m-キノジメタンを基盤とする縮合多環ジラジカルの創出

抄録

Diradicals have been actively studied because of their unique electronic structures and properties not observed in closed-shell molecules. Quinodimethane is one of the basic motifs of diradicals. p-quinodimethane (p-QDM) and o-quinodimethane (o-QDM) are singlet Kekulé hydrocarbons, while m-quinodimethane (m-QDM) is a triplet non-Kekulé hydrocarbon. Most of the hydrocarbon diradicals studied to date have been limited to non-fused-ring and fused-ring open-shell singlet diradicals based on p-QDM and o-QDM and non-fused-ring triplet diradicals based on m-QDM.

In this study, various fused-ring diradicals based on m-QDM, that is, quinoidal and zwitterionic open-shell singlet diradicals and non-Kekulé and Kekulé triplet diradicals, have been designed, synthesized, and isolated as crystals. Their electronic structures and properties have been elucidated by optical, electrochemical, and magnetic measurements and DFT calculations. The keys to the success include original molecular designs to control the interaction of unpaired electrons and developments of methods for introducing substituent groups at appropriate positions and purifying reactive diradicals.