficient method for the introduction of nitrogen fragments into organic molecules. [START_REF] Müller | Hydroamination: direct addition of amines to alkenes and alkynes[END_REF] Pioneered by Tanaka et al. [START_REF] Mizushima | I)-Catalyzed Highly Efficient Intermolecular Hydroamination of Alkynes[END_REF] using (PPh3)AuNTf2, the field of coinage metal hydroamination catalysis has witnessed an outstanding development in recent years. [START_REF] Widenhoefer | Gold-catalyzed hydroamination of C-C multiple bonds[END_REF] Xu et al. 4 observed a remarkable ligand effect 5 in the intermolecular hydroamination of phenyl acetylene with aniline, using a set of phosphine ligands. Sophisticated phosphines, 6,7 such as the WangPhos LA, [START_REF] Wang | A general ligand design for gold catalysis allowing ligand-directed antinucleophilic attack of alkynes[END_REF] or the Lavallo anionic phosphine LB, [START_REF] Lavallo | Perhalogenated Carba-closo-dodecaborate Anions as Ligand Substituents: Applications in Gold Catalysis[END_REF] allowed to achieve up to 22,000 TON for the hydroamination of phenyl acetylene with aniline. More recently, NHC ligands have become popular replacements for phosphines.

As an illustration, Ceśar, Michelet and co-workers reported that a gold complex bearing NHC LC, [START_REF] Tang | An original L-shape, tunable N-heterocyclic carbene platform for efficient gold(i) catalysis[END_REF] which features a barbituric heterocycle, efficiently promotes the same transformation up to 7600 TON (Scheme 1).

From this short analysis, it appears that phosphines and carbenes, capitalizing on elaborate secondary interactions, afford the most efficient catalysts. However, the presence of these complex motifs clouds an understanding of the electronic contributions from the core of the ligand. 11 To better understand, we herein report a detailed investigation of the influence of core ligand structures (R3P, NHC, CAAC-5, CAAC-6, BiCAAC) on the catalytic performance of gold complexes in the hydroamination and hydrohydrazination of alkynes. For a thorough comparison, in-situ kinetic measurements were conducted to determine the order of each reactant and the influence of the electronic properties of the substrates (Hammett plot). Moreover, reactivity studies and DFT calculations enable a rationalization of the catalytic performance of each ligand system. Finally, we show that the readily accessible BiCAAC, [START_REF] Tomás-Mendivil | Bicyclic (alkyl)(amino)carbenes (Bi-CAACs): stable carbenes more ambiphilic than CAACs[END_REF] which does not feature secondary interactions, competes with state-of-the-art ligands.

Results and Discussion

We have already shown that gold complexes bearing a 5-membered cyclic (alkyl)(amino) carbene (CAAC-5) 13 are excellent catalysts for the intermolecular hydroamination and hydrohydrazination of alkynes and allenes. [START_REF] Kinjo | Gold-catalyzed hydroamination of alkynes and allenes with parent hydrazine[END_REF]15,[START_REF] Zeng | Serendipitous discovery of the catalytic hydroammoniumation and methylamination of alkynes[END_REF] They survive drastic conditions (up to 200 o C), [START_REF] Lavallo | Homogeneous catalytic hydroamination of alkynes and allenes with ammonia[END_REF] which allowed the use of ammonia and parent hydrazine that are difficult substrates for transition metal catalysts. Recently, we extended the family of CAACs to the bicyclic version (BiCAAC) [START_REF] Tomás-Mendivil | Bicyclic (alkyl)(amino)carbenes (Bi-CAACs): stable carbenes more ambiphilic than CAACs[END_REF] and the 6membered CAAC (CAAC-6), [START_REF] Weinstein | Highly ambiphilic room temperature stable sixmembered cyclic (alkyl)(amino)carbenes[END_REF] which feature distinct electronic and steric properties (Figure 1).

