Oxidation-induced double aromaticity in periodo-polycyclic hydrocarbons

Abstract

The doubly oxidized hexaiodobenzene [C₆I₆]²⁺ is a well-known example of a double aromatic molecule, exhibiting both π- and σ-aromaticity. In this study, a series of periodo-monocyclic molecules and their doubly oxidized forms were systematically investigated to explore the origin of their double aromaticity. These molecules were employed to provide insights into how the size and aromaticity of the central carbon atom ring influence the aromaticity of the resulting doubly oxidized structures. The knowledge gained in this study was subsequently applied to model periodo-derivatives of polycyclic (anti)aromatic hydrocarbons in which oxidation can induce additional σ-electron cyclic delocalization along the macrocyclic iodine ring, thus also achieving their double aromaticity.