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).
Sucena et al. (Sat,) studied this question.