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.