I. Hydroamination reaction

Reaction optimization. Inspired by Blackmond et al., [START_REF] Blackmond | Kinetic Profiling of Catalytic Organic Reactions as a Mechanistic Tool[END_REF] we envisaged the use of in-situ kinetic measurements to optimize the catalytic system. Using 1 H NMR spectroscopy, we monitored the formation of imine 1a in the reaction of aniline with para-(methoxyphenyl)

Figure 1. Electronic properties of different families of carbene ligands.

acetylene. The reactions were carried out at room temperature in air, using KBAr F as a chloride scavenger, meanwhile changing the nature of the catalyst (Figure 2a-b), the solvent (Figure 2c), the concentration and catalyst loading (Figure 2d). No reaction was observed with (THT)AuCl and using (Ph3P)AuCl, we confirmed the accuracy of our kinetic protocol by obtaining comparable results to those reported by Xu et al. 4a We found that all the carbene ligands that we considered give rise to more active catalysts than PPh3; , it appears that neither the steric hindrance nor the electronic factors are decisive on their own. Using DFT calculations, we realized that the steric demands of BiCAAC L4 are variable, due to the rotation of the iso-propyl group (Figure 3). Concomitantly, BiCAAC L4 is both more electron donating and withdrawing than the other carbenes, except for CAAC-6 L2 (Figure 1). Thus, we rationalize the superior performance of IPr- BiCAAC L4 as a compromise between moderate steric bulk, approaching that of L5, and significant ambiphilicity, nearing L2. With respect to the nature of the solvent (Figure 2c), using L4 we found that the catalytic activity is greatly impaired by strongly coordinating solvents. This is readily rationalized as a competition between the solvent and the substrates for binding to the metal. Finally, we optimized the concentration and the catalyst loading (Figure 2d) and selected 2.5 mol% and 1.5 M, respectively, as a middle point between conversion and reaction time.

Reaction Scope. Using the optimized catalytic system (2.5 mol% of IPr BiCAACAuCl/KBAr F in benzene -1.5 M), we evaluated the scope of the hydroamination using a variety of alkynes and anilines (Scheme 2). p-Toluidine efficiently added to aryl substituted terminal alkynes; all reactions proceeded within a few hours in very high yields at 20 °C (1a-1e). Alkyl substituted terminal alkynes required higher reaction temperatures to achieve high conversions within a reasonable timeframe (1f-1g). Note that even with these alkynes, full conversion can still be Scheme 2. Substrate scope with amines and alkynes. NMR yields (isolated yields).

R 2 H 2 N-R 3 + N R 3 R 1 R 2 L 4 AuCl / KBAr F (2.5 mol %) C 6 D 6 (1.5 M) 20-100 o C N 1a 96% (95%) 20 o C, 5.5 h 1e 90% (90%) 20 o C, 5.5 h 1c 95% (95%) 20 o C, 4.5 h 1b 95% (90%) 20 o C, 5 h 1f 92% (92%) 80 o C, 3.5 h 1g 94% (93%) 80 o C, 3.5 h 1i 63% (50%) 100 o C, 20 h N N 1j 77% (76%) 80 o C, 5.5 h N 1k 58% 100 o C, 36 h N N R 1 1a-r 1h 99% (97%) 20 o C, 23 h N N 1d 98% (97%) 20 o C, 3.5 h N N N N F TMS O 1l 95% (95%) 20 o C, 4.5 h 1m 99% (99%) 20 o C, 4.5 h 1n 94% (94%) 20 o C, 5.5 h N N 1o 96% (96%) 20 o C, 8 h CF 3 N N F 1p 93% (42%) 20 o C, 5 h N iPr iPr Cl Cl F F F F MeO 1q 90% (87%) 80 o C, 6 h 1r 69% (67%) 80 o C, 6 h N N
achieved at room temperature albeit with a longer reaction time, which is useful for low boiling point substrates such as ethoxyethyne (1h). We also found internal alkynes to be more challenging (1i-1k) requiring longer reaction times and higher temperatures.

