Computational Investigation of the N NQR Parameters of Borazyne

In this study, the N NQR parameters of the possible isomers of borazyne were reported in the singlet and triplet states at the M062X/6-311G(d,p) level of theory. Electric field gradient tensors (q, q, q), nuclear quadrupole coupling constants (η, η, η), asymmetry parameter (η), and nuclear quadrupole resonance frequencies (ν, ν, ν) were estimated. Relative energy, frontier orbital energy, and HOMO–LUMO gap values of these isomers were calculated. From the energetic aspect, ortho and meta(2) isomers were the most stable isomers in the singlet and triplet states, respectively. The singlet state was a more stable spin isomer compared to the triplet state between all isomers, except for the meta(2) isomer. Aromaticity analysis of the studied molecules on the basis of nucleus-independent chemical shift values showed that the aromaticity of the triplet state was stronger than that of the singlet state for ortho and para isomers. For the meta(2) isomer, the aromaticity of the singlet state was stronger than that of the triplet state. To calculate the atomic charge of nitrogen atoms, natural bonding orbital method analysis was used.