Structures and properties of complexes [MCl(C5Me5)(N∧S)](PF6), M=Rh, Ir, with N∧S=1-methyl-2-(alkylthiomethyl)-1H-benzimidazole ligands

The four complexes [MCl(C5Me5)(N∧S)](PF6), M=Rh, Ir; N∧S=1-methyl-2-(methylthiomethyl)-1H-benzimidazole (mmb) and 1-methyl-2-(tert-butylthiomethyl)-1H-benzimidazole (mtb) were synthesized and characterized by spectroscopy, electrochemistry and X-ray crystallography (as methanol solvates). The essential coordination features, viz., longer M–S (ca. 2.38 Å) and shorter M–N bonds (ca. 2.09 Å) in five-membered chelate rings are common to all four species. Cyclic voltammetry reveals irreversible two-electron reduction to MI complexes and partially reversible oxidation to IrIV species for [IrCl(C5Me5)(mtb)]+. The results are discussed in comparison with those obtained for α-diimine (N∧N) complexes of the [MCl(C5Me5)]+ fragments.