Higher sulfur oxides
Higher sulfur oxides are a group of chemical compounds with the formula SO3+x where x lies between 0 and 1. They contain peroxo groups, and the oxidation state of sulfur is +6 as in SO3.
Monomeric SO4 can be isolated at low temperatures following the reaction of SO3 and atomic oxygen or photolysis of SO3–ozone mixtures. The favoured structure is:
Colourless polymeric condensates are formed in the reaction of gaseous SO3 or SO2 with O2 in a silent electric discharge. The structure of the polymers is based on β-SO3 with oxide bridges replaced randomly by peroxide bridges. As such these compounds are non-stoichiometric.Footnotes
