Tetrathionate

 ( Corrosion ) 

The tetrathionate ion, , is a sulfur oxyanion derived from the compound tetrathionic acid, H₂S₄O₆. Two of the sulfur present in the ion are in oxidation state 0 and two are in oxidation state +5. Alternatively, the compound can be viewed as the adduct resulting from the binding of disulfide to sulfur trioxide. Tetrathionate is one of the Polythionic acid, a family of anions with the formula S _n(SO₃)₂²⁻. Its IUPAC name is 2-(dithioperoxy)disulfate, and the name of its corresponding acid is 2-(dithioperoxy)disulfuric acid. The Chemical Abstracts Service identifies tetrathionate by the CAS Number 15536-54-6.

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Formation Tetrathionate is a product of the redox of thiosulfate, , by iodine, I₂:

2 + I₂ → + 2iodide

The use of bromine instead of iodine is dubious as excess bromine will oxidize the thiosulfate to sulfate.

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Structure Tetrathionate's structure can be visualized by following three edges of a rectangular cuboid, as in the diagram below. The structure shown is the configuration of in BaS₄O₆·2H₂O and Na₂S₄O₆·2H₂O. Dihedral S–S–S–S angles approaching 90° are common in .

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Compounds Compounds containing the tetrathionate anion include sodium tetrathionate, Na₂S₄O₆, potassium tetrathionate, K₂S₄O₆, and barium tetrathionate hydrate, BaS₄O₆·2H₂O.

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Properties As other species of sulfur at intermediate oxidation state, such as thiosulfate, tetrathionate can be responsible for the pitting corrosion of carbon steel and stainless steel.

Tetrathionate has also been found to serve as a terminal electron acceptor for Salmonella enterica serotype Typhimurium, whereas existing thiosulfate in the of mammals is oxidized by reactive oxygen species released by the immune system (mainly NADPH oxidase produced superoxide) to form tetrathionate. This aids in the growth of the bacterium, helped by the inflammatory response.Winter, Sebastian E. "Gut Inflammation Provides a Respiratory Electron Acceptor for Salmonella." Nature, 23 Sept. 2010. Web. 28 Mar. 2013.

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See also

• Corrosion
• Dithionite
• Polysulfides
• Thiosulfate

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