Sodium aurothiosulfate, or sanocrysin, is the

inorganic compound An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''. Inorgan ...

with the

formula In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwe ...

. It is the trisodium salt of the

coordination complex A coordination complex is a chemical compound consisting of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of chemical bond, bound molecules or ions, that are in turn known as ' ...

of gold(I), . The dihydrate, which is colorless, crystallizes with two waters of crystallization. The compound has some medicinal properties as well as potential for

hydrometallurgy Hydrometallurgy is a technique within the field of extractive metallurgy, the obtaining of metals from their ores. Hydrometallurgy uses solutions to recover metals from ores, concentrates, and recycled or residual materials. Usually the extracti ...

Structure

left, X-ray crystallographic structure of . Color code: red = O, orange = Au, yellow = S, violet = Na. Hydrogen atoms are omitted. The anionic complex features a linear AuS2 core and is overall

centrosymmetric In crystallography, a centrosymmetric point group contains an inversion center as one of its symmetry elements. In such a point group, for every point (x, y, z) in the unit cell there is an indistinguishable point (-x, -y, -z). Such point grou ...

. Like most other thiosulfate complexes, only the planetary sulfur of thiosulfate is coordinated to the metal.

History

The salt is typically prepared by reduction of gold(III) chloride with thiosulfate: : The compound was first synthesized in 1845 by Mathurin-Joseph Fordos and A. Gélis who were researching chemicals used in the

Daguerrotype Daguerreotype was the first publicly available photographic process, widely used during the 1840s and 1850s. "Daguerreotype" also refers to an image created through this process. Invented by Louis Daguerre and introduced worldwide in 1839, t ...

photographic process. It then came to be called Fordos and Gélis salt. It went out of interest until 1924 when it was noted as a chemotherapeutic agent for tuberculosis by Holger Møllgaard in Copenhagen. Other methods of synthesis were then identified.

Potential applications

Like several other gold compounds, this species is used as an antirheumatic. The first placebo-controlled trial was probably conducted in 1931, when sanocrysin was compared with distilled water for the treatment of tuberculosis. Aurothiosulfate complexes have also been discussed in the context of the extraction of

gold Gold is a chemical element; it has chemical symbol Au (from Latin ) and atomic number 79. In its pure form, it is a brightness, bright, slightly orange-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal ...

from its ores. The general approach would employ sodium or ammonium thiosulfate in place of cyanide salts as lixiviants.

References

{{sodium compounds Thiosulfates Gold(I) compounds Sodium compounds Antirheumatic products Metal-containing drugs Gold–sulfur compounds Aurates