Palladium(II) acetate
2691266
219462553
2008-06-15T10:17:50Z
Rifleman 82
1255637
/* Preparation */ *ensure*
{{Chembox new
| Name = Palladium(II) acetate
| ImageFile = Palladium(II) acetate.jpg
<!-- | ImageSize = 200px -->
| ImageName = Palladium(II) acetate
| IUPACName = Palladium(II) acetate
| OtherNames = Palladium diacetate<br />hexakis(acetato)tripalladium<br />bis(acetato)palladium
| Section1 = {{Chembox Identifiers
| SMILES = C(CO)OPdO(CO)C
| CASNo = 3375-31-3
| RTECS = AJ1900000
}}
| Section2 = {{Chembox Properties
| Formula = C<sub>4</sub>H<sub>6</sub>O<sub>4</sub>Pd
| MolarMass = 224.50 g/mol
| Appearance = Brown yellow solid
| Density = 2.19 g/cm³
| Solubility = low
| MeltingPt = 205 °C (478 K), decomposes
| BoilingPt = decomp.
}}
| Section3 = {{Chembox Structure
| Coordination = Square Planar
| CrystalStruct = [[monoclinic]]
| Dipole = 0 [[Debye|D]]
}}
| Section7 = {{Chembox Hazards
| ExternalMSDS = [http://www.gfschemicals.com/Search/MSDS/2425MSDS.PDF MSDS]
| MainHazards = considered nonhazardous
| RPhrases = 41
| SPhrases = 24/25
}}
| Section8 = {{Chembox Related
| OtherAnions = [[Palladium(II) chloride]]
| OtherCations = [[Platinum(II) acetate]]
}}
}}
'''Palladium(II) acetate''' is a [[chemical compound]] of [[palladium]] described by the formula Pd(O<sub>2</sub>CCH<sub>3</sub>)<sub>2</sub> or Pd(OAc)<sub>2</sub>. It is considered more reactive than the related platinum. It is soluble in many organic solvents.
==Structure==
Palladium(II) acetate is trimeric, consisting of an equilateral triangle of Pd atoms each pair of which is bridged with two acetate groups in a butterfly conformation. Each metal atom achieves approximate square planar co-ordination.<ref name=Skapski>{{cite journal | author = Skapski, A C.; M. L. Smart | title = The Crystal Structure of Trimeric Palladium(II) Acetate | journal = [[J. Chem. Soc.]] D | year = 1970 | pages = 658b-659 | doi = 10.1039/C2970000658b}}</ref>
==Preparation==
It can be prepared in two steps from palladium sponge, hot glacial [[acetic acid]], and [[nitric acid]] via the intermediacy of the dinitrate:<ref name=bakhmutov>{{cite journal | author = Bakhmutov, V. I.,; Berry, J. F.; Cotton, F. A.; Ibragimov, S.; Murillo, C. A. | title = Non-Trivial Behavior of Palladium(II) Acetate | journal =[[Dalton Transactions]] | year = 2005 | pages = 1989–1992 | doi = 10.1039/b502122g}}</ref><ref>"High Purity Homogeneous Catalyst." ''Engelhard''. Sept. 2005. Engelhard Corp. 24 Feb. 2006.<http://www.engelhard.com/documents/High%20Purity%20Homo%20Cat%20_Pd-acetate_%20A4%20Revised%20Final.pdf>.</ref>
::Pd + 2 HNO<sub>3</sub> → Pd(NO<sub>3</sub>)<sub>2</sub> + H<sub>2</sub>
::Pd(NO<sub>3</sub>)<sub>2</sub> + 2 CH<sub>3</sub>COOH → Pd(O<sub>2</sub>CCH<sub>3</sub>)<sub>2</sub> + 2 HNO<sub>3</sub>
An excess of palladium sponge is used to ensure that all HNO<sub>3</sub> is consumed.
