Predicting Dinitrogen Activation by Borenium and Borinium Cations
Activation of thermodynamically stable and kinetically inert dinitrogen (N2) has been a great challenge due to a significantly strong triple bond. Recently, the experimental study on the N2 activation by boron species, a highly reactive two-coordinated borylene, broke through the limitation of traditional strategy of N2 activation by metal species. Still, the study on metal-free N2 activation remains undeveloped. Here, we systematically investigate frustrated Lewis pair (FLP) combining the carbene and borenium (or borinium) cation to screen potential candidates for N2 activation via density functional theory calculations. As a result, we find two FLPs (closed form FLP, borenium and open form FLP, borinium) are able to activate N2 in a thermodynamically and kinetically favorable manner, with a low energy barrier of 9.0 and 7.9 kcal/mol, respectively. Furthermore, aromaticity is found to play an important role in the stabilization of products, supported by nucleus-independent chemical shift (NICS), anisotropy of the current-induced density (ACID) and electron density of delocalized bonds (EDDB) analysis. Our findings provide an alternative approach for a metal-free N2 activation, highlighting an importance of FLP chemistry and aromaticity towards N2 activation.