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]

Thermolysis (refluxing toluene, 60 h) of [Ru-3(mu-H)(mu(3)-C2But)(mu-dppm)(CO)(7)] resulted in phenyl transfer from co-ordinated dppm to the mu(3)-acetylide to give [Ru-3(mu-H)(mu(3)-PPhCH2PPh2)(mu(3)-PhC2But)(CO)(6)] in 41% yield, fully characterised by X-ray determinations of thf and CH2Cl2 monosolvates. The alkyne is co-ordinated to the Ru, cluster such that the C(1)-C(2) vector forms an angle of 23 degrees 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 Huckel 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.