Lower sulfur oxides

The lower sulfur oxides are a group of inorganic compounds with the formula SmOn, where 2m > n. These species are often unstable and thus rarely encountered in everyday life.

Some compounds reported by early workers such as the blue "sesquioxide", S2O3, formed by dissolving sulfur in liquid SO3 appears to be a mixture of polysulfate salts of the S2+4 and S2+8 ions.

[1] These species are well characterized in the gas phase, but they cannot be isolated as solids or liquids.

The two dipole moment components are μa = 0.875 D and μb = 1.18 D.[3] This species decomposes to give a polymeric sulfur oxides ("PSO's") with the approximate formula [S3O]n. PSO's decompose at room temperature to elemental sulfur and SO2.

[2] They can be prepared by oxidising the homocycles with trifluoroperoxyacetic acid:[1] The compounds are yellow or orange-coloured and thermally unstable near room temperature.