Département de chimie moléculaire

Mixed uranyl aqua chloro complexes of the type [UO2(H2O)xCly]2-y (y = 1, 2, 3, 4; x + y = 4, 5) have been optimized at the BLYP, BP86, and B3LYP levels of d. functional theory in vacuo and in a polarizable continuum modeling bulk water (PCM) and have been studied at the BLYP level with Car-Parrinello mol. dynamics (MD) simulations in the gas phase and in explicit aq. soln. Free binding energies were evaluated from static PCM data and from pointwise thermodn. integration involving constrained MD simulations in water. The computations reveal significant solvent effect on geometric and energetic parameters. Based on the comparison of PCM-optimized or MD-averaged uranyl-ligand bond distances with EXAFS-derived values, the transition between five- and four-coordination about uranyl is indicated to occur at a Cl content of y = 2 or 3. [on SciFinder(R)]