Transmetalation is a general chemical reaction

Chemical reaction

A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...

 type in organometallic chemistry

Organometallic chemistry

Organometallic chemistry is the study of chemical compounds containing bonds between carbon and a metal. Since many compounds without such bonds are chemically similar, an alternative may be compounds containing metal-element bonds of a largely covalent character...

 describing the exchange of ligand

Ligand

In coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding between metal and ligand generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal-ligand bonding can range from...

s between two metal

Metal

A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

 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. Transmetalation is important in the synthesis of various organometallic compounds.

Synthesis of Grignard reagents

Using transmetalation, unusual Grignard reagents can be prepared from commercially available isopropylmagnesium bromide. In this way, problems with slow initiation of the Grignard reagent are avoided and precious halides are used more efficiently. Since transmetalation occurs under conditions that tolerate diverse functional groups, this approach expands the utility of the Grignard reaction

Grignard reaction

The Grignard reaction is an organometallic chemical reaction in which alkyl- or aryl-magnesium halides add to a carbonyl group in an aldehyde or ketone. This reaction is an important tool for the formation of carbon–carbon bonds...

:

i-PrMgBr + IC₆H₄-4-CO₂Me → BrMgC₆H₄-4-CO₂Me + i-PrI

Synthesis of NHC's by transmetalation

Silver N-heterocyclic carbene complexes

Transition metal carbene complex

A transition metal carbene complex is a organometallic compound featuring a divalent organic ligand. The divalent organic ligand coordinated to the metal center is called a carbene. Carbene complexes for almost all transition metals have been reported. Many methods for synthesizing them and...

 are easily formed from stable precursors such as imidazolium salts. Once formed, the Ag-NHC reagent can be used to transfer the carbene ligands to other metals containing labile ligands such as acetonitrile

Acetonitrile

Acetonitrile is the chemical compound with formula . This colourless liquid is the simplest organic nitrile. It is produced mainly as a byproduct of acrylonitrile manufacture...

 or 1,5-cyclooctadiene

1,5-Cyclooctadiene

1,5-Cyclooctadiene is the organic compound with the chemical formula C8H12. Generally abbreviated COD, this diene is a useful precursor to other organic compounds and serves as a ligand in organometallic chemistry.- Synthesis :...

. Where L-H⁺ denotes the ligand precursor:

Use in cross-coupling

Transmetalation appears frequently in the catalytic cycle

Catalytic cycle

A catalytic cycle in chemistry is a term for a multistep reaction mechanism that involves a catalyst . The catalytic cycle is the main method for describing the role of catalysts in biochemistry, organometallic chemistry, materials science, etc. Often such cycles show the conversion of a...

 of various metal-catalysed organic reaction

Organic reaction

Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, photochemical reactions and redox reactions. In organic synthesis,...

s, such as the Stille reaction

Stille reaction

The Stille reaction is a chemical reaction coupling an organotin compound with an sp2-hybridized organic halide catalyzed by palladium. The reaction is widely used in organic synthesis....

 and the Negishi coupling

Negishi coupling

The Negishi coupling is a cross coupling reaction in organic chemistry involving an organozinc compound, an organic halide and a nickel or palladium catalyst creating a new carbon-carbon covalent bond:* The halide X can be chloride, bromine or iodine but also a triflate or acetyloxy group with as...

.