DINUCLEAR GOLD(I) AND SILVER(I) DERIVATIVES WITH BRIDGING PHOSPHINES CONTAINING AN IMIDAZOLE RING - X-RAY CRYSTAL-STRUCTURE OF (1-BENZYL-2-IMIDAZOLYL)DIPHENYLPHOSPHINEGOLD(I)CHLORIDE

(1-Benzyl-2-imidazolyl)diphenylphosphine [(BzIm)Ph(2)P] can act as a monodentate or bidentate ligand to afford mononuclear (BzIm)Ph(2)PAuCl (I) or dinuclear [mu-(BzIm)Ph(2)PAu](2+)(2)2X(-) (X = PF6-, BF4- or NO,-) (IIa,b,c) derivatives of gold(I). Analogous dinuclear silver(I) derivatives were obtained reacting the ligand [(BzIm)Ph(2)P] with AgX salts (X=NO3-, BF4-) (IIIa,b). In solution the silver complexes show a fluxional behaviour, and two conformers were observed by P-31 NMR spectroscopy. The structure of compound I was established by X-ray crystallography (monoclinic, space group C2/c, a = 18.068(2), b = 16.576(2), c = 15.391(2) Angstrom, beta = 117.2(2)degrees, Z = 8). The short intermolecular An Au distance of 3.03(2) Angstrom indicates a metal-metal interaction. The Au-197 Mossbauer parameters of compounds I and IIa are consistent with IR, NMR and crystallographic data.