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Stepwise Reduction of Dinitrogen by a Uranium–Potassium Complex Yielding a U(VI)/U(IV) Tetranitride Cluster

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Jori Nadir, Barluzzi Luciano, Douair Iskander, Maron Laurent, Fadaei-Tirani Farzaneh, Zivković Ivica, Mazzanti Marinella,
Project Versatile high sensitivity and throughput magnetometer for quantum, functional and applied materials
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Original article (peer-reviewed)

Journal Journal of the American Chemical Society
Volume (Issue) 143(29)
Page(s) 11225 - 11234
Title of proceedings Journal of the American Chemical Society
DOI 10.1021/jacs.1c05389

Open Access

URL https://pubs.acs.org/doi/abs/10.1021/jacs.1c05389
Type of Open Access Publisher (Gold Open Access)

Abstract

Multimetallic cooperativity is believed to play a key role in the cleavage of dinitrogen to nitrides (N3–), but the mechanism remains ambiguous due to the lack of isolated intermediates. Herein, we report the reduction of the complex [K2{[UV(OSi(OtBu)3)3]2(μ-O)(μ-η2:η2-N2)}], B, with KC8, yielding the tetranuclear tetranitride cluster [K6{(OSi(OtBu)3)2UIV}3{(OSi(OtBu)3)2UVI}(μ4-N)3(μ3-N)(μ3-O)2], 1, a novel example of N2 cleavage to nitride by a diuranium complex. The structure of complex 1 is remarkable, as it contains a unique uranium center bound by four nitrides and provides the second example of a trans-N═UVI═N core analogue of UO22+. Experimental and computational studies indicate that the formation of the U(IV)/U(VI) tetrauranium cluster occurs via successive one-electron transfers from potassium to the bound N24– ligand in complex B, resulting in N2 cleavage and the formation of the putative diuranium(V) bis-nitride [K4{[UV(OSi(OtBu)3)3]2(μ-O)(μ-N)2}], X. Additionally, cooperative potassium binding to the U-bound N24– ligand facilitates dinitrogen cleavage during electron transfer. The nucleophilic nitrides in both complexes are easily functionalized by protons to yield ammonia in 93–97% yield and with excess 13CO to yield K13CN and KN13CO. The structures of two tetranuclear U(IV)/U(V) bis- and mononitride clusters isolated from the reaction with CO demonstrate that the nitride moieties are replaced by oxides without disrupting the tetranuclear structure, but ultimately leading to valence redistribution.
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