Synthesis of gold-(<scp>I</scp>) and -(<scp>III</scp>) complexes with carbonyl-stabilized phosphorus ylides. Crystal structure of [{Au(PPh₃)}₂{µ-C(PPh₃)CO₂Et}]ClO₄

Phosphonium salts (Ph3PCH2CO2R)ClO4(R = Me or Et) react with [Au(acac)L′](acac = acetylacetonate, L′= PPh3 or AsPh3), displacing acac as acetylacetone and yielding cationic complexes of the corresponding phosphorus ylides L (L = Ph3PCHCO2Me, L′= PPh3; L = Ph3PCHCO2Et, L′= PPh3 or AsPh3). These complexes react with [Au(acac) L′] to give dinuclear species [(AuL′)2{µ-C(PPh3)CO2R}]ClO4(R = Et, L′= PPh3 or AsPh3; R = Me, L′= PPh3). The displacement of the ligand tetrahydrothiophene (tht) in [AuCl(tht)] by the ylides Ph3PCHCO2R (R = Me or Et) forms complexes [AuCl(L)], which react (i) with chlorine to give [AuCl3L] or (ii) with L in the presence of NaClO4 to give complexes [AuL2]ClO4, which also react with chlorine to form gold(III) complexes [AuCl2L2]ClO4. The crystal structure of the complex [{Au(PPh3)}2{µ-C(PPh3)CO2Et}]ClO4 has been determined: space group P21/c, with a= 18.666(6), b= 17.490(5), c= 16.413(5)Å, β 95.10(3)°, and R= 0.055. A short Au ⋯ Au contact of 2.892(2)Å is observed.