Chloro(1,5-cyclooctadiene)iridium(I) dimer
[CAS# 12112-67-3]

Identification

• Classification: Organic raw materials >> Organometallic compound >> Organic iridium
• Name: Chloro(1,5-cyclooctadiene)iridium(I) dimer
• Synonyms: Bis(1,5-cyclooctadiene)diiridium(I) dichloride
• Molecular Formula: C₁₆H₂₄Cl₂Ir₂
• Molecular Weight: 671.71
• CAS Registry Number: 12112-67-3
• EC Number: 235-170-7
• SMILES: C1/C=CCC/C=CC1.C1/C=CCC/C=CC1.[Cl-].[Cl-].[Ir].[Ir]

Properties

• Melting point: 205 °C (dec.)
• Water solubility: insoluble

Safety Data

• Hazard Symbols: GHS02;GHS07 Warning
• Risk Statements: H252-H302+H312+H332-H302-H312-H315-H319-H332-H335-H413
• Safety Statements: P235-P261-P264-P264+P265-P270-P271-P273-P280-P301+P317-P302+P352-P304+P340-P305+P351+P338-P317-P319-P321-P330-P332+P317-P337+P317-P362+P364-P403+P233-P405-P407-P410-P413-P420-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Acute toxicity	Acute Tox.	4	H302
Acute toxicity	Acute Tox.	4	H312
Acute toxicity	Acute Tox.	4	H332
Eye irritation	Eye Irrit.	2A	H319
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412

Discovery and Applications

Chloro(1,5-cyclooctadiene)iridium(I) dimer is an organoiridium complex with the empirical formula [IrCl(C₈H₁₂)]₂. It consists of two iridium(I) centers, each coordinated by one 1,5-cyclooctadiene (COD) ligand and bridged by two chloride ligands. The compound typically appears as a dark red or brown crystalline solid that is soluble in various organic solvents such as dichloromethane and toluene.

The complex was first characterized during studies of iridium coordination chemistry in the mid-20th century, when researchers explored the bonding of unsaturated hydrocarbons to low-valent transition metals. The dimeric structure with chloride bridges and bidentate COD ligands was confirmed through X-ray crystallographic analysis, revealing square planar geometry around each iridium(I) center, which is typical for d⁸ metal ions.

Chloro(1,5-cyclooctadiene)iridium(I) dimer is commonly prepared by reacting hydrated iridium(III) chloride salts with 1,5-cyclooctadiene under reducing conditions or by direct reaction of iridium metal or iridium precursors in the presence of COD and chloride sources. The synthesis often involves thermal or chemical reduction steps to access the Ir(I) oxidation state and induce dimer formation.

This complex is widely used as a precursor in homogeneous catalysis and organometallic synthesis. The COD ligands are labile and can be displaced by other ligands such as phosphines, amines, or olefins to generate catalytically active monomeric iridium species. It finds applications in catalytic hydrogenation, hydroformylation, C–H activation, and various carbon–carbon bond-forming reactions.

The compound is also valuable for preparing iridium-based catalysts for industrial and synthetic organic chemistry. Its stability and solubility facilitate handling and enable mechanistic studies of iridium-catalyzed transformations.

From a safety perspective, chloro(1,5-cyclooctadiene)iridium(I) dimer should be handled with care due to potential toxicity and reactivity. It may cause irritation upon skin contact or inhalation of dust or vapors, and proper personal protective equipment and ventilation are recommended during handling.

In summary, chloro(1,5-cyclooctadiene)iridium(I) dimer is a stable dimeric iridium(I) complex with bridging chloride ligands and coordinated 1,5-cyclooctadiene. It serves as a widely used precursor to catalytically active iridium species in homogeneous catalysis and organometallic chemistry.

References

2000. Antifungal activity of rhodium, iridium, and ruthenium tripodal phosphine complexes. The new microbiologica, 23(3).
URL: https://pubmed.ncbi.nlm.nih.gov/10946408