Diamminedichloropalladium
[CAS# 13782-33-7]

Identification

• Classification: Inorganic chemical industry >> Inorganic salt
• Name: Diamminedichloropalladium
• Synonyms: trans-Diamminedichloropalladium(II)
• Molecular Formula: Cl₂H₆N₂Pd
• Molecular Weight: 211.39
• CAS Registry Number: 13782-33-7
• EC Number: 237-437-3
• SMILES: N.N.Cl[Pd]Cl

Properties

• Density: 2.5 g/mL

Safety Data

• Hazard Symbols: GHS06;GHS07 Danger
• Risk Statements: H301-H311-H315-H319-H331-H335
• Safety Statements: P261-P262-P264-P264+P265-P270-P271-P280-P301+P316-P302+P352-P304+P340-P305+P351+P338-P316-P319-P321-P330-P332+P317-P337+P317-P361+P364-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315
Specific target organ toxicity - single exposure	STOT SE	3	H335
Acute toxicity	Acute Tox.	3	H301
Acute toxicity	Acute Tox.	3	H331
Acute toxicity	Acute Tox.	3	H311
Serious eye damage	Eye Dam.	1	H318
Skin sensitization	Skin Sens.	1	H317
Chronic hazardous to the aquatic environment	Aquatic Chronic	4	H413
Acute toxicity	Acute Tox.	4	H302

Discovery and Applications

Diamminedichloropalladium, commonly referred to as cis-diamminedichloropalladium(II), is a coordination complex of palladium with the formula PdCl₂(NH₃)₂. It features palladium in the +2 oxidation state coordinated in a square planar geometry to two chloride ions and two ammonia molecules positioned cis to each other. This compound is an important member of the palladium coordination chemistry family and shares structural similarity to the well-known platinum anticancer drug cisplatin, although with distinct chemical and biological properties.

The synthesis of diamminedichloropalladium typically involves reacting palladium(II) chloride with aqueous ammonia. This reaction proceeds by ligand substitution, where chloride ligands partially or fully exchange with ammonia molecules. Careful control of stoichiometry, temperature, and pH allows isolation of the cis isomer, which is the most stable and commonly studied form. The trans isomer, where the two ammonia ligands are opposite each other, can also be prepared but is less commonly encountered due to its relative instability.

Structurally, diamminedichloropalladium exhibits a square planar coordination environment around the palladium center, characteristic of d⁸ metal ions. The cis arrangement of ammonia and chloride ligands significantly influences the compound’s reactivity and interaction with substrates. Bond lengths and angles are consistent with typical palladium(II) ammine and chloride coordination complexes.

Chemically, diamminedichloropalladium is notable for its reactivity in ligand substitution reactions. The ammonia and chloride ligands can be displaced or modified under various conditions, enabling the preparation of a wide range of palladium complexes with different ligands. This property makes it a valuable precursor in organometallic synthesis and homogeneous catalysis.

Unlike cisplatin, diamminedichloropalladium does not exhibit significant anticancer activity, largely due to the higher lability of palladium(II) complexes compared to their platinum(II) analogues. Palladium complexes tend to undergo faster ligand exchange, resulting in reduced stability in biological environments and different pharmacokinetic profiles. Despite this, the compound and its derivatives are widely used as models in studying metal–ligand interactions and mechanisms relevant to platinum-based drugs.

Diamminedichloropalladium and related complexes have important applications in catalysis. Palladium is a key transition metal catalyst in numerous carbon–carbon and carbon–heteroatom bond-forming reactions, including Suzuki, Heck, and Stille couplings. Diamminedichloropalladium serves as a precursor to these catalytic systems, either directly or through further ligand modification. Its square planar geometry facilitates substrate coordination and activation during catalytic cycles.

The compound’s ability to form stable yet reactive complexes has also made it useful in mechanistic studies of palladium catalysis. Researchers have employed diamminedichloropalladium to investigate ligand effects, electronic properties, and reaction intermediates in catalytic processes. Insights gained from these studies contribute to the design of more efficient and selective palladium catalysts.

Handling diamminedichloropalladium requires standard laboratory safety precautions. The compound can be irritant to skin and mucous membranes, and palladium salts may pose environmental and health hazards. It should be stored in tightly sealed containers, protected from moisture and strong reducing or oxidizing agents.

In summary, diamminedichloropalladium is a cis-configured palladium(II) complex with two ammonia and two chloride ligands in a square planar arrangement. It is synthesized via ligand substitution reactions and serves as a versatile precursor in coordination chemistry and catalysis. While lacking the medicinal applications of its platinum analogues, it remains important in synthetic chemistry and mechanistic studies. Its well-defined structure and reactivity underpin many developments in palladium-catalyzed transformations and organometallic research.

References

2007. Ion-exchange recovery of palladium(II) from multicomponent chloride solutions. Russian Journal of Applied Chemistry, 80(7).
DOI: 10.1134/s1070427207070087

1984. Synthesis of Dichloropalladium II Polyamines. New Monomers and Polymers.
DOI: 10.1007/978-1-4684-4619-7_9