Dinitrogen Activation by Heteronuclear Metal Carbide Cluster Anions FeTaC: A 5d Early and 3d Late Transition Metal Strategy.

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.