Snapshots of Early-Stage Quantitative N₂ Electrophilic Functionalization

Gao-Xiang Wang#, Xueli Wang#, Yang Jiang, Wang Chen, Chunxiao Shan, Peng Zhang, Junnian Wei*, Shengfa Ye*, Zhenfeng Xi*

J. Am. Chem. Soc., 2023. DOI: 10.1021/jacs.3c01497.

        Electrophilic functionalization of N₂ moieties in metal dinitrogen complexes typically initiates the catalytic synthesis of N-containing molecules directly from N₂. Despite intensive research in the last six decades, how to efficiently and even quantitatively convert N₂ into diazenido and hydrazido species still poses a great challenge. In this regard, systematic and comprehensive investigations to elucidate the reaction intricacies are of profound significance. Herein, we report a kinetic dissection on the first and second electrophilic functionalization steps of a new Cr⁰–N₂ system with HOTf, MeOTf, and Me₃SiOTf. All reactions pass through fleeting diazenido intermediates and furnish long-lived final hydrazido products, and both steps are quantitative conversions at low temperatures. All of the second-order reaction rates of the first and second transformations were determined as well as the lifetimes of the intervening diazenido species. Based on these findings, we succeeded in large-scale and near-quantitative preparation of all hydrazido species.