We also changed the nature of the aniline (1l-1p), and observed very good conversions even with the sterically demanding 2,6-diisopropylaniline (1m) and electron-poor perfluorinated aniline (1o). Finally, alkyl amines (1q,r) proved less reactive but were successfully converted to the desired products by performing the reaction at 80 o C.

Hammett correlation study. We conducted a Hammett correlation study to quantify the electronic influence of the substrates (Figure 4). Both anilines and arylalkynes with electron-donating para-substituents showed faster reaction kinetics (ρ value < 0). Electronrich alkynes favor a forward equilibrium by stabilizing the cationic Au-π complex, whereas electron-rich anilines push a forward equilibrium by favoring the nucleophilic attack on the positively charged carbon. Note, that we observed a nonlinear behavior with the p-NMe2 substituent, likely due to a competitive binding of this group to the gold center.

Rate order. We established the rate order in the alkyne and the amine under pseudo first-order conditions (excess of the spectator substrate; Figure 5). In both cases, we found first order dependence on these substrates which suggests that both of them are involved in the rate-limiting step.

II. Hydrohydrazination reaction

Hydrazines are inherently more challenging than amines due to their propensity to generate inert gold(0) nanoparticles 20 or unreactive Werner complexes. [START_REF] Klinkenberg | Catalytic Organometallic Reactions of Ammonia[END_REF]22 We have shown that (CAAC-5)AuCl in the presence of KBAr F is active for the hydrohydrazination of a variety of alkynes at rather high temperatures (90-150 o C). [START_REF] Kinjo | Gold-catalyzed hydroamination of alkynes and allenes with parent hydrazine[END_REF] Although the scope of applications is much narrower, gold complexes bearing the saturated abnormal NHC (saNHC) [START_REF] Manzano | Room-Temperature Hydrohydrazination of Terminal Alkynes Catalyzed by Saturated Abnormal N-Heterocyclic Carbene-Gold(I) Complexes[END_REF] or the anti-Bredt-NHC, [START_REF] Martin | Cyclic Diaminocarbene with a Pyramidalized Nitrogen Atom: A Stable N-Heterocyclic Carbene with Enhanced Electrophilicity. Angew[END_REF][START_REF] López-Gómez | Anti-Bredt N-Heterocyclic Carbene: An Efficient Ligand for the Gold(I)-Catalyzed Hydroamination of Terminal Alkynes with Parent Hydrazine[END_REF] which are p-accepting carbenes, promote this transformation under milder conditions.

Reaction conditions: As we did for amines, we began our investigation with a kinetic survey using 1 H NMR spectroscopy to monitor the formation of 2c in the reaction of phenyl hydrazine with para-methoxy-phenyl acetylene at room temperature. We varied the nature of the catalyst (Figure 6a-b), the solvent (Figure 6c), the concentration and the catalyst loading (Figure 6d).

Here again using KBAr F as a chloride scavenger we confirmed the accuracy of our kinetic protocol by verifying that (Ph3P)AuCl is not an efficient catalyst for this transformation. 4 Upon comparing the catalytic activity of the CAAC complexes, we found that the smaller Et CAAC-5 (L1, %Vbur : 43.2) was deactivated by hydrazines in marked contrast with the bulkier Ad- CAAC-5 (L3, %Vbur : 48.4) and Et CAAC-6 (L2, %Vbur : 47.4). We attribute this peculiar result to the propensity of L1 to favor disproportionation to a catalytically inactive bis-ligated (L1)2Au + in polar solvents. 26 Apart from L1, the order of activity L3 < L2 < L5 < L4 resembles that observed for the hydroamination, with the Bi-CAAC L4 gold complex being the most active catalyst.

As in the case of amines, we found that the catalytic activity is greatly impaired by strongly coordinating solvents (Figure 6c). Moreover, the early precipitation of the product prevented accurate reaction monitoring in benzene. Thus, using chloroform, we evaluated the concentration and the catalyst loading (Figure 6d). We selected 0.5 mol% and 1.8 M as a middle point between conversion and reaction time.

