Tetraamminepalladium dinitrate
[CAS# 13601-08-6]

Identification

• Classification: Inorganic chemical industry >> Inorganic salt >> Metal nitrates and nitrites
• Name: Tetraamminepalladium dinitrate
• Synonyms: Tetraamminepalladium nitrate
• Molecular Formula: H12N4Pd(NO₃)₂
• Molecular Weight: 298.55
• CAS Registry Number: 13601-08-6
• EC Number: 237-078-2
• SMILES: N.N.N.N.[N+](=O)([O-])[O-].[N+](=O)([O-])[O-].[Pd+2]

Properties

• Density: 1.04 g/mL (25 °C) (Expl.)
• Solubility: water 10 wt. % (Expl.)
• Refraction index: 1.348 (Expl.)

Safety Data

• Hazard Symbols: GHS01;GHS03;GHS07;GHS09 Danger
• Risk Statements: H240-H272-H302-H315-H317-H319-H335-H400-H410
• Safety Statements: P210-P220-P234-P235-P240-P261-P264-P264+P265-P270-P271-P272-P273-P280-P301+P317-P302+P352-P304+P340-P305+P351+P338-P319-P321-P330-P332+P317-P333+P317-P337+P317-P362+P364-P370+P372+P380+P373-P370+P378-P391-P403-P403+P233-P405-P410-P411-P420-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Oxidising solids	Ox. Sol.	2	H272
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Acute toxicity	Acute Tox.	4	H302
Skin sensitization	Skin Sens.	1A	H317
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Self-reactive substances or mixtures	Self-react.	A	H240
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin irritation	Skin Irrit.	2	H315
Unstable Explosives	Unst. Expl.		H200

Discovery and Applications

Tetraamminepalladium dinitrate is a coordination compound with the formula [Pd(NH₃)₄](NO₃)₂. It consists of a palladium(II) center coordinated by four ammonia (NH₃) ligands forming the cationic complex [Pd(NH₃)₄]²⁺, paired with two nitrate (NO₃^–) anions to balance the charge. The compound is a crystalline solid, typically soluble in water due to its ionic character.

The synthesis of tetraamminepalladium dinitrate commonly involves reacting palladium nitrate salts with an excess of ammonia in aqueous solution. In this process, ammonia coordinates to the palladium ion through nitrogen lone pairs, replacing weaker ligands and forming the stable square planar [Pd(NH₃)₄]²⁺ complex. The nitrate ions remain outside the coordination sphere as counterions.

Structurally, the palladium center adopts a square planar geometry typical of d⁸ Pd(II) complexes, with four ammonia ligands symmetrically bound via Pd–N bonds. The nitrate ions are not coordinated directly to palladium but are present in the lattice to maintain charge neutrality.

Tetraamminepalladium dinitrate serves as a useful intermediate in palladium chemistry, especially as a precursor to a variety of palladium complexes used in catalysis and synthetic applications. The complex’s relatively labile ammonia ligands can be substituted by other ligands such as phosphines, nitrogen heterocycles, or olefins, enabling the preparation of catalysts with tailored properties.

In catalysis, palladium complexes derived from this compound play crucial roles in cross-coupling reactions (Suzuki, Heck, Sonogashira), which are essential for constructing carbon–carbon bonds in pharmaceuticals, agrochemicals, and advanced materials synthesis. The stability of the tetraammine complex facilitates handling and storage, while its reactivity allows generation of active catalytic species upon ligand exchange.

Beyond catalysis, tetraamminepalladium dinitrate has applications in material science where it can serve as a precursor to palladium nanoparticles and films used in electronic components, sensors, and fuel cell catalysts. Controlled decomposition or reduction yields palladium metal with desirable particle sizes and morphologies.

Handling this compound requires standard precautions due to the toxicity of palladium compounds and the oxidative nature of nitrate ions. It should be stored in a cool, dry environment, and appropriate protective equipment is necessary to minimize exposure risks.

In summary, tetraamminepalladium dinitrate is a well-defined palladium(II) coordination complex with four ammonia ligands and two nitrate counterions. It is synthesized by coordination of ammonia to palladium nitrate salts and serves as an important intermediate in the preparation of palladium catalysts and materials. Its structural features and chemical reactivity make it valuable in synthetic chemistry and nanomaterial fabrication, while proper safety measures ensure its responsible use.

References

2024. Determination of Hydrogen Sulphide in Air with an Indium Oxide Semiconductor Sensor. Journal of Analytical Chemistry, 79(9).
DOI: 10.1134/s1061934824700709

2023. Dynamic and reversible transformations of subnanometre-sized palladium on ceria for efficient methane removal. Nature Catalysis, 6(7).
DOI: 10.1038/s41929-023-00983-8

2022. Pd single-atom catalysts derived from strong metal-support interaction for selective hydrogenation of acetylene. Nano Research, 15(10).
DOI: 10.1007/s12274-022-4376-5