Topological symmetry control in spin density distribution: spin chemistry of phenalenyl-based neutral monoradical systems.

[structure: see text] Topological symmetry-based extensions of a pi-conjugation network in an odd alternant phenalenyl radical have enabled us to control the spin density distribution systematically. ESR/ENDOR and NICS studies on the topological isomers of oxophenalenoxyl have revealed that the unpaired electron tends to localize in the antiaromatic ring systems.