Predicting Dinitrogen Activation by Boron Radical Cations

Abstract

Activation of dinitrogen (N₂) under mild conditions has been a particularly challenging project for decades, owing to the highly strong N≡N triple bond. In recent years, the main group species have emerged as a prominent strategy in the field of dinitrogen activation, but the reported examples remain particularly rare compared with transition metal complexes. Herein, we performed a comprehensive density functional theory (DFT) calculation of N₂ activation by boron radical cations. The calculations demonstrated that N₂ activation by boron radical cations was favorable both kinetically and thermodynamically, with high exothermicity (ΔG value of −36.8 kcal/mol) and a low reaction barrier (7.3 kcal/mol), indicating feasibility under mild conditions. Moreover, principal interacting spin orbitals (PISOs) and intrinsic bond orbitals (IBOs) analyses revealed that the boron radical cation activated N₂ through two perpendicular interactions, including σ-type donation and π-type backdonation. Additionally, further analysis implied that π-type backdonation is essential for N₂ activation. Our findings offer an alternative approach for metal-free N₂ activation, highlighting the significance of boron chemistry in N₂ activation.