CATALYTIC-HYDROGENATION OF THE PHOSPHORUS CARBON DOUBLE-BOND IN PHOSPHAALKENE COMPLEXES

The catalytic transformations of phosphaalkene P-W(CO)5 complexes under H-2 pressure in the presence of rhodium catalysts have been studied. In the presence of the cationic complex Rh(diphos)+ isomerization of phosphaalkene into secondary vinylphosphine complexes is greatly favoured. On the other hand, in the presence of the covalent Rh(diphos)Cl complex hydrogenation of the P = C double bond is greatly predominant. Experiments with deuterium in place of hydrogen indicated that there is clean cis addition of H-2 or D2 to the double bond. No scrambling between tungsten and rhodium is observed in the postulated transient eta-1-P, eta-2-PC 4-electron phosphaalkene complexes.