Density functional studies on the complexation and spectroscopy of uranyl ligated with acetonitrile and acetone derivatives.

The coordination of nitrile (acetonitrile, propionitrile, and benzonitrile) and carbonyl (formaldehyde, acetaldehyde, and acetone) ligands to the uranyl dication (UO(2)(2+)) has been examined using density functional theory (DFT) utilizing relativistic effective core potentials (RECPs). Complexes containing up to six ligands have been modeled in the gas phase for all ligands except formaldehyde, for which no minimum could be found. A comparison of relative binding energies indicates that 5-coordinate complexes are predominant, while 6-coordinate complexes involving propionitrile and acetone ligands might be possible. Additionally, the relative binding energy and the weakening of the uranyl bond is related to the size of the ligand, and in general, nitriles bind more strongly to uranyl than carbonyls.