Ruthenium Complexes of CP₃: A New Carbon-Centered Polydentate Podand Ligand

A new tripodal, tetradentate, carbon-centered podand ligand based on HC­(CH2CH2PPh2)3 (HCP3) has been prepared. In the presence of [RuCl2(PPh3)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.