<unk>  (alt. spelling:<unk>  is a general chemical reaction type in organometallic chemistry describing the exchange of ligands between two metal centers.
The metal centers need not be the same. The ligands R and R' can be organic or inorganic. The double displacement reaction is conceptually related.<unk>  is important in the synthesis of various organometallic compounds. Silver N-heterocyclic carbene complexes are easily formed, and are often used to transfer the carbene ligands to other metals containing labile ligands such as acetonitrile or 1,5-cyclooctadiene. Where L-H+ denotes the ligand precursor:
This reaction type also appears frequently in the catalytic cycle of various metal catalysed organic reactions such as the Stille reaction and the Negishi coupling.
Transmetalation
Detoxification
Hydrogenation
Halogenation
Deprotonation
Carboxylation
Wasting
Hydrolysis