[1,3-Bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene]dichloro(2-isopropoxyphenylmethylene)ruthenium
[CAS# 301224-40-8]

Identification

• Classification: Organic raw materials >> Organometallic compound >> Organic ruthenium
• Name: [1,3-Bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene]dichloro(2-isopropoxyphenylmethylene)ruthenium
• Synonyms: Hoveyda-Grubbs Catalyst 2nd Generation
• Molecular Formula: C₃₁H₃₈Cl₂N₂ORu
• Molecular Weight: 626.62
• CAS Registry Number: 301224-40-8
• EC Number: 608-446-3
• SMILES: CC1=CC(=C(C(=C1)C)N2CCN(C2=[Ru](=CC3=CC=CC=C3OC(C)C)(Cl)Cl)C4=C(C=C(C=C4C)C)C)C

Properties

• Melting point: 216-220 °C

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H315-H319-H332-H335
• Safety Statements: P261-P280-P305+P351+P338

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Acute toxicity	Acute Tox.	4	H302
Acute toxicity	Acute Tox.	4	H312
Chronic hazardous to the aquatic environment	Aquatic Chronic	4	H413
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	4	H332

Discovery and Applications

[1,3-Bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene]dichloro(2-isopropoxyphenylmethylene)ruthenium is a well-defined organometallic complex belonging to the family of ruthenium-based catalysts used primarily for olefin metathesis reactions. This compound is a type of ruthenium carbene complex characterized by a N-heterocyclic carbene (NHC) ligand derived from the imidazolidinylidene moiety substituted with 2,4,6-trimethylphenyl groups, two chloride ligands, and a benzylidene ligand substituted with an isopropoxy group at the ortho position on the phenyl ring.

The complex is typically synthesized via ligand substitution reactions starting from a suitable ruthenium precursor such as the Grubbs second-generation catalyst or related species. The introduction of the bulky NHC ligand enhances the catalytic activity and stability of the ruthenium center. The presence of the 2-isopropoxyphenylmethylene (benzylidene) ligand provides the active carbene site essential for the initiation of olefin metathesis.

This ruthenium complex is used extensively in olefin metathesis reactions, including ring-closing metathesis (RCM), cross-metathesis (CM), and ring-opening metathesis polymerization (ROMP). Olefin metathesis is a versatile and powerful synthetic tool for forming carbon-carbon double bonds, widely applied in organic synthesis, materials science, and pharmaceutical manufacturing.

The NHC ligand plays a crucial role by stabilizing the ruthenium center through strong σ-donation and steric protection, which improves the catalyst’s lifetime and functional group tolerance compared to phosphine-based analogs. The bulky 2,4,6-trimethylphenyl substituents on the imidazolidinylidene ring enhance the catalyst’s selectivity and prevent decomposition pathways.

The dichloro ligands serve as labile sites that can be displaced or remain coordinated during catalytic cycles. The 2-isopropoxy substitution on the benzylidene ligand can influence catalyst solubility and electronic properties, potentially modifying reactivity and substrate scope.

Applications of this complex are found in the synthesis of pharmaceuticals, fine chemicals, and polymers. It enables the construction of cyclic and acyclic alkenes with precise control over stereochemistry and molecular architecture. In polymer chemistry, it facilitates the preparation of functionalized polymers with tailored properties.

Handling of this ruthenium complex requires inert atmosphere conditions to prevent degradation by moisture or oxygen. It is generally soluble in common organic solvents such as dichloromethane, toluene, and tetrahydrofuran, which are used during catalytic reactions.

In summary, [1,3-Bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene]dichloro(2-isopropoxyphenylmethylene)ruthenium is a specialized ruthenium carbene complex notable for its efficiency and stability as a catalyst in olefin metathesis. Its design incorporating N-heterocyclic carbene and substituted benzylidene ligands underpins its wide utility in synthetic and industrial chemistry.

References

2023. Multi-carbon labelling of active pharmaceutical ingredients enabled by a three-gas surrogate hydroformylation. Nature Synthesis, 2(3).
DOI: 10.1038/s44160-022-00223-0

2023. Triple 13C-labelling via hydroformylation. Nature Synthesis, 2(3).
DOI: 10.1038/s44160-022-00229-8

2020. Formal Synthesis of (±)-Aplykurodinone-1 Based on the Indium-Catalyzed Conia-Ene Reaction. Synlett, 31(10).
DOI: 10.1055/s-0040-1707883