Crystal structure and normal co-ordinate analysis of diaqua(oxydiacetato)sulphatothorium(IV) monohydrate

Abstract

The structure of the title compound has been determined by single-crystal X-ray techniques, using diffractomer data. The compound crystallizes in the monoclinic space group C2 with a= 10.67(1), b= 8.35(1), c= 6.73(1)Å, Z= 2, and β= 110.96(2)°. Refinement of the structure led to a final R value of 0.048 using 1 931 observed data. The thorium atom, which lies on a crystallographic two-fold axis, is nine-co-ordinate in the monocapped square antiprismatic geometry. Both the oxydiacetate and sulphate ligands are shared between different thorium atoms allowing the formation of a rather compact polymeric network. The length of the Th–O bond to the apical ether oxygen, 2.63(1)Å, is significantly greater than the average, 2.42 Å, for the other bonds to carboxylate or water oxygen. For this complex the fundamentals have been assigned on the basis of a normal co-ordinate analysis and potential-energy distribution obtained by use of a 48-parameter Urey–Bradley force field. The stretching force constant of the Th–O(ether) bond is greater than that of the corresponding U–O(ether) bond in the analogous uranium-containing compound (1.37 × 10²versus 1.10 × 10² N m^–1 respectively).