An Abnormal N‐Heterocyclic Carbene–Carbon Dioxide Adduct from Imidazolium Acetate Ionic Liