Electronic and Magnetic Characteristics of Polycyclic Aromatic Hydrocarbons with Factorizable Kekulé Structure Counts

The Kekulé structure count (K) for some types of polycyclic aromatic hydrocarbons (PAHs), such as fluoranthene and perylene, can be factorized into the product of those for two or more aromatic subunits. The ring-current map for these PAHs placed in a perpendicular magnetic field exhibits a substantial localization on aromatic subunits. We found that such localization of π circulation is a characteristic of fairly small K-factorizable species in the neutral electronic state. Even in such a case, no single π molecular orbital (πMO) is associated with localized π circulation. Apparent localization of π circulation is caused by the superposition of currents induced by all occupied πMOs. π circulation is less localized in larger K-factorizable species.