Chloroosmic acid
 Solution of chloroosmic acid
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| Names | |
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| IUPAC name
Dihydrogen hexachloroosmate(2-)
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Other names
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| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.043.797 |
| EC Number |
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PubChem CID
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| Properties | |
| Cl6H2Os | |
| Molar mass | 404.95 g·mol−1 |
| very soluble | |
| Hazards | |
| GHS labelling:[1] | |
 
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| Danger | |
| H301, H311, H314, H331 | |
| P260, P262, P264, P264+P265, P270, P271, P280, P301+P316, P301+P330+P331, P302+P352, P302+P361+P354, P304+P340, P305+P354+P338, P316, P317, P321, P330, P361+P364, P363, P403+P233, P405, P501 | |
| Related compounds | |
Other anions
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Hexachloroplatinic acid |
Other cations
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Sodium hexachloroosmate, Potassium hexachloroosmate, Ammonium hexachloroosmate(IV) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Chloroosmic acid (also known as hexachloroosmic acid, and dihydrogen hexachloroosmate) is an inorganic chemical compound with the chemical formula H2OsCl6. It exists as a dark deliquescent solid. It forms a hexahydrate.[1]
Synthesis
[edit]Hexachloroosmic acid can be prepared by reducing osmium tetroxide in hydrochloric acid with alcohol and heating.[2][3] Ferrous chloride is sometimes used in place of alcohol.[4]
- OsO4 + 4FeCl2 + 10HCl → H2OsCl6 + 4FeCl3 + 4H2O
Another way of preparing it is by dissolving osmium dioxide in hydrochloric acid.[5]
- OsO2 + 6HCl → H2OsCl6 + 2H2O[6]
Properties
[edit]Owing to its deliquesent nature, solutions of hexachloroosmic acid can be evaporated down to a syrup without crystallization.[2] As an acid, it is corrosive.
Reactions
[edit]When strong alkali is added to hexachloroosmic acid, it decomposes and precipitates osmium dioxide.[5][3]
It also reacts with alkali chlorides to yield hexachloroosmate salts, such as ammonium hexachloroosmate(IV).[2]
The coordination complex [H(DMSO)2]2(OsCl6) can be made by reacting chloroosmic acid in ethanol with dimethyl sulfoxide.[7]
Salts
[edit]Hexachloroosmates vary in color both in and out of solution depending on the cation. While solutions of the acid possess an amber-orange color, solutions of hexachloroosmate salts are yellow, sodium being the exception which forms deep red solutions. When isolated the sodium, potassium, rubidium, and ammonium salts are all red, while the cesium, silver, and thallium salts are orange, green-brown, and orange-green respectively. It also forms salts with many complex organic cations, yielding yellow, orange, red, and brown crystals.[8][9]
References
[edit]- ^ "Dihydrogen hexachloroosmate (IV) hexahydrate". Strem Catalog. Retrieved 19 June 2025.
- ^ a b c Gilchrist, Raleigh (June 8, 1932). "A new determination of the atomic weight of Osmium" (PDF). Bureau of Standards Journal of Research. 9 (3): 279–290. doi:10.6028/jres.009.021. Retrieved 19 June 2025.
- ^ a b Gilchrist, Raleigh (1931). "A method for the separation and gravimetric determination of osmium" (PDF). J Res Bur Stand. 6 (3): 421–448. doi:10.6028/jres.006.028. Retrieved 19 June 2025.
- ^ Buckingham, D.A. (1961). Preparation and Oxidation-Reduction Potentials of Some Osmium Compounds (PhD thesis). Australian National University. p. 4.
- ^ a b Stopinski, Orin (September 1977). "Platinum-Group Metals" (PDF). Environmental Health Effects Research Series. Washington, DC: Environmental Protection Agency: 85–86. Retrieved 19 June 2025.
- ^ Sidgwick, N.V. (1950). The Elements and Their Compounds (PDF). Vol. 2. London: Oxford University Press. p. 1494. Retrieved 20 November 2025.
- ^ Rudnitskaya, O.V.; Kultyshkina, E.K.; Dobrokhotova, E.V.; Anan'ev I.V. (2014). "Synthesis and Structure of [H(DMSO)2]2[OsX6] (X=Cl, Br)". Russian Journal of Coordination Chemistry. 20: 911–912. Retrieved 21 November 2025.
- ^ Griffith, W.P. "Osmium and its Compounds". Quarterly Reviews, Chemical Society. 19: 254–273. Retrieved 18 June 2026.
- ^ J.W. Mellor (May 1936). "Osmium". A comprehensive treatise on inorganic and theoretical chemistry, Volume 15. London: Longmans, Green and Co. pp. 718–720. Retrieved 18 June 2026.