Palladium(II) chloride

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Palladium(II) chloride

General
Other names	Palladium dichloride
Molecular formula	PdCl₂
Molar mass	177.33 g/mol
Appearance	dark red solid
CAS number	[7647-10-1]
EINECS number	231-596-2
Properties
Density and phase	4 g/cm³, solid
Solubility in water	insol
Other solvents	hydrochloric acid
Melting point	675 °C decomp
Structure
Coordination geometry	square planar
Structure	(i) infinite chain with bridging chloride ions (i) cubic cluster
Thermodynamic data
Standard enthalpy of formation Δ_fH°_solid	? kJ/mol
Standard molar entropy S°_solid	? J.K^–1.mol^–1
Safety data
PEL-TWA (OSHA)	—
RTECS number	RT3500000
Supplementary data page
Structure & properties	n, ε_r, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Other anions	Palladium(II) fluoride Palladium(II) bromide Palladium(II) iodide
Other cations	Nickel(II) chloride Platinum(II) chloride
Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Infobox disclaimer and references

Palladium(II) chloride, also known as palladium dichloride, is the chemical compound with the formula PdCl₂. It is a common starting material in palladium chemistry – palladium-based catalysts are of particular value in organic synthesis. It is prepared by chlorination of palladium.

1 Structure
2 Uses
3 Safety
4 References
5 External links

[edit] Structure

Two forms of PdCl₂ are known. In both forms, the palladium centres adopt the square-planar coordination geometry that is characteristic of Pd(II). Furthermore, in both forms, the Pd(II) centres are linked by μ₂-chloride bridges. The α-form of PdCl₂ is a polymer, consisting of "infinite" slabs or chains. The β-form of PdCl₂ is molecular, consisting of an octahedron of six Pd atoms. Each of the twelve edges of this octahedron is spanned by Cl^-. PtCl₂ adopts similar structures, whereas NiCl₂ adopts the CdCl₂ motif, featuring hexacoordinated Ni(II).^[1]

[edit] Uses

Palladium(II) chloride is a common starting point in the synthesis of other palladium compounds. It is not particularly soluble in water or non-coordinating solvents, so the first step in its utilization is often the preparation labile but soluble Lewis base adducts, such as those derived from acetonitrile or benzonitrile. The acetonitrile complex is prepared by treating PdCl₂ in refluxing acetonitrile:

PdCl₂ + 2MeCN → PdCl₂(MeCN)₂

Although occasionally recommended, inert-gas techniques are not necessary if the complex is to be used in situ.

Even when dry, palladium(II) chloride is able to rapidly stain stainless steel. Thus, palladium(II) chloride solutions are sometimes used to test for the corrosion-resistance of stainless steel. Palladium(II) chloride is sometimes used in carbon monoxide detectors.

[edit] Safety

The related nickel and platinum compounds are known to be irritants of the skin and the respiratory system and, in some cases, carcinogenic, and its is generally accepted as prudent to assume that palladium compounds share these risks.