Iridium (III) chloride

Crystal structure
__ Ir 3+      __ Cl -
Crystal system	orthorhombic
Space group	Fddd (No. 70) (β modification)
Lattice parameters	a = 6.95 ± 0.02  Å , b = 9.81 ± 0.02 Å, c = 20.82 ± 0.05 Å (β modification)
General
Surname	Iridium (III) chloride
other names	Iridium trichloride Iridium chloride
Ratio formula	IrCl 3
Brief description	olive green powder
External identifiers / databases
CAS number 10025-83-9 14996-61-3 ( hydrate ) EC number 233-044-6 ECHA InfoCard 100.030.028 PubChem 25563 ChemSpider 23837 Wikidata Q418647
properties
Molar mass	298.58 g mol −1
Physical state	firmly
density	5.3 g cm −3
Melting point	763 ° C
solubility	almost insoluble in water and ethanol (anhydrous)
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 319 P: 305 + 351 + 338
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Iridium (III) chloride is a chemical compound . It exists as iridium (III) chloride hydrate IrCl ₃  · x H ₂ O and as iridium (III) chloride anhydrous IrCl ₃ . The hydrate is a dark green, very hygroscopic chemical compound. It serves as the starting material for the production of most other iridium compounds . The anhydrous salt, on the other hand, is insoluble in water.

Extraction and presentation

The anhydrous iridium (III) chloride is produced by chlorinating pure iridium at high temperatures (600 ° C).

${\displaystyle {\ce {2Ir + 3Cl2 -> 2IrCl3}}}$

By smoking an ammonium hexachloroiridate (IV) solution ([NH ₄ ] ₂ [IrCl ₆ ]) with aqua regia and hydrochloric acid and then reducing z. B. with oxalic acid , the iridium (III) chloride hydrate is produced. This must be kept in the absence of air because it is very easy to oxidize to Ir (IV).

properties

Iridium (III) chloride has a standard enthalpy of formation of −257 kJ / mol. It is resistant up to approx. 760 ° C and 1 bar chlorine pressure. There are two modifications , a monoclinically crystallizing α-form and an orthorhombic β-form.

use

Iridium (III) chloride is used as a starting material for the production of most other iridium compounds such as Vaska's complex trans- [IrCl (CO) (PPh ₃ ) ₂ ]) or iridium-alkene complexes such as [Ir (COD) Cl] ₂ , the can be used as catalysts . It is also used to manufacture electrodes in electrochemistry.

Individual evidence

1. ^ Heinrich Remy: Textbook of Inorganic Chemistry Volume I + II, Leipzig 1973.
2. ↑ ^{a b} data sheet iridium (III) chloride from AlfaAesar, accessed on February 3, 2010 ( PDF )(JavaScript required) . .
3. ↑ David R. Lide: CRC Handbook of Chemistry and Physics . 85th edition, 2005, CRC Press, chap. 4, p. 62.
4. ↑ ^{a b} data sheet Iridium (III) chloride from Sigma-Aldrich , accessed on February 3, 2018 ( PDF ).
5. ↑ ^{a b c d} Georg Brauer (Ed.) U. a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume III, Ferdinand Enke, Stuttgart 1981, ISBN 3-432-87823-0 .
6. ↑ A. Meisel, G. Leonhardt: The crystal structure of β-iridium (III) chloride. In: Journal of Inorganic and General Chemistry. 339, 1965, p. 57, doi : 10.1002 / zaac.19653390109 .
7. ↑ Iridium (III) chloride from Heraeus, accessed on September 17, 2011.