Synthesis and characterisation of the hexanuclear ruthenium diphosphine clusters [Ru6C(CO)(15){mu-Ph(2)P(CH2)(n)PPh(2)}] (n=1-4); Crystal structures where n=1-3

Treatment of a hexane solution of the complex [Ru6C(CO)(17)] and 1 equivalent of the organodiphosphine ligands Ph(2)P(CH2)(n)PPh(2) (n = 1-3) produced the series of derivatives [Ru6C(CO)(15){mu-Ph(2)P(CH2)(n)PPh(2)}] 1-3, respectively, in ca. 74-94% yield. These clusters have been characterised by IR and NMR spectroscopy and in the solid state by X-ray analyses. The three related compounds all adopt a similar octahedral metal core geometry with the bidentate diphosphine ligand bridging one Ru-Ru edge of the metal polyhedron. Reaction of [Ru6C(CO)(17)] with 1,4-bis(diphenylphosphine)butane, Ph(2)P(CH2)(4)PPh(2), yielded two products which differ in the mode of bonding of the disphospine ligand, the major product [Ru6C(CO)(16){Ph(2)P(CH2)(4)PPh(2)-P}] 4a in ca. 74% yield and the minor product [Ru6C(CO)(15){mu-Ph(2)P(CH2)(4)PPh(2)}] 4b in ca. 10% yield.