Mou Li-Hui, Li Yao, Li Zi-Yu, Liu Qing-Yu, Chen Hui, He Sheng-Gui
State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China.
University of Chinese Academy of Sciences, Beijing 100049, P. R. China.
J Am Chem Soc. 2021 Nov 17;143(45):19224-19231. doi: 10.1021/jacs.1c10018. Epub 2021 Nov 3.
Cleavage of the strong N≡N bond has long been a great challenge for energy-efficient dinitrogen (N) fixation; thus a reasonable design of reactive species to activate N under mild conditions is highly desirable and meaningful. Herein a novel N activation strategy of combining 5d early (E) and 3d late (L) transition metals (TMs) is proposed, which is verified by the facile and complete N≡N cleavage via the polarized Fe-Ta bond in gas-phase cluster FeTaC. The efficient N≡N cleavage benefits from an electronic-level design of highly strengthened donor-acceptor interactions, in which the 5d-ETM (Ta) mainly pushes electrons from occupied 5d-orbitals to N π*-orbitals while the 3d-LTM (Fe) simultaneously pulls electrons from N σ/π-orbitals to its unoccupied 3d-orbitals. Through employing 5d-ETM and 3d-LTM to play their respective roles, this work provides a new and versatile idea for activating the inert N≡N bond and inspires relevant design of TM-based catalysts.
长期以来，断裂强N≡N键一直是高效固氮面临的巨大挑战；因此，在温和条件下合理设计能激活N₂的活性物种是非常必要且有意义的。本文提出了一种结合5d早期（E）和3d晚期（L）过渡金属（TMs）的新型N₂活化策略，通过气相团簇FeTaC中极化的Fe-Ta键对N≡N键进行简便且完全的断裂来验证该策略。高效的N≡N键断裂得益于高度强化的供体-受体相互作用的电子能级设计，其中5d-E-TM（Ta）主要将占据的5d轨道中的电子推向N₂的π*轨道，而3d-L-TM（Fe）同时将N₂的σ/π轨道中的电子拉向其未占据的3d轨道。通过利用5d-E-TM和3d-L-TM发挥各自的作用，这项工作为激活惰性N≡N键提供了一种新的通用思路，并激发了基于过渡金属的催化剂的相关设计。
