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
3D model (JSmol)
ECHA InfoCard100.151.226 Edit this at Wikidata
UNII
  • InChI=1S/4ClH.Os/h4*1H;/q;;;;+4/p-4
  • Cl[Os](Cl)(Cl)Cl
Properties
OsCl4
Molar mass332.041 g/mol
Appearancered-black orthorhombic crystals
Density4.38 g/cm3
Melting pointdecomposes at 323°C
reacts with water
Solubilitysoluble in hydrochloric acid
Structure
Orthorhombic, oS10
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).
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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 + 2 SOCl2 → OsCl4 + 2 Cl2 + 2 SO2

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

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

References