Cleavage of the N≡N Triple Bond and Unpredicted Formation of the Cyclic 1,3‐diaza‐2,4‐diborete (FB)2N2 from N2 and Fluoroborylene BF

A complete cleavage of the triple bond of N-2 by fluoroborylene (:BF) was achieved in a low-temperature N-2 matrix by the formation of the four-membered heterocycle FB(mu-N)(2)BF, which lacks a trans-annular N-N bond. Additionally, the linear complex FB=N-N=BF and cyclic FB(eta(2)-N-2) were formed. These novel species were characterized by their matrix infrared spectra and quantum-chemical calculations. The puckered four-membered-ring B2N2 complex shows a delocalized aromatic two-electron p-system in conjugation with the exo-cyclic fluorine pi lone pairs. This work may contribute to a rational design of catalysts based on borylene for artificial dinitrogen activation.