Density functional theory (B3LYP) and correlated molecular orbital theory (CCSD(T)) calculations were used to predict the properties of novel actinide-fluoride complexes formed by the addition of a fluorine to AnFn compounds, with actinides in their normal maximum oxidation state (n), leading to the formation of an ion-pair complex AnFn-1+F2- for the earlier actinides (Ac, Th, and Pa). UF7 prefers a structure with a weakly associated fluorine, forming a UF6F• complex, likely due to steric hindrance. Ionization of AnFn-1+F2- forms a weakly bound AnFn-1+F2 complex. Ionization of AnFn leads to the formation of AnFn-22+F2- complex so that the electron is not removed from the actinide and maintains the An oxidation state. The ionization energies, An-F bond dissociation energies, and enthalpy for the loss of F20/- of these complexes are in agreement with the available experimental data. The fluoride affinities of AnFn and the electron affinities of AnFn+1 were calculated. The fluoride affinities are large and comparable to those of AsF5 and SbF5 so they are strong Lewis acids. The electron affinities are sizable, indicating that AnFn+1- will be powerful oxidizing agents and should be considered in models of molten salt reactors when fluoride is present.
Autry et al. (Fri,) studied this question.