GAS-PHASE RADICALS IN CO-CONDENSED ADAMANTANE MATRIX: PROTON SPLITTING IN THE ESR SPECTRUM OF THE CYCLOHEPTATRIENYLPEROXYL RADICAL

Article abstract of DOI:10.1016/0040-4020(89)80115-2

The cycloheptatrienyl (tropenyl) radical was generated by the gas-phase pyrolysis of ditropenyl at 473-723 K and was trapped in co-condensed adamantane at 77 K.Well-resolved isotropic ESR spectra of the tropenyl radical showed a linear temperature dependence of a_iso in the range 77-226 K.The tropenylperoxyl radical was obtained if the ditropenyl pyrolysis was carried out in the presence of dioxygen.The anisotropic ESR spectrum of the tropenylperoxyl radical obtained in the adamantane matrix at 77 K was characterized by g₁=2.035, g₂=2.009, g₃=2.002 and a₁=8.4 G, a₂=9.6 G and a₃=5.35 G.The values of g_iso and a_iso were found experimentally in the freely rotating radical at 130 K to be g=2.0157 and a=7.5 G respectively.The hyperfine coupling arises from coupling to the β-H atom via a hyperconjugative mechanism.