==Uses==
Palladium acetate is a catalyst for many organic reactions by combining with many common classes of organic compounds such as alkenes, dienes, and alkyl, aryl, and vinyl halides to form reactive adducts. Alkenes and π-[[allyl]] coordination to palladium(II) acetate involves sigma-type donation from the pi orbital of the alkene or π-allyl with concomitant pi-backbonding into an empty pi* orbital on the alkene or π-allyl. The greater the sigma donation to the metal is, the greater the pi-backbonding. The greater the pi-backbonding is, the greater the reduction in the bond order of the alkene or π-allyl.<ref name=Toreki>Toreki, R. "Allyl Ligands." The Organometallic HyperTextBook. 20 Nov. 2003. Chemglass. 01 Apr. 2006<http://www.ilpi.com/organomet/allyl.html>.</ref> Reduction of the alkenes or π-allyl by coordination to palladium(II) acetate reverses the reactivity of the organic ligand allowing them to undergo reactions with nucleophiles rather than electrophiles.<ref name=suggs>Suggs, J W. "Palladium: Organometallic Chemistry." Encyclopedia of Inorganic Chemistry. Ed. R B. King. 8 vols. Chichester: Wiley, 1994.</ref>
Examples of palladium(II) acetate catalyzed reactions are:
*Vinylation: An example is the [[Heck reaction]]
*Rearrangement of Acyclic Dienes: An example is the [[Cope reaction]]
*Carbonylation reaction: carboxylation of aryl halides and benzyl chloride derivatives in ionic liquid media (l-butyl-3-methylimidazolium hexafluorophosphate, tetrafluoroborate, and Aliquat336 )
*[[Reductive amination]] of aldehydes or ketones using potassium formate.<ref name=basu>{{cite journal | author = Basu, B., Satadru J., Mosharef H. B., and Pralay D. | title = A Simple Protocol for the Direct Reductive Amination of Aldehydes and Ketones Using Potassium Formate and Catalytic Palladium Acetate | journal = [[ChemInform]] | volume = 34 | issue = 30 | year = 2003 | pages = 555–557 | doi = 10.1002/chin.200330069}}</ref>
*[[Wacker process]]: the oxidation of ethylene in water to form acetaldehyde (precursor to poly(vinyl acetate), a common glue).
*Buchwald-Hartwig synthesis of aryl amines from aryl halides/pseudohalides and primary or secondary amines.<ref name=Buchwald>{{cite web | publisher = Organic Chemistry Portal | url = http://www.organic-chemistry.org/namedreactions/buchwald-hartwig-reaction.shtm | title = Buchwald-Hartwig Cross Coupling Reaction}}</ref>
Pd(O<sub>2</sub>CCH<sub>3</sub>)<sub>2</sub> converts aryl bromides into aryltrimethylsilanes, an important functional group in many organic compounds including the fungicide "Latitude".
::RC<sub>6</sub>H<sub>4</sub>Br + Si<sub>2</sub>(CH<sub>3</sub>)<sub>6</sub> → RC<sub>6</sub>H<sub>4</sub>Si(CH<sub>3</sub>)<sub>3</sub> + Si(CH<sub>3</sub>)<sub>3</sub>Br
Pd(O<sub>2</sub>CCH<sub>3</sub>)<sub>2</sub> is compatible with the electronic properties of aryl bromides, and unlike other methods of synthesis, this method does not require high pressure equipment.<ref name=gooben>Gooben, L J. "Research Area "New Pd-Catalyzed Cross-Coupling Reactions"" 28 Feb. 2006<http://www.mpi-muelheim.mpg.de/kofo/bericht2002/pdf/2.1.8_gossen.pdf>.
</ref>
===Precursor to other Pd compounds===
Palladium acetate is used to produce other palladium(II) compounds. For example, phenylpalladium acetate, used to isomerize allylic alcohols to aldehydes, is prepared by the following reaction:
Hg(C<sub>6</sub>H<sub>5</sub>)(CH<sub>3</sub>COO) + Pd(CH<sub>3</sub>COO)<sub>2</sub> → Pd(C<sub>6</sub>H<sub>5</sub>)(O<sub>2</sub>CCH<sub>3</sub>) + Hg(O<sub>2</sub>CCH<sub>3</sub>)<sub>2</sub><ref name=heck>{{OrgSynth | author =
[[Richard F. Heck]] | title = Aldehydes from Allylic Alcohols and Phenylpalladium Acetate: 2-Methyl-3-Phenylpropionaldehyde | collvol = 6 | collvolpages = 815 | prep = cv6p0815}}</ref>
<!--what is the structure of "phenylpalladium acetate"? probably not a monoPd thing-->
Palladium(II) acetate reacts with [[acetylacetone]] to produce Pd(acac)<sub>2</sub>, a precursor to Pd(0).{{Fact|date=January 2008}}
Light or heat reduce palladium acetate to give thin layers of palladium and can produce nanowires and colloids.<ref name=bakhmutov/>
==References==
{{reflist}}
[[Category:Palladium compounds]]
[[Category:Acetates]]