Triiron and triruthenium carbonyl clusters bearing bridging long chain diphosphine and capping chalcogenido ligands

Treatment of Ru-3(CO)(12) with dpphSe(2) (dpph = 1,6-bis(diphenylphosphino)-hexane) in refluxing toluene in the presence of Me3NO afforded two new compounds, Ru-3(CO)(7)(mu-CO)(mu(3)-Se)(mu-dpph) (1) and Ru-3(CO)(7)(mu(3)-Se)(2)(mu-dpph) (2). A similar reaction of Ru-3(CO)(12) with dpppeSe(2)(dpppe=1,5-bis(diphenylphosphino)pentane) gave exclusively Ru-3(CO)(7)(mu(3)-Se)(2)(mu-dpppe) (3). Treatment of Ru-3(CO)(12) with dpphS(2) and dpppeS(2) at 110 degrees C in the presence of Me3NO afforded Ru-3(CO)(7)(mu(3)-S)(2)(mu-dpph) (4) and Ru-3(CO)(7)(mu(3)-S)(2)(mu-dpppe) (5), respectively. Reactions of Fe-3(CO)(12) with dpphSe(2) and dpppeSe(2), under identical conditions, afforded Fe-3(CO)(7)(mu(3)-Se)(2)(mu-dpph) (6) and Fe-3(CO)(7)(mu(3)-Se)(2)(mu-dpppe) (7), respectively. Compounds 1-7 were characterized spectroscopically and the molecular structures of compounds 1-4 were determined by single crystal X-ray crystallography. The core of 1 contains an equilateral triangle of ruthenium atoms with one capping selenium, one bridging dpph, one doubly bridging carbonyl and seven terminal carbonyl ligands. Complexes 2-4 have a square-pyramidal structure with two metal and two chalcogenide atoms alternating in the basal plane and the third metal atom at the apex of the pyramid, and belong to the family of well-known nido clusters with seven skeletal electron pairs.