复旦大学施章杰团队报道了(n-Bu) 4nbr促进N₂裂解成氮化钼。相关研究成果于2022年7月26日发表在《美国化学会杂志》。

通过六电子还原将N₂裂解并进一步功能化为增值产物，是N₂固定中最重要和最具挑战性的化学转化之一。然而，大多数N₂裂解方法依赖于强烈的化学或电化学还原，来生成高活性金属物种以结合和激活N₂，这通常与功能化剂不兼容。在温和的条件下，催化和可持续的N₂裂解生成金属氮化物可以为含氮有机化合物创造高效和直接的方法。

该文中，研究人员提出通过Mo（III）平台现成的非还原（n-Bu）4NBr可以促进N₂裂解。实验和理论机理研究均表明，简单的X–（X=Br，Cl等）阴离子可以在催化早期诱导MoIII[N（TMS）Ar]3歧化，生成具有催化活性的{MoII[N（TMS）Ar]3}物种。与四重MoII相比，五重MoII物种在动力学和热力学上更有利于N₂固定。特别是，计算研究揭示了一种用于N≡N三键断裂的独特的杂价{MoII–N2–MoIII}二聚体中间体。

附：英文原文

Title: (n-Bu)4NBr-Promoted N2 Splitting to Molybdenum Nitride

Author: Dan-Dan Zhai, Shuo-Qing Zhang, Si-Jun Xie, Rong-Kai Wu, Feng Liu, Zhen-Feng Xi, Xin Hong, Zhang-Jie Shi

Issue&Volume: July 26, 2022

Abstract: Splitting of N2 via six-electron reduction and further functionalization to value-added products is one of the most important and challenging chemical transformations in N2 fixation. However, most N2 splitting approaches rely on strong chemical or electrochemical reduction to generate highly reactive metal species to bind and activate N2, which is often incompatible with functionalizing agents. Catalytic and sustainable N2 splitting to produce metal nitrides under mild conditions may create efficient and straightforward methods for N-containing organic compounds. Herein, we present that a readily available and nonredox (n-Bu)4NBr can promote N2-splitting with a Mo(III) platform. Both experimental and theoretical mechanistic studies suggest that simple X– (X = Br, Cl, etc.) anions could induce the disproportionation of MoIII[N(TMS)Ar]3 at the early stage of the catalysis to generate a catalytically active {MoII[N(TMS)Ar]3} species. The quintet MoII species prove to be more favorable for N2 fixation kinetically and thermodynamically, compared with the quartet MoIII counterpart. Especially, computational studies reveal a distinct heterovalent {MoII–N2–MoIII} dimeric intermediate for the N≡N triple bond cleavage.

DOI: 10.1021/jacs.2c01507

Source: https://pubs.acs.org/doi/10.1021/jacs.2c01507