Computational Studies of Uranium Hexafluoride Interacting with Functionalized Organics. I. Screening Intermolecular Potentials between UF6and Small Organic Functional Groups


We report the intermolecular binding energies (IBEs) between UF6 and over 50 different functionalized small organic molecules as predicted by electronic structure calculations. Optimized geometries of UF6-molecule dimers were found at the MP2/aug-cc-pwCVDZ (non-U), cc-pVDZ-PP (U) level. IBEs were calculated using MP2 and dispersion-corrected DFT theory. We characterize the various functional groups based on the inclusion of specific heteroatoms. Those functional groups containing "nitrogen only"heteroatoms result in larger IBEs than groups containing both nitrogen and oxygen or oxygen alone. Halogen-containing and regular hydrocarbon molecules show the lowest IBEs with UF6. Nonorganic phosphoryl species are also shown to display large IBEs with UF6. These interactions are characterized in part by how much the impinging functionalized molecule distorts the UF6 from its optimal octahedral geometry. Of all the investigated groups, the amine group displayed the largest IBE values (IBE ∼>12-14 kcal/mol for methyl amine), while hydrocarbons and perfluorocarbons both showed the weakest interactions (IBE ∼0.5-1.5 and 0.1-0.8 kcal/mol for methane and perfluoromethane, respectively). The study examines how the strength of the IBE is contingent on a combination of conformational deformation, stabilizing nonbonding interactions, and sterics.

Publication Title

Journal of Physical Chemistry A