SYNTHESIS AND CHARACTERIZATION OF 2,2'-BIIMIDAZOLE COMPLEXES OF OXOCATIONS OF MOLYBDENUM (VI, V) AND URANIUM(VI)

2,2'-Biimidazole complexes of MoO2(+2), MoO2+ and UO2(+2) have been prepared and characterized by elemental analysis, conductance; and H-1 NMR, IR and electronic spectra. Two types of complexes have been identified. Those obtained from slightly acidic solutions have the formulae MoO2(H2bim)Cl2.2H2O 1, UO2(H2bim)(Ac)2 2 and UO2(H2bim)Cl2.2H2O 3; whereas those from alkaline solutions have the formulae Mo2O4(Hbim)2.2H2O 4, and MO2(Hbim)2 (M = Mo(VI) 5, U(VI) 6). The infrared spectra of these complexes show characteristic biimidazole frequencies in the 3200-2500, 1550-1000 and 750 cm-1 regions as well as metal oxygen double bonds in the 900 cm-1 region. The stoichiometries of the acetate complex has been confirmed from H-1 NMR signal ratios of biimidazole to acetate protons at 7.3 and 2.3 ppm, respectively. The electronic spectrum of molybdenum(V) complex showed d-d transition band at congruent-to 13,500 cm-1 in accord with that reported for copper (d9) imidazole complexes; as well as peaks due to charge transfer bands at 30,000-26,000 cm-1. Peaks assignable to BIM --> U(VI) were located at congruent-to 26,600 cm-1. The most probable structures of these complexes have been suggested.