Electrochemical studies on bis(β-diketonato)(dimethyl sulfoxide)dioxouranium(VI) in dimethyl sulfoxide

Abstract

Electrochemical studies on U VIO 2(β-diketonato) 2dmso [β-diketonate=dibenzoylmethanate (dbm), trifluoroacetylacetonate (tfacac), hexafluoroacetylacetonate (hfacac), dmso=dimethyl sulfoxide] complexes in DMSO containing tetrabutylammonium perchlorate (supporting electrolyte) have been carried out using cyclic voltammetry (CV) and normal pulse voltammetry (NPV). As a result, it was found that the U VIO 2(tfacac or hfacac) 2dmso complexes are reduced to U(V) species reversibly and that the U VIO 2(dbm) 2dmso complex is quasi-reversibly reduced to U(V) species. The formal redox potentials ( E°/V, vs. Ag/AgCl and vs. ferrocene/ferricinium in parentheses) for the U(VI)/U(V) couple are −0.44 (−0.97) for U VIO 2(hfacac) 2dmso, −0.52 (−1.05) for U VIO 2(tfacac) 2dmso, and −0.83 (−1.36) for U VIO 2(dbm) 2dmso. Furthermore, the E° values were found to correlate with the p K a values of β-diketones, i.e. the E° values decrease with an increase in the p K a value.