Synthesis and characterization of ruthenium complexes with 1-aryl-2-mercaptoimidazole ligands

Reactions of the vinyl ruthenium starting material Ru(CHdouble bond; length as m-dashCHPh)Cl(CO)(PPh3)2 (1) with 1-aryl-2-mercaptoimidazole (HLa, aryl = 4-chloro-phenyl; HLb, aryl = 4-methyl-phenyl; HLc, aryl = 4-nitro-phenyl) in the presence of sodium methoxide in dichloromethane and methanol afforded [Ru(CHdouble bond; length as m-dashCHPh)(κ2-L)(CO)(PPh3)2] (2a–2c). Treatment of 1 with HL in THF gave [RuCl(κ2-L)(CO)(PPh3)2] (3a–3c) contaminant with formation of styrene as byproduct. Interactions of 1 with HLa in dichloromethane led to isolation of a novel dinuclear ruthenium complex [(CO)(PPh3)(CHNCH2Ph)Ru(μ-Cl)2(μ-S)RuCl(CO)(PPh3)] (4a) via N–H bond addition to styryl ligand. Complexes 2a–2c, 3a–3c, and 4a were characterized by microanalyses, IR, and (1H, 13C, 31P) NMR spectroscopies. The molecular structures of 3a–3c and 4a have been determined by single-crystal X-ray diffraction.