The electronic structures of two uranium compounds supported by redox-active α-diimine ligands, (^MesDAB^Me)₂U(THF) (1) and Cp₂U(^MesDAB^Me) (2) (^MesDAB^Me = [ArNâ•�C(Me)C(Me)â•�NAr]; Ar = 2,4,6-trimethylphenyl (Mes)), have been investigated using both density functional theory and multiconfigurational self-consistent field methods. Results from these studies have established that both uranium centers are tetravalent, that the ligands are reduced by two electrons, and that the ground states of these molecules are triplets. Energetically low-lying singlet states are accessible, and some transitions to these states are visible in the electronic absorption spectrum.

Recent studies of organouranium chemistry have provided unusual pairs of similar polymetallic molecules containing (N)^3− and (O)^2− ligands, namely [(C₅Me₅)U(μ-I)₂]₃(μ₃-N), 1, and [(C₅Me₅)U(μ-I)₂]₃(μ₃-O), 2, and chair and boat conformations of [(C₅Me₅)₂U(μ-N)U(μ-N₃)(C₅Me₅)₂]₄, 3. These compounds were analyzed by density functional theory and multiconfigurational quantum chemical studies to differentiate nitride versus oxide in molecules for which the crystallographic data were not definitive and to provide insight into the electronic structure and unique chemical bonding of these polymetallic compounds. Calculations were also performed on [(C₅Me₅)₂UN₃(μ-N₃)]₃, 4, and [(C₆F₅)₃BNU(N[Me]Ph)₃], 5, for comparison with 1 and 3. On the basis of these results, the complex, [(C₅Me₅)U(μ₃-E)]₈, 6, for which only low-quality X-ray crystallographic data are available, was analyzed to predict if E is nitride or oxide.