Electrochemical properties of dinuclear [Ru([n]aneS4)] complexes of 2,3-bis(2-pyridyl)pyrazine

The syntheses of three new dinuclear [Ru([n]aneS4)] complexes, where n = 12, 14, 16, bridged by the ligand 2,3-bis(2-pyridyl)pyrazine, (dpp) are reported. The absorption spectra of the complexes show changes in the energy of the MLCT bands within the series, indicating that the thiacrown ligands stabilise the RuII oxidation state to different degrees. Electrochemical studies are also consistent with these observations, and reveal that the π-acceptor properties of [n]aneS4 ligands lead to metal based oxidation couples occurring at potentials that are more anodic than those observed in the analogous dinuclear [Ru(bpy)2]2+ complex. Despite the back-bonding properties of the thiacrown ligands leading to a reduction in ligand-bridge mediated metal–metal coupling, electrochemical interactions between the metals are still considerable.