Transmetalation

spelling: transmetallation) is a type of organometallic reaction that involves the transfer of ligands from one metal to another.

It has the general form: where R and R′ can be, but are not limited to, an alkyl, aryl, alkynyl, allyl, halogen, or pseudohalogen group.

The first is an associative intermediate, where the R and X ligands bridge the two metals, stabilizing the transition state.

Hg(C6F5)2 is a better RT reagent to use with lanthanides than HgPh2 because it does not require a step to activate the metal.

The use of HgPh2 led to the synthesis of a ytterbium complex with different oxidation states on the two Yb atoms:[9] In the Ln(C6F5)2 complexes, where Ln = Yb, Eu, or Sm, the Ln–C bonds are very reactive, making them useful in RTLE reactions.

It is possible to avoid the challenges of working with the unstable Ln(C6F5)2 complex by forming it in situ by the following reaction: Organotins are also kinetically inert RT and RTLE reagents that have been used in a variety of organometallic reactions.

RT has been used to synthesize uranium halides using uranium metal and mercury halides as shown: This actinide RT reaction can be done with multiple mercury compounds to coordinate ligands other than halogens to the metal: Alkaline earth metal complexes have been synthesized by RTLE, employing the same methodology used in synthesizing lanthanide complexes.

The use of diphenylmercury in alkaline-earth metal reactions leads to the production of elemental mercury.

The handling and disposal of elemental mercury is challenging due to its toxicity to humans and the environment.

This led to the desire for an alternative RTLE reagent that would be less toxic and still very effective.