Reaction Scope: Using the optimized conditions obtained from our kinetic study (0.5 mol% of L4AuCl/KBAr F in CHCl3 -1.8 M), we evaluated the scope of the reaction using a range of alkynes and

Solvent effect

product crystallization hydrazines (Scheme 3). With phenylhydrazine, we found this catalytic system to be very efficient with aryl substituted terminal alkynes at room temperature (2a-2e). With 3-ethynylpyridine (2f), however, the reaction was much slower, requiring 2.5 mol% catalyst loading and 80 o C for 10 h. Similarly, in the case of alkyl substituted terminal alkynes, as well as internal alkynes, higher reaction temperatures were required to reach high conversion within a reasonable timeframe (2g-2k). While both mono-substituted and parent hydrazine were readily converted under mild conditions (2l-2m), we found 1,1-disubstituted hydrazines (2o 27 and 2p) to be much less reactive.

H 2 N-NHPh + N LAuCl / KBAr F C 6 D 6 20 o C MeO MeO HN Ph 2c [Au] = 2.5 mol% in C 6 D 6 in CDCl 3 L 4 L 4 [Au] = 2.5 mol% R 2 H 2 N-NHR 3 + N H N R 1 R 2 CDCl 3 (1.8 M) 20-100 o C N H N R 1 2a-p R 3 N H N N H N N H N N H N O N F 2a a 99% (100%) 20 o C, 2 h 2e a 95% (95%) 20 o C, 5 h 2c a 99% (99%) 20 o C, 0.5 h 2d a 99% (95%) 20 o C, 0.5 h 2b a 95% (95%) 20 o C, 2 h N H N N H N N H N N H N N H N TMS 2g b 99% (91%) 80 o C, 4 h

Hammett correlation study.

A Hammett correlation study was performed to quantify the electronic influence of the substrates in the gold catalyzed hydrohydrazination of alkynes (Figure 7). Faster reaction kinetics were obtained for alkynes bearing electron donating phenyl para-substituents (ρ value < 0), as observed in the hydroamination. The reverse is observed with phenyl-hydrazine, with decreasing rates obtained for electron donating substituents (ρ value > 0). This observation is in good agreement with the experimental results (2l-2o), and could be due to the higher binding affinity of the most basic hydrazines to the gold center. However, a computational study by Ujaque, Lledós et al. [START_REF] Couce-Rios | Hydroamination of C-C Multiple Bonds with Hydrazine Catalyzed by N-Heterocyclic Carbene-Gold(I) Complexes: Substrate and Ligand Effects[END_REF] showed that the catalytic cycle of hydrohydrazination of alkynes does not depend on the energy barrier for the nucleophilic addition of the hydrazine on the Au-π complex, but rather relies on hydrazine assisted intermolecular proton transfer. As a result, it is likely that the increased hydrazine N-H bond acidity with electron-withdrawing phenyl substituents favors the reaction. Rate order. We established the rate order in the alkyne and the hydrazine under pseudo first-order conditions (excess of the spectator substrate; Figure 8). We found first order dependence for both reactants supporting that both alkyne and hydrazine are involved in the rate-limiting step. Together with the results obtained for the hydroamination, our data are in good agreement with both processes falling into the category of reactions involving nucleophilic attack of an amine on a gold activated carbon-carbon triple bond, followed by nucleophile assisted nitrogen to carbon atom proton transfer. Buchwald-type biphenyl phosphine ligands were shown to afford very stable cationic gold complexes, [START_REF] Gorin | Relativistic effects in homogeneous gold catalysis[END_REF]4 likely owing to secondary coordination to the distal phenyl substituent of the biphenyl unit. 29 To estimate the propensity of CAAC ligands to stabilize cationic gold (L)Au + (p-alkyne) under pseudo-catalytic conditions, we performed a similar study. We examined the rate of decay at room temperature in cationic gold species bearing L1-L4 ligands, as well as the smaller Me BiCAAC L6 and Ph3P, in the presence of excess nhexyne (Figure 9). As expected, we found Et CAAC-5 L1, Ad CAAC-5 L3, and IPr BiCAAC L4 to yield very stable cationic gold species over a period of 4 days, whereas a rapid decay was observed with Et CAAC-6 L2, Me BiCAAC L6 and PPh3. For L2 and PPh3, we attributed the decomposition to the formation of gold(0) nanoparticles as highlighted by the observation of insoluble black deposits on the NMR sample. [START_REF]The formation of such black deposits in the presence of reducing substrates in gold catalysis has been described early[END_REF] Because of the very different lifetime of ( IPr BiCAAC)AuCl and ( Me BiCAAC)AuCl, we took a closer look at their behavior under catalytic conditions. As shown in Figure 10, in both hydroamination and hydrohydrazination, we found that ( IPr BiCAAC)AuCl outperforms ( Me BiCAAC)AuCl. We next attempted to isolate the putative intermediates of the catalytic cycle (Scheme 4). Complex (L4)AuCl reacted with a terminal or an internal alkyne affording stable (L4)Au + (alkyne) adducts with either BF4 or BAr F anions. One of these complexes was characterized by X-ray crystallography. In contrast, even with a large excess of alkyne, (L6)Au + (alkyne) can only be characterized by NMR spectroscopy. After 2 days at room temperature, this complex disproportionates into the bis-ligated (L6)2Au+ (characterized by X-ray crystallography) and gold nanoparticles. Note that the predisposition of Me BiCAAC L6 over IPr BiCAAC L4 to favor the formation of such bis-ligated complexes has already been observed with copper.

