Synthesis and characterization of dinuclear complexes of 3,3′,4,4′-tetraminobiphenyl with tetramminoruthenium and bis(bipyridine)ruthenium residues and their two- and four-electron oxidized products including a ZINDO study of orbital mixing as a function of ligand oxidation state†

Abstract

This paper reports the synthesis, characterisation and reactivity of new complexes of ruthenium, the symmetric dinuclear complex of ruthenium tetrammine [(Ru(NH₃)₄)₂(catH₄·catH₄)](PF₆)₄ and the asymmetric dinuclear complex of ruthenium bis(bipyridine) and ruthenium tetrammine [Ru(NH₃)₄(catH₄·catH₄)Ru(bpy)₂](PF₆)₄ where (catH₄·catH₄) represents the bridging ligand 3,3′,4,4′-tetraminobiphenyl. These complexes can be oxidized to the two-electron oxidized ligand mixed valence (qH₂·catH₄) species and the four-electron oxidized ligand (qH₂·qH₂) species. Further oxidation yields a range of Ru(III) species. These complexes were studied by proton NMR, UV–VIS spectra, cyclic voltammetry and ZINDO/1 and ZINDO/S calculations.