Beta-hydrogen elimination from late transition metal alkoxide complexes, nitrogen-hydrogen bond forming reductive elimination, and nitrogen-hydrogen oxidative addition to late transition metal complexes

A series of Vaska-type iridium alkoxide complexes have been prepared and underwent beta-hydrogen elimination to form Ir(CO)(PPh3) 3H and the corresponding ketones or aldehydes. Studies on the mechanism of the beta-hydrogen elimination from these iridium alkoxides revealed a reaction pathway similar to those from alkyl complexes.;The mechanistic analysis of the beta-hydrogen elimination from late transition metal alkoxides led to studies on catalytic acceptorless dehydrogenation of 1,4-butanediol to gamma-butyrolactone. In an effort to develop catalysts for acceptorless dehydrogenation of 1,4-butanediol to gamma-butyrolactone, ruthenium-based catalysts that react through the metal-ligand bifunctional mechanism were synthesized and tested.;The complex (DtBPP)Ir(propene) (DtBPP = 1,5-bis(di-tert-butylphosphino)pentane) underwent oxidative addition of ammonia to form the hydrido parent amide complex (DtBPP)IrH(NH 2). Mechanistic analysis of this transformation indicated a reaction pathway involving dissociation of olefin and addition of ammonia to the resulting three-coordinate 14-electron intermediate to form the amido hydride product. The complex (PCP)IrH(NH2) (PCP = eta3-C6 H3-2,6-(CH2PR2)2) underwent nitrogen-hydrogen bond-forming reductive elimination to from an ammine complex (PCP)Ir(NH3). Upon heating, complex (PCP)IrH(NH2)(CN tBu) underwent nitrogen-hydrogen bond-forming reductive elimination to from (PCP)Ir(CNtBu) and ammonia.