Electron spin resonance investigation of the persistent free radicals formed from sulphur–nitrogen compounds and olefins

Abstract

Free radicals, believed to be dithiazolidine derivatives, have been shown to be formed readily from tetrasulphur dinitride and norbornene compounds in organic solvents: it is also possible to form these radicals from other sulphur–nitrogen compounds and from other types of olefins. A feature of the e.s.r. spectra is the resolution at low temperatures of small splittings caused by longrange coupling to hydrogen nuclei. The hyperfine coupling constants are solvent and temperature dependent. The latter effect is attributed to out-of-plane vibrations of the —S—[graphic omitted]—S— group of the dithiazolidine ring. At low temperatures the radicals dimerise reversibly and the thermodynamic parameters have been evaluated for several different types of olefin.