SYNTHESIS, CHARACTERIZATION AND ELECTROCHEMICAL PROPERTIES OF BETA-DIKETONE COMPLEXES OF RUTHENIUM(III)

The reactions of ruthenium(III) chloride (1 mol) with acetylacetonylid ene-4-aminoantipyrine (HL1), monobenzoylacetylacetonylidene-4-aminoant ipyrine (HL2), dibenzoylmethanylidene-4-aminoantipyrine (HL3) and anti pyrine-4-azo-beta-ethylacetoacetate (HL4) (1 mol) produce complexes of the general formula RuHLCl3. The ligand antipyrine-4-azo-beta-acetyla cetone (HL5) (1 mol) reacts with RuCl3.3H2O to produce RuL5 Cl2(H2O).H 2O. The ligands HL1-HL3 react as neutral bidentates in the ketoenamine form, whereas HL4 reacts as a neutral bidentate in the hydrazo form. HL5 reacts as a monobasic tridentate in the azo form. The complexes we re characterized using a variety of analytical, spectral, magnetic and thermal measurements. The electrochemical redox properties of complex es I-V have been studied by cyclic voltammetry in acetonitrile. The ch loro-bridged dimer complexes I-IV showed two reversible diffusion-cont rolled oxidation peaks. The first was attributed to the oxidation of t he ruthenium(III) to the corresponding mixed-valence complex and the s econd to the ruthenium(IV) complex. The redox properties of complexes I-IV are dependent on the nature of ligand. The monomeric complex V ha s quite different properties.