(Acetylacetonato)dicarbonyliridium
[CAS# 14023-80-4]

Identification

• Classification: Organic raw materials >> Organometallic compound >> Organic iridium
• Name: (Acetylacetonato)dicarbonyliridium
• Synonyms: Dicarbonylacetylacetonatoiridium(I)
• Molecular Formula: C₇H₇IrO₄
• Molecular Weight: 347.35
• CAS Registry Number: 14023-80-4
• EC Number: 621-500-0
• SMILES: CC(=O)/C=C(/C)O[Ir].[C-]#[O+].[C-]#[O+]

Properties

• Melting point: >145 °C

Safety Data

• Hazard Symbols: GHS07;GHS08 Warning
• Risk Statements: H302-H312-H315-H319-H332-H335-H361
• Safety Statements: P203-P261-P264-P264+P265-P270-P271-P280-P301+P317-P302+P352-P304+P340-P305+P351+P338-P317-P318-P319-P321-P330-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H312
Acute toxicity	Acute Tox.	4	H302
Skin irritation	Skin Irrit.	2	H315
Reproductive toxicity	Repr.	2	H361
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	4	H332
Specific target organ toxicity - single exposure	STOT SE	3	H335

Discovery and Applications

(Acetylacetonato)dicarbonyliridium, often referred to as Ir(acac)(CO)₂, is an organometallic coordination complex consisting of an iridium center bonded to an acetylacetonate ligand and two carbonyl (CO) groups. In this complex, the iridium is typically in the +1 oxidation state, coordinated in a square planar or slightly distorted geometry, characteristic of low-spin d⁸ transition metal complexes.

The acetylacetonate (acac) ligand acts as a bidentate chelating ligand, binding to the iridium through two oxygen atoms from the β-diketone functional group. This chelation stabilizes the complex and influences its electronic and steric properties. The two carbonyl ligands bind via their carbon atoms to the iridium center, providing strong metal-to-ligand back-donation, which affects the complex’s reactivity and spectroscopic features.

Synthesis of (acetylacetonato)dicarbonyliridium generally involves the reaction of iridium precursors such as iridium trichloride or dicarbonyl iridium complexes with acetylacetone under controlled conditions. Carbonylation or ligand substitution reactions introduce the carbonyl groups, often performed under CO atmosphere or by using CO-releasing reagents. The product is typically isolated as a crystalline solid, soluble in organic solvents such as dichloromethane or toluene.

This complex is widely used in organometallic chemistry as a catalyst or catalyst precursor. The combination of a stable chelating acac ligand and labile carbonyl groups makes it versatile for catalytic transformations involving hydrogenation, hydroformylation, and carbonylation reactions. The carbonyl ligands can be displaced under reaction conditions, allowing substrate coordination and activation at the metal center.

In addition to catalytic applications, (acetylacetonato)dicarbonyliridium is used in mechanistic studies and synthesis of other iridium complexes. Its well-defined structure facilitates spectroscopic investigations such as infrared and nuclear magnetic resonance spectroscopy, aiding understanding of metal-ligand interactions and electronic properties.

The compound’s stability and reactivity are influenced by the strong chelation of the acac ligand and the π-acceptor ability of the CO ligands. These features make it a useful model compound in exploring the chemistry of iridium carbonyl complexes and their potential in industrial and synthetic applications.

Handling (acetylacetonato)dicarbonyliridium requires standard laboratory safety measures typical for organometallic carbonyl compounds, including use of gloves and fume hoods to avoid exposure to toxic metal complexes and carbon monoxide released under decomposition.

In summary, (acetylacetonato)dicarbonyliridium is a square planar iridium(I) complex coordinated by a bidentate acetylacetonate ligand and two carbonyl ligands. It is synthesized via ligand substitution or carbonylation of iridium precursors and serves as a versatile catalyst precursor and research compound in organometallic chemistry, valued for its stability and reactive carbonyl ligands.

References

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