IMes

IMes

Names
Other names 1,3-bis(2,4,6-trimethylphenyl)-imidazolium, 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene
Identifiers
CAS Number	141556-42-5
3D model (Jmol)	Interactive image
ChemSpider	9298886
ECHA InfoCard	100.154.201
PubChem CID	11123757
InChI InChI=1S/C21H24N2/c1-14-9-16(3)20(17(4)10-14)22-7-8-23(13-22)21-18(5)11-15(2)12-19(21)6/h7-12H,1-6H3 Key: JCYWCSGERIELPG-UHFFFAOYSA-N InChI=1/C21H24N2/c1-14-9-16(3)20(17(4)10-14)22-7-8-23(13-22)21-18(5)11-15(2)12-19(21)6/h7-12H,1-6H3 Key: JCYWCSGERIELPG-UHFFFAOYAJ
SMILES Cc1cc(c(c(c1)C)N2C=CN([C]2)c3c(cc(cc3C)C)C)C
Properties
Chemical formula	C21H24N2
Molar mass	304.43
Appearance	white solid
Melting point	150 to 155 °C (302 to 311 °F; 423 to 428 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

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.

Bulkier than IMes is the NHC ligand IPr. IPr features diisopropylphenyl in place of the mesityl substituents.

Some variants of IMes and IPr have saturated backbones, two such ligands are SIMes and SIPr. They are prepared by alkylation of substituted anilines with dibromoethane followed by ring closure and dehydrohalogenation of the dihydroimidazolium salt.