Dinitrogen Activation and Functionalization by Heteronuclear Metal Cluster Anions FeV2C2– at Room Temperature

It is of great importance to study the mechanisms to activate dinitrogen (N₂), the very inert molecule, under mild conditions. Gas-phase metal clusters are being actively generated to react with N₂ to identify new reaction types and mechanisms. Herein, an unprecedented, mechanistically unique metal atom (Fe or V) ejection in the thermal reaction of FeV₂C₂^- with N₂ has been identified using mass spectrometry, photoelectron imaging spectroscopy, and quantum chemistry calculations. Strong evidence suggests that the complete cleavage of the N≡N triple bond and subsequent functionalization of two N atoms via C-N coupling were achieved in this reaction. The complementary cooperation between V atoms with strong electron-donating ability and an Fe atom with large electron-withdrawing ability as well as the geometric flexibility of the Fe-V-V ring drives the whole reaction. The important role of C ligands in N≡N cleavage was also revealed. This study emphasizes the importance of heteronuclear metal systems for N₂ fixation.