Chemistry and catalytic properties of oxidized rhodium chlorocarbonyl complexes, Rh4Cl4(CO)4(O2)2P2; P = tertiary phosphine ligands

The reactions of the title complexes Rh4Cl4(CO)4(O2)2P2 (where P is a tertiary phosphine type ligand, in particular diphenylisobutylphosphinite) with both dihydrogen and carbon monoxide were studied in solution in the absence and presence of excess P. The reaction stoichiometries, particularly a measured carbon dioxide evolution, confirm the formulation of the reactant tetranuclear complexes. The complexes are effective for catalytic hydrogenation and hydroformylation of olefinic substrates, and the nature of the active catalysts is considered.