CATALYTIC ACTIVITIES OF PD(II), PD(I) AND PD(O)-DIPHOSPHINE COMPLEXESFOR STYRENE OXIDATION

The catalytic activities of palladium(O, I, II)-diphosphine complexes were investigated in styrene oxidation using H2O2 as terminal oxidant. The rates showed a dependence on the chelate ring patterns of complex es (PdCl(2)L); 5-membered ring (L = dppe: 12-bis(diphenylphosphino) et hane)<6-membered ring (L = dppp: 1,3-bis(diphenylphosphino)propane)< 4 -membered ring (L=dppm: bis(diphenylphosphino)methane). This sequence correlates with the ligand field strength and interactions between met al and phosphine ligands. Pd(II, I)-diphosphine complexes which are ca pable of making 4-membered chelate ring showed an enhancement of catal ytic activities for styrene oxidation. The catalytic activities of Pd( O, I, II)-diphosphine complexes are described in terms of electronic a nd steric factors.