Facile CO Cleavage by a Multimetallic CsU₂ Nitride Complex

Abstract

Uranium nitrides are important materials with potential for application as fuels for nuclear power generation, and as highly active catalysts. Molecular nitride compounds could provide important insight into the nature of the uranium-nitride bond, but currently little is known about their reactivity. In this study, we found that a complex containing a nitride bridging two uranium centers and a cesium cation readily cleaved the C≡O bond (one of the strongest bonds in nature) under ambient conditions. The product formed has a [CsU2 (μ-CN)(μ-O)] core, thus indicating that the three cations cooperate to cleave CO. Moreover, the addition of MeOTf to the nitride complex led to an exceptional valence disproportionation of the CsU(IV) -N-U(IV) core to yield CsU(III) (OTf) and [MeN=U(V) ] fragments. The important role of multimetallic cooperativity in both reactions is illustrated by the computed reaction mechanisms.

CO Cleavage and CO2 Functionalization under Mild Conditions by a Multimetallic CsU2 Nitride Complex

“…The unusually high nucleophilic character of the nitride leads to complete cleavage of the CO triple bond. We also demonstrated [9] that the direct methylation of the nitride complex 1 leads to Lewis-acid-to 1 (Scheme 1c). The crystal structure of 4 (Fig.…”

“…[4] It is desirable to design synthetic methods involving the use of cheap and available C 1 feedstock such as carbon dioxide. [5] A handful of examples of transition metals complexes able to form N-C bonds from carbon dioxide and activated dinitrogen or nitride complexes [6,7] have been reported but before our reports reviewed here, [8,9] f elements molecular nitrides had not been shown to react with CO 2 . Another readily available C 1 feedstock used in industry for the production of a wide variety of chemicals such as methanol, acetic acid, phosgene and hydrocarbons [10] is carbon monoxide.…”

“…Deltate, [16] squarate [16b,17] or ethynediolate dianions [18] have been identified as products in the reaction of uranium(iii) compounds with CO. Here, we review the previously reported [8,9] ability of the nitride-bridged diuranium(iv…”

“…The nitride group, bridging two uranium(iv) centers, is highly nucleophilic, and its ability to lead to N-C bond formation allowed us to characterize several new compounds. In particular, in the reactions with CS 2 , CO 2 [8] and CO, [9] a cyanate/thiocyanate complex, a dicarbamate complex and a cyanide/ oxo complex were formed, respectively. The unusually high nucleophilic character of the nitride leads to complete cleavage of the CO triple bond.…”

Use of 15N NMR spectroscopy to probe covalency in a thorium nitride

“…2,[8][9][10][11][12][13][14][15][16][17][18][19][20][21] The study of these complexes has allowed actinide chemists to reveal fundamentally important insights into 5f covalency, as well as uncover novel modes of reactivity. 12,[15][16][17][18][22][23][24] In contrast, no isolable molecular thorium nitride complexes are known. 25 A handful of thorium nitrides have been identied in matrix isolation studies, such as ThN, NThN, and NThO, but these are only stable at cryogenic temperatures.…”