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

S. R. and S. Đ. would like to dedicate this paper to students and teachers who stood against corruption and the collapse of the educational system in Serbia during the 2024–2025 academic year. S. Đ. and S. R. thank the Serbian Ministry of Science, Technological Development, and Innovation (Agreement No. 451-03-137/2025-03/200122). J. P. and M. S. thank the Spanish Ministerio de Ciencia, Innovación y Universidades (MCIN/AEI/10.13039/501100011033, projects: PID2023-147424NB-I00, PID2022-138861NB-I00, and CEX2021-001202-M) and the Generalitat de Catalunya (projects: 2021SGR442 and 2021SGR623 and ICREA Academia 2024 Prize to M. S.)