SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF GOLD-(I), GOLD-(III) AND SILVER(I) COMPLEXES OF THE YLIDE LIGAND PH3P=CHC(O)NME2 - CRYSTAL-STRUCTURE OF [(AUPPH3)2(MU-C(PPH3)C(O)NME2)]CLO4

The reaction between [AuCl(tht)] (tht = tetrahydrothiophene) and the ylide Ph3P = CHC(O)NMe2 gives [AuCl{CH(PPh3)C(O)NMe2}] 1, which reacts with chlorine to give [AuCl3{CH(PPh3)C(O)-NMe2}] 2 and with the same ylide and NaClO4 to form [Au{CH(PPh3)C(O)NMe2}2]ClO4 3. The analogous silver complex [Ag{CH(PPh3)C(O)NMe2}2]ClO4 4 is obtained by the reaction of AgClO4 with the ylide in molar ratio 1:2. The phosphonium salt [Ph3PCH2C(O)NMe2]ClO4 reacts with [Au(acac)(PPh3)] (acac = acetylacetonate) to give [Au{CH(PPh3)C(O)NMe2}(PPh3)]ClO4 5 or [(AuPPh3)2{mu-C(PPh3)C(O)NMe2}]ClO4 6 depending on the reaction conditions. The structure of 6 was confirmed by an X-ray diffraction study at -95-degrees-C [space group P1BAR, a = 11.572(3), b = 11.836(3), c = 21.627(7) angstrom, alpha = 78.29(2), beta = 87.19(2), gamma = 75.65(2)-degrees, R = 0.076]; the Au...Au bond length is 2.938(1) angstrom.