Structural diversity in gold(I) complexes of 4-sulfanylbenzoic acid

Treatment of the gold(I) halide species AuLCl (where L = PMe3, PEt3, PPh3, PPh2(C5H4N-2) or SPPh3) and (AuCl)2(P–P) (where P–P = 1,4-bis(diphenylphosphino)butane or 1,1′-bis(diphenylphosphino)ferrocene) with 4-sulfanylbenzoic acid (1 or 2 equivalents as required) in the presence of sodium methoxide provided the corresponding phosphine gold(I) thiolate complexes AuL(4-SC6H4CO2H) and [Au(4-SC6H4CO2H)]2(P–P), respectively. Addition of two equivalents of the acid (in the presence of NaOMe) to [N(PPh3)2][AuCl2] yielded the dithiolate species [N(PPh3)2][Au(4-SC6H4CO2H)2]. A polyaurated product [(Ph3PAu)2(4-SC6H4CO2H)]BF4 was obtained on treating the acid with the oxonium complex [(Ph3PAu)3O]BF4. The species AuL(4-SC6H4CO2H) (L = PEt3, PPh3 or PPh2(C5H4N-2)) have been investigated crystallographically and reveal diverse structures incorporating aurophilic contacts, Au ⋯ S interactions and hydrogen bonding.