Synthesis, structure, and redox properties of a new aqua ruthenium complex containing the tridentate [9]aneS3 and the didentate 1,10-phenanthroline ligands

The synthesis of a new Ru-H2O complex [Ru(phen)(H2O)([9]aneS(3))](ClO4)(2), 2, (phen = 1,10-phenanthroline, [9]aneS(3) = 1,4,7-trithiacyclononane) is described. The complex is characterized by UV/Vis and I-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-p,E-a = 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 M(-1)s(-1). ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).