Migration of a phenyl group from co-ordinated CH2(PPh2)2 to an acetylide on an Ru3 cluster: crystal structure of [Ru3(µ-H)(µ3-PPhCH2PPh2)(µ3-PhC2But)(CO)6]†

Abstract

Thermolysis (refluxing toluene, 60 h) of [Ru₃(µ-H)(µ₃-C₂Bu^t)(µ-dppm)(CO)₇] resulted in phenyl transfer from co-ordinated dppm to the µ₃-acetylide to give [Ru₃(µ-H)(µ₃-PPhCH₂PPh₂)(µ₃-PhC₂Bu^t)(CO)₆] in 41% yield, fully characterised by X-ray determinations of thf and CH₂Cl₂ monosolvates. The alkyne is co-ordinated to the Ru₃ cluster such that the C(1)–C(2) vector forms an angle of 23° with the Ru(1)–Ru(2) vector. This distortion brings two C atoms of the alkyne Ph group close to Ru(2). Density functional and extended Hückel calculations carried out on the new compound indicated that the unusual co-ordination of the alkyne ligand can be attributed to the stereoelectronic asymmetry of the metallic fragment.