Self-Activation of a Cluster-Bound Alkyne toward Carbon−Carbon Bond Forming Reactions

The methanol-catalyzed elimination of Cl- from the “activated” anionic species [PPN][Ru3(μ-Cl)(μ-PhCCPh)(CO)9] (1) in the presence of bis(diphenylphosphino)methane (dppm) constitutes a rational high-yield route (>90%) to either the unique unsaturated 46-e (alkyne)triruthenium cluster, Ru3(μ-PhCCPh)(CO)7(dppm) (2), or its 48-e CO adduct, Ru3(μ-PhCCPh)(CO)8(dppm) (3). Whereas the CO-induced conversion of 2 into 3 is complete within few seconds at 25 °C under 1 atm of CO, the reverse transformation takes 1 h at 80 °C. The X-ray structure analysis of 2 is reported, revealing a perpendicular conformation of the alkyne relative to the metal triangle. The high reactivity of 2 is substantiated by a high chemical reactivity toward 2-e donors. Its reaction with 1 equiv of dppm (25 °C, 3 h) leads to the bis-dppm-substituted complex, Ru3(μ-PhCCPh)(CO)6(dppm)2 (4) (53% yield). Reaction of 2 with hydrogen gas (1 atm, 25 °C, 10 min) yields the dihydrido species, Ru3(μ-H)2(μ-PhCCPh)(CO)7(dppm) (5) (89% yield) existing as...