Phenalenyl‐Based Open‐Shell Polycyclic Aromatic Hydrocarbons

Abstract The phenalenyl radical is a polycyclic aromatic hydrocarbon ( PAH ) radical. Owing to its widely distributed spin structure, phenalenyl is relatively stable compared to other hydrocarbon radicals and has been studied from the viewpoint of its application to electroconductive and magnetic materials. In addition, a strong intermolecular spin–spin coupling nature is another feature of phenalenyl. This account summarizes my studies so far into PAH radicals containing the phenalenyl scaffold in terms of their amphoteric redox properties and singlet biradical character, which strongly rely on the characteristic electronic structure, that is, non‐bonding character and sixfold symmetry of a singly occupied molecular orbital of the phenalenyl radical.