SYNTHESIS AND CHARACTERIZATION OF COPPER-CONTAINING AND SILVER-CONTAINING PLATINUM GOLD CLUSTER COMPOUNDS - X-RAY CRYSTAL-STRUCTURE OF [PT(CUCL)(AUPPH3)8](NO3)2.CH3OH

The reactions of CuCl with [Pt(AuPPh3)8]2+ and [Pt(CO)(AuPPh3)8]2+ lead to the formation of [Pt(CuCl)(AuPPh3)8]2+ (1) and [Pt(CO)(CuCl)(AuPPh3)8]2+ (2), respectively. On addition of PPh3 to a reaction mixture containing CuCl and [Pt(CO)(AuPPh3)8]2+, two CuCl groups are incorporated, yielding [Pt(CO)(CuCl)2(AuPPh3)7]+ (3). A cluster with two Ag atoms, [Pt(CO)(Ag)2(AuPPh3)7]3+ (4), was obtained by treatment of [Pt(CO)(AuPPh3)8]2+ with 2 equiv of Ag(PPh3)NO3. The structure of 1 was determined by a single-crystal X-ray analysis. It crystallizes in the triclinic space group P1BAR with Z = 2, a = 17.057 (8) angstrom, b = 16.260 (2) angstrom, c = 26.446 (5) angstrom, alpha = 96.64 (6)-degrees, beta = 97.88 (2)-degrees, gamma = 78.10 (6)-degrees, and V = 70.80 (4) angstrom 3 (Mo K-alpha radiation). The residuals are R = 0.060 and R(w) = 0.069 for 8071 observed reflections and 460 variables. The probable presence of solvent molecules in the crystal was deduced from this structural analysis. The symmetry of the metal cluster is nearly C(s). The central Pt atom is surrounded by eight Au atoms and one Cu atom. A phosphine is attached to each of the Au atoms, and a Cl atom is attached to the Cu atom. Compared to its parent cluster [Pt(AuPPh3)8]2+ the cluster has retained its electron count and toroidal geometry. The other PtCu compounds are assumed to contain Pt-Cu bonds as well. They were characterized by elemental analyses and by P-31 and Pt-195 NMR spectroscopic properties. The Pt-195 NMR spectrum of 3 gives evidence for the presence of two Pt-Ag bonds.