Initially considered as an inert metal, gold is now recognized as very powerful catalyst in organic synthesis. One very important area in homogenous catalysis for which gold complexes have not been considered yet, is the field of polymerization catalysis, particularly for the coordination-insertion polymerization of olefins. In contrast, late transition metal complexes such as Pd(II) and Ni(II) have been shown to be very good catalyst for the polymerization of olefins and the incorporation of polar monomers. However several limitations are still observed with these complexes, in particular for the copolymerization of olefins and polar monomers. Stimulated by the isolobal analogy between Au(III) and Pd(II) complexes, we propose in this project to prepare original bidentate Au(III)-alkyl complexes and investigate their behaviour in coordination-insertion polymerization of olefins. The main objective of this project is to shed light on a new facet of gold chemistry, we aim to thoroughly investigate the reactivity of gold towards olefins and to highlight that gold(III) complexes should be seriously considered for coordination-insertion polymerization catalysis. For that purpose, a set of gold(III)-alkyl complexes will be prepared using two main synthetic strategies. The reaction of selected complexes with model monomers such as ethylene and acrylonitrile will be explored by combining a set of experimental and theoretical techniques. In depth mechanistic studies of the coordination-insertion reaction will be carried out to gain fundamental knowledge on the key parameters governing the reactivity and selectivity of these gold complexes. Best representatives will be evaluated for ethylene and propylene polymerization and for copolymerization of ethylene with polar vinyl monomers.

ENigM proposes a family of evolutionary mimics of nitrogenase cofactor FeMo-co, for the understanding of the structure/properties relationship accounting for the exceptional reducing power of this complex structure. As a benchmark reaction, we choose the reduction of CO2, as it will enlarge and complete the information provided in the frame of N2 reduction usually considered in the field of nitrogenase mimics. This work will allow for the identification of systems able to perform the multi-electron reduction of small molecules, as the conversion of CO2 to formate, methanol or methane. The initial platform shows several structural analogies with FeMo-co: coordination sphere made of carbon and sulfur only, strongly charged carbon bridging between two iron centers. The easy modification of the ligand brings a strong modularity to our system, without the risk of denaturing the central metal-carbon interaction. A methodological ground will be established : redox and acido-basic properties of the initial platform, reactivity in the presence of CO2. This family of FeMo-co mimics will then be extended by stepwise increase of the number of metallic centers, while studying the properties of the obtained clusters.

The CONFICAT project aims at exploring the reactivity of transition metal (particularly gold) complexes in confined environments. The main concept is to generate, stabilize and use cationic metal complexes within anionic supramolecular cages. Although this strategy has started to be explored recently, it is so far restricted to a single anionic cage and small model gold complexes with little catalytic relevance. The lack of large, modulable and stable anionic cages is a serious bottleneck to develop this concept further. Therefore, this project first aims at preparing anionic polyhydroxyarene and truxene cages with different sizes, and at studying their host properties. With these cages in hand, two different problematics will be explored in order to substantiate the beneficial effect of confinement, namely oxidative addition to gold and gold-catalyzed macrocyclizations. The CONFICAT project seeks to progress our understanding of confinement effects in supramolecular catalysis, but also to benefit from the confinement-driven reactivity and selectivity in a useful but challenging catalytic transformation.

One of the most recent fascinating discoveries in main group element chemistry is that certain non-metallic reactive species behave quite similarly to transition metals (TMs) and are able to activate small molecules (with strong bonds) such as H-H, previously believed to be only possible using TMs. This discovery, providing interesting perspectives such as the use of such non-metallic species as an alternative to TMs with original properties to exploit new chemistry, is particularly important. However, our current knowledge to master the parameters controlling such properties is still far from satisfactory. In this project, we propose a fundamental and exploring research to establish a new methodology to induce the TM-like behavior of Si(II) [and Al(I)] species (silylenes and alumylenes) taking advantage of electronic and steric effects of TM-substituents. We expect to use such TM-substituted silylenes as unprecedented hybrid (non-metal and metal) binuclear complexes.

Organofluorine compounds exhibit relevant biological properties and have important applications in many fields (pharmacy, agrochemicals and material science, among others). However, the introduction of fluorinated groups in organic backbones (especially in aromatic rings) is not an easy task and no (industrially) efficient methods are known for installing trifluoromethyl groups in a specific position. Over the last few years, many procedures to achieve the C-CF3 bond formation via cross-coupling reactions have been developed (typically promoted by palladium and copper complexes), but these methods are not suitable for industrial applications due to their low efficiency and high cost. The Ni4Rf project will seek to develop new alternatives of catalytic trifluoromethylation reactions. Our proposal will target the preparation of high-valent Ni(IV)Rf species to achieve the reductive elimination of Ar-CF3 coupled products under mild conditions. Three different approaches will be addressed: i) the use of solvent stabilized high-valent NiRf fragments (in both oxidation states +3 and +4; task 1); ii) the synthesis of NiRf clusters favored by the presence of diphosphine oxide ligands that will be used as promoters in aromatic trifluoromethylations (task 2); and iii) the formation of mononuclear Ni(IV)Rf complexes stabilized by N-donor ligands [particularly, to meet success in the isolation of the highly attractive Ni(IV)F species] and the study of their implications in C-CF3 bond forming reactions (task 2). The final goal of this proposal focuses in the development of catalytic procedures for C-CF3 bond formation reactions involving a Ni(II)/Ni(IV) redox scenario (task 3). To increase our chances of success, an original approach combining experimental/theoretical work will be performed. Encouraged by the preliminary results carried out in our team, we plan to find a rational pathway to access different high-valent NiRf platforms, which will be reacted with a broad variety of organic substrates to afford the trifluoromethylation of many different scaffolds. This proposal focuses two long-term goals: i) the deep understanding about the nature of M-Rf bonds; and ii) the development of stoichiometric and catalytic processes for aromatic trifluoromethylations induced by Ni-complexes. Thus, our main goal addresses the isolation and full characterization of ArNi(IV)Rf species, and the study of their propensity to promote the reductive elimination of Ar-CF3 coupled products under mild conditions. The acquired information will be decisive in order to achieve the challenging task of developing the unprecedented Ni-catalyzed trifluoromethylation of aromatics via Ni(IV)-intermediates taking place in a SELECTIVE fashion.