Appearance white solid | ||
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IMes is an abbreviation for organic compound that is a common ligand in organometallic chemistry. It is an N-heterocyclic carbene (NHC). The compound, a white solid, is often not isolated but instead is generated upon attachment to the metal centre.
First prepared by Arduengo, the heterocycle is synthesized by condensation of 2,4,6-trimethylaniline and glyoxal to give the diimine. In the presence of acid, this diimine condenses with formaldehyde to give the dimesitylimidazolium cation. This cation is the conjugate acid of the NHC.
Related compounds
Related to IMes another popular NHC ligand is IPr, featuring diisopropylphenyl groups in place of the mesityl groups, IPr is even bulkier.
Important variants of IMes and IPr have saturated backbones, these ligands are called SIMes and SIPr. They are prepared by alkylation of substituted anilines with dibromoethane followed by ring closure and dehydrohalogenation of the dihydroimidazolium salt.