Reactions of ethyne with some ruthenium cluster complexes containing dppm

Abstract

Reactions of ethyne with [Ru3(-dppm)(CO)10] have given isomeric complexes [Ru3(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 C6H6 ligand forming a vinylruthenacyclopentadiene system. Also isolated was the open-chain Ru3 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 [Ru3(-H)(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 [Ru3(-H)(3-C2SiMe3)(-dppm)(CO)7] (8; refluxing MeOH) in the presence of KF gave [Ru6(-CCH2)2(-dppm)2(CO)12] (9; 80%); similar reactions carried out with [RuClCp(PPh3)2] also present gave 9 (67%) together with [Ru3(-H)(3-C2H)(-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 X-ray studies.