Synthesis and characterization of mixed-ligand ruthenium(III) complexes with oxalate and acetylacetonate ions

Two mononuclear mixed-ligand ruthenium(III) complexes with oxalate dianion (ox2−) and acetylacetonate ion (2,4-pentanedionate, acac−), K2[Ru(ox)2(acac)] (1) and K[Ru(ox)(acac)2] (2), were prepared as a candidate for a building block. In fact, reaction of complex 2 with manganese(II) sulfate gave a heterometallic tetranuclear complex, TBA[MnII{(μ-ox)RuIII(acac)2}3] (5) in the presence of tetrabutylammonium (TBA) bromide. The 1H NMR, UV–Vis, selected IR and FAB mass spectral data of these complexes are presented. Both mixed-ligand ruthenium(III) complexes gave a Nernstian one-electron reduction step in 0.1 mol dm−3 Na2SO4 aqueous solution on a mercury electrode at 25 °C. Comparison of observed reversible half-wave potentials with calculated values for a series of [Ru(ox)n(acac)3 − n]n− (n=0–3) complexes by using Lever’s ligand electrochemical parameters is presented.