Allylpalladium chloride dimer

<h2 id="structure">Structure</h2>
<p>The compound has a dimeric structure that is <a href="/facts/Centrosymmetry/nIFJqujU">centrosymmetric</a>. Each allyl group lies in a plane at an angle of about 111.5° to the square formed by the palladium and carbon atoms, and the Pd–C distances are all equal. Its unit cell is monoclinic.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a>
</p>
<h2 id="synthesis">Synthesis</h2>

<p>The compound is prepared by purging <a href="/facts/Carbon_monoxide/CKuLtEMJ">carbon monoxide</a> through a methanolic <a href="/facts/Aqueous_solution/eRNr3MH2">aqueous solution</a> of <a href="/facts/Sodium_tetrachloropalladate/leHvvczX">sodium tetrachloropalladate</a> (prepared from <a href="/facts/Palladium(II)_chloride/ECyezouw">palladium(II) chloride</a> and <a href="/facts/Sodium_chloride/MWcXl3Mb">sodium chloride</a>), and <a href="/facts/Allyl_chloride/saGo9WGr">allyl chloride</a>.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a>
</p>
2 Na2PdCl4   +   2 CH2=CHCH2Cl   +   2 CO   +   2 H2O   →   [(η3-C3H5)PdCl]2   +   4 NaCl   +   2 CO2   +   4 HCl
<p>Another method is the reaction of <a href="/facts/Propene/5eLDmPvm">propene</a> with palladium(II) <a href="/facts/Trifluoroacetate/2SAfAXWv">trifluoroacetate</a>, followed by <a href="/facts/Ion_exchange/C2DPoGqg">ion exchange</a> with chloride:<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a>
</p>
2 (CF3COO)2Pd + 2 CH2=CHCH3 → [(η3-C3H5)Pd(CF3COO)]2
[(η3-C3H5)Pd(CF3COO)]2 + 2 Cl− → [(η3-C3H5)PdCl]2 + 2 CF3COO−
<h2 id="reactions">Reactions</h2>
<p>APC reacts with sources of <a href="/facts/Cyclopentadienyl_anion/11slGTQo">cyclopentadienyl anion</a> to give the corresponding <a href="/facts/18_electron_rule/KNfG6tpM">18e− complex</a> <a href="/facts/Cyclopentadienyl_allyl_palladium/nXyVJuJD">cyclopentadienyl allyl palladium</a>:
</p>
[(η3-C3H5)PdCl]2   +   2 NaC5H5   →   2 [(η5-C5H5)Pd(η3-C3H5)]   +   2 NaCl
<p>The dimer reacts with a variety of Lewis bases (:B)  to form adducts (<a href="/facts/Hapticity/7MDtzehL">η</a>3-C3H5)PdCl:B. Its reaction with <a href="/facts/Pyridine/X817hCch">pyridine</a> and the corresponding enthalpy are:
</p>
1/2 [(η3-C3H5)PdCl]2 + :NC5H5 → (η3-C3H5)PdCl:NC5H5 Δ<i>H</i>=−30.1 kJ.mol−1
<p>This enthalpy corresponds to the enthalpy change for a reaction forming one mole of the product, (<a href="/facts/Hapticity/7MDtzehL">η</a>3-C3H5)PdCl:NC5H5, from the acid dimer.
The dissociation energy for the Pd dimer, which is an energy contribution prior to reaction with the donor, 
</p>
[(η3-C3H5)PdCl]2 → 2 (η3-C3H5)PdCl
<p>has been determined by the <a href="/facts/ECW_model/xyCvhKX6">ECW model</a> to be 28 kJ.mol−1.
</p><p>APC catalyzes many organic reactions, such as <a href="/facts/Cross-coupling/cF8RBvCx">cross-coupling</a>, <a href="/facts/Nucleophilic_addition/1HL9WlD6">nucleophilic addition</a> to <a href="/facts/Diene/F5NxrLPW">dienes</a>, and decomposition of <a href="/facts/Diazo_compounds/qNcCkYb8">diazo compounds</a> to reactive <a href="/facts/Carbenes/3WxNSStY">carbenes</a>. It is also a useful precursor of other Pd catalysts.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a>
</p>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Tatsuno, Y.; Yoshida, T.; Otsuka, S. "(η3-allyl)palladium(II) Complexes" Inorganic Syntheses, 1990, volume 28, pages 342-345. ISBN 0-471-52619-3 <a href="/wiki/Inorganic_Syntheses" target="_blank">/wiki/Inorganic_Syntheses</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Smith, A. E. (1965). "The structure of the allylpalladium chloride complex (C3H5PdCl)2 at –140°C". Acta Crystallographica. 18 (3): 331–340. Bibcode:1965AcCry..18..331S. doi:10.1107/S0365110X65000774. ISSN 0365-110X. <a href="http://scripts.iucr.org/cgi-bin/paper?S0365110X65000774" target="_blank">http://scripts.iucr.org/cgi-bin/paper?S0365110X65000774</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Tatsuno, Y.; Yoshida, T.; Otsuka, S. "(η3-allyl)palladium(II) Complexes" Inorganic Syntheses, 1990, volume 28, pages 342-345. ISBN 0-471-52619-3 <a href="/wiki/Inorganic_Syntheses" target="_blank">/wiki/Inorganic_Syntheses</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>Godleski, Stephen A.; Michelet, Véronique; Genêt, Jean-Pierre (2006), "Bis(allyl)di-μ-chlorodipalladium", Encyclopedia of Reagents for Organic Synthesis, Chichester, UK: John Wiley & Sons, Ltd, doi:10.1002/047084289x.rb098s.pub2, ISBN 978-0-471-93623-7, retrieved 2020-09-06 <a href="978-0-471-93623-7" target="_blank">978-0-471-93623-7</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>Godleski, Stephen A.; Michelet, Véronique; Genêt, Jean-Pierre (2006), "Bis(allyl)di-μ-chlorodipalladium", Encyclopedia of Reagents for Organic Synthesis, Chichester, UK: John Wiley & Sons, Ltd, doi:10.1002/047084289x.rb098s.pub2, ISBN 978-0-471-93623-7, retrieved 2020-09-06 <a href="978-0-471-93623-7" target="_blank">978-0-471-93623-7</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
</ol>

Allylpalladium chloride dimer open-in-new

Allylpalladium chloride dimer