Tetrakis(triphenylphosphine)palladium
[CAS# 14221-01-3]

Identification

• Classification: Organic raw materials >> Organometallic compound >> Organic palladium
• Name: Tetrakis(triphenylphosphine)palladium
• Synonyms: Palladium(0)tetrakis(triphenylphosphine)
• Molecular Formula: C₇₂H₆₀P₄Pd
• Molecular Weight: 1155.58
• CAS Registry Number: 14221-01-3
• EC Number: 238-086-9
• SMILES: C1=CC=C(C=C1)P(C2=CC=CC=C2)C3=CC=CC=C3.C1=CC=C(C=C1)P(C2=CC=CC=C2)C3=CC=CC=C3.C1=CC=C(C=C1)P(C2=CC=CC=C2)C3=CC=CC=C3.C1=CC=C(C=C1)P(C2=CC=CC=C2)C3=CC=CC=C3.[Pd]

Properties

• Solubility: Insoluble (water), soluble (benzene, ethanol and chloroform)
• Melting point: 103-107 ºC

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H302-H317-H413
• Precautionary Statements: P261-P264-P270-P272-P273-P280-P301+P317-P302+P352-P321-P330-P333+P317-P362+P364-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H302
Chronic hazardous to the aquatic environment	Aquatic Chronic	4	H413
Skin sensitization	Skin Sens.	1A	H317
Acute toxicity	Acute Tox.	4	H332
Acute toxicity	Acute Tox.	4	H312
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin irritation	Skin Irrit.	2	H315
Carcinogenicity	Carc.	2	H351
Eye irritation	Eye Irrit.	2	H319
Skin sensitization	Skin Sens.	1	H317
Eye irritation	Eye Irrit.	2A	H319

Discovory and Applicatios

Tetrakis(triphenylphosphine)palladium, often abbreviated as Pd(PPh₃)₄, is a well-known organometallic complex with the molecular formula Pd[P(C₆H₅)₃]₄. This compound is composed of a central palladium atom coordinated to four triphenylphosphine ligands. Its discovery marked a significant advancement in the field of catalysis, as it became a cornerstone in many catalytic processes, especially in cross-coupling reactions.

The discovery of tetrakis(triphenylphosphine)palladium dates back to the 1960s, a period when chemists were exploring palladium compounds for their potential in organometallic chemistry and catalysis. Early work by Akio Yamamoto and collaborators highlighted the use of palladium complexes in homogeneous catalysis, where tetrakis(triphenylphosphine)palladium emerged as one of the key compounds. Its structure, featuring a palladium atom stabilized by the electron-donating triphenylphosphine ligands, enabled it to act as an effective catalyst in various organic transformations.

One of the most significant applications of Pd(PPh₃)₄ is in cross-coupling reactions, where it serves as a highly efficient catalyst. Notably, it plays a critical role in the Suzuki-Miyaura, Heck, and Stille reactions, which involve the formation of carbon-carbon bonds. These reactions are essential in organic synthesis, enabling the construction of complex molecules used in pharmaceuticals, agrochemicals, and materials science. The ability of Pd(PPh₃)₄ to facilitate these reactions with high selectivity and yield has made it a valuable tool in modern synthetic chemistry.

In the Suzuki-Miyaura reaction, for example, Pd(PPh₃)₄ catalyzes the coupling of an aryl or vinyl halide with an organoboron compound, a process widely used in the synthesis of biaryls and other complex organic molecules. This reaction has become one of the most utilized methods in the pharmaceutical industry for drug discovery and development, as it allows for the efficient creation of molecular diversity.

Beyond its use in carbon-carbon coupling reactions, tetrakis(triphenylphosphine)palladium has found applications in the polymerization of olefins and the formation of conjugated polymers, which are important in the production of advanced materials, such as conductive polymers and organic light-emitting diodes (OLEDs). These materials have applications in electronic devices, displays, and solar cells, highlighting the versatility of Pd(PPh₃)₄ in facilitating cutting-edge technological advancements.

While Pd(PPh₃)₄ has proven invaluable in synthetic chemistry, its use is not without challenges. The compound is sensitive to air and moisture, which can lead to decomposition and loss of catalytic activity. As a result, it is typically handled under inert atmospheres, such as nitrogen or argon, to maintain its stability. Despite these handling requirements, its catalytic efficiency and broad applicability continue to make it a widely used and studied compound in both academic and industrial research settings.

In summary, tetrakis(triphenylphosphine)palladium represents a milestone in the field of organometallic chemistry and catalysis. Its discovery enabled a wide range of chemical transformations, particularly in carbon-carbon bond formation, which are critical to the synthesis of complex organic molecules. The compound's impact on pharmaceutical development, materials science, and industrial chemistry underscores its significance as one of the most important catalysts in modern chemistry.

References

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DOI: 10.1007/s10895-018-2287-3

2014. (m.n)-Homorubins: syntheses and structures. Monatshefte f�r Chemie - Chemical Monthly, 145(12).
DOI: 10.1007/s00706-014-1288-4