(Pentamethylcyclopentadienyl)iridium(III) chloride dimer
[CAS# 12354-84-6]

Identification

• Classification: Organic raw materials >> Organometallic compound >> Organic iridium
• Name: (Pentamethylcyclopentadienyl)iridium(III) chloride dimer
• Synonyms: Dichloro(pentamethylcyclopentadienyl)iridium(III) dimer
• Molecular Formula: C₂₀H₃₀Cl₄Ir₂
• Molecular Weight: 796.71
• CAS Registry Number: 12354-84-6
• EC Number: 680-648-4
• SMILES: C[C-]1C(=C(C(=C1C)C)C)C.C[C-]1C(=C(C(=C1C)C)C)C.[Cl-].[Cl-].[Cl-].[Cl-].[Ir+3].[Ir+3]

Safety Data

• Hazard Symbols: GHS05;GHS07 Warning
• Risk Statements: H290-H302-H312-H315-H319-H332-H335-H413
• Safety Statements: P234-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-P390-P403+P233-P405-P406-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
Substances or mixtures corrosive to metals	Met. Corr.	1	H290
Acute toxicity	Acute Tox.	4	H312
Acute toxicity	Acute Tox.	4	H302
Chronic hazardous to the aquatic environment	Aquatic Chronic	4	H413
Acute toxicity	Acute Tox.	4	H332

Discovery and Applications

(Pentamethylcyclopentadienyl)iridium(III) chloride dimer is an organoiridium complex with the formula [(C₅Me₅)IrCl₂]₂, where C₅Me₅ represents the pentamethylcyclopentadienyl ligand. This complex features two iridium(III) centers, each coordinated by a pentamethylcyclopentadienyl ligand and two chloride ligands, with the two iridium units bridged by chloride ligands, forming a dimeric structure. The compound typically appears as an orange to red crystalline solid, soluble in common organic solvents like dichloromethane and chloroform.

The compound was first reported during investigations into cyclopentadienyl-based transition metal complexes. The pentamethylcyclopentadienyl ligand (Cp*) stabilizes the iridium(III) center through its η⁵-coordination, providing strong electron donation and steric protection. X-ray crystallographic studies have confirmed the dimeric nature of the complex, showing each iridium center in a pseudo-octahedral environment with the Cp* ligand occupying one face and chlorides completing the coordination sphere.

Preparation of the dimer generally involves the reaction of iridium trichloride hydrate with pentamethylcyclopentadiene under reflux in appropriate solvents, sometimes in the presence of a base to facilitate ligand coordination. The resulting complex is isolated by crystallization or filtration.

This dimer serves as a versatile precursor for various iridium-based catalysts and complexes. The chloride ligands can be substituted by other ligands such as phosphines, nitrogen donors, or carbenes, enabling the synthesis of monomeric or polynuclear complexes with tailored reactivity. Such derivatives are used extensively in homogeneous catalysis including hydrogenation, C–H activation, and transfer hydrogenation.

In addition to catalysis, this complex is important in organometallic synthesis and mechanistic studies, offering insights into the coordination chemistry and reactivity of iridium in the +3 oxidation state with Cp* ligands.

Safety considerations include handling the compound with care due to potential toxicity and irritancy. It should be handled in a well-ventilated area using appropriate personal protective equipment.

In summary, (pentamethylcyclopentadienyl)iridium(III) chloride dimer is a stable dimeric iridium complex with Cp* and chloride ligands. It is widely used as a precursor in organometallic chemistry and homogeneous catalysis due to its structural features and ligand substitution versatility.

References

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