palladium(II) acetate (3375-31-3) Physical and Chemical Properties
palladium(II) acetate
A palladium(II) acetate is a metal-organic salt used as a catalyst precursor in process and research chemistry for method development and scale-up applications.
| CAS Number | 3375-31-3 |
| Family | Metal acetates |
| Typical Form | Powder or crystalline solid |
| Common Grades | EP |
Palladium(II) acetate is an inorganic metal salt of acetic acid in which palladium is present in the +2 oxidation state; its empirical composition is \(\ce{C4H6O4Pd}\). Structurally the material is best described as a palladium(II) acetate species that exists in equilibrium between monomeric and oligomeric (notably trimeric) acetate-bridged forms; a commonly cited structural motif is the μ2-acetate-bridged trimer \(\ce{[Pd(OAc)2]3}\). Electronic configuration of the central metal is consistent with a d8 system leading to square-planar coordination at each palladium center when ligated; acetate anions act as O,O'-chelating or bridging ligands enabling polymeric/oligomeric assemblies.
Chemically the substance behaves as a Lewis acidic transition-metal salt and a versatile precatalyst. It is formally the palladium(II) salt of acetic acid and therefore displays limited Brønsted acidity under standard conditions; hydrolysis and ligand-exchange reactions (replacement of acetate by stronger donor ligands) are typical. The compound is polar overall (high topological polar surface area and multiple oxygen donors) and is essentially non-volatile; lipophilicity is low relative to neutral organic molecules of similar molecular weight. In anoxic or reducing environments the palladium(II) center is readily reduced to metallic palladium(0), a key step in many catalytic cycles.
Industrial and laboratory relevance is dominated by its role as a homogeneous precatalyst or catalyst precursor in organic synthesis and as a synthetic intermediate to other palladium(II) complexes. Common commercial grades reported for this substance include: EP.
Basic Physical Properties
The solid is reported as a reddish-brown powder and is described as insoluble in water. The computed and experimental descriptors indicate a non-volatile, covalently associated material composed of three covalently-bonded units per defined covalent unit count.
Solubility and Hydration
Experimental description: Reddish-brown solid; Insoluble in water; Powder.
Solubility is limited in protic aqueous media owing to the low solubility of the neutral/oligomeric acetate-bridged palladium species; ligand substitution by stronger donors (e.g., phosphines, amines, acetylacetonate) or coordination by polar organic solvents increases apparent solubility by producing discrete solvated palladium complexes.
Thermal Stability and Decomposition
No experimentally established value for this property is available in the current data context.
Chemical Properties
Complex Formation and Coordination
Palladium(II) acetate is a Lewis-acidic palladium(II) source that forms coordination complexes by substitution of acetate ligands. The palladium center typically adopts a square-planar coordination geometry in four-coordinate complexes (d8 electronic configuration). The material exists in oligomeric forms mediated by bridging acetate ligands (e.g., \(\ce{[Pd(OAc)2]3}\)), and readily undergoes ligand exchange with phosphines, nitrogen donors, and π-acceptor ligands to generate catalytically active species. Formation of stable chelate complexes and mixed-ligand species is common, facilitating its use as a versatile precursor in homogeneous catalysis.
Reactivity and Stability
Palladium(II) acetate is chemically reactive toward reducing agents, converting to palladium(0) and thus initiating catalytic cycles for many carbon–carbon and carbon–heteroatom bond-forming reactions. The acetate ligands are labile and readily displaced by stronger donors; hydrolysis under strongly aqueous or basic conditions can alter coordination and solubility. Under reducing or high-temperature conditions the compound will decompose to metallic palladium and volatile or condensable organic degradation products derived from acetate. The material is chemically stable under dry, inert storage but will undergo predictable ligand-exchange and reduction reactions when exposed to nucleophiles, reducing agents, or coordinating solvents.
Molecular Parameters
Molecular Weight and Composition
- Molecular formula: \(\ce{C4H6O4Pd}\)
- Molecular weight: 224.51
- Exact mass: 223.93009
- Monoisotopic mass: 223.93009
- Heavy atom count: 9
- Covalently-bonded unit count: 3
LogP and Ionization State
- Formal charge: 0
- The compound is formally a neutral coordination compound in its common solid forms (oligomeric acetate-bridged species). Ionization in strongly acidic or basic media may occur via ligand protonation/deprotonation or dissociation to give aquo- or hydroxido-palladium species; no experimental \(\mathrm{p}K_a\) value is provided in the current data context.
