THE CHEMISTRY AND CATALYTIC PROPERTIES OF RUTHENIUM AND OSMIUM COMPOUNDS .7. REGIOSELECTIVE HYDROGENATION OF CINNAMALDEHYDE (3-PHENYL-2-PROPENAL) CATALYZED BY RU AND OS TRIPHENYLPHOSPHINE COMPLEXES IN HOMOGENEOUS SOLUTION AND BY META-SULFONATOPHENYL-DIPHENYLDIPHOSPHINE (TPPMS) AND TRIS-META-SULFONATO-PHENYLPHOSPHINE (TPPTS) DERIVATIVES IN AN AQUEOUS BIPHASIC SYSTEM

NMR data for two Ru-TPPMS complexes previously described as unsaturate d monomeric species have led to their reformulation as the chloro-brid ged dimers [RuCl(TPPMS)(2)(mu-Cl)](2) (1) and [RuH(TPPMS)(2)(mu-Cl)](2 ) (2); three new water-soluble complexes OsH4(TPPMS)(3) (3), OsHCl(CO) (TPPMS)(2) (4), and [OsCl(TPPMS)(2)(mu-Cl)](2) (5) have been synthesiz ed and characterized. Complexes 1-5, as well as mixtures of Ru and Os salts with TPPMS and TPPTS catalyze the hydrogenation of cinnamaldehyd e under mild reaction conditions in aqueous biphasic systems; the acti vities and selectivities of these catalysts have been compared with th ose of homogeneous PPh(3) analogues. In general there is a clear advan tage in using the aqueous biphasic mixtures over their analogous homog eneous solutions, since catalyst recovery and recycling are easy and b ecause the regioselectivity towards the production of the alpha, beta- unsaturated alcohol is considerably enhanced on going from the homogen eous PPh(3) to the biphasic TPPMS and TPPTS systems, particularly in t he case of Ru.