X-ray of 2q

Tol-NH 2 (2.1 eq.)

+ N Tol Tol 1b R 2 R 1 [L 4 Au + (TolNH 2 )][BF 4 -] [L 4 Au + (TosNHNH 2 )][BF 4 -] X-ray of [L 4 Au + (TolNH 2 )][BF 4 -] X-ray of [(L 6 ) 2 Au + ][BF 4 -] N Dipp Me Au Cl N Dipp Me Au N Dipp Me Au H C 4 H 9 N Dipp Me BF 4 " Au 0 " + [(L 6 ) 2 Au + ][BF 4 -] 10 eqv., n-hexyne DCM, 20 o C KBF 4 2 days BF 4 DCM, RT with R 1 = H, R 2 = Tol; X = BF 4 DCM, RT with R 1 = H, R 2 = Tol; X = BF 4 L 6 AuCl L 4 AuCl BF 4 BF 4 X-ray [L 4 Au + (PhCCPh)][BAr F-] [L 4 Au + (alkyne)][X -] R 1 ,R 2 = Ph; X = BAr F R 1 = H, R 2 = Tol; X = BF 4
NB: solid state structure's anions were omited for clarity Rationalizing the ligand effects by DFT: All calculations were performed with the Gaussian09 program suite 31 using ultrafine 32 (99,590) integration grids. [START_REF]All computational results are available for download free[END_REF] All structures were optimized with the ωB97X-D 34 functional and 6-31g** 35 basis set for all atoms except Au, which was treated with the SDD 36 basis set and ECP. Solvent was treated as a polarizable continuum of benzene. [START_REF] Tomasi | Quantum Mechanical Continuum Solvation Models[END_REF] Ujaque, Lledós et al. computationally demonstrated that the energy of the transition state for substrate exchange between the Werner complex (catalyst resting state) and the active species (η 2 -π complex) follows the order of stability of the π-complex, [START_REF] Couce-Rios | Hydroamination of C-C Multiple Bonds with Hydrazine Catalyzed by N-Heterocyclic Carbene-Gold(I) Complexes: Substrate and Ligand Effects[END_REF] meaning that the more stable the π-complex, the lower the barrier for a given ligand. Using their work as a guiding principle we compared the energy differences between the Werner complexes of aniline and phenylhydrazine and the η 2 -π complex of phen ylacetylene for (L)Au + complexes bearing ligands L1 to L4 (Figure 11). Our DFT study clearly shows that in both cases the IPr BiCAAC L4 affords the most accessible η 2 -π adducts. As highlighted previously, [START_REF] Couce-Rios | Hydroamination of C-C Multiple Bonds with Hydrazine Catalyzed by N-Heterocyclic Carbene-Gold(I) Complexes: Substrate and Ligand Effects[END_REF] the barrier determining the rate of the catalytic cycle is not the barrier for the nucleophilic attack on the π-complex but rather the protonolysis of the migrated Au-amide bond. [START_REF] Hashmi | The critical influence of basicity on the protodeauration step has been demonstrated experimentally[END_REF] In their report, Ujaque, Lledós et al. noted the trend of increasing barrier height for proton transfer with increasing donor-strength of the ligand (barrier height: CAAC > saNHC). This principle provides a conundrum for chemists designing catalysts, 39 where there is a trade-off between the strength of the ligand to metal (L-M) bonds allowing for more durable catalysts and lower barriers to promote proton transfer. 40 Unarguably, the most ambiphilic ligands provide the strongest L-M bonds (i.e. L2 > L4 > L1 = L3) at the expense of an increased barrier for proton transfer. This could also explain why L2 performs much worse than several carbenes despite having the strongest M-L bond and a sterically flexible backbone. A good illustration of this statement is given by NHC L5 which performs surprisingly well compared to the more ambiphilic carbenes thanks to its relatively weak donor-ability resulting in a low barrier for proton transfer. Altogether, our data suggest that IPr BiCAAC L4 occupies the "sweet spot", featuring both a strong M-L bond and a relatively low barrier for proton transfer.

