Ligand exchange at palladium

Nucleophilic attack on alkene-palladium(ll) complexes became commercially important when the Wacker process was developed. In this process, ethylene is converted to acetaldehyde (Scheme 6.4). This involves coordination of ethylene to palladium. The oxygen atom, which comes from water, may then become attached to carbon in one of two different ways. Direct nucleophilic attack on one carbon atom of the t -ethylene complex 6.1 by water can form an t -complex 63. Alternatively, ligand exchange at palladium, with water replacing chloride, can be followed by insertion of the coordinated ethylene into the palladium-oxygen bond to give the same t -complex 63, via the hydroxy complex 6.2. Which of these two variants of the mechanism... 

An intramolecular nucleophile, such as an alcohol, may also be used in place of the first acetate (Scheme 9.77). Treatment of the dienyl alcohol 9.284 with palladium acetate gives the T -allyl complex 9.285 by intramolecular nucleophilic attack, which gives the rran -acetate 9.287 by reductive elimination. In the presence of a small amount of lithium chloride, however, ligand exchange at palladium occurs. Now, the -palladium complex 9.286 does not have an acetate available for intramolecular transfer. Instead,... 

Kinetics of diethyl sulphide, diethyl selenide, and diethyl telluride exchange at [PdX2(ZEta)2] (X=C1 or Br, Z=S, Se, or Te) have been reported. Ligand exchange at palladium(ii) is considerably faster than at platinum(ii) in the analogous [PtXa-(ZEt2)2l series of compounds. ... 

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