REACTION-MECHANISMS OF METAL-METAL-BONDED CARBONYLS .22. FRAGMENTATION REACTIONS OF NONACARBONYLTRIS(TRI-NORMAL-BUTYLPHOSPHINE)TRIRUTHENIUM AND NONACARBONYLTRIS(TRIPHENYL PHOSPHITE)TRIRUTHENIUM

The complexes Ru3(CO)9L3 (L=P-n-Bu3 and P(OPh)3) undergo thermal fragmentation reactions in decalin to form mononuclear products, and the kinetics of these reactions have been studied. A major path is shown to involve initial rate-determining dissociation of a CO ligand. When L=PPh3, P(OPh)3, and P-n-Bu3, the activation enthalpies are 33.0 27.4, and 19.4 kcal mol-1, respectively, and this can only be explained by major differences in the bonding within the intermediates Ru3(CO)8L3. Some possibilities are discussed. The detailed nature of the kinetics requires that these intermediates are not susceptible to direct attack by L but that they undergo reversible isomerization to a form that is. Fragmentation follows this attack. Assessment of results of these and other kinetic studies of triruthenium clusters suggests that initial ligand dissociation is generally much more facile than cluster fragmentation. © 1979, American Chemical Society. All rights reserved.