Versatile cooperative ligand effects in group 9 transition metal catalysis: Applications in transfer hydrogenation & hydrogen autotransfer reactions, ketene & ketene imine synthesis and hydroformylation

Cooperative ligand effects of transition metal complexes have a profound impact on the reaction outcome of catalytic reactions, and development of (new) cooperative metal-ligand systems is a hot topic in current catalysis research. Conventional ligands with hydride-accepting/delivering activities are thus far widely underexplored. The aim of the research described in this thesis was to develop such kind of metal-ligand cooperative systems for (de)hydrogenation related catalysis and beyond.
In Chapter 2, a unique geometric arrangement between the metal and the ligand of N-methyl-1-(pyridin-2-yl)methanamine-based iridium and rhodium complexes upon deprotonation and oxidation was elucidated with NMR and X-ray structure determination.
In Chapter 3, the catalytic activity of an iridium-pma complex in a series of transfer hydrogenation-related reactions was studied. An unusual mechanism involving ligand-assisted hydride transfer was proposed and examined both experimentally and computationally.
In Chapter 4, a rhodium carbonyl complexes bearing a new PNN pincer ligand incorporating both an electrophilic and a nucleophilic arm was prepared. Its unique ligand-centered "Janus-type" reactivity was demonstrated in reactions involving a sulfonamide as the substrate.
In Chapter 5, the catalytic activity of a series of rhodium-PNN carbonyl complexes was examined for the synthesis of ketenes and ketene imines from carbene precursors. The mechanism was investigated with DFT calculations.
In Chapter 6, the catalytic hydroformylation activity of some rhodium-PNN carbonyl complexes was studied, focusing on the potential cooperative effect of the new PNN ligands. The nature of a potential active species was studied with NMR and IR spectroscopy.