IrCl4

Iridium tetrachloride (IrCl4) is an inorganic compound of iridium in the +4 oxidation state. It is typically discussed as a coordination compound and can exist as an anhydrous solid or as solvates with donor ligands. In practice, IrCl4 is prepared by chlorination of iridium metal or lower-valent iridium chlorides under an atmosphere of chlorine, in an anhydrous solvent. The compound is sensitive to moisture and air; hydrolysis and oxidation can lead to iridium oxychloride species and polymeric chlorides.

In solid form IrCl4 often exists as polymeric aggregates, with chloride ligands bridging between iridium centers; in solution it forms various coordination complexes with donor ligands, including solvent molecules. The chemistry of IrCl4 and its derivatives is relevant to the preparation of more complex iridium coordination compounds and catalysts, as a starting material for ligand substitution reactions that furnish Ir(III) and Ir(V) species.

Applications of IrCl4 include serving as a precursor to organoiridium compounds and as a research reagent in inorganic synthesis and catalysis. Its reactivity is typical of high-oxidation-state metal chlorides: it engages in ligand substitution and oxidation reactions, enabling formation of diverse coordination environments.

Safety: Iridium compounds are relatively low in toxicity compared to many heavy metals, but IrCl4 is corrosive and moisture-sensitive. Chlorine gas and chlorides require appropriate handling in a fume hood, with protective equipment to avoid inhalation or contact.