Effects of group 14–16 heteroatoms on the aromaticity of benzene at DFT level

Abstract

Benzene aromaticity and energy gap (Δ E HOMO–LUMO) are compared and contrasted to those of 11 heterobenzenes containing group 14–16 atoms (Si, Ge, Sn, N, P, As, Sb, O +, S +, Se +, and Te +), at B3LYP/6-311++G ∗∗ level. Four diverse quantitative aromaticity indices are used: the nucleus independent chemical shifts (NICS), the aromatic stabilization energies (ASE), harmonic oscillator measure of aromaticity (HOMA), and Bird aromaticity index. The aromaticity appears with a general decrease in going from the top to the bottom of the periodic table (columns 14–16). The main exception is thiopyranium for showing more aromaticity than pyranium. Some inconsistencies are found among results of various indices employed.