Tetrakis(triphenylphosphine)palladium(0)

Tetrakis(triphenylphosphine)palladium(0)

General
Systematic name	Tetrakis(triphenylphosphine)palladium(0)
Other names	TPP palladium(0)
Molecular formula	C₇₂H₆₀P₄Pd
Molar mass	1155.56 g/mol
Appearance	Bright yellow crystals
CAS number	[14221-01-3]
Properties
Density and phase	? g/cm³, ?
Solubility in water	Insoluble
In benzene, dichloromethane, chloroform	Approx 5 g/100ml
Melting point	decomposes around 115 °C
Structure
Molecular shape	tetrahedral
Coordination geometry	four triphenylphosphine unidentate ligands attached to a central Pd(0) atom in a tetrahedral geometry
Crystal structure	?
Dipole moment	0 D
Hazards
MSDS	External MSDS
Main hazards	PPh₃ is an irritant
NFPA 704	1 2 0
R/S statement	R: n/a S: S22, S24/25
RTECS number	Unregistered
Supplementary data page
Structure and properties	n, ε_r, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Related complexes	chlorotris(triphenylphosphine)rhodium(I) tris(dibenzylideneacetone)dipalladium(0)
Related compounds	triphenylphosphine
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

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.

Additional recommended knowledge

What is the Sensitivity of my Balance?

Weighing the right way

Essential Laboratory Skills Guide

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.^[1] 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.^[2] 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

^ C. Elschenbroich, A. Salzer ”Organometallics : A Concise Introduction” (2nd Ed) (1992) from Wiley-VCH: Weinheim. ISBN 3-527-28165-7
^ Homogeneous Catalysis: Understanding the Art” by P. W. van Leeuwen, Springer; 2005. ISBN 1-4020-3176-9

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Tetrakis(triphenylphosphine)palladium(0)". A list of authors is available in Wikipedia.