Reactivity of ruthenium carbonyl carboxylates under hydroformylation conditions

Ru(CO)2(MeCOO)2(PBu3)2, Ru2(CO)4(MeCOO)2(PBu3)2, Ru4(CO)8(MeCOO)4(PBu3)2 and [Ru2(CO)4(MeCOO)2]n react, in the presence of CO, with molecular hydrogen, losing the carboxylate ligand while the metal is reduced to Ru (0). Evidence is given of the involvement of ruthenium hydrides in this reaction. The role of the above precursors in the catalytic cycle of the hydroformylation of olefins is discussed.