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

Abstract

A complete cleavage of the triple bond of N2 by fluoroborylene (:BF) was achieved in a low-temperature N2 matrix by the formation of the four-membered heterocycle FB(μ-N)2BF, which lacks a trans-annular N−N bond. Additionally, the linear complex FB=N−N=BF and cyclic FB(η2-N2) 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 π-system in conjugation with the exo-cyclic fluorine π lone pairs. This work may contribute to a rational design of catalysts based on borylene for artificial dinitrogen activation.