Dipotassium hexachloropalladate
[CAS# 16919-73-6]

Identification

• Classification: Food additive >> Nutrition supplements >> Inorganic salts
• Name: Dipotassium hexachloropalladate
• Synonyms: Potassium hexachloropalladate
• Molecular Formula: K₂PdCl₆
• Molecular Weight: 397.33
• CAS Registry Number: 16919-73-6
• EC Number: 240-974-6
• SMILES: Cl[Pd-2](Cl)(Cl)(Cl)(Cl)Cl.[K+].[K+]

Properties

• Density: 2.738 g/mL (25 ºC) (Expl.)

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H315-H319
• Precautionary Statements: P264-P264+P265-P280-P302+P352-P305+P351+P338-P321-P332+P317-P337+P317-P362+P364

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Skin sensitization	Skin Sens.	1B	H317
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Serious eye damage	Eye Dam.	1	H318
Acute toxicity	Acute Tox.	4	H302
Skin irritation	Skin Irrit.	2	H315

Discovory and Applicatios

Dipotassium hexachloropalladate, with the chemical formula K₂\[PdCl₆], is an inorganic coordination compound consisting of a palladium ion in the +4 oxidation state surrounded octahedrally by six chloride ligands, forming the hexachloropalladate(IV) anion \[PdCl₆]²⁻. The charge on the complex anion is balanced by two potassium cations (K⁺). This compound typically appears as a yellow to orange crystalline solid and is soluble in water due to its ionic nature.

The synthesis of dipotassium hexachloropalladate generally involves the oxidation of palladium metal or palladium(II) compounds in the presence of chlorine or hydrochloric acid with an oxidizing agent, forming palladium(IV) chloride complexes. Subsequent treatment with potassium chloride leads to the precipitation or crystallization of the potassium salt K₂\[PdCl₆]. The compound can also be prepared by reacting palladium(II) chloride with chlorine gas and potassium chloride in aqueous solution under controlled conditions.

Structurally, dipotassium hexachloropalladate features a central palladium(IV) ion coordinated by six chloride ligands arranged octahedrally, providing a stable, low-spin d⁶ electronic configuration. The potassium ions balance the charge and interact ionically with the complex anion in the crystal lattice, resulting in well-defined crystalline materials.

This compound is significant in palladium chemistry as a stable palladium(IV) precursor, which can be used in the synthesis of other palladium complexes via ligand substitution or redox reactions. It serves as an important starting material for the preparation of catalysts in organic synthesis, including cross-coupling reactions, oxidation processes, and C–H activation chemistry.

Dipotassium hexachloropalladate is employed in homogeneous catalysis research due to the versatility of palladium complexes in facilitating carbon–carbon and carbon–heteroatom bond-forming reactions. The palladium(IV) oxidation state in this complex allows for redox cycling in catalytic cycles, enabling efficient catalytic transformations in fine chemical and pharmaceutical synthesis.

In addition to catalysis, K₂\[PdCl₆] is used in materials science for the preparation of palladium-containing films and nanomaterials. Controlled decomposition or reduction of this complex can yield palladium metal nanoparticles, which have applications in electronics, sensing, and environmental catalysis.

Handling of dipotassium hexachloropalladate requires standard laboratory safety procedures. Palladium compounds can be irritants or sensitizers, and inhalation or skin exposure should be avoided. The compound is stable under normal conditions but should be stored in a dry, cool place, away from reducing agents and incompatible materials.

In summary, dipotassium hexachloropalladate is a yellow-orange crystalline palladium(IV) coordination compound featuring an octahedral hexachloropalladate anion balanced by potassium cations. It is widely used as a precursor for palladium catalysts and materials, valued for its stability and role in advanced palladium chemistry and catalysis.

References

2011. Effects of Palladium Nanoparticles on the Cytokine Release from Peripheral Blood Mononuclear Cells of Palladium-Sensitized Women. Journal of Occupational and Environmental Medicine, 53(9).
DOI: 10.1097/jom.0b013e318228115e

2008. Effects of sub-chronic exposure to palladium (as potassium hexachloro-palladate) on cytokines in male Wistar rats. Human & Experimental Toxicology, 27(6).
DOI: 10.1177/0960327108090489

1976. Inhibition of hydroxyproline synthesis by palladium ions. Biochimica et Biophysica Acta (BBA) - Enzymology, 428(2).
DOI: 10.1016/0005-2744(76)90030-9