Dearomatization Approach Toward a Superbenzoquinone-Based Diradicaloid, Tetraradicaloid, and Hexaradicaloid.

Reported here is the step-by-step dearomatization of a highly aromatic polycyclic aromatic hydrocarbon (PAH), the hexa-peri-hexabenzocoronene (also called as "superbenzene"), to give a series of superbenzoquinones containing two, four, and six ketone groups. Different from traditional PAH-based quinones, these superbenzoquinones show open-shell multiradical character by rearomatization in the open-shell forms as experimentally validated by X-ray crystallographic analysis, NMR and ESR spectroscopy, and FT-IR measurements, as well as theoretically supported by restricted active space spin-flip calculations. These compounds exhibit structure- and molecular-symmetry-dependent optical, electrochemical, and magnetic properties.