Complexes de métaux non-nobles de fer et de nickel portant des ligands redox non-innocents et leurs applications en catalyse : de l'activation C-H aux réactions de couplages croisés

摘要

This PhD work has focused on the development of complexes of non-noble metals bearing non-innocent ligands and their catalytic applications as efficient alternatives to noble metal complexes, in the light of increasing concerns regarding cost and sustainability-related issues of noble metals. Towards this goal, we have developed and characterized complexes of non-noble metals (Fe, Ni) with non-innocent ligands using multiple spectroscopic techniques. This work was aimed at broadening the field of useful catalytic applications of these particular complexes. For our dedicated program in iron catalysis, a new method for tandem C–H activation/arylation of unactivated arenes catalyzed by iron complexes bearing redox-active bis(imino)pyridine ligands was developed. Preliminary mechanistic insights were gained based on combined spectroscopic data (NMR, in situ IR, EPR), reactivity studies as well as DFT calculations. The results obtained are clearly in favor of a mechanism distinct to that previously reported for iron-based catalytic systems and are not compatible with homolytic aromatic substitution (HAS). We have also focused on another challenging field in catalysis: cross-coupling reactions catalyzed by nickel as base metal, bearing redox non-innocent ligands. Several challenges in cross-coupling reactions remain among which coupling of non-activated alkyl halides. Mechanisms involving nickel catalysts often differ from those involved in palladium catalyzed cross-coupling reactions. The behavior of nickel complexes bearing redox non-innocent ligands was studied in order to unveil new reactivites and gain a better understanding of the catalytic cycles at stake.