Higher sulfur oxides
# Higher sulfur oxides

Higher sulfur oxides are a group of chemical compounds with the formula $SO_{3+x}$ where x lies between 0 and 1. They contain peroxo (O−O) groups, and the oxidation state of sulfur is +6 as in $SO_3.$

Monomeric $SO_4$ can be isolated at low temperatures (below 78 K) following the reaction of $SO_3$ and atomic oxygen or photolysis of $SO_3–ozone$ mixtures. The favoured structure is:

Colourless polymeric condensates are formed in the reaction of gaseous $SO_3$ or $SO_2$ with $O_2$ in a silent electric discharge. The structure of the polymers is based on $β-SO_3$ (one of the three forms of solid $SO_3)$ with oxide bridges (−O−) replaced randomly by peroxide bridges(−O−O−). As such these compounds are non-stoichiometric.

