Iridium(III) chloride

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Iridium(III) chloride
Iridium(III) chloride
CAS number 10025-83-9 YesY
PubChem 82301
ChemSpider 23837 N
EC number 233-044-6
Molecular formula IrCl3
Molar mass 298.58 g/mol (anhydrous)
Appearance dark green solid
Density 5.30 g/cm3, solid
Melting point 763 °C (1,405 °F; 1,036 K) (decomposes)
Solubility in water insoluble (anhydrous IrCl3), soluble (hydrated derivative)
Crystal structure Monoclinic, mS16
Space group C12/m1, No. 12
Std enthalpy of
-257 kJ/mol
EU classification not listed
Flash point non-flammable
Related compounds
Other cations Rhodium(III) chloride
Related compounds Platinum(II) 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

Iridium(III) chloride is the inorganic compound with the formula IrCl3. This material is relatively rare, but the related hydrate is useful for preparing other iridium compounds. The anhydrous salt is a dark green crystalline solid. More commonly encountered is the trihydrate IrCl3(H2O)3 (CAS number [14996-61-3]).


Iridium is separated from the other platinum group metals as crystalline ammonium hexachloroiridate(IV), (NH4)2[IrCl6] (CAS number [16940-92-4]), which can be reduced to iridium metal in a stream of hydrogen. The spongy Ir thus produced reacts with chlorine at 300–400 °C to produce iridium(III) chloride. Like the related rhodium compound, IrCl3 adopts the structure seen for aluminium chloride.[1]

The hydrated form is obtained by heating hydrated iridium(III) oxide with hydrochloric acid.


Hydrated iridium(III) chloride is used in the laboratory for the preparation of other iridium compounds such as Vaska's complex, trans-[IrCl(CO)(PPh3)2].[2] Alkene complexes such as the dimeric {Ir(COD)Cl}2[3][4] and {Ir(cyclooctene)2Cl}2[4][3] can also be prepared by heating the trichloride with the appropriate alkene in water/alcohol mixtures. Industrially, most iridium complexes are generated from H2IrCl6 or (NH4)2IrCl6 as these salts are the most common commercial forms of iridium chlorides, being directly obtained in the purification of iridium.


Iridium(III) chloride is not listed under Annex I of Directive 67/548/EEC, but is usually classified as irritant, R36/37/38: Irritating to eyes, respiratory system and skin. It is listed in the inventory of the Toxic Substances Control Act (TSCA).


  1. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0080379419. 
  2. ^ Vaska, L.; & DiLuzio, J. W. (1961) J. Am. Chem. Soc. 83:2784. Girolami, G.S.; Rauchfuss, T.B.; Angelici, R.J. (1999). Synthesis and Technique in Inorganic Chemistry (3rd Edn.). Sausalito:University Science Books.
  3. ^ a b Winkhaus, G.; & Singer, H. (1966). Iridium(I)-Olefinkomplexe. Chem. Ber. 99:3610–18.
  4. ^ a b Herde, J. L.; Lambert, J. C.; & Senoff, C. V. (1974). Cyclooctene and 1,5-Cyclooctadiene Complexes of Iridium(I). Inorg. Synth. 1974, volume 15, pages 18–20. doi:10.1002/9780470132463.ch5.