SYNTHESIS, THERMOGRAVIMETRY AND X-RAY-ANALYSIS OF URANYL BENZOATE AND BUTYRATE DERIVATIVES

The structures of the complexes Na[UO2(C6H5COO)(3)].C6H5COOH . H2O (1) and Ca[UO2(C2H5COO)(3)](2) . 6H(2)O (2) have been determined by X-ray diffraction techniques. Complex 1 crystallizes in the triclinic system, space group P (1) over bar with a=9.443(2), b = 12.141 (3), c = 14.205(3) Angstrom, alpha = 109.81(2), beta = 107.47(2), gamma = 93.70(2)degrees and d(calc) = 1.84 g cm(-3) with Z = 2, R = 0.023, R(w) = 0.030 for 6819 observed reflections (I greater than or equal to 3 sigma I). Complex 2 crystallizes in the monoclinic system space group P2(1)/c with /c a = 15.564(2), b = 12.697 (3), c = 18.238(3) Angstrom, beta = 94.73(3)degrees and d(calc) = 2.08 g cm(-3) with Z = 4, R = 0.047, R(w) = 0.062 for 5813 observed reflections (I greater than or equal to 3 sigma I). 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.