Competitive acetylide C-C bond scission vs formation of a quadruply bridging carbonyl ligand. X-ray crystal structures of the two pentanuclear clusters Cp*3W3Ru2(μ4-C)(μ 3-CPh)(CO)9 and Cp*3W3Ru2(μ3-CCBu t)(CO)9

Reactions of Cp*WRu2(CCPh)(CO)8 (1a) with excess Cp*W(CO)3H, Cp* = C5Me5, affords a carbido - alkylidyne cluster Cp*3W3Ru2(μ4-C)(μ 3-CPh)(CO)9 (5) alone with three byproducts, which are identified as hydride cluster Cp*WRu3(μ-H)3(CO)11 (2), vinylidene cluster Cp*2W2-Ru2(CCHPh)(CO)9 (4), and a pentanuclear oxo-carbido cluster Cp*2W2(O)Ru3(μ5-C)(CO) 11 (3). In contrast, the respective condensation using tert-butyl derivative Cp*WRu2-(CCBut)(CO)8 (1b) gives an acetylide cluster Cp*3W3Ru2(μ3-CCBu t)(CO)9 (6). The X-ray structural determinations of 5 and 6 reveals the existence of an edge-bridged tetrahedral core, in which the butterfly crater is occupied by a μ4-carbide in 5 or a quadruply bridging CO ligand in 6. A plausible mechanism leading to the formation of these two cluster compounds is also presented.