ESR Study of Free Radicals Produced in Irradiated Cyclopentadiene and Cyclohexene: The Cyclopentadienyl and Cyclohexenyl Radicals

The ESR spectra of irradiated cyclopentadiene and cyclohexene were measured at various temperatures. The spectra showed motional narrowing on raising temperature and the free radicals were identified from analysis of the narrowed spectra. Cyclopentadiene showed a well‐resolved sextet spectrum of 5.6‐G splitting, which was assigned to the cyclopentadienyl radical. Cyclohexene gave a spectrum consisting at least of 26 lines, which can be reasonably attributed to the cyclohexenyl radical by assuming appropriate hyperfine constants.