Synthesis, Molecular and Electronic Structure of U^V(O)[N(SiMe₃)₂]₃

Addition of 1 equiv of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) to U­(NR₂)₃ in hexanes affords U­(O)­(NR₂)₃ (2), which can be isolated in 73% yield. Complex 2 is a rare example of a terminal U­(V) oxo complex. In contrast, addition of 1 equiv of Me₃NO to U­(NR₂)₃ (R = SiMe₃) in pentane generates the U­(IV) bridging oxo [(NR₂)₃U]₂(μ-O) (3) in moderate yields. Also formed in this reaction, in low yield, is the U­(IV) iodide complex U­(I)­(NR₂)₃ (4). The iodide ligand in 4 likely originates from residual NaI, present in the U­(NR₂)₃ starting material. Complex 4 can be generated rationally by addition of 0.5 equiv of I₂ to a hexane solution of U­(NR₂)₃, where it can be isolated in moderate yield as a tan crystalline solid. The solid-state molecular structures and magnetic susceptibilities of 2, 3, and 4 have been measured. In addition, the electronic structures of 2 and 3 have been investigated by density functional theory (DFT) methods.