M(CO)4[2-(2′-pyridyl)benzimidazole] complexes; M = Mo or W

Heating a mixture of M(CO)(6), M = Mo or W, and 2-(2'-pyridyl)benzimidazole, PBI, in THF under reduced pressure gave the tetracarbonyl monosubstituted derivative M(CO)(4)(PBI). Spectroscopic studies showed that these complexes have octahedral structures with two axial and two equatorial carbonyl groups, the PBI ligand occupying two equatorial positions. Electrochemical studies showed reversible and quasi-reversible redox couples due to ligand-based reduction and metal-based oxidation, respectively.