The blue solutions of sulphur in oleum
Abstract
The blue colour and the two-line e.s.r. absorption at 90°K of solutions of sulphur in oleum are ascribed to a planar S4+ ion which is in equilibrium with a yellow S82+ ion and another radical exhibiting a double-headed optical absorption band at 10,600/13,900 cm–1 and a three-line e.s.r. spectrum at 90°K.