Dioxouranium(VI) and thorium(IV) complexes of 1-methyl-2,2'-bisimidazole

Abstract

The biheterocyclic nitrogen donor ligand 1-methyl2,2'- bisimidazole (MBIM) reacts with UO₂X₂ and ThX₄ to form mononuclear complexes of the types UO₂(MBIM)X₂ (X=Cl, I, NCS, NO₃, CH₃COO, 0.5 SO₄) and Th(MBIMj₂X₄ (X=NO₃, I). The complexes are characterised by elemental analyses, conductivity, thermogravimetry and IR, NMR as well as mass spectra. The IR spectra of uranyl complexes exhibit <b><i>n</i></b>(U= 0) in the regions 900-925 and 825-860 cm^{- 1} in addition to the vibrational bands of the ligand and those of the polyatomic anions. The ¹H NMR spectra of the ligand and the complexes are identical, with the - CH₃ group resonating at 3.5 ppm and the NH proton at 3.9 ppm region. The ring protons are observed as multiplets in the region of 7.0 to 8.0 ppm. The mass spectra of the ligand gives molecular ion peak at <i>m/z </i> 148 and other fragmentation products, which are appropriately assigned. However, for the complexes neither the molecular ion peak nor the metallated fragmentation patterns are observed. Thermogravimetry shows the loss of ligands in stages, finally forming the stable metal oxides as the end product.