Thiosulfuric acid is the inorganic compound with the formula . It has attracted academic interest as a simple, easily accessed compound that is
labile
Lability refers to something that is constantly undergoing change or is likely to undergo change.
Biochemistry
In reference to biochemistry, this is an important concept as far as kinetics is concerned in metalloproteins. This can allow for th ...
. It has few practical uses.
Preparation and degradation
The acid cannot be made by acidifying aqueous
thiosulfate
Thiosulfate ( IUPAC-recommended spelling; sometimes thiosulphate in British English) is an oxyanion of sulfur with the chemical formula . Thiosulfate also refers to the compounds containing this anion, which are the salts of thiosulfuric acid, ...
salt solutions as the acid readily decomposes in water. The decomposition products can include
sulfur,
sulfur dioxide,
hydrogen sulfide,
polysulfane
A polysulfane is a chemical compound of formula , where ''n'' > 1 (although disulfane () is sometimes excluded). Polysulfanes consist of unbranched chains of sulfur atoms terminated with hydrogen atoms. Compounds containing 2 – 8 concatenated ...
s,
sulfuric acid and
polythionates, depending on the reaction conditions.
[.] Anhydrous methods of producing the acid were developed by Max Schmidt:
:
:
:
The anhydrous acid also decomposes above −5 °C:
:
Structure
![HS2O3anion](https://upload.wikimedia.org/wikipedia/commons/c/cc/HS2O3anion.svg)
The isomer is more stable than the isomer as established by
Hartree–Fock/
ab initio calculations with a 6-311 G**
basis set and MP2 to MP4 refinements.
The theoretically predicted structure conforms with the
double bond rule
In chemistry, the double bond rule states that elements with a principal quantum number greater than 2 for their valence electrons ( period 3 elements and higher) tend not to form multiple bonds (e.g. double bonds and triple bonds). The double b ...
.
An isomer of thiosulfuric acid is the
adduct
An adduct (from the Latin ''adductus'', "drawn toward" alternatively, a contraction of "addition product") is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all co ...
of
hydrogen sulfide and
sulfur trioxide, , which can also be prepared at low temperature. It is a white crystalline solid.
References
{{Hydrogen compounds
Hydrogen compounds
Sulfur oxoacids
*