IV. Benchmarking IPr BiCAAC L4 against state-ofthe-art ligands

The stability of gold complexes under prolonged reaction times and high temperatures is a prototypical limitation of most gold catalytic reactions. Capitalizing on the robustness of the L4-Au bond, we envisaged that this complex should survive the experimental conditions used in the hydroamination of alkynes with the state-of-the-art phosphines LA and LB, and NHC LC gold complexes, namely between 50 and 80 °C. [START_REF] Wang | A general ligand design for gold catalysis allowing ligand-directed antinucleophilic attack of alkynes[END_REF][START_REF] Tang | An original L-shape, tunable N-heterocyclic carbene platform for efficient gold(i) catalysis[END_REF] We were pleased to witness a catalytic activity reaching nearly 17,000 TON in 19 h at 80 °C (Figure 12). We also evaluated the ( IPr BiCAAC)AuCl complex in the hydrohydrazination reaction, and obtained, under the same conditions, up to 27,000 TON.

Conclusions

In summary, we have reported a comprehensive study highlighting the reactivity of CAAC gold complexes in the hydroamination and hydrohydrazination of alkynes. Our kinetic measurements demonstrate that the IPr BiCAAC L4 provides a very active catalysts for these transformations, which is rationalized through mechanistic and DFT studies. We propose that the unique steric and electronic environment provided by the L4 ligand singlehandedly shields the metal from degradation. Concomitantly it stabilizes the key π-alkyne complex active intermediate, and favors a low barrier for proton transfer. High TONs were obtained in the hydroamination and hydrohydrazination of alkynes, competing with recently reported, highly sophisticated phosphine and NHC complexes. Contrad- icting a general consensus that gold catalysts must be improved through the design of tailored secondary interactions, we have provided compelling evidence that there is still much to be gained in controlling the ligand core -that is, the metal-ligand bond itself. The remarkable progress made in the past 30 years in the design of stable carbenes have taught us that these species provide an exceptional handle for the tuning of the electronic and steric environment of a metal, including now the readily available BiCAAC ligands, [START_REF] Tomás-Mendivil | Bicyclic (alkyl)(amino)carbenes (Bi-CAACs): stable carbenes more ambiphilic than CAACs[END_REF] one of the most recent additions to the CAAC family.

