Bifunctional N-Heterocyclic Ligands : Versatile Ligands for the Preparation of New, Air-stable Catalysts – BIFUNC-NHC

N-Heterocyclic carbenes (NHCs) have become widely used ligands since the beginning of this century. They are compatible with most transition metals and generally lead to air-stable and thermally robust complexes which do not undergo ligand dissociation. More importantly, they have shown a great potential in homogeneous catalysis, and there is more and more evidence in the literature that these ligands can outperform phosphanes in catalytic activity. My major preoccupation, since the beginning of my independent research activities in 2003, has been to design bifunctional ligands for the generation of air-stable, robust catalysts – with the help of the substitutionally inert NHC moiety, that would keep an optimal activity with the presence of a second, more labile coordinating unit. The strength of NHC ligands is their structural versatility: they can easily be functionalised. Thus, we can consider the introduction of chirality – via a chiral centre or planar chirality, of hydrosoluble groups, or even of electroactive units. According to the metal and medium chosen, the ligands can find applications in catalytic reactions for fine chemicals synthesis (asymmetric C-C coupling), or of industrial importance (hydroamination). They can also help us understand specific reactivity issues, for example with the use of redox-switchable hemilabile ligands in isomerisation reactions. This project will follow three directions. In the first part we will develop bifunctional, chiral ligands, and study their coordination chemistry, mainly with nickel and palladium. The metal complexes will be tested in asymmetric C-C coupling reactions, such as Kumada-Corriu and Suzuki reactions, with the help of an expert in asymmetric catalysis. The second topic will deal with the application of new NHC ligands in the intermolecular hydroamination of non-activated alkenes. The activity of both achiral and chiral rhodium(I) and iridium(I) complexes will be evaluated in the hydroamination of ethylene and hexane with aniline, in collaboration with a hydroamination specialist. Finally, the third part of the project will be devoted to the development of redox-active hemilabile NHC ligands and coordination studies with rhodium(I) or ruthenium(II). The redox behaviour of both ligands and complexes will be studied by electrochemical methods, and their potential as isomerisation catalysts will be investigated.