Sodium aurothiosulfate, or sanocrysin, is the
inorganic compound with the
formulaNa3[Au(S2O3)2]·2H2O. It is the trisodium salt of the
coordination complex of gold(I), [Au(S2O3)23−. The dihydrate, which is colorless, crystallizes with two
waters of crystallization. The compound has some medicinal properties as well as potential for
hydrometallurgy.
Structure
The anionic complex features a linear AuS2 core and is overall
centrosymmetric. Like most other
thiosulfate complexes, only the planetary sulfur of thiosulfate is coordinated to the metal.[1][2][3]
History
The salt is typically prepared by reduction of gold(III) chloride with thiosulfate:[3]
The compound was first synthesized in 1845 by
Mathurin-Joseph Fordos and A. Gélis who were researching chemicals used in the
Daguerrotype photographic process. It then came to be called Fordos and Gélis salt.[4][5] It went out of interest until 1924 when it was noted as a chemotherapeutic agent for tuberculosis by Holger Møllgaard in Copenhagen.[6] Other methods of synthesis were then identified.[7]
Potential applications
Like several other gold compounds, this species is used as an
antirheumatic.[8] The first placebo-controlled trial was probably conducted in 1931, when sanocrysin was compared with distilled water for the treatment of tuberculosis.[9]
Aurothiosulfate complexes have also been discussed in the context of the extraction of
gold from its ores. The general approach would employ sodium or ammonium thiosulfate in place of cyanide salts as
lixiviants.[10][11]
References
^Baggio RF, Baggio S (1973). "Crystal and molecular structure of trisodium dithiosulphate aurate(I), dihydrate, Na3[Au(S2O3)2],2H2O". Journal of Inorganic and Nuclear Chemistry. 35 (9): 3191–3200.
doi:
10.1016/0022-1902(73)80019-3.
^Tobön-Zapata G, Etcheverry SB, Baran EJ (1997). "Vibrational spectrum of Sanocrysin". Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 53 (2): 183–188.
Bibcode:
1997AcSpA..53..183T.
doi:
10.1016/S1386-1425(97)83024-7.