Solvation of UCl62− Anionic Complex by MeBu3N+, BuMe2Im+, and BuMeIm+ Cations

The complexes [MeBu 3 N] 2 [UCl 6 ] and [BuMe 2 Im] 2 [UCl 6 ] were characterized in the solid state and in solution of [MeBu 3 N][Tf 2 N], [BuMe 2 Im][Tf 2 N], and [BuMeIm][Tf 2 N] room-temperature ionic liquids using single-crystal XRD, EXAFS, electrochemistry, UV−visible absorption spectroscopy, and NMR. In the solid state and in solution, the existence of hydrogen bonding between the UCl 6 2− complex and the ionic liquid cations was revealed by these techniques. The MeBu 3 N + cation interacts with UCl 6 2− via the protons on the α-carbon atoms of nitrogen. The protons of the imidazolium ring account for the interaction between the BuMe 2 Im + cation and the UCl 6 2− anion. For the BuMeIm + cation the major interaction was confirmed between the most acidic proton on C(2) and the chlorides of UCl 6 2− . The experimental results also show that the intensity of the interaction between the UCl 6 2− anion and the cation varies with the ionic liquid cation in the following order: MeBu 3 N + ≈ BuMe 2 Im + ≪ BuMeIm + .