Chemical Bonding in Coronene, Isocoronene, and Circumcoronene

Chemical-bonding analysis in coronene, isocoronene, and circumcoronene has been performed by using the Adaptive Natural Density Partitioning (AdNDP) method. This analysis revealed that coronene and isocoronene have two globally delocalized concentric p-systems. Circumcoronene does not have globally delocalized p-systems; instead, it has seven local sextets and can be represented by a single Clar structure. Thus, today there are a few known polycyclic aromatic hydrocarbons with two concentric p-systems, but there are as yet no examples of such molecules with three or more concentric p-systems. The results revealed by the AdNDP analysis are consistent with the results obtained by the current-density maps, NICS and NICSZZ indices as well as MCI, PDI, Iring and d indices.