[摘要]：1,3-Diphenyl-7-trifluoromethyl-1,4-dihydro-1,2,4-benzotriazin-4-yl (4), prepared in high yield via the catalytic oxidation of the corresponding amidrazone 5 by using Pd/C (1.6 mol %) and 1,8-diazabicyclo[5.4.0]undec-7-ene (0.1 equiv) in air, is stable in dichloromethane solutions in the presence of MnO2 and KMnO4. Furthermore, radical 4 is thermally stable well past its melting point (160-161 degrees C) with a decomposition onset temperature of 288 degrees C. X-ray studies show that radical 4 packs in equidistant slipped pi-stacks along the a axis. Cyclic voltammetry shows two fully reversible waves, corresponding to the -1/0, 0/+1 processes. EPR studies indicate that the spin density is mainly delocalized on the triazinyl fragment of the heterocycle. Magnetic susceptibility measurements in the 5-300 K region showed that the radical obeys Curie Weiss behavior down to 10 K (C = 0.376 emu .K. mol(-1) and 0 = +1.41 K) consistent with weak ferromagnetic interactions between S = 1/2 radicals. Subsequent fitting of the magnetic data to a 1D ferromagnetic chain model provided an excellent fit (g = 2.00, J/k = +1.49K) down to 10 K but failed to reproduce the subsequent decrease in T-X at lower temperatures, which has been ascribed to the onset of weaker antiferromagnetic interactions between ferromagnetic chains.
