Synthesis and Characterization of Plutonium(IV), Uranium(VI), Morium(IV) and Neodymium(III) Nitrate Complexes with Bidentate Organophosphorus Ligands

Abstract

Solid adducts of actinide and lanthanide nitrates of the type [M(NO₃(X)_y], where M = Pu⁴⁺, UO₂ ²⁺, Th⁴⁺ and Nd³⁺; n = 2 for UO₂ ²⁺, 3 for Nd³⁺ and 4 for Th⁴⁺ and Pu⁴⁺; y = 1 for UO₂ ²⁺, 1.5 for Th⁴⁺ and 2 for Pu⁴⁺ and Nd³⁺; and X = dihexyl N, N-diethylcarbamoylmethylphosphonate (DHDECMP) or octyl (phenyl) (N, N-diisobutylcarbamoylmethyl) phosphine oxide (CMPO), were isolated and purified by a solvent extraction route from benzene. These compounds have been characterized by elemental analyses, and their melting points. The IR and visible absorption spectra of these complexes indicate that they are O-bonded. The extract ant in all the complexes acts as a bidentate ligand whereas the nitrate ion acts as a bidentate group in the Th⁴⁺, UO₂ ²⁺ and Nd³⁺ complexes but in the case of the Pu⁴⁺ complexes one of the nitrate ions probably is acting as monodentate ligand. A slight upfield shift of phenyl, methyl and methylene protons around phosphoryl and carbamoyl oxygens in the ¹H NMR spectra of the uranium, thorium and neodymium complexes, as compared to the pure ligand, further reaffirms the bidentate nature of CMPO. Thermal studies of the uranyl and thorium complexes are reported.