Osmium(IV) chloride

Osmium(IV) chloride or osmium tetrachloride is the inorganic compound composed of osmium and chlorine with the empirical formula OsCl₄. It exists in two polymorphs (crystalline forms). The compound is used to prepare other osmium complexes.

Osmium(IV) chloride

Names
IUPAC name Osmium(IV) chloride
Other names Osmium chloride, osmium tetrachloride
Identifiers
CAS Number	10026-01-4 Y
3D model (JSmol)	Interactive image
ChemSpider	3285990
ECHA InfoCard	100.151.226
EC Number	622-467-5
PubChem CID	4070891
UNII	950AA6B72O N
UN number	2471
CompTox Dashboard (EPA)	DTXSID30143075
InChI Key: IHUHXSNGMLUYES-UHFFFAOYSA-J InChI=1S/4ClH.Os/h4*1H;/q;;;;+4/p-4
SMILES Cl[Os](Cl)(Cl)Cl
Properties
Chemical formula	OsCl4
Molar mass	332.041 g/mol
Appearance	red-black orthorhombic crystals
Density	4.38 g/cm3
Melting point	decomposes at 323°C
Solubility in water	reacts with water
Solubility	soluble in hydrochloric acid
Structure
Crystal structure	Orthorhombic, oS10
Space group	Cmmm, No. 65
Related compounds
Other anions	Osmium tetrabromide
Other cations	Iron(III) chloride Ruthenium(III) chloride Osmium(III) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Preparation, structure, reactions

It was first reported in 1909 as the product of chlorination of osmium metal.^[1] This route affords the high temperature polymorph:^[2]

Os + 2 Cl₂ → OsCl₄

This reddish-black polymorph is orthorhombic and adopts a structure in which osmium centres are octahedrally coordinated, sharing opposite edges of the OsCl₆ octahedra to form a chain.^[3] A brown, apparently cubic polymorph forms upon reduction of osmium tetroxide with thionyl chloride:^[4]

OsO₄ + 4 SOCl₂ → OsCl₄ + 2 Cl₂ + 4 SO₂

Osmium tetraoxide dissolves in hydrochloric acid to give the hexachloroosmate anion:

OsO₄ + 10 HCl → H₂OsCl₆ + 2 Cl₂ + 4 H₂O