Electron Spin Resonance Spectroscopy of and Free Radicals

Article abstract of DOI:10.1002/mrc.1260311114

Solution and powder ESR spectra of the 4-trifluoromethyl-1,2,3,5-dithiadiazolyl and 4-pentafluorophenyl-1,2,3,5-dithiadiazolyl free radicals were analyzed.Comparison of the ESR parameters with those obtained for the protonated equivalents shows that fluorination produces a drift of unpaired electron spin density away from the nitrogen 2p_x orbitals towards sulphur 3p_x orbitals (x is the direction perpendicular to the heterocyclic ring), consistent with an increase in electronegativity of the substituent.The fluorinated radicals dimerize more readily than their protonated counterparts. - Key words: ESR Isotropic spectra Powder soectra Dithiadiazolyl radicals Dimerization