Osmyl tetra-ammine chloride

Osmyl tetra-ammine chloride

Short-lived precipitate of [OsO2(NH3)4]Cl2
Names
IUPAC name TetraamminedioxoOsmium(VI)Chloride
Other names Osmyl tetramminochloride Dioxoosmium(2+) chloride ammoniate (1:2:4)
Identifiers
CAS Number	18496-70-3  N
3D model (JSmol)	Interactive image
ChemSpider	21241731
ECHA InfoCard	100.206.699
EC Number	681-563-5
PubChem CID	56845690
InChI InChI=1S/2ClH.4H3N.2O.Os/h2*1H;4*1H3;;;/q;;;;;;;;+2/p-2 Key: UHBAHWDZFKVBSS-UHFFFAOYSA-L
SMILES N.N.N.N.O=[Os+2]=O.[Cl-].[Cl-](Cl)Cl
Properties
Chemical formula	[OsO2(NH3)4]Cl2
Molar mass	361.3 g/mol
Appearance	Yellow powder [1]
Solubility in water	slightly soluble [2]
Solubility	Insoluble in alcohol, HCl, and solutions of ammonium salts. [3]
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319, H335
Precautionary statements	P261, P264, P264+P265, P271, P280, P302+P352, P304+P340, P305+P351+P338, P319, P321, P332+P317, P337+P317, P362+P364, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Osmyl tetra-ammine chloride (also known as osmyl tetramminochloride ^[3] and tetraamminedioxoosmium (VI) chloride ^[1] ) is an inorganic chemical compound with the formula [OsO₂(NH₃)₄]Cl₂. ^[4]

Synthesis

Osmyl tetra-ammine chloride can be prepared by adding ammonium chloride to a solution of potassium osmate. ^{[4] [3] [5]}

K₂[OsO₂(OH)₄] + 4NH₄Cl → [OsO₂(NH₃)₄]Cl₂ + 2KCl + 4H₂O ^[6]

Properties

Osmyl tetra-ammmine chloride is prone to decomposition. In boiling water it disproportionates to osmium tetroxide and osmium diammine chloride. ^[3] When calcined in hydrogen, it yields osmium metal sponge. ^{[4] [7]}

Despite its low solubility in water, solutions of the tetra-ammine chloride react with potassium ferrocyanide to produce a violet color. ^{[3] [4]}

Uses

Osmyl tetra-ammine chloride was used to recover metallic osmium. However, this application was abandoned in favor of ammonium hexachloroosmate(IV) due to unsatisfactory yields. ^[7] Despite this, it is still readily available to purchase from some chemical suppliers. ^{[1] [8] [9]}

Related compounds

Other osmyl tetra-ammine salts are known, such as the sulfate, nitrate, and oxalate. Their syntheses and characteristics are similar to those of the chloride. ^{[2] [3] [4] [5]}

Their parent base, osmyl tetra-ammine hydroxide, is unstable and known only in solution. ^{[2] [3] [4]}

References

1. "Tetraamminedioxoosmium(VI) Chloride". American Elements . Retrieved 23 June 2025.
2. Comey, Arthur Messinger (1896). A Dictionary of Chemical Solubilities: Inorganic. Macmillan and Company. p. 279. Retrieved 22 June 2025.
3. J.W. Mellor (May 1936). "Osmium". A comprehensive treatise on inorganic and theoretical chemistry, Volume 15. London: Longmans, Green and Co. pp. 706–727. Retrieved 22 June 2025.
4. 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. pp. 216–231. Retrieved 22 June 2025.
5. Prakash Satya (2013). "Platinum Metals-IV:Osmium". Advanced Chemistry of Rare Elements, 5th Ed. India: S Chand and Company Limited. pp. 613–616. Retrieved 24 July 2025.
6. Griffith, William (1967). "Osmium". Chemistry of the Rarer Platinum Metals. Interscience Publishers. p. 82. Retrieved 25 July 2025.
7. 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 22 June 2025.
8. "Tetraamminedioxoosmium(VI) chloride". Stanford Advanced Materials. Retrieved 23 June 2025.
9. "Tetraamminedioxoosmium(VI) chloride". Colonial Metals Inc. Retrieved 23 June 2025.