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

Abstract

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.