Ruthenium complexes of CP3: A new carbon-centered polydentate podand ligand

Abstract

A new tripodal, tetradentate, carbon-centered podand ligand based on HC(CH2CH2PPh2)3 (HCP 3) has been prepared. In the presence of [RuCl2(PPh 3)3], HCP3 dehydrogenates on heating to yield [Ru(C(CH2CH2PPh2)2(= CHCH2PPh2))Cl2], where three phosphorus donors and a constrained alkene bind the metal. The metal-carbon bond is then formed by reduction with hydride in the presence of an ancillary ligand, to give [Ru(C(CH2CH2PPh2)3)LX] (L = ancillary ligand; X = H, Cl), where the metal has the full CP3 donor set. The complex [Ru(CP3)(CO)H] displays moderate catalytic activity for the transfer hydrogenation of acetophenone. © 2011 American Chemical Society.