TRIOSMIUM CLUSTERS AS MODELS FOR INTERMEDIATES IN CATALYTIC CARBON MONOXIDE HYDROGENATION REACTIONS (METHYLENE, KETENE, INSERTION, PHOSPHIDO, PLATINUM)

Triosmium cluster compounds have been studied as models for intermediates in catalytic CO hydrogenation reactions. Os(,3)(CO)(,11)((mu)-CH(,2)), 1, reacted with CO to give the ketene complex Os(,3)(CO)(,12)((eta)('2)-(C,C),(mu)(,2)-CH(,2)CO), 2. The reaction was partially reversed by heating in vacuo. X-ray diffraction of complex 2 showed that the ketene ligand is incorporated into a triosmacyclopentanone ring. Complex 2 reacted with H(,2)O and CH(,3)OH to give acetic acid and methyl acetate, respectively. Hydrogenation of 2 gave acetaldehyde. Labeling studies showed that one of the original carbonyl ligands in 1 inserts into the Os-(mu)-CH(,2) bond to give the ketene ligand.;The (mu)-CH(,2) clusters 3-5 and 7 reacted reversibly with CO to give the (mu)-ketene clusters PPN Os(,3)(CO)(,10)((mu)-CH(,2)CO)((mu)-X) (8, X = Cl; 9, X = Br; 10, X = I; 11, X = NCO). These reactions were >10('2) faster than the corresponding reaction of 1 with CO to give 2. The ability of the ketene ligand to accept increased electron density created by the presence of the X ligands appeared to be the important factor in accelerating the insertion reaction. Equilibrium constants of 3.5 atm('-1) and 3.0 atm('-1) have been derived for the 5 + CO (DBLARR) 10 and 7 + CO (DBLARR) 11 reactions, respectively.;Reactions of Os(,3)(CO)(,11)((mu)-CH(,2)) (1) and PPN Os(,3)(CO)(,10)((mu)-CH(,2)) ((mu)-I) with SO(,2) gave (mu)-sulfene complexes Os(,3)(CO)(,11)((mu)-CH(,2)SO(,2)) and PPN Os(,3)(CO)(,10)((mu)-CH(,2)SO(,2))((mu)-I) . Alkynes reacted with 5 to give (mu)(,3)-alkyne, (mu)-methylene complexes Os(,3)(CO)(,9)((mu)-CH(,2))((mu)(,3)-R-C(TBOND)CCO(,2)CH(,3)) (R = H, CO(,2)CH(,3)).;The phosphido-bridged complexes (CO)(,4)W((mu)-PPh(,2))(,2)M(PPh(,3)) (15, M = Pt; 16, M = Pd; and 17, M = Ni) were prepared by the reaction of Li(,2) (CO)(,4)W(PPh(,2))(,2) with cis PtCl(,2)(PPh(,3))(,2), trans PdCl(,2)(PPh(,3))(,2), and NiI(,2)(PPh(,3))(,2). The reactivity of these complexes has been briefly explored, and complex 15 and its derivative(' )(CO)(,4)W((mu)-PPh(,2))(,2)Pt- (CH(,3)CO(,2)C(TBOND)CCO(,2)CH(,3)) were fully characterized by X-ray diffraction.;Reaction of complex 1 with PPN X salts gave the new clusters PPN Os(,3)(CO)(,10)((mu)-CH(,2))((mu)-X) (3, X = Cl; 4, X = Br; 5, X = I; 6, X = NO(,2)). A similar reaction of 1 with PPN N(,3) gave PPN Os(,3)(CO)(,10)((mu)-CH(,2))((mu)-NCO) , 7. X-ray diffraction of complexes 5 and 7 showed that both structures are similar with the X and CH(,2) ligands bridging the same metal-metal bond.