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

Abstract The four complexes [MCl(C 5 Me 5 )(N ∧ S)](PF 6 ), M=Rh, Ir; N ∧ S=1-methyl-2-(methylthiomethyl)-1 H -benzimidazole (mmb) and 1-methyl-2-( tert -butylthiomethyl)-1 H -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 A) and shorter M–N bonds (ca. 2.09 A) in five-membered chelate rings are common to all four species. Cyclic voltammetry reveals irreversible two-electron reduction to M I complexes and partially reversible oxidation to Ir IV species for [IrCl(C 5 Me 5 )(mtb)] + . The results are discussed in comparison with those obtained for α-diimine (N ∧ N) complexes of the [MCl(C 5 Me 5 )] + fragments.