Experimental Section

All the catalytic experiments were performed in air using commercial grade solvents and reagents unless otherwise noted. All the kinetic experiments were performed three times to verify the reproducibility of the results. All other manipulations were performed using standard glovebox and Schlenk techniques. Glassware was dried in an oven overnight at 150 °C or flame-dried before use. Benzene, diethyl ether, and n-pentane were freshly distilled over Na/benzophenone. Hexanes, dichloromethane, and chloroform were freshly distilled over CaH2. Deuterium-labeled solvents were purchased from Cambridge Isotope Laboratories. NMR: Multinuclear NMR data were recorded on a Varian INOVA 400 and 500 MHz or a Bruker Avance 300 and 600 MHz. Single-crystal X-ray structure determinations were carried out at low temperature on a Bruker P4, Platform, or Kappa diffractometer equipped with a Mo (λ = 0.710 73 A) or Cu (λ = 1.541 78 A) radiation source and a Bruker APEX detector. Crystals were selected under oil, mounted on nylon loops, then immediately placed in a cold stream of nitrogen. All structures were solved by direct methods with SIR 2004 or SHELXS and refined by full-matrix leastsquares procedures utilizing SHELXL within the Olex 2 small-molecule solution, [START_REF] Dolomanov | OLEX2: a complete structure solution, refinement and analysis program[END_REF] refinement, and analysis software package.

General method for the hydroamination

In air, a scintillation vial (3 mL) was charged with IPrBi-CAAC)AuCl/ KBArF (2.5 mol%), C6H6 (1 mL) and the alkyne (1.163 mmol, 1.0 eq.). After stirring for two minutes, the amine (1.163 mmol, 1.0 eq.) was added as a solution in C6H6 (0.5 mL). The mixture was then set stirring according to reaction time and temperature listed in scheme 3. The products were purified by column chromatography using Florisil and eluting with a gradient mixture of DCM/hexane.

General method for the hydrohydrazination

In air, a scintillation vial (3 mL) was charged with IPrBi-CAAC)AuCl/ KBArF (0.5 mol% for 2a-2e; 2.5 mol% for 2f-2p), C6H6 (200 µL) and the alkyne (0.357 mmol, 1.0 eq.).

After stirring for two minutes, the amine (0.357 mmol, 1.0 eq.) was added as a solution in C6H6 (200 µL). The mixture was then set to stir according to the reaction time and the temperature listed in scheme 4. The products were purified by column chromatography using Florisil and eluting with a gradient mixture of DCM/hexane. NB: Air sensitive products were purified under argon using dried Florisil.

Table of Content Graphic

Scheme 1 .

 1 Scheme 1. Comparison of the most efficient tailormade phosphines and carbenes in the hydroamination of phenyl acetylene with aniline.

Figure 2 .

 2 Figure 2. Optimization of the reaction conditions for the hydroamination reaction using 1 H NMR kinetic monitoring.

Figure 3 .

 3 Figure 3. Illustrating the flexible sterics in IPr Bi-CAACAuCl.

Figure 4 .

 4 Figure 4. Hammett correlations of rates and substituents on either alkyne (a) or amine (b).

Figure 5 .

 5 Figure 5. Rate dependence of the hydroamination on the concentration of alkyne (a) and amine (b).

Figure 6 .

 6 Figure 6. Optimization of the reaction conditions of the hydrohydrazination reaction using 1 H NMR kinetic monitoring Scheme 3. Substrate scope with hydrazines. NMR yields (isolated yields)

Figure 7

 7 Figure 7 Hammett correlations of rates and substituents on either alkyne (a) or hydrazine (b).

4, 28 -Figure 8 .

