Abstract:
The coordination chemistry of d6 ruthenium and d8 iridium metal amido complexes was examined, with particular emphasis on cooperative reactivity in catalysis. The used ethylene bridged tridentate diphosphine amido chelate framework (PNP) uniquely combines M−N bifunctionality, as typically found for electron rich transition metal amido complexes, with ligand backbone cooperativity. Besides mechanistic information on stoichiometric C-H and H2 activation, the high potential of the Ru(PNP) platform as catalyst for ionic (de)hydrogenation is presented. Of great current interest both for chemical hydrogen storage and the synthesis of novel inorganic polymeric materials is the dehydrogenation of ammonia borane; detailed studies with Ru(H)PMe3(PNP), the most active known catalyst to date, suggest a bifunctional mechanism for this reaction. The proposed mechanism accounts for the structural control of the polymeric B-N coupling product.