Inorganic Chemistry, Vol.57, No.14, 8106-8115, 2018
A Pseudotetrahedral Uranium(V) Complex
A series of uranium amides were synthesized from N,N,N-cyclohexyl(trimethylsilyl)lithium amide [Li][N-(TMS)Cy] and uranium tetrachloride to give U-(NCySiMe3)(x) (Cl)(4-x), where x = 2, 3, or 4. The diamide was isolated as a bimetallic, bridging lithium chloride adduct ((UCl2(NCyTMS)(2))(2)-LiCl(THF)(2)), and the tris(amide) was isolated as the lithium chloride adduct of the monometallic species (UCl(NCyTMS)3-LiCl(THF)(2)). The tetraamide complex was isolated as the four-coordinate pseudotetrahedron. Cyclic voltammetry revealed an easily accessible reversible oxidation wave, and upon chemical oxidation, the U-V amido cation was isolated in near-quantitative yields. The synthesis of this family of compounds allows a direct comparison of the electronic structure and properties of isostructural U-IV and U-V tetraamide complexes. Spectroscopic investigations consisting of UV-vis, NIR, MCD, EPR, and U L-3-edge XANES, along with density functional and wave function calculations, of the four coordinate U-IV and U-V complexes have been used to understand the electronic structure of these pseudotetrahedral complexes.