The reaction of hydridocarbonyltris(triphenylphosphine)rhodium with carbon monoxide, and of the reaction products, hydridodicarbonylbis(triphenylphosphine)rhodium and dimeric species, with hydrogen

Abstract

A detailed study has been made, using infrared and nuclear magnetic resonance techniques, of the interaction of carbon monoxide and hydridocarbonyltris(triphenylphosphine)rhodium(I), RhH(CO)(PPh₃)₃. The latter, which dissociates in solution to the square complex trans-RhH(CO)PPh₃)₂, initially forms the dicarbonyl complex RhH(CO)₂(PPh₃)₂; in the presence of CO, this species loses hydrogen to give a yellow dimeric complex (Ph₃P)₂(CO)Rh(CO)₂Rh(CO)(PPh₃)₂. These reactions are reversed by hydrogen to re-form RhH(CO)(PPh₃)₂. By sweeping with an inert gas, the yellow dimer loses carbon monoxide to form a red, solvated dimer, (Ph₃P)₂(S)Rh(CO)₂Rh(S)(PPh₃)₂, which reacts with carbon monoxide to re-form the yellow dimer.