Predicting\nSmall Molecule Activations Including Dinitrogen\nBased on an Inorganic Benzene B<sub>4</sub>N<sub>2</sub> Framework

Although main group species have emerged in the field\nof dinitrogen\nactivation in recent years, the reported examples are particularly\nrare in comparison with transition metal complexes due to their significant\nchallenges. Herein, we demonstrate a [4 + 2] cycloaddition reaction\nof N<sub>2</sub> (with an activation energy as low as 12.5 kcal mol<sup>–1</sup>) initiated by an inorganic benzene via density functional\ntheory calculations. Such N<sub>2</sub> activation is supported by\nthe elongated nitrogen–nitrogen bond distance (<i>d</i><sub>NN</sub>), decreased vibration frequency (ν<sub>NN</sub>), and weakened Wiberg bond index (WBI<sub>NN</sub>). Subsequently,\nthe “push-pull” electronic effect, formed by introducing\na Lewis acid, HB(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>, facilitates\nthe generation of thermodynamically more stable products. In addition,\nthis inorganic benzene could also be used to activate a series of\nsmall molecules, including carbon dioxide, acetylene, ethylene, and\nacetonitrile with reaction barriers ranging from 4.7 to 11.6 kcal\nmol<sup>–1</sup>. Our findings provide an alternative approach\nto N<sub>2</sub> activation and functionalization, theoretically validating\nthe feasibility of the dual Lewis acid strategy for dinitrogen activation.