OD ESR Detection of Benzene Radical Cation in Liquid Nonpolar Solution

摘要

To present time, resolved ESR spectrum of benzene radical cation (RC) has been obtained only in matrix-isolation studies at low temperatures. As for liquid-phase experiments, to the best of our knowledge, only the narrow OD ESR signal from exchanging solvent holes in neat benzene has been obtained [1]. However, resolved spectra of methyl substituted benzene derivative RC's are known to be observed in liquid solutions by conventional ESR as well as by OD ESR technique. The only exception is mesitylene (1,3,5-trimethylbenzene) RC. Based on the fact that only highly symmetrical benzene and mesitylene RC's demonstrate such an unusual behavior, it is thought to be due to fast spin-lattice relaxation peculiar to Jahn-Teller active systems.