Osmium(IV) chloride

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Osmium(IV) chloride
CAS number 10026-01-4
PubChem 4070891
Jmol-3D images Image 1
Molecular 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
Crystal structure Orthorhombic, oS10
Space group Cmmm, No. 65
Related compounds
Other anions Osmium(IV) oxide
Other cations Iron(III) chloride
Ruthenium(III) chloride
Osmium(III) chloride
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

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.

Preparation, structure, reactions[edit]

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 + 8 HCl → H2OsCl6 + Cl2 + 4 H2O


  1. ^ Otto Ruff and Ferd. Bornemann (1910). "Über das Osmium, seine analytische Bestimmung, seine Oxyde und seine Chloride". Zeitschrift für anorganische Chemie 65: 429–456. doi:10.1002/zaac.19100650126. 
  2. ^ Cotton, S. A. (1997). Chemistry of Precious Metals. London: Chapman and Hall. ISBN 0-7514-0413-6. 
  3. ^ Wells A.F. (1984). "Structural Inorganic Chemistry" (5th ed.). Oxford Science Publications. ISBN 0-19-855370-6. 
  4. ^ Paul Machmer (1967). "On the polymorphism of osmium tetrachloride". Chem. Commun. (12): 610a–610a. doi:10.1039/C1967000610A.