Unstable intermediates. Part CII. Electron spin resonance studies of solutions of sulphur in oleum: the S8+ cation

Solutions enriched in 33S have liquid-phase e.s.r. spectra which indicate eight equivalent sulphur atoms per radical. In contrast, at 77 K the intensities indicate only one or possibly two equivalent sulphur atoms per radical. The results are discussed in terms of the cation S8+, and it is suggested that the unpaired electron is largely localised onto one sulphur atom, but that intramolecular charge-transfer around the ring is rapid in solution.