Palladium(II) acetylacetonate
[CAS# 14024-61-4]

Identification

• Classification: Organic raw materials >> Organometallic compound >> Organic palladium
• Name: Palladium(II) acetylacetonate
• Synonyms: Palladium(II) 2,4-pentanedionate; Bis(2,4-pentanedionato-O,O')palladium(II)
• Molecular Formula: C₁₀H₁₄O₄Pd
• Molecular Weight: 304.64
• CAS Registry Number: 14024-61-4
• EC Number: 237-859-8
• SMILES: CC(=CC(=O)C)[O-].CC(=CC(=O)C)[O-].[Pd+2]

Properties

• Melting point: 200 - 251 °C (Decomposes) (Expl.)
• Boiling point: 751.9 °C (Expl.)
• Solubility: Soluble (benzene, chloroform) (Expl.)

Safety Data

• Hazard Symbols: GHS02;GHS05;GHS07;GHS09 Danger
• Risk Statements: H228-H251-H302-H315-H317-H318-H319-H335-H400-H410
• Safety Statements: P210-P235-P240-P241-P261-P264-P264+P265-P270-P271-P272-P273-P280-P301+P317-P302+P352-P304+P340-P305+P351+P338-P305+P354+P338-P317-P319-P321-P330-P332+P317-P333+P317-P337+P317-P362+P364-P370+P378-P391-P403+P233-P405-P407-P410-P413-P420-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315
Flammable solids	Flam. Sol.	2	H228
Specific target organ toxicity - single exposure	STOT SE	3	H335
Self-heating substances or mixtures	Self-heat.	1	H251
Flammable solids	Flam. Sol.	1	H228
Acute toxicity	Acute Tox.	4	H302
Serious eye damage	Eye Dam.	1	H318
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Skin sensitization	Skin Sens.	1A	H317
Chronic hazardous to the aquatic environment	Aquatic Chronic	4	H413
Oxidising solids	Ox. Sol.	3	H272
Acute toxicity	Acute Tox.	4	H332
Skin sensitization	Skin Sens.	1	H317
Acute toxicity	Acute Tox.	4	H312

• Transport Information: UN 3181

Discovery and Applications

Palladium(II) acetylacetonate, commonly abbreviated as Pd(acac)₂, is a coordination complex consisting of a palladium ion in the +2 oxidation state coordinated by two acetylacetonate ligands. Each acetylacetonate (acac) ligand is a bidentate chelating ligand derived from acetylacetone (2,4-pentanedione), which coordinates to the metal center through its two oxygen atoms. The compound is typically a yellow to pale orange crystalline solid and is soluble in organic solvents such as benzene, toluene, and chloroform.

The synthesis of palladium(II) acetylacetonate generally involves reacting palladium(II) salts such as palladium(II) chloride with acetylacetone in the presence of a base. This process results in ligand exchange and chelation, forming the stable Pd(acac)₂ complex. The compound can be purified by recrystallization and is often used as a convenient source of palladium in various chemical reactions.

Structurally, Pd(acac)₂ adopts a square planar geometry typical for d⁸ palladium(II) complexes. The two acetylacetonate ligands coordinate through their oxygen atoms to the palladium center, forming a stable chelate ring. This arrangement stabilizes the metal center and influences the complex’s electronic properties and reactivity.

Palladium(II) acetylacetonate is widely used as a catalyst precursor in homogeneous catalysis, particularly in carbon–carbon coupling reactions such as Suzuki, Heck, and Sonogashira couplings. These palladium-catalyzed reactions are crucial in organic synthesis for constructing complex molecules, including pharmaceuticals, agrochemicals, and advanced materials. The Pd(acac)₂ complex serves as a stable, easily handled source of palladium that can generate the active catalytic species under reaction conditions.

In addition to catalysis, Pd(acac)₂ is used in materials science and nanotechnology. It is employed as a palladium precursor for the preparation of palladium nanoparticles and thin films, which find applications in sensors, electronics, and fuel cells. Controlled thermal decomposition or chemical reduction of Pd(acac)₂ allows tuning of particle size and morphology.

The complex is also valuable in coordination and organometallic chemistry research as a model compound for studying ligand effects, metal–ligand bonding, and reaction mechanisms. Its well-defined structure and reactivity facilitate the exploration of palladium chemistry in various environments.

Handling palladium(II) acetylacetonate requires standard laboratory precautions. The compound should be stored in a cool, dry place, protected from moisture and strong oxidizing or reducing agents. It can be irritant to the skin and respiratory tract, and proper protective equipment such as gloves and masks should be used when handling.

In summary, palladium(II) acetylacetonate is a square planar palladium complex with two bidentate acetylacetonate ligands. It is synthesized by reaction of palladium salts with acetylacetone and serves as an important catalyst precursor in organic synthesis, as well as a palladium source for materials applications. Its stability, solubility, and well-characterized structure contribute to its wide use in chemical research and industry.

References

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