Ammonium hexachloroosmate(IV)
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2OsCl6(s).jpg) Microcrystals of ammonium hexachloroosmate | |
| Names | |
|---|---|
| IUPAC name
Ammonium hexachloroosmate(IV) | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.031.977 |
| EC Number |
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PubChem CID |
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CompTox Dashboard (EPA) |
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| Properties | |
| Cl6H8N2Os | |
| Molar mass | 439.01 g·mol−1 |
| Appearance | red crystals |
| Density | 2.93 g/cm3 |
| Melting point | 170 |
| poorly soluble | |
| Hazards | |
| GHS labelling: | |
 [1] | |
| Warning | |
| NFPA 704 (fire diamond) | |
| Related compounds | |
Other anions |
Ammonium hexachloroplatinate, Ammonium hexachloropalladate, Ammonium hexachloroiridate |
Other cations |
Sodium hexachloroosmate, Potassium hexachloroosmate, 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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Ammonium hexachloroosmate(IV) is an inorganic chemical compound with the chemical formula (NH4)2OsCl6.[3][4]
Ammonium hexachloroosmate(IV) can be produced by the reduction of osmium tetroxide or potassium osmate with iron dichloride in hydrochloric acid in the presence of ammonium ions:[5][6][7]
- OsO4 + 4FeCl2 + 8HCl + 2NH4Cl → (NH4)2[OsCl6] + 3FeCl3 + 4H2O
- K2[OsO2(OH)4] + FeCl2 + 2NH4Cl conc hcl
———→ (NH4)2OsCl6 + FeCl3 + 4H2O + 2KCl
It can also be prepared by addition of an ammonium chloride solution to hexachloroosmic acid,[8] or by addition of ammonium chloride to a solution of sodium hexachloroosmate.[9]
Physical properties
Ammonium hexachloroosmate(IV) forms dark red crystals of the cubic system,[10] space group Fm3m, cell parameters a = 0.9729 nm, Z = 4.
It is poorly soluble in cold water.[11]
Chemical properties
The compound is reduced by hydrogen to metallic osmium:[12][13]
- 3(NH4)2[OsCl6] → 3Os + 2N2 + 16HCl + 2NH4Cl
- (NH4)2[OsCl6] + 2H2 → Os + NH4Cl + 4HCl
When exposed to strong alkali, ammonium hexachloroosmate reacts to produce osmium oxydiammine dihydroxide, OsO(NH3)2(OH)2.[9]
Ammonium hexachloroosmate is stable in hydrochloric acid, but it is oxidized by nitric acid, forming osmium tetroxide.[14]