Deoxygenative reduction of diruthenium carbonyl complexes (eta(5)-C(5)H(4)R)(2)Ru-2(mu-CO)(2)(CO)(2) with hydrosilanes leading to bridging methylene complexes (eta(5)-C(5)H(4)R)(2)Ru-2(mu-CH2)(n)(mu-CO)(2-n)(CO)(2) (n=1, 2; R=H, CH3)

Reaction of diruthenium carbonyl complexes (eta(5)-C(5)H(4)R)(2)Ru-2(mu-CO)(2)(CO)(2) (1) With di- or trihydrosilane H(n)SiR'(4-n) (n = 2, 3) at 150 degrees C results in sequential formation of the mono(eta(5)-C(5)H(4)R)(2)Ru-2(mu-CH2)(mu-CO)(CO)(2) (2) and di-mu-methylene complexes (eta(5)-C(5)H(4)R)(2)Ru-2(mu-CH2)(2)(CO)(2) (3). Labeling experiments confirm that the C and H atoms in the resulting mu-CH2 moieties come from CO attached to Ru and H(n)SiR'(4-n), respectively, and that neither intermolecular CH2 transfer nor H transfer between bridging ligands is involved in the present methylenation. The reduction mechanism of bridging carbonyl ligands has been assumed to be deoxygenative hydrosilation (a direct thermal reaction or a catalytic reaction effected by a ruthenium species present in a reaction mixture). Thus, the present system serves as a model system for formation of a bridging methylene species following Fischer-Tropsch mechanism. The molecular structures of the cis- and trans-isomers of 3a (R = H) have been determined by X-ray crystallography.