VARIABLE-TEMPERATURE ESR-SPECTRA OF 1-(3,4,5-TRIMETHOXY-BENZOYL)-2, 2-BIS(3,5-DI-TERT-BUTYL-PHENYL) HYDRAZYL AND ITS 1-N-15-CONGENER

The title free radicals were obtained by oxidation of the correspondin g hydrazines which were synthesized and characterized by elemental ana lysis, IR and H-1-NMR spectra. The ESR spectra of the free radicals we re recorded in toluene in the temperature range - 50-degrees to + 90-d egrees. The simulated ESR spectra indicate a higher spin density at th e tricoordinated N-2 nitrogen of the diarylamino group (hfc a(N) = = 0 .862 mT) than at the dicoordinated N-1 nitrogen atom (hfc a(N) = 0.830 mT). In the temperature range 0-degrees to 30-degrees the activation free energy for interconversion of conformers was determined to be DEL TAGnot-equal = 7.80 kcal/mol.