Tetrakis(triphenylphosphine)palladium(0)

Chembox new
Name = Tetrakis(triphenylphosphine)palladium(0)
ImageFile = Tetrakis(triphenylphosphine)palladium(0)-3D-sticks.png ImageName = 3D model of the tetrakis(triphenylphosphine)palladium(0) molecule
ImageFile1 = Tetrakis(triphenylphosphine)palladium(0).jpg
ImageName1 = Tetrakis(triphenylphosphine)palladium(0)
IUPACName = Tetrakis(triphenylphosphane)palladium(0)
OtherNames = TPP palladium(0)
Section1 = Chembox Identifiers
CASNo = 14221-01-3
RTECS = Unregistered
Section2 = Chembox Properties
Formula = carbon₇₂hydrogen₆₀phosphorus₄palladium
MolarMass = 1155.56 g/mol
Appearance = Bright yellow crystals
Density = ? g/cm³, ?
Solubility = Insoluble
MeltingPt = decomposes around 115 °C
Section3 = Chembox Structure
MolShape = tetrahedral
Coordination = four triphenylphosphine unidentate
ligands attached to a central Pd(0)
atom in a tetrahedral geometry
CrystalStruct =
Dipole = 0 D
Section7 = Chembox Hazards
ExternalMSDS =
MainHazards = PPh₃ is an irritant
NFPA-H = 2
NFPA-F = 1
NFPA-R =
RPhrases = n/a
SPhrases = S22, S24/25
Section8 = Chembox Related
Function = complexes
OtherFunctn = chlorotris(triphenylphosphine)rhodium(I)
tris(dibenzylideneacetone)dipalladium(0)
OtherCpds = triphenylphosphine

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.

Preparation, structure, and properties

This complex is 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^-
Reductants other than hydrazine can be employed.

The four P atoms are at the corners of a tetrahedron surrounding the palladium(0) center. This structure is typical for four-coordinate 18e complexes. [C. Elschenbroich, A. Salzer ”Organometallics : A Concise Introduction” (2nd Ed) (1992) from Wiley-VCH: Weinheim. ISBN 3-527-28165-7] The corresponding complexes Ni(PPh₃)₄ and Pt(PPh₃)₄ are also well known. Such complexes reversibly dissociate PPh₃ ligands in solution, releasing the 16e M(PPh₃)₃. Thus, reactions attributed to Pd(PPh₃)₄ in fact arise from Pd(PPh₃)₃ or even Pd(PPh₃)₂.

If the tetrakis(triphenylphosphine)palladium (0) is an orange brown, triturate with methanol and filter to give the desired yellow powder. Store under nitrogen in the fridge.

Applications

Pd(PPh₃)₄ is widely used as a catalyst for coupling reactions. [Homogeneous Catalysis: Understanding the Art” by P. W. van Leeuwen, Springer; 2005. ISBN 1-4020-3176-9] Prominent applications include the Heck reaction and Suzuki coupling. These processes begin with the oxidative addition of an aryl halide to the Pd(0) center::Pd(PPh₃)₄ + ArBr → PdBr(Ar)(PPh₃)₂ + 2 PPh₃

References

External links

* [http://www.chemexper.com/index.shtml?main=http://www.chemexper.com/search/cas/14221-01-3.html ChemExper Chemicals database]
* [http://www.sciencelab.com/page/S/PVAR/10427/SLT3655 Science lab product sheet]
* [http://designer-drugs.com/pte/12.162.180.114/dcd/chemistry/pph3.noble.metal.catalysts.html D.R. Coulson, "Tetrakis(triphenylphosphine)palladium(0)", Inorg. Synth., No 21]