- Topological polar surface area (TPSA): 80.3
- Hydrogen bond donor count: 0
- Hydrogen bond acceptor count: 4
- Rotatable bond count: 0
- Complexity: 25.5
SMILES and InChI identifiers (inline code as provided):
- SMILES: CC(=O)[O-].CC(=O)[O-].[Pd+2]
- InChI: InChI=1S/2C2H4O2.Pd/c2*1-2(3)4;/h2*1H3,(H,3,4);/q;;+2/p-2
- InChIKey: YJVFFLUZDVXJQI-UHFFFAOYSA-L
Identifiers and Synonyms
Registry Numbers and Codes
- CAS number: 3375-31-3
- Additional registry identifiers reported: 19807-27-3 (alternate CAS references present)
- European Community (EC) numbers: 222-164-4; 243-333-9
- UNII: 0LTG3460Y5
- DSSTox Substance ID: DTXSID10890575
Synonyms and Structural Names
Reported synonyms include: palladium(II) acetate; Pd(OAc)2; Palladium diacetate; Diacetoxypalladium; Diacetatopalladium; Bis(acetato)palladium; Palladous acetate; Palladium(2+) diacetate; Acetic acid palladium salt; Acetic acid, palladium salt; Palladium acetate monomer; \(\ce{[Pd(OAc)2]3}\).
Industrial and Commercial Applications
Use as Salt Form or Excipient
Palladium(II) acetate is not used as an excipient; its primary role is as a transition-metal precatalyst or reagent in synthetic chemistry. It is supplied as a metal salt/complex for use in catalytic and synthetic applications rather than as a formulation excipient.
Representative Use Cases
- Employed as a homogeneous precatalyst or catalyst precursor for a broad range of palladium-catalyzed organic transformations, particularly those requiring in situ generation of palladium(0) or formation of organopalladium intermediates.
- Used as a starting material to prepare other palladium(II) complexes by ligand exchange (e.g., formation of phosphine-ligated Pd complexes).
- Selected for research and process chemistry where a soluble, readily handled palladium source is required.
If a concise application summary is required beyond the general roles above, no additional detailed use-case data is available in the current data context.
Safety and Handling Overview
Toxicological Considerations
Palladium compounds and palladium ions can be absorbed via oral, dermal, and inhalation routes and distribute to multiple organs including kidney, liver, spleen, lymph nodes, adrenal gland, lung and bone. Palladium has the capacity to form coordination complexes with amino acids, proteins and nucleic acids, potentially perturbing cellular equilibria and inhibiting enzymatic functions. Reported health concerns include skin sensitization (contact dermatitis), potential organ damage in animal studies (liver and kidney), and the ability of some palladium complexes to bind DNA and RNA. No indication of carcinogenicity to humans is listed in the available classification summary.
Aggregated hazard classifications and statements reported: - Signal: Danger - GHS Hazard Statements (as reported): - H302 (11.3%): Harmful if swallowed [Warning Acute toxicity, oral] - H317 (73.6%): May cause an allergic skin reaction [Warning Sensitization, Skin] - H318 (98.9%): Causes serious eye damage [Danger Serious eye damage/eye irritation] - H400 (67.5%): Very toxic to aquatic life [Warning Hazardous to the aquatic environment, acute hazard] - H410 (67.5%): Very toxic to aquatic life with long lasting effects [Warning Hazardous to the aquatic environment, long-term hazard]
Reported precautionary codes include: P261, P264, P264+P265, P270, P272, P273, P280, P301+P317, P302+P352, P305+P354+P338, P317, P321, P330, P333+P317, P362+P364, P391, and P501.
For laboratory and industrial practice, control measures typically include elimination or control of dust/aerosol formation, use of appropriate gloves and eye protection, and measures to avoid skin contact and inhalation.
Storage and Handling Guidelines
Store in a cool, dry, well-ventilated area in tightly closed containers; avoid exposure to strong reducing agents and sources of ignition. Because the compound can be reduced to metallic palladium and undergo ligand-exchange reactions, maintain storage conditions that minimize moisture and reactive contaminants. Use standard precautions for transition-metal powders and salts: engineering controls to limit inhalation exposure, gloves and eye protection to prevent skin and eye contact, and segregation from incompatible reagents. For detailed hazard, transport and regulatory information, users should refer to the product-specific Safety Data Sheet (SDS) and local legislation.
Specifications and Grades
Typical commercial supply concepts for palladium(II) acetate include analytical, reagent and technical grades tailored for research or process chemistry; specifications focus on palladium content, ligand purity, and residual solvent or inorganic impurity profiles. Reported commercial grade in the supplied context: EP. Specific assay values, impurity limits and certification details are not provided in the current data context.
