title: X-ray Absorption Spectroscopy of Tricarbonatodioxouranate(V), [UO(2)(CO(3))(3)](5)(-), in Aqueous Solution.
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.
authors.affiliation: 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.
authors.forename: T. I.
authors.initials: TI
authors.lastname: Docrat
authors.forename: J. F. W.
authors.initials: JF
authors.lastname: Mosselmans
authors.forename: J. M.
authors.initials: JM
authors.lastname: Charnock
authors.forename: M. W.
authors.initials: MW
authors.lastname: Whiteley
authors.forename: D.
authors.initials: D
authors.lastname: Collison
authors.forename: F. R.
authors.initials: FR
authors.lastname: Livens
authors.forename: C.
authors.initials: C
authors.lastname: Jones
authors.forename: M. J.
authors.initials: MJ
authors.lastname: Edmiston