Allylpalladium chloride dimer

Allylpalladium(II) chloride dimer (APC) is a chemical compound with the formula [(η3-C3H5)PdCl]2. This yellow air-stable compound is an important catalyst used in organic synthesis.[1] It is one of the most widely used transition metal allyl complexes.

Allylpalladium(II) chloride dimer
IUPAC name
Allylpalladium(II) chloride dimer
Other names
Allylpalladium chloride dimer
3D model (JSmol)
ECHA InfoCard 100.031.423
EC Number
  • 234-579-8
Molar mass 365.85 g/mol
Appearance Pale yellow, crystalline solid
Density Solid
Melting point decomp at 155-156 °C
Solubility in other solvents Chloroform
Safety data sheet
GHS pictograms GHS07: Harmful
GHS Signal word Warning
H302, H312, H315, H319, H332, H335
P261, P264, P270, P271, P280, P301+312, P302+352, P304+312, P304+340, P305+351+338, P312, P321, P322, P330, P332+313, P337+313, P362, P363, P403+233, P405, P501
Related compounds
Related compounds
3-allyl)(η5 – cyclopentadienyl)palladium(II)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Synthesis and reactionsEdit

The compound is prepared by purging carbon monoxide through a methanolic aqueous solution of sodium tetrachloropalladate (prepared from palladium(II) chloride and sodium chloride), and allyl chloride.[1]

2 Na2PdCl4   +   2 CH2=CHCH2Cl   +   2 CO   +   2 H2O   →   [(η3-C3H5)PdCl]2   +   4 NaCl   +   2 CO2   +   4 HCl

APC reacts with sources of cyclopentadienyl anion to give the corresponding 18e complex cyclopentadienyl allyl palladium:

[(η3-C3H5)PdCl]2   +   2 NaC5H5   →   2 [(η5-C5H5)Pd(η3-C3H5)]   +   2 NaCl

The dimer reacts with a variety of Lewis bases (:B) to form adducts (η3-C3H5)PdCl:B. Its reaction with pyridine and the corresponding enthalpy are:

1/2[(η3-C3H5)PdCl]2 + :NC5H5 → (η3-C3H5)PdCl:NC5H5   ΔH= -30.1 kJ mol−1

This enthalpy corresponds to the enthalpy change for a reaction forming one mole of the product, (η3-C3H5)PdCl:NC5H5, from the acid dimer. The dissociation energy for the Pd dimer, which is an energy contribution prior to reaction with the donor,

[(η3-C3H5)PdCl]2 →2 (η3-C3H5)PdCl

has been determined by the ECW model to be 28 kJ mol−1


  1. ^ a b Tatsuno, Y.; Yoshida, T.; Otsuka, S. "(η3-allyl)palladium(II) Complexes" Inorganic Syntheses, 1990, volume 28, pages 342-345. ISBN 0-471-52619-3