The dithionate (or metabisulfate)

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

, , is a

sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formul ...

oxoanion derived from dithionic acid, H₂S₂O₆. Its

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

is sometimes written in a semistructural format, as ₃SSO₃sup>2−. It is the first member of the

polythionates Polythionates are oxoanions with the formula (''n'' ≥ 0). They occur naturally and are the products of redox reactions of thiosulfate. Polythionates are readily isolable, unlike the parent polythionic acids. Preparation Many members of the poly ...

. The sulfur atoms of the dithionate ion are in the +5

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. ...

due to the presence of the S–S bond. Generally, dithionates form stable compounds that are not readily oxidised or reduced. Strong oxidants oxidise them to

sulfate The sulfate or sulphate ion is a polyatomic ion, polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salt (chemistry), ...

s and strong reducing agents reduce them to sulfites and

dithionite The dithionite is the oxyanion with the formula 2O4sup>2−. It is commonly encountered as the salt sodium dithionite. For historical reasons, it is sometimes called hydrosulfite, but it contains no hydrogen and is not a sulfite. The diani ...

s. Aqueous solutions of dithionates are quite stable and can be boiled without decomposition. The γ-irradiation of crystalline dithionates produces radical ions. The unpaired electron in the radical can be detected with

electron paramagnetic resonance Electron paramagnetic resonance (EPR) or electron spin resonance (ESR) spectroscopy is a method for studying materials that have unpaired electrons. The basic concepts of EPR are analogous to those of nuclear magnetic resonance (NMR), but the sp ...

and barium dithionate has been proposed as the basis for a radiation dosimeter. The dithionate ion can act as a bidentate

ligand In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's ele ...

.''Structures of Some Copper (II) Complexes Containing Ion'' Ishii M. ''Bulletin of the Yamagata University'' 5, 1,(2001), 7 The structure of the dithionate ion in the solid state is

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in Na₂S₂O₆·2H₂O, whereas in the anhydrous potassium salt it is nearly eclipsed.

Compounds

Compounds containing the dithionate ion include: * sodium dithionate, Na₂S₂O₆ * potassium dithionite, K₂S₂O₆ * barium dithionate, BaS₂O₆

References

External links

{{commons category-inline, Dithionate ion Sulfur oxyanions