Electron spin resonance study of CH3CNSSN˙, C6H5CNSSN˙, and SNSSN˙+ free radicals

Abstract

Isotropic and powder e.s.r. spectra have been recorded for CH₃[graphic omitted]˙, C₆H₅[graphic omitted]˙, and [graphic omitted]˙⁺. Isotropic labelling with nitrogen-15 and sulphur-33 has been accomplished for [graphic omitted]˙⁺ and it has been possible to prepare ³³[graphic omitted]˙⁺. Sulphur-33 satellites have been observed for C₆H₅[graphic omitted]˙. MNDO and Gaussian 76 calculations have been used to calculate the minimum-energy structures of the radicals, while INDO calculations have provided values for the hyperfine coupling constants. Unfortunately, poor agreement was obtained between the latter and the corresponding experimental values. All the radicals dimerise in solution at low temperatures and we have been able to measure the energetics of dimerisation for C₆H₅[graphic omitted]˙ and [graphic omitted]˙⁺. The dimers exist as crystalline solids which contain readily detectable amounts of the monomeric free radical.