Synthesis, thermogravimetry and X-ray analysis of uranyl benzoate and butyrate derivatives

Abstract

The structures of the complexes Na[UO 2(C 6H 5COO) 3].C 6H 5COOH · H 2O ( 1) and Ca[UO 2(C 2H 5COO) 3] 2 · 6H 2O ( 2) have been determined by X-ray diffraction techniques. Complex 1 crystallizes in the triclinic system, space group P 1 with a = 9.443(2), b = 12.141 (3), c = 14.205(3) Å, α = 109.81(2), β = 107.47(2), γ = 93.70(2)° and d calc = 1.84 g cm −3 with Z = 2, R = 0.023, R w = 0.030 for 6819 observed reflections ( I ⩾ 3 σI). Complex 2 crystallizes in the monoclinic system space group P2 1/ c with a = 15.564(2), b = 12.697 (3), c = 18.238(3) Å, β = 94.73(3)° and d calc = 2.08 g cm −3 with Z = 4, R = 0.047, R w = 0.062 for 5813 observed reflections ( I ⩾ 3 σI). Both compounds present the usual hexagonal bipyramidal coordination geometry around uranium ions, with three bidentate chelating benzoate or butyrate ligands occupying the equatorial plane in 1 and 2 respectively. Different sets of interactions between the sodium ions and the uranyl complex anions in 1 and calcium ions and the respective uranyl anions in 2 are present in the two structures. X-ray powder patterns and thermogravimetric analyses further characterize the two compounds.