Structure, spectra and electrochemistry of ruthenium-carbonyl complexes of naphthylazoimidazole

[Ru(H)(CO)(PPh3)2(α/β-NaiR)](ClO4) (3, 4) are synthesized by the reaction of [Ru(H)(Cl)(CO)(PPh3)3] with 1-alkyl-2-(naphthyl-α/β-azo)imidazole (α-NaiR (3); β-NaiR (4)). One of the complexes [Ru(H)(CO)(PPh3)2(α-NaiMe)](ClO4) (3a) has been structurally established by X-ray diffraction study. Upon addition of Cl2 saturated in MeCN to 3 or 4 gives [Ru(Cl)(CO)(α/β-NaiR)(PPh3)2](ClO4) (for α-NaiR (5); β-NaiR (6)), without affecting metal oxidation state, which were characterized by spectroscopic measurements. The redox property of the complexes is examined by cyclic voltammetry.