Searching for double σ- and π-aromaticity in borazine derivatives.

Inspired by the double-aromatic (σ and π) CH , CI , and C(SePh) ring-shaped compounds, herein we theoretically study their borazine derivative analogues. The systems studied are the cation and dications with formulas BNH , BNBr , BNI , BN(SeH) , and BN(TeH) . Our DFT calculations indicate that the ring-shaped planar structures of BNH , BNI , and BN(TeH) are more stable in the singlet state, while those of BNBr and BN(SeH) prefer the triplet state. Besides, exploration of the potential energy surface shows that the ring-shaped structure is the putative global minimum only for BNI . According to chemical bonding analysis, BNH , BNI , and BN(TeH) have σ and π delocalized bonds. The number of delocalized σ/π electrons is 2/6 for the first, and 10/6 for the second and third, similar to what their carbon analogs exhibit. Finally, the analysis of the magnetically induced current density allows BNH , BNI , and BN(TeH) to be classified as strongly σ aromatic, and poorly π aromatic compounds.