Synthesis, Structure, and Redox Properties of a New Aqua Ruthenium Complex Containing the Tridentate [9]aneS<INF>3</INF> and the Didentate 1,10-Phenanthroline Ligands

The synthesis of a new Ru−H<INF>2</INF>O complex [Ru(phen)(H<INF>2</INF>O)([9]aneS<INF>3</INF>)](ClO<INF>4</INF>)<INF>2</INF>, 2, (phen = 1,10-phenanthroline, [9]aneS<INF>3</INF> = 1,4,7-trithiacyclononane) is described. The complex is characterized by UV/Vis and 1-D and 2-D NMR spectroscopy in solution. The complex has been further characterized in the solid-state by X-ray diffraction analysis which displays a distorted octahedral coordination geometry around the Ru metal center. The cyclic voltammetric experiments of the complex show a pH-dependent chemically irreversible wave at E<INF>p,</INF><INF>a</INF> = 0.82 V, at pH = 7.0, indicating the low stability of the higher oxidation states. Nevertheless, before the complex decomposes, it is capable of electrocatalytically oxidizing benzyl alcohol (BzOH) to benzaldehyde with a second-order rate constant of 19.8 <SC>M</SC>⁻¹s⁻¹. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)