PREPARATION, CHARACTERIZATION AND ELECTROCHEMICAL PROPERTIES OF MIXED-LIGAND RUTHENIUM(III) AND RUTHENIUM(II) COMPLEXES WITH 2 KINDS OF BETA-DIKETONES

The mixed-ligand ruthenium(III) complexes with the following compositions were synthesized and isolated chromatographically: [Ru(acac)2(tfpb)], [Ru(acac)(tfpb)2], [Ru(acac)2(hfac)] and [Ru(dpm)2(hfac)] (acac-, 2, 4-pentanedionate ion; tfpb-, 4,4,4-trifluoro-1-phenyl-1,3-butanedionate ion; hfac-, 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate ion; dpm-, 2,2,6,6-tetramethyl-3,5-heptanedionate ion). Attempts to isolate [Ru(acac)(hfac)2] failed; but a mixture of K[Ru(acac)(hfac)2] and K[Ru(hfac)3] was obtained. The structure of one of the three geometrical isomers of [Ru(acac)(tfpb)2] was determined by means of single-crystal X-ray structure analysis. The 1H NMR and UVVis spectral data of the isolated complexes are presented. Each of these complexes gave a Nernstian one-electron reduction step and a Nernstian or quasi-Nernstian one-electron oxidation step in 0.1 mol dm-3 (C2H5)4NClO4- acetonitrile solution at 25 °C. The linear dependence of their reversible half-wave potentials on the ligand composition is discussed in detail. © 1990.