A DFT study of uranyl hydroxyl complexes: structure and stability of trimers and tetramers.

A DFT study of U(VI) hydroxy complexes was performed with special attention paid to the [(UO)(OH)(HO)] and [(UO)(OH)(HO)] species. It was established that the ionicity of the U=O bond increased when moving from [(UO)(HO)], [(UO)(OH)(HO)], [(UO)(OH)(HO)], [(UO)(OH)(HO)] to [(UO)(OH)(HO)] species. In both [(UO)(OH)(HO)] and [(UO)(OH)(HO)] complexes, the U=O bond was observed to have a range of different lengths which depended on the composition of the first coordination sphere of UO. The cyclic structures of trimeric complexes were somewhat more stable than their linear structures, which was probably due to the steric effect.