The structural chemistry of gold(I) quinoline-2-thiolate and iodide complexes of polytertiary phosphines

Treatment of (chloro)gold(I) complexes of di- and tetra-tertiary phosphines with equivalent quantities of sodium quinoline-2-thiolate in methanol/dichloromethane affords the corresponding (phosphine)gold(I) quinoline-2-thiolates in high yields. The di- and tetranuclear complexes, respectively, of α,ω-bis(diphenylphosphino)-propane (1), -butane (2) and -pentane (3) and of tris(2-diphenylphosphino-ethyl)phosphine (4) have been obtained as crystalline solids, and the structures of 2 and 4 have been determined by single crystal X-ray diffraction studies. Unexpectedly, the molecules of 2 are loosely aggregated into strings via weak intermolecular gold-sulfur, not via Au⋯Au interactions. Compound 4 is a monomeric tetranuclear cluster in the solid state with two intramolecular gold-gold bonds. Bis(2-diphenylphosphino-ethyl)-phenylphosphine (PPP) forms trinuclear complexes with gold(I) chloride, bromide and iodide (5a - c). The iodide complex features a chain structure through intermolecular Au⋯Au contacts between the two terminal P-Au-I units. The closest contacts between the chains are determined by Au⋯I and I⋯I interactions of the central P-Au-I unit.