[Ru(bpy)₃]²⁺ Analogues Containing an N-Heterocyclic Carbene Ligand

A synthetic procedure is described that provides access to [Ru(bpy)3]2+ analogues in which one bpy ligand is replaced by a C,N-bidentate-coordinating carbene-benzimidazole ligand (bpy = 2,2′-bipyridine). These new complexes were prepared by first installing the chelating carbene ligand onto a Ru(cymene) platform and subsequent ligand substitution using bpy or terpy (terpy = 2:2′,6′:2′′-terpyridine). The carbene ligand significantly affects the optical properties of the complex and lowers the ruthenium(II) oxidation potential substantially. Such modifications may be advantageous for the development of new classes of photosensitizer materials.