Allylpalladium

Organopalladium chemistry is a branch of organometallic chemistry that deals with organic palladium compounds and their reactions. Palladium is often used as a catalyst in the reduction of alkenes and alkynes with hydrogen. This process involves the formation of a palladium-carbon covalent bond. Palladium is also prominent in carbon-carbon coupling reactions, as demonstrated in tandem reactions.

In contrast to its next-door neighbors the group 11 elements, the element palladium in organic chemistry does not involve preparation of organopalladium compounds itself but rather organopalladium reactive intermediates. On top of that in many reactions only catalytical amounts of the metal are used.

Palladium reacts with alkenes to form a pi complex which can react with a multitude of nucleophiles akin a oxymercuration reaction. The C-Pd bond is then removed by a reduction or an elimination. In the industrially important Wacker process, ethylene is converted to acetaldehyde with palladium chloride. Fullerene ligands also bind with palladium in similar ways as ethylene.

Allyl compounds with suitable leaving groups react with palladium(II) salts to pi-allyl complexes having hapticity 3 such as the allylpalladium chloride dimer. These intermediates too react with nucleophiles for example carbanions derived from malonates or with amines in allylic amination as depicted below

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