Article Dans Une Revue Chemical Science Année : 2021

Single metal four-electron reduction by U(II) and masked "U(II)" compounds

Résumé

The redox chemistry of uranium is dominated by single electron transfer reactions while single metal four-electron transfers remain unknown in f-element chemistry. Here we show that the oxo bridged diuranium(iii) complex [K(2.2.2-cryptand)](2)[{((Me3Si)(2)N)(3)U}(2)(mu-O)], 1, effects the two-electron reduction of diphenylacetylene and the four-electron reduction of azobenzene through a masked U(ii) intermediate affording a stable metallacyclopropene complex of uranium(iv), [K(2.2.2-cryptand)][U(eta(2)-C2Ph2){N(SiMe3)(2)}(3)], 3, and a bis(imido)uranium(vi) complex [K(2.2.2-cryptand)][U(NPh)(2){N(SiMe3)(2)}(3)], 4, respectively. The same reactivity is observed for the previously reported U(ii) complex [K(2.2.2-cryptand)][U{N(SiMe3)(2)}(3)], 2. Computational studies indicate that the four-electron reduction of azobenzene occurs at a single U(ii) centre via two consecutive two-electron transfers and involves the formation of a U(iv) hydrazide intermediate. The isolation of the cis-hydrazide intermediate [K(2.2.2-cryptand)][U(N2Ph2){N(SiMe3)(2)}(3)], 5, corroborated the mechanism proposed for the formation of the U(vi) bis(imido) complex. The reduction of azobenzene by U(ii) provided the first example of a "clear-cut" single metal four-electron transfer in f-element chemistry.

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hal-03717255 , version 1 (24-09-2024)

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Dieuwertje K. Modder, Chad T. Palumbo, Iskander Douair, Rosario Scopelliti, Laurent Maron, et al.. Single metal four-electron reduction by U(II) and masked "U(II)" compounds. Chemical Science, 2021, 12 (17), pp.6153-6158. ⟨10.1039/d1sc00668a⟩. ⟨hal-03717255⟩
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