Complexation of Uranium(VI) with Aromatic Acids in Aqueous Solution: A Combined Computational and Experimental Study

The complexes of uranium(VI) with salicylhydroxamate, benzohydroxamate, and benzoate have been investigated in a combined computational and experimental study using density functional theory methods and extended X-ray absorption fine structure spectroscopy, respectively. The calculated molecular structures, relative stabilities, as well as excitation spectra from time-dependent density functional theory calculations are in good agreement with experimental data. Furthermore, these calculations allow the identification of the coordinating atoms in the uranium(VI)-salicylhydroxamate complex, i.e. salicylhydroxamate binds to the uranyl ion via the hydroxamic acid oxygen atoms and not via the phenolic oxygen and the nitrogen atom. Carefully addressing solvation effects has been found to be necessary to bring in line computational and experimental structures, as well as excitation spectra.