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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,〔Arduengo, Anthony J., III; Dias, H. V. Rasika; Harlow, Richard L.; Kline, Michael "Electronic Stabilization of Nucleophilic Carbenes" Journal of the American Chemical Society 1992, volume 114, pp. 5530-4. 〕 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.〔Elon A. Ison, Ana Ison "Synthesis of Well-Defined Copper N-Heterocyclic Carbene Complexes and Their Use as Catalysts for a “Click Reaction”: A Multistep Experiment That Emphasizes the Role of Catalysis in Green Chemistry" J. Chem. Educ., 2012, volume 89, pp 1575–1577. 〕 ==Related compounds== Related to IMes another popular NHC ligand is IPr, featuring diisopropylphenyl groups in place of the mesityl groups, IPr is even bulkier.〔Morgan Hans and Lionel Delaude "Microwave-Assisted Synthesis of 1,3-Dimesitylimidazolium Chloride" Org. Synth. 2010, vol. 87, 77. 〕 Important variants of IMes and IPr have saturated backbones, these ligands are called SIMes and SIPr.〔Steven P. Nolan "N-Heterocyclic Carbenes in Synthesis" Wiley-VCH, 2006. ISBN 978-3-527-60940-6.〕 They are prepared by alkylation of substituted anilines with dibromoethane followed by ring closure and dehydrohalogenation of the dihydroimidazolium salt.〔Arnaud Gautier, Federico Cisnetti, Silvia Díez-González, Clémentine Gibard "Synthesis of 1,3–bis(2,4,6–trimethylphenyl)–imidazolinium salts : SIMes.HCl, SIMes.HBr, SIMes.HBF4 and SIMes.HPF6" Protocol Exchange 2012. . http://www.nature.com/protocolexchange/protocols/2488#/procedure〕 : 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「IMes」の詳細全文を読む スポンサード リンク
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