Binuclear Gold(I) Complexes with a Potentially Tetradentate S,N,N,S Ligand

The potentially tetradentate SNNS ligand N,N′-(ethane-1,2-diyl)bis(N″-(diethylcarbamothioyl)benzimidamide, H2L, was synthesized by the reaction of ethylenediamine with two equivalents of the corresponding benzimide chloride. H2L readily reacts with [AuCl(tht)] (tht = tetrahydrothiophene) under formation of the binuclear gold(I) complex [(AuCl)2(H2L-κS,S′)] (1) using its thiocarbonyl units as donors, while the nitrogen atoms remain uncoordinated, and no deprotonation was observed. The gold atoms establish almost linear Cl–Au–S bonds. The terminal Cl− ligands can be replaced with thiocyanate units, giving [Au(SCN-κS)}2((H2L-κS,S′)] (2). The use of [Au(PPh3)Cl] as a starting material gives the cation [{Au(PPh3)}2(H2L-κS,S′)]2+ (3), which can be isolated as its PF6− salt. The products are air-stable compounds, which have been isolated in crystalline form and studied by X-ray diffraction and spectroscopic methods (IR, NMR, and MS).