Reactions of Ethyne with Some Ruthenium Cluster Complexes Containing dppm

Reactions of ethyne with [Ru-3(mu -dppm)(CO)(10)] have given isomeric complexes [Ru-3(mu (3)-C6H6)(CO)(6)(dppm)], one of which, 2, contains the dppm chelating an Ru-atom, together with a hexatrienetriyl ligand attached to the Ru3 cluster to form a methylideneruthenacyclohexadiene system. The second isomer 3 contains the dppm bridging an Ru-Ru bond, with the CH, ligand forming a vinylruthenacyclopentadiene system. Also isolated was the open-chain Ru-3 Complex 4 containing a ruthenacyclopentadiene attached to the central Ru-atom; the other Ru-Ru vector is bridged by a PPh2CHPPh2C4H5 ligand, formed by a novel insertion of two ethyne molecules into an Ru-P bond. The reaction of ethyne with [Ru-3(mu -H)(mu (3)-C2H2)(CO)(9)] proceeded by attack at the coordinated alkyne and at the cluster to give a cluster-bonded PPh2CH2PPh2CCH system in 7. Thermolysis of [Ru-3(mu -H)(mu (3)-C2SiMe3)(mu -dppm)(CO)(7)] (8; refluxing MeOH) in the presence of KF gave [Ru-6(mu -CCH2)(2)(mu -dppm)(2)(CO)(12)] (9; 80%); similar reactions carried out with [RuClCp(PPh3)(2)] also present gave 9 (67%) together with [Ru-3(mu -H)(mu (3)-C2H)(mu -dppm)(CO)(6)(PPh3)] (11; 23%). The molecular structures of 2, 3, 4, 7, 9, and 11, some as differently solvated forms, have been determined by single-crystal Xray studies.