Dihydroxydisulfane or hypodithionous acid is a reduced sulfur

oxyacid An oxyacid, oxoacid, or ternary acid is an acid that contains oxygen. Specifically, it is a compound that contains hydrogen, oxygen, and at least one other element, with at least one hydrogen atom bonded to oxygen that can dissociate to produce ...

with sulfur in a formal

oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical Electrical charge, charge of an atom if all of its Chemical bond, bonds to other atoms are fully Ionic bond, ionic. It describes the degree of oxidation (loss of electrons ...

of +1, but the valence of sulfur is 2. The structural formula is , with all atoms arranged in a chain. It is an isomer of

thiosulfurous acid Thiosulfurous acid is a hypothetical chemical compound with the formula HS−S(=O)−OH or HO−S(=S)−OH. Attempted synthesis leads to polymers. It is a low oxidation state (+1) sulfur acid. It is the Arrhenius acid for disulfur monoxide. Salts d ...

but is lower in energy. Other isomers include HOS(=O)SH, HOS(=S)OH, and HS(=O)₂SH.

Disulfur monoxide Disulfur monoxide or sulfur suboxide is an inorganic compound with the formula S2O, one of the lower sulfur oxides. It is a colourless gas and condenses to give a roughly dark red coloured solid that is unstable at room temperature. occurs rar ...

, S₂O, can be considered as the anhydride. Unlike many of these other reduced sulfur acids, dihydroxydisulfane can be formed in a pure state by reacting

hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is toxic, corrosive, and flammable. Trace amounts in ambient atmosphere have a characteristic foul odor of rotten eggs. Swedish chemist ...

with

sulfur dioxide Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is r ...

at −70 °C in

dichlorodifluoromethane Dichlorodifluoromethane (R-12) is a colorless gas popularly known by the genericized brand name Freon (as Freon-12). It is a chlorofluorocarbon halomethane (CFC) used as a refrigerant and aerosol spray propellant. In compliance with the Montreal ...

. :H₂S + SO₂ → H₂S₂O₂ Dihyroxydisulfane may exist in an equilibrium with thiosulfurous acid. Organic derivatives such as dimethoxydisulfane, diaceto disulfide, and bis(trifluoroaceto) disulfide also exist. The conjugate bases are called disulfanediolate and hypodithionite .

Properties

Calculations predict that the S−S bond length is 2.013 Å, O−S bond length is 1.645 Å, H−O bond length is 0.943 Å.

Related compounds

Related compounds include the isoelectronic substances

hydrogen tetroxide Tetraoxidane is an inorganic compound of hydrogen and oxygen with the chemical formula . This is one of the unstable hydrogen polyoxides. Synthesis The compound is prepared by a chemical reaction between hydroperoxyl radicals () at low temperatur ...

HOOOOH, hydroxotrisulfane HOSSSH, HSOSSH, and tetrasulfane HSSSSH.

References

Sulfur oxoacids Disulfides {{Inorganic-compound-stub