The preparation and some catalytic properties of a number of rhodium(I) diolefin complexes

Abstract The syntheses of the complexes [RhCl(cod)L], [RhX(cod)]2, [Rh(OCOPh)(cod)(PPh 3 )], [Rh(S 2 CNEt 2 )(cod)] and [Rh(cod)L 2 ]PF 6 (L = a variety of amines or phosphines, X = OCOPh or SPh) are described, together with some exchange reactions of the type [Rh(cod)(PR 3 ) 2 ] + + [Rh(cod)(pyridine) 2 ] + → [Rh(cod)(PR 3 )(pyridine)] + in which the isolable mixed ligand complexes are the only detectable species at equilibrium. Some of these complexes are active homogeneous hydrogenation catalysts for alkenes, alkynes and ketones in non-coordinating solvents such as benzene (in the presence of NEt 3 ) and dichloromethane (with or without NEt 3 ). [Rh(OCOPh)(cod)(PPh 3 )] selectively reduces 1-alkynes to 1-alkenes.