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

Abstract

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 Ru^II 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.