Spectra of the f-d transitions of solutions of uranium(III) halides in organic solvents

The absorption spectra of the f-d transitions of uranium(III) halides in tetrahydrofuran (THF), hexamethylphosphoric triamide (HMPA), acetonitrile, and water have been studied, and some energy characteristics of the uranium(III) ion in these solvents have been obtained on their basis. It has been shown that the crystal-field splitting parameter for uranium(III) in aqueous solutions is not dependent on the halide ion and that in HMFA and acetonitrile its value decreases along the series Cl- > Br- > I-, while in THF the reverse order for the influence of the halide ions is observed, i.e., the series Cl- < Br- < I- is found. It has been established that decreases in the dielectric constant of the solvent and its solvating ability result in enhancement of the interaction of the U3+ ion with the halide ion