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Iridium(III) chloride is the inorganic compound with the formula IrCl3. The anhydrous compound 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.

Iridium(III) chloride
Iridium(III) chloride
Other names
Iridium trichloride
ECHA InfoCard 100.030.028
EC Number
  • 233-044-6
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)
insoluble (anhydrous IrCl3), soluble (hydrated derivative)
−14.4·10−6 cm3/mol
Monoclinic, mS16
C12/m1, No. 12
-257 kJ/mol
not listed
Flash point non-flammable
Related compounds
Other cations
Rhodium(III) chloride
Related compounds
Platinum(II) 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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Infobox references


Iridium is separated from the other platinum group metals as crystalline ammonium hexachloroiridate, (NH4)2[IrCl6], 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 give iridium(III) chloride. Like the related rhodium compound, IrCl3 adopts the structure seen for aluminium chloride.[1]

Hydrated iridium trichloride is obtained by heating hydrated iridium(III) oxide with hydrochloric acid.


Industrially, most iridium complexes are generated from ammonium hexachloroiridate or the related chloroiridic acid (H2IrCl6) as these salts are the most common commercial forms of iridium chlorides.

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 cyclooctadiene iridium chloride dimer[3][4] and chlorobis(cyclooctene)iridium dimer[4][3] can also be prepared by heating the trichloride with the appropriate alkene in water/alcohol mixtures.


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 978-0-08-037941-8.
  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.