Chemical Oxidation of Coronene: A Crystallographic and Computational Study of Charge-Regulated π-Stacking

Chemical oxidation of coronene with Et3O+SbCl6– in dichloromethane allowed the isolation and crystallization of a dimeric coronene radical cation in the form of (C24H12)2•+(SbCl6–)Et3O+SbCl6–2, as revealed crystallographically. The crystal structure exhibits π-stacked columns of coronene molecules, wherein alternating average interplanar contacts of 3.357(2) and 3.452(2) Å show the distinct formation of the coronene dimers. This packing is accompanied by an atom-over-atom overlap motif and core deformation often associated with a unique intermolecular interaction called pancake bonding. A combined computational analysis employing finite cluster and periodic density functional theory (DFT) calculations confirms the presence of pancake bonding and delineates its hierarchical strength along the column. Charge-distribution analyses identify the molecular oxidation states and demonstrate that Coulombic repulsion between charged dimers plays a decisive role in enforcing the observed alternation of interplanar distances. Periodic DFT modeling of an infinite coronene stack faithfully reproduces the experimental structural parameters and provides insight into the electronic structure of the resulting one-dimensional π-radical assembly.