Iridium(III) chloride
Encyclopedia
Iridium 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]).
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
.
The hydrated form is obtained by heating hydrated iridium(III) oxide with hydrochloric acid
.
, trans-[IrCl(CO)(PPh3)2]. Alkene
complexes such as the dimeric {Ir(COD
)Cl}2, and {Ir(cycloctene)2Cl}2 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.
, 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).
Inorganic compound
Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...
with the formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
IrCl3. This material is relatively rare, but the related hydrate
Hydrate
Hydrate is a term used in inorganic chemistry and organic chemistry to indicate that a substance contains water. The chemical state of the water varies widely between hydrates, some of which were so labeled before their chemical structure was understood....
is useful for preparing other iridium
Iridium
Iridium is the chemical element with atomic number 77, and is represented by the symbol Ir. A very hard, brittle, silvery-white transition metal of the platinum family, iridium is the second-densest element and is the most corrosion-resistant metal, even at temperatures as high as 2000 °C...
compounds. The anhydrous salt is a dark green crystalline solid. More commonly encountered is the trihydrate IrCl3(H2O)3 (CAS number [14996-61-3]).
Preparation
Iridium is separated from the other platinum group metalsPlatinum group
The platinum group metals is a term used sometimes to collectively refer to six metallic elements clustered together in the periodic table.These elements are all transition metals, lying in the d-block .The six...
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
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
. The spongy Ir thus produced reacts with chlorine
Chlorine
Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...
at 300-400 °C to produce iridium(III) chloride. Like the related rhodium compound, IrCl3 adopts the structure seen for aluminium chloride
Aluminium chloride
Aluminium chloride is the main compound of aluminium and chlorine. It is white, but samples are often contaminated with iron trichloride, giving it a yellow colour. The solid has a low melting and boiling point. It is mainly produced and consumed in the production of aluminium metal, but large...
.
The hydrated form is obtained by heating hydrated iridium(III) oxide with hydrochloric acid
Hydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....
.
Uses
Hydrated iridium(III) chloride is used in the laboratory for the preparation of other iridium compounds such as Vaska's complexVaska's complex
Vaska's complex is the trivial name for the chemical compound trans-chlorocarbonylbisiridium, which has the formula IrCl[P3]2. This square planar diamagnetic organometallic complex consists of a central iridium atom bound to two mutually trans triphenylphosphine ligands, carbon monoxide, and a...
, trans-[IrCl(CO)(PPh3)2]. Alkene
Alkene
In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...
complexes such as the dimeric {Ir(COD
Cyclooctadiene
A cyclooctadiene is a cyclic diene with the formula C8H12. Focusing only on cis derivatives, four isomers are possible: 1,2, which is an allene, 1,3-, 1,4-, and 1,5-. Commonly encountered isomers are 1,3-cyclooctadiene and 1,5-cyclooctadiene, which is used as a ligand for transition...
)Cl}2, and {Ir(cycloctene)2Cl}2 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.
Safety
Iridium(III) chloride is not listed under Annex I of Directive 67/548/EECDirective 67/548/EEC
The Dangerous Substances Directive is one of the main European Union laws concerning chemical safety. It was made under Article 100 of the Treaty of Rome...
, but is usually classified as irritant
Irritation
Irritation or exacerbation, in biology and physiology, is a state of inflammation or painful reaction to allergy or cell-lining damage. A stimulus or agent which induces the state of irritation is an irritant...
, R36/37/38: Irritating to eyes, respiratory system and skin. It is listed in the inventory of the Toxic Substances Control Act
Toxic Substances Control Act
The Toxic Substances Control Act is a United States law, passed by the United States Congress in 1976, that regulates the introduction of new or already existing chemicals. It grandfathered most existing chemicals, in contrast to the Registration, Evaluation and Authorization of Chemicals ...
(TSCA).