Dithionate

    The dithionate anion, S₂O₆²⁻, is a sulfur oxoanion derived from dithionic acid, H₂S₂O₆. Its chemical formula is sometimes written in a semistructural format, as [O₃SSO₃]²⁻.

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The sulfur atoms of the dithionate ion are in the +5 oxidation state 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 sulfates and strong reducing agents reduce them to sulfites and dithionites^[1]. Aqueous solutions of dithionates are quite stable and can be boiled without decomposition ^[2].
The γ irradiation of crystalline dithionates produces SO₃⁻ radical ions^[3]. The unpaired electron in the SO₃⁻ radical can be detected with electron paramagnetic resonance and barium dithionate has been proposed as the basis for a radiation dosimeter^[4] The dithionate ion can act as a bidentate ligand ^[5].
The structure of the dithionate ion in the solid state is staggered in Na₂S₂O₆.2H₂O whereas in the anyhydrous potassium salt it is nearly eclipsed^[1].

Compounds

Compounds containing the dithionate ion include:

• sodium dithionate, Na₂S₂O₆
• potassium dithionate, K₂S₂O₆
• barium dithionate, BaS₂O₆

References