 288 Figure 8. Rate dependence of the hydrohydrazination on the concentration of alkyne (a) and hydrazine (b).III. Rationalizing the ligand effectCatalyst stability. As already mentioned, low turnover numbers in gold catalysis often originate from catalyst degradation giving unreactive Au 0 nanoparticles or unreactive (L)2Au + species. Xu and coworkers disclosed that the decay of cationic gold [(R3P)Au + (p-alkyne)][OTf -] in solution is phosphine dependent. 4 Buchwald-type biphenyl phosphine ligands were shown to afford very stable cationic gold complexes,[START_REF] Gorin | Relativistic effects in homogeneous gold catalysis[END_REF]4 likely owing to secondary coordination to the distal phenyl substituent of the biphenyl unit.29 To estimate the propensity of CAAC ligands to stabilize cationic gold (L)Au + (p-alkyne) under pseudo-catalytic conditions, we performed a similar study. We examined the rate of decay at room temperature in cationic gold species bearing L1-L4 ligands, as well as the smaller Me BiCAAC L6 and Ph3P, in the presence of excess nhexyne (Figure9). As expected, we found Et CAAC-5 L1, Ad CAAC-5 L3, and IPr BiCAAC L4 to yield very stable cationic gold species over a period of 4 days, whereas a rapid decay was observed with Et CAAC-6 L2, Me BiCAAC L6 and PPh3. For L2 and PPh3, we attributed the decomposition to the formation of gold(0) nanoparticles as highlighted by the observation of insoluble black deposits on the NMR sample.[START_REF]The formation of such black deposits in the presence of reducing substrates in gold catalysis has been described early[END_REF] Because of the very different lifetime of ( IPr BiCAAC)AuCl and ( Me BiCAAC)AuCl, we took a closer look at their behavior under catalytic conditions. As shown in Figure10, in both hydroamination and hydrohydrazination, we

Figure 9 .

 9 Figure 9. Ligand effects on the decay of [LAu(alkyne) + ][BAr F-].

12

 12

Figure 10 .

 10 Figure 10. Comparison of the catalytic activity of L4 and L6 in the hydroamination (a) and hydrohydrazination (b) reactionsReaction of (L4)Au + (TolCCH) with an excess of tolylamine or tosyl-hydrazine led to the expected formation of the corresponding imine 1b and hydrazone 2q. More interestingly, these experiments also showed the concomitant formation of the Werner adducts (L4)Au + (TolNH2) and (L4)Au + (TosNHNH2) which further illustrates that IPr BiCAAC L4 is capable of stabilizing the gold center at every step of the catalytic cycle.

Figure 11 .

 11 Figure 11. Energy profiles of substrate ligand exchanges as a function of L1-L4.

Figure 12 .

 12 Figure 12. Benchmarking the catalytic activity of IPr Bi-CAAC gold chloride (L4AuCl) against state-of-the-art ligands.

ACKNOWLEDGMENT

This work was supported at UCSD by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Catalysis Science Program, under Award No. DE-SC0009376 (GB). At SDSU, experimental work was supported by NSF award CHE-1800598 (D.B.G.), and by a SDSU University Graduate Fellowship (S.Y.). Thanks are due to the Alfred P. Sloan Foundations University Centre for Exemplary Mentoring (G.P.J.). This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. (DGE-1650112; G.P.J. and J. L. P.). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. We also acknowledge the Keck Foundation for provided computational resources.

ASSOCIATED CONTENT

Supporting information

The Supporting Information is available free of charge at htpps://pubs.acs.org/doi/ Experimental procedures and characterization data, Xray crystallographic data and computational details.

AUTHOR INFORMATION

Corresponding Author guybertrand@ucsd.edu dbgrotjahn@sdsu.edu rjazzar@ucsd.edu ORCID Sima Yazdani : 0000-0003-0261-7146 Glen P. Junor : 0000-0002-6733-3577 Jesse L. Peltier : 0000-0002-3493-2127 Rodolphe Jazzar : 0000-0002-4156-7826 Douglas B. Grotjahn : 0000-0002-2481-7889 Guy Bertrand : 0000-0003-2623-2363

Funding Sources

The authors declare no financial competing interests.