X-ray Absorption Spectroscopy of Tricarbonatodioxouranate(V), [UO(2)(CO(3))(3)](5)(-), in Aqueous Solution

T. I. Docrat; J. F. W. Mosselmans; J. M. Charnock; M. W. Whiteley; D. Collison; F. R. Livens; C. Jones; M. J. Edmiston

doi:10.1021/ic9814423

X-ray Absorption Spectroscopy of Tricarbonatodioxouranate(V), [UO(2)(CO(3))(3)](5)(-), in Aqueous Solution

Inorg Chem. 1999 Apr 19;38(8):1879-1882. doi: 10.1021/ic9814423.

Authors

T. I. Docrat¹, J. F. W. Mosselmans, J. M. Charnock, M. W. Whiteley, D. Collison, F. R. Livens, C. Jones, M. J. Edmiston

Affiliation

¹ Research & Technology, BNFL Springfields, Preston PR4 0XJ, England, CLRC Daresbury Laboratory, Warrington WA4 4AD, England, Department of Chemistry, The University of Manchester, Manchester M13 9PL, England, and Research & Technology, BNFL Sellafield, Seascale, Cumbria CA20 1PG, England.

PMID: 11670960
DOI: 10.1021/ic9814423

Abstract

Actinyl ions (AnO(2)(+) and AnO(2)(2+)) are strongly complexed by CO(3)(2)(-) in aqueous solution, and tricarbonato complexes of UO(2)(2+) and NpO(2)(+), in particular, have been widely studied. Cyclic voltammetry shows that, whereas the Np(V)/Np(VI) couple is reversible in aqueous CO(3)(2)(-) solution, the analogous U couple is irreversible, suggesting significant conformational change on one-electron reduction of [UO(2)(CO(3))(3)](4)(-). EXAFS spectroscopy has been used to define the coordination geometry of the reduced species and shows that both axial and equatorial U-O distances increase on reduction, from 1.80 to 1.90 Å and from 2.43 to 2.50 Å, respectively. The basic geometry of the U complex is apparently unchanged by reduction so any conformational change which does occur must be subtle.