Sodium_aurothiosulfate

Sodium aurothiosulfate

Sodium aurothiosulfate

Chemical compound


Sodium aurothiosulfate, or sanocrysin, is the inorganic compound with the formula Na3[Au(S2O3)2]·2H2O. It is the trisodium salt of the coordination complex of gold(I), [Au(S2O3)2]3−. The dihydrate, which is colorless, crystallizes with two waters of crystallization. The compound has some medicinal properties as well as potential for hydrometallurgy.

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Structure

X-ray crystallographic structure of Na3[Au(S2O3)2]·2H2O. 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. 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]

4 Na2S2O3 + AuCl3 → Na3[Au(S2O3)2] + Na2S4O6 + 3 NaCl

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

  1. 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.
  2. 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.
  3. Ruben H, Zalkin A, Faltens MO, Templeton DH (1974). "Crystal structure of sodium gold(I) thiosulfate dihydrate, Na3Au(S2O3)2.2H2O". Inorganic Chemistry. 13 (8): 1836–1839. doi:10.1021/ic50138a011.
  4. Fordos MJ, Gélis A (1843). "Recherches sur la liqueur d'or employée en photographie". C.-R. Acad. Sc. (Paris). 17: 629–630.
  5. Fordos MJ, Gélis A (1845). "Action du perchlorure d'or sur l'hyposulfite de soude". Ann. Chim. Phys. 3. 13: 394–404.
  6. McCluskey KL, Eichelberger L (1926). "New methods for the preparation of sodium aurothiosulfate". Journal of the American Chemical Society. 48 (1): 136–139. doi:10.1021/ja01412a018. ISSN 0002-7863. S2CID 101829332.
  7. Shaw III CF (September 1999). "Gold-based therapeutic agents". Chemical Reviews. 99 (9): 2589–2600. doi:10.1021/cr980431o. PMID 11749494.
  8. Emanuel EJ, Crouch RA, Arras JD, Moreno JD, Grady C, eds. (2003). Ethical and regulatory aspects of clinical research: readings and commentary. Johns Hopkins University Press. p. 140. ISBN 978-0801878138.
  9. Aylmore MG, Muir DM (2001). "Thiosulfate Leaching of Gold - a Review". Minerals Engineering. 14 (2): 135–174. doi:10.1016/s0892-6875(00)00172-2.
  10. Barbera JJ, Metzger A, Wolf M. "Sulfites, Thiosulfates, and Dithionites". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a25_477. ISBN 978-3527306732.

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