The alkylhyphen;substituted compounds of DPPH were investigated by ESR methods. Accurate values of the splitting constants were determined by calculating the experimental spectra. The activation energy of the hindered oscillation of the methylene group, as evaluated from the temperature dependence of the ethyl derivative, was found to be 910 cal/mole. Theoretical investigations, using the Huuml;ckel, McLachlan, and Louml;wdin method show an inversion in the spin density ratio at the two nitrogen nuclei.
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