Single-Crystal Electron-Spin Resonance Study of the 4-Phenyl-1,2,3,5-dithiadiazolyl Radical

Article abstract of DOI:10.1002/mrc.1260271210

Single crystals of 4-phenyl-1,2,3,5-dithiadiazolium trithiatriazinide , prepared by the reduction of S5N5⁺AlCl4^- in SO2 with , contain a trace paramagnetic impurity which is shown by EPR spectroscopy to be the dithiadiazolyl free radical .The g and 14N hyperfine tensors of the radical were deduced from measurements made throughout three mutually orthogonal planes of crystallographically aligned specimens: g = (2.0011, 2.0075, 2.0197); 14N(2) = (37.1, 11.3, 3.4 MHz).Within experimental error, the two nitrogen hyperfine interaction tensors are collinear and have their maximum principal value aligned parallel to g_min and perpendicular to the plane of the host cation.The results are interpreted in terms of a planar ?-radical which substitutes for the planar host cation, and which has considerable unpaired spin density in N(2p_x) atomic orbitals directed perpendicular to the heterocyclic ring.KEY WORDS - Electron spin resonance Electron paramagnetic resonance Free radical, ?-Radical, Heterocylic free radical g Tensor Hyperfine interaction tensor Nitrogen hyperfine interaction Dithiadiazolyl Dithiadiazolylium Dithiadiazolium Unpaired electron Unpaired electron spin density