Jump to main content
Jump to site search

Issue 18, 2009
Previous Article Next Article

Uranyl monocarboxylates of aromatic acids: A density functional model study of uranyl humate complexation

Author affiliations

Abstract

Using a scalar relativistic all-electron density functional method, we studied uranium(VI) complexation with benzoic acid and its derivatives in aqueous solution as models of uranyl humates. We explored monodentate, bidentate, and chelate coordination of various isomers of methyl and hydroxyl substituted benzoic acid ligands. Monodentate complexes were determined to be energetically preferred as long as entropy effects were neglected. However, bidentate structures were favored at the Gibbs free energy level. Coordination of aromatic carboxylic acids tends to be weaker than that of aliphatic ones, while structural characteristics were determined to be quite similar. Optimized geometries yield uranyl bonds and U–C distances in agreement with EXAFS results for monocarboxylate of benzoate and p-hydroxy benzoate. Average uranyl–oxygen distances to equatorial ligands, U–Oeq, are shorter than in experiment, which is tentatively rationalized by variations in the coordination numbers. As for aliphatic monocarboxylate complexes studied earlier, U–Oeq values of benzoic acid derivatives do not discriminate mono- and bidentate coordinated species. Structures and energies determined support the interpretation of uranyl humate complexes as bidentate carboxylate species with fivefold coordination of uranyl.

Graphical abstract: Uranyl monocarboxylates of aromatic acids: A density functional model study of uranyl humate complexation

Back to tab navigation

Supplementary files

Publication details

The article was received on 22 Sep 2008, accepted on 27 Feb 2009 and first published on 23 Mar 2009


Article type: Paper
DOI: 10.1039/B816513K
Dalton Trans., 2009, 3590-3598

  •   Request permissions

    Uranyl monocarboxylates of aromatic acids: A density functional model study of uranyl humate complexation

    R. S. Ray, S. Krüger and N. Rösch, Dalton Trans., 2009, 3590
    DOI: 10.1039/B816513K

Search articles by author

Spotlight

Advertisements