Uranium (VI) and Thorium (IV) Complexes with bis-benzimidazoles

Abstract: Uranyl nitrate and thorium nitrate react with different bis-benzimidazoles in suitable solvents to yield products of the type [UO2(L1)2NO3]NO3.H2O, [Th(L1)2(NO3)4]4H2O, [UO2(L2)2NO3]NO3. H2O, [Th(L2)2(NO3)4]4H2O, [UO2(L3)2NO3]NO3.H2O and [Th(L3)2(NO3)4]4H2O where L1=1,3-bis(benzimidazol-2-yl)benzene, L2=1,3-bis(1- methylbenzimidazol-2-yl)benzene and L3=2,6-bis(1-methylbenzimidazol-2-yl) pyridine. All these complexes are insoluble in common organic solvents and are soluble in DMF and DMSO. All the complexes were characterized by elemental analysis, infrared spectra, 1H NMR spectra, TGA and conductivity studies in addition to magnetic susceptibility measurements. All the ligands act as bidentate with tertiary nitrogen as donor site. A coordination number of eight for dioxouranium ion, UO22+ and twelve for Th(IV) complexes were proposed.

Keywords: Bis-benzimidazoles, Elemental analysis, Thermal gravimetric studies, FT-IR.