Two‐Electron Oxidative Atom and Group Transfer Reactions at a Well‐Defined Uranium(II) Center

Abstract The multi‐electron redox chemistry of uranium(II) compounds remains largely unexplored. Herein, we report a series of two‐electron oxidative atom and group transfer reactions at a well‐defined uranium(II) center. The reactions of uranium(II) complexes [M][( Ad TPBN 3 )U] (M=K(2,2,2‐cryptand) and K(18‐crown‐6)(THF)) with pyridine‐ N ‐oxide or nitrosobenzene, elemental sulfur/selenium or triphenylphosphine sulfide/selenide, and ditellurium salt led to the isolation of uranium(IV) terminal oxo and chalcogenido complexes [M][( Ad TPBN 3 )UX] (X=O, S, Se, Te). In addition, the reactions of [M][( Ad TPBN 3 )U] with aryl azides ArN 3 or diazoalkanes R 2 CN 2 quantitatively yielded uranium(IV) terminal imido [M][( Ad TPBN 3 )UNAr] or hydrazonido(2−) complexes [M][( Ad TPBN 3 )UN 2 CR 2 ], respectively. Notably, the low‐temperature reaction between [M][( Ad TPBN 3 )U] and mesityl azide allowed the isolation of the first uranium(IV) aryldiazenylimido complex as an intermediate. These uranium(IV)−element multiply bound compounds were fully characterized by X‐ray crystallography, 1 H NMR spectroscopy, absorption spectroscopy, solution and solid‐state magnetometry, and elemental analysis. The controlled two‐electron oxidative reactions at a uranium(II) center not only expand the redox reactivity of uranium(II) but also offer a convenient new route to access uranium−element multiply bound compounds.