Binuclear beta-diketonatoruthenium(III) complexes [[Ru(acac)(2)](2)(tae)], [[Ru(phpa)(2)](2)(tae)], and [(acac)(2)Ru(tae)Ru(phpa)(2)] and binuclear and mononuclear bipyridine complexes [[Ru(bpy)(2)](2)(tae)](PF(6))(2) and [Ru(bpy)(2)(Htae)]PF(6) (acac = 2,4-pentanedionate ion, phpa = 2,2,6,6-tetramethyl-3,5-heptanedionate ion, tae = 1,1,2,2-tetraacetylethanate dianion, and bpy = 2,2'-bipyridine) were synthesized. The new complexes have been characterized by (1)H NMR, MS, and electronic spectral data. Crystal and molecular structures of [[Ru(acac)(2)](2)(tae)] have been solved by single-crystal X-ray diffraction studies. Crystal data for the meso isomer of [[Ru(acac)(2)](2)(tae)] have been confirmed by the dihedral angle result that two acetylacetone units of the bridging tae ligand are almost perpendicular to one another. A detailed investigation on the electrochemistry of the binuclear complexes has been carried out. The electrochemical behavior details of the binuclear complexes have been compared with those of the mononuclear complexes obtained from the half-structures of the corresponding binuclear complexes. Studies on the effects of solvents on the mixed-valence states of Ru(II)-Ru(III) and Ru(III)-Ru(IV) complexes have been carried out by various voltammetric and electrospectroscopic techniques. A correlation between the comproportionation constant (K(c)) and the donor number of the solvent has been obtained. The K(c) values for the binuclear complexes have been found to be low because of the fact that two acetylacetone units of the bridging tae ligand are not in the same plane, as revealed by the crystal structure of [[Ru(acac)(2)](2)(tae)].

The reflux of mononuclear ruthenium precursor [RuII(acac)2(CH3CN)2] (acac = acetylacetonate) in 2-methyl-2-propanol formed the novel diamagnetic β-diketonato ruthenium tetranuclear complex [Ru(μ-acac)2(μ3-O)2Ru3(acac)6] (1), in which was contained the deltoid core, [Ru4(μ3-O)2]8+, consisting of four ruthenium and two oxygen atoms. The complex 1 has been characterized on the basis of elemental analysis, 1H NMR, structural and cyclic voltammetric analyses. The molecular structure of 1 showed that each ruthenium ion was bridged by two oxygen atoms and two ruthenium ions link to γ-carbon on acetylacetonate coordinated to another ruthenium. The cyclic voltammogram of 1 showed two reversible one-electron oxidation peaks and an one-electron reduction peak corresponding to the redox of [Ru4(μ3-O)2]8+ core.