Cas No.: 14221-01-3 

Molecular formula: Pd(P(C6H5)3)4 or Pd(PPh3)4

Molecular weight: 1155.5

Palladium content: 9.2%

Property: Light yellow powder, instable in the air, soluble in toluene

Stock:5kg usually

Package:Nitrogen bottle

Validity:3 to 6month

Tetrakis(triphenylphosphine)palladium(0) is the chemical compound Pd[P(C₆H₅)₃]₄, often abbreviated Pd(PPh₃)₄, or even PdP₄. It is a bright yellow crystalline solid that becomes brown upon decomposition in air.

[edit] Structure and properties

The four phosphorus atoms are at the corners of a tetrahedron surrounding the palladium(0) center. This structure is typical for four-coordinate 18e complexes.^[1] The corresponding complexes Ni(PPh₃)₄ and Pt(PPh₃)₄ are also well known. Such complexes reversibly dissociate PPh₃ ligands in solution, so reactions attributed to Pd(PPh₃)₄ often in fact arise from Pd(PPh₃)₃ or even Pd(PPh₃)₂.

[edit] Preparation

Tetrakis(triphenylphosphine)palladium(0) was first prepared by Lamberto Malatesta and his group in Milan in the 1960s by reduction of sodium chloropalladate with hydrazine in the presence of the phosphine.^[2] It is commercially available, but can be prepared in two steps from Pd(II) precursors:

PdCl₂ + 2 PPh₃ → cis-PdCl₂(PPh₃)₂

cis-PdCl₂(PPh₃)₂ + 2 PPh₃ + 2.5 N₂H₄ → Pd(PPh₃)₄ + 0.5 N₂ + 2 N₂H₅⁺Cl^-

Both steps may be carried out in a one-pot reaction, without isolating and purifying the cis-PdCl₂(PPh₃)₂ intermediate.^[3] Reductants other than hydrazine can be employed. The compound is sensitive to air, but can be purified by washing with methanol to give the desired yellow powder. It is usually stored cold under argon.

[edit] Applications

Pd(PPh₃)₄ is widely used as a catalyst for palladium-catalyzed coupling reactions.^[4] Prominent applications include the Heck reaction, Suzuki coupling, Stille coupling, Sonogashira coupling, and Negishi coupling. These processes begin with two successive ligand dissociations followed by the oxidative addition of an aryl halide to the Pd(0) center:

Pd(PPh₃)₄ + ArBr → PdBr(Ar)(PPh₃)₂ + 2 PPh₃