Higher sulfur oxides are a group of

chemical compounds A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

with the formula SO_3+x where x lies between 0 and 1. They contain peroxo (O−O) groups, and the

oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...

of sulfur is +6 as in SO₃. Monomeric SO₄ can be isolated at low temperatures (below 78 K) following the reaction of SO₃ and atomic oxygen or photolysis of SO₃–

ozone Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lo ...

mixtures. The favoured structure is: Sulfur tetroxide 2-D structure

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 (one of the three forms of solid SO₃) with oxide bridges (−O−) replaced randomly by peroxide bridges(−O−O−). As such these compounds are

non-stoichiometric In chemistry, non-stoichiometric compounds are chemical compounds, almost always solid inorganic compounds, having elemental composition whose proportions cannot be represented by a ratio of small natural numbers (i.e. an empirical formula); m ...

References

* Sulfur oxides Sulfur(VI) compounds Non-stoichiometric compounds Interchalcogens {{chemistry-stub