Tris(dibenzylideneacetone)dipalladium-chloroform adduct
[CAS# 52522-40-4]

Identification

• Classification: Organic raw materials >> Organometallic compound >> Organic palladium
• Name: Tris(dibenzylideneacetone)dipalladium-chloroform adduct
• Molecular Formula: C₅₂H₄₃Cl₃O₃Pd₂
• Molecular Weight: 1035.09
• CAS Registry Number: 52522-40-4
• EC Number: 610-856-2
• SMILES: C1=CC=C(C=C1)/C=C/C(=O)/C=C/C2=CC=CC=C2.C1=CC=C(C=C1)/C=C/C(=O)/C=C/C2=CC=CC=C2.C1=CC=C(C=C1)/C=C/C(=O)/C=C/C2=CC=CC=C2.C(Cl)(Cl)Cl.[Pd].[Pd]

Properties

• Melting point: 131-135 °C (Expl.)

Safety Data

• Hazard Symbols: GHS07;GHS08 Warning
• Risk Statements: H302-H315-H351-H373
• Safety Statements: P203-P260-P264-P270-P280-P301+P317-P302+P352-P318-P319-P321-P330-P332+P317-P362+P364-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Carcinogenicity	Carc.	2	H351
Acute toxicity	Acute Tox.	4	H302
Skin irritation	Skin Irrit.	2	H315
Flammable solids	Flam. Sol.	1	H228
Acute toxicity	Acute Tox.	3	H311
Acute toxicity	Acute Tox.	3	H301

Discovery and Applications

Tris(dibenzylideneacetone)dipalladium-chloroform adduct, commonly referred to as Pd2(DBA)3·CHCl3, is a well-established organopalladium complex that has been extensively studied in the field of catalysis. This compound consists of a dimer of palladium (Pd), coordinated with three dibenzylideneacetone (DBA) ligands, and the structure is further stabilized by the presence of chloroform (CHCl3) as a solvent molecule.

The discovery of this compound emerged from the broader interest in organopalladium chemistry, particularly in relation to the development of palladium-catalyzed reactions. The use of palladium as a catalyst for various organic transformations has been a significant area of research since the mid-20th century, and Pd2(DBA)3·CHCl3 is a direct result of this effort to enhance the reactivity and stability of palladium complexes.

The core feature of Pd2(DBA)3·CHCl3 is the presence of the DBA ligands, which are bidentate chelating agents. These ligands coordinate to the palladium centers, forming a stable structure that is capable of facilitating a variety of catalytic reactions. The chloroform molecule is typically not directly involved in the catalysis but serves to solvate the palladium complex and maintain the stability of the structure in solution. This adduct is commonly used as a catalyst precursor in several important organic reactions, including cross-coupling reactions such as the Heck reaction.

One of the most prominent applications of Pd2(DBA)3·CHCl3 is in the Heck reaction, a widely used method for the formation of carbon-carbon bonds between aryl or vinyl halides and alkenes. The Pd2(DBA)3·CHCl3 complex is a particularly useful catalyst precursor in this reaction due to the stabilizing effect of the DBA ligands and the ability of the palladium center to undergo the required oxidative addition and reductive elimination steps. The DBA ligands help prevent catalyst deactivation and promote high catalytic activity under a range of reaction conditions.

In addition to the Heck reaction, Pd2(DBA)3·CHCl3 has also been used in other important catalytic processes such as the Suzuki-Miyaura coupling, which enables the formation of biaryl compounds, and the Buchwald-Hartwig amination, which is crucial for the formation of carbon-nitrogen bonds. These reactions are of great importance in the pharmaceutical, agrochemical, and materials science industries, as they allow for the synthesis of a wide array of complex organic molecules.

The complex Pd2(DBA)3·CHCl3 is known for its excellent stability, which makes it particularly attractive in catalytic processes that require long reaction times or harsh conditions. The presence of the chloroform solvent molecule ensures that the palladium centers remain well-solvated and active throughout the reaction. This stability, combined with the effectiveness of the DBA ligands in stabilizing the palladium metal, makes Pd2(DBA)3·CHCl3 a versatile and reliable catalyst in synthetic organic chemistry.

Another important application of Pd2(DBA)3·CHCl3 is in the formation of other organometallic compounds. The complex has been used as a precursor for the synthesis of more reactive palladium species in various reaction setups. By manipulating the reaction conditions, researchers can achieve the selective formation of palladium complexes with different ligand environments, which are essential for targeting specific reactions or improving catalytic efficiency.

In summary, Pd2(DBA)3·CHCl3 is a highly valuable catalyst precursor in organopalladium chemistry. Its discovery has significantly contributed to the advancement of palladium-catalyzed reactions, particularly in carbon-carbon and carbon-nitrogen bond formation. The unique structure of this complex, with its stabilizing DBA ligands and solvating chloroform molecule, makes it an essential tool in the synthesis of complex organic molecules, with broad applications in the fields of pharmaceuticals, materials science, and industrial chemistry.

References

2023. Recent Advances in Palladium-Catalyzed [4 + n] Cycloaddition of Lactones, Benzoxazinanones, Allylic Carbonates, and Vinyloxetanes. Topics in Current Chemistry, 381(6).
DOI: 10.1007/s41061-023-00442-9

2022. Multilayer stacks of polycyclic aromatic hydrocarbons. Nature Chemistry, 14(4).
DOI: 10.1038/s41557-021-00861-5