Evidence for single metal two electron oxidative addition and reductive elimination at uranium

• Published in: Nature communications 2017-12, Vol.8 (1), p.1898-10, Article 1898
• Main Authors: Gardner, Benedict M., Kefalidis, Christos E., Lu, Erli, Patel, Dipti, McInnes, Eric J. L., Tuna, Floriana, Wooles, Ashley J., Maron, Laurent, Liddle, Stephen T.
• Format: Article
• Language: English
• Subjects: 639/638/263/406; 639/638/77; 639/638/911; Catalysis; Chemical reduction; Chemical Sciences; Electrons; Extrusion; Heavy metals; Humanities and Social Sciences; Labeling; Metals; multidisciplinary; Organic compounds; Oxidation; Physics; Science; Science (multidisciplinary); Transition metals; Uranium
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-017-01363-0

Reversible single-metal two-electron oxidative addition and reductive elimination are common fundamental reactions for transition metals that underpin major catalytic transformations. However, these reactions have never been observed together in the f-block because these metals exhibit irreversible one- or multi-electron oxidation or reduction reactions. Here we report that azobenzene oxidises sterically and electronically unsaturated uranium(III) complexes to afford a uranium(V)-imido complex in a reaction that satisfies all criteria of a single-metal two-electron oxidative addition. Thermolysis of this complex promotes extrusion of azobenzene, where H-/D-isotopic labelling finds no isotopomer cross-over and the non-reactivity of a nitrene-trap suggests that nitrenes are not generated and thus a reductive elimination has occurred. Though not optimally balanced in this case, this work presents evidence that classical d-block redox chemistry can be performed reversibly by f-block metals, and that uranium can thus mimic elementary transition metal reactivity, which may lead to the discovery of new f-block catalysis. The reactivity of f-block complexes is primarily defined by single-electron oxidations and σ-bond metathesis. Here, Liddle and co-workers provide evidence that a uranium complex can undergo reversible oxidative addition and reductive elimination, demonstrating transition metal-like reactivity within f-block chemistry.