Electrochemical and spectroscopic investigations of oxime complexes of bis(bipyridyl)ruthenium(II)

A series of cis-[Ru(bpy)(2)(oxime)](2+) complexes (where bpy = 2,2'-bipyrid ine and oxime = cyclohexanedione dioxime (cyclodioxH(2)), diphenylglyoxime (dpgH(2)), difurilglyoxime (dfgH(2)), and 2-acetylpyridine oxime (acetoxH)) have been synthesized and characterized. H-1 and C-13 NMR spectra indicate that the complexes are cis-configured. The vicinal dioxime complexes displ ay solvent and pH-dependent electronic spectra as well as proton-coupled el ectron transfer, as determined by cyclic and differential pulse voltammetri es. pK(a) determinations on the ruthenium complexes were conducted and corr elated with electronic and NMR spectroscopic and electrochemical data. The energy of the visible region MLCT band correlates with the redox potential of the Ru(III/II) center. (C) 2001 Elsevier Science B.V. All rights reserve d.