A simple and convenient synthesis of a new class of air-stable mononuclear cyclometallated ruthenium(II) carbonyl 2-(arylazo)phenolate complexes bearing triphenylarsine [Ru(ap-R)(AsPh3)(2)(CO)] has been described. The 2-(arylazo)phenolate ligands behave as dianionic tridentate ligands and are coordinated to ruthenium through C, N and 0 by dissociation of the phenolic proton and the phenyl proton at the ortho position of the phenyl jing forming two five-membered chelate rings. These complexes have been characterized by elemental analysis, and FT-IR, H-1 NMR and UV-vis spectroscopies. In dichloromethane solution all the metal complexes exhibit characteristic metal-to-ligand charge transfer (MLCT) absorption and emission bands in the visible region. One of the complexes [Ru(ap-Cl)(AsPh3)(2)(CO)] was successfully characterized by X-ray crystallography. Cyclic voltammetric data of all the complexes show Ru-III/Ru-II oxidation and Ru-II/Ru-I reduction within the range of +0.75 to +0.86 V and -0.50 to -0.57 V respect to Ag/AgCl, respectively. The potentials are observed with respect to the electronic nature of substituents (R) in the 2-(arylazo)phenolate ligands. Further, a complex (2) was tested as a new catalyst in the oxidation of primary and secondary alcohols in the presence of NMO as a more viable oxidant with moderate to high conversion. The formation of high valent Ru-IV = 0 species as a catalytic intermediate is proposed for the catalytic process. (c) 2006 Elsevier B.V. All rights reserved.