Reactivity Of 16-Electron And 18-Electron Mixed Platinum Gold Clusters With Halides - Crystal And Molecular-Structures Of [Pt(Pph3)(Aupph3)6(Aucl)3].2c4h10o

In the reaction of the 16-electron cluster [Pt(AuPPh3)8](NO3)2 with X- (X = I, SCN, Cl) [Pt(PPh3)(AuPPh3)6(AuX)3] is formed in about 40% yield. The crystal and molecular structures of [Pt(PPh3)(AuPPh3)6(AuCl)3].2C4H10O have been investigated by X-ray analysis (monoclinic, space group P2(1)/n, a = 15.938 (4) angstrom, b = 52.764 (14) angstrom, c = 16.747 (4) angstrom, beta = 105.06 (3)-degrees, V = 13 600 angstrom 3, Z = 4, Cu K-alpha radiation). The residuals are R = 0.060 and R(w) = 0.068 for 8243 observed reflections and 466 variables. The symmetry of the metal cluster is C3-upsilon. In the metal cluster the central Pt atom is surrounded by six AuPPh3 groups, three AuCl groups, and one phosphine. The reaction of the 18-electron systems [Pt(CO)(AuPPh3)8](NO3)2 and [Pt(H)(PPh3)(AuPPh3)7](NO3)2 with NBu4+ halides leads to the substitution of one Au-bonded PPh3 and the formation of respectively [Pt(CO)(AuPPh3)7(AuX)]+ and [Pt(H)(PPh3)(AuPPh3)6(AuX)]+ (X = Cl, Br, I). The products are characterized by elemental analysis and P-31, Pt-195, and C-13 NMR spectroscopy and are discussed in terms of the electronegativity of the ligand X. The reactions of [Pt(H)(AuPPh3)8]+ and [Pt(CO)(Ag)(AuPPh3)8]3+ with Cl-, Br-, or I- lead to a decomposition of the clusters.