Effect of Bond-Length Alternation on the Aromaticity of Benzene

Abstract

Dewar-de Llano PPP-SCF-MO calculations were performed to examine the effect of bond-length alternation on the σ and π frames of benzene. It was confirmed that the equalization of the CC bond lengths in benzene was caused primarily by a high degree of aromaticity. Benzene still is highly aromatic even if it is deformed artificially. Adiabatic and vertical resonance energies were defined for this compound.