A Classical Approach to Aromaticity and a New Representation of Benzene

The classical chemical structure theory (CST) provides “localised” qualitative models for the structure and reactivity of organic molecules, while, in addition to quantitative methods, the modern molecular orbitals (MO) theory provides “delocalised” qualitative models. In particular, these two theories provide two different descriptions of the ethylenic double bond, bent bonds and σ/π orbitals, respectively. In the framework of CST, a graphical model of aromaticity and antiaromaticity, related to a classical model of Woodward–Hoffmann rules, is presented. By application of Linnett's double-quartet theory, a new representation for benzene is proposed. It can be easily visualised when a new split representation of Linnett-type formulae is used.