Insights into the Electronic Structure of a U(IV) Amido and U(V) Imido Complex.

Reaction of the N-heterocylic carbene ligand i PrIm (L 1 ) and lithium bis(trimethylsilyl)amide (TMSA) as a base with UCl 4 resulted in U(IV) and U(V) complexes. Uranium's +V oxidation state in (HL 1 ) 2 [U(V)(TMSI)Cl 5 ] (TMSI=trimethylsilylimido) (2) was confirmed by HERFD-XANES measurements. Solid state characterization by SC-XRD and geometry optimisation of [U(IV)(L 1 ) 2 (TMSA)Cl 3 ] (1) indicated a silylamido ligand mediated inverse trans influence (ITI). The ITI was examined regarding different metal oxidation states and was compared to transition metal analogues by theoretical calculations.