Potassium hexachloroosmate
 K2OsCl6 in an evaporating dish
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| Identifiers | |
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3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.037.160 |
| EC Number |
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PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| K2OsCl6 | |
| Molar mass | 481.13 g/mol |
| Appearance | Dark red to black solid |
| Density | 2.03 g/cm3 |
| slightly soluble | |
| Hazards | |
| GHS labelling:[1] | |
  
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| Danger | |
| H301, H302, H311, H314, H331, H335 | |
| P260, P261, P262, P264, P264+P265, P270, P271, P280, P301+P316, P301+P317, P301+P330+P331, P302+P352, P302+P361+P354, P304+P340, P305+P354+P338, P316, P317, P319, P321, P330, P332+P317, P337+P317, P361+P364, P363, P403+P233, P405, P501 | |
| Related compounds | |
Other anions
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Potassium hexachloroplatinate, Potassium hexachloropalladate(IV) |
Other cations
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Sodium hexachloroosmate, Ammonium hexachloroosmate(IV), Hexachloroosmic acid |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Potassium hexachloroosmate is an inorganic chemical compound with the chemical formula K2OsCl6. It is a darkly colored solid with limited solubility in water.
Synthesis
[edit]There are several methods for producing potassium hexachloroosmate. The first involves reducing osmium tetroxide to chloroosmic acid with hydrochloric acid and alcohol, followed by addition of potassium chloride.[1]
It can also be obtained by heating finely divided osmium metal with potassium chloride and chlorine.
Addition of potassium chloride to a solution of sodium hexachloroosmate will precipitate this salt, and the last method involves treating potassium osmyl oxynitrite with hydrochloric acid.[2]
Properties
[edit]
Potassium hexachloroosmate forms dark red octahedral crystals of the space group Fm3m, which produce a dark yellow color when dissolved in water. The crystal structure is isomorphic to the corresponding cations of palladium, platinum, and iridium. It is slightly soluble in water, and is insoluble in saline solutions as well as alcohol.[3][1]
Potassium hexachloroosmate is most stable in acidic solutions, although with nitric acid it reacts to form osmium tetroxide. It slowly hydrolyses in water yielding osmium dioxide, and in strong alkali it also decomposes to the dioxide.[4][5]
Reactions
[edit]Potassium hexachloroosmate reacts with a variety of reagents to produce different compounds. It reacts with pyridine and hydrazine to form Os(py)2Cl4 and Os(NH3)5N2 respectively. When it reacts with a mixture of nitrogen dioxide, nitric oxide, and hydrochloric acid, Os(NO)Cl5 is formed. Sodium phosphate and borax both react with it to yield the dioxide.[6][5]
The reaction of K2OsCl6 with BrF3 results in a stepwise substitution.[6]
- OsCl2−
6 → OsCl5F2−
→ cis-OsCl4F2−
2 → fac-OsCl3F2−
3 → cis-OsCl2F2−
4 → OsClF2−
5 → OsF2−
6
The reaction time determines which isomers are obtained and in which ratio they're present. Advantageously, the stronger trans effect of the chloride ion can yield the following reaction:[6]
- cis-OsCl2F2−
4 → mer-OsCl3F2−
3
- cis-OsCl2F2−
References
[edit]- ^ a b Turner, A.G.; Clifford, A.F.; Ramchandra Rao, C.N. (October 1, 1958). "Potassium Hexachloroosmate, K2OsCl6, and Potassium Hexabromoosmate, K2OsBr6". Analytical Chemistry. 30 (10): 1708–1709. doi:10.1021/ac60142a602. Retrieved 6 October 2025.
- ^ J. Newton Friend (1920). "Osmium and its compounds". A textbook of inorganic chemistry, vol.IX Part I Cobalt, Nickel, and The Elements of The Platinum Group (PDF). London: Charles Griffin and Company, Limited. p. 216. Retrieved 6 October 2025.
- ^ Fremy, Edmund. (1900). "Osmium". Encyclopédie chimique.Tome III.- Métaux. 17e cahier : platine et métaux qui l'accompagnent. Paris : Dunod. pp. 36–40. Retrieved 6 October 2025.
{{cite book}}: CS1 maint: publisher location (link) - ^ Jones, Terence (June 2002). "Electrodeposition of Osmium". Metal Finishing. 100 (6): 85. doi:10.1016/S0026-0576(02)80443-3. Retrieved 7 October 2025.
- ^ a b J.W. Mellor (May 1936). "Osmium". A comprehensive treatise on inorganic and theoretical chemistry, Volume 15. London: Longmans, Green and Co. p. 718. Retrieved 7 October 2025.
- ^ a b c Cotton, S. A. (1997). "Ruthenium and Osmium". Chemistry of Precious Metals (PDF). Rutland, UK: Blackie Academic & Professional. pp. 11–12. Retrieved 7 October 2025.