Theoretical investigation of the anion binding affinities of the uranyl salophene complexes

The uranyl salophene complex and its co-complexes with several anions (H2PO4-, HSO4-, NO2-, OH-, Cl-, F-) in the gas phase are investigated theoretically. Equilibrium geometries of relevant species and complexation-induced structural changes are discussed. The C-13 NMR chemical shifts calculated at the gas-phase optimized geometry agree very well with experimental liquid-phase results. The optimized geometry agrees also very well with available crystallographic data. This indicates that the gas-phase structures derived from theoretical calculations can be considered representative also for the condensed phase. For all anions, except H2PO4-, the calculated gas-phase binding energies correlate well with experimental Gibbs free energies of complexation. The possible role of the solvent in the case of H2PO4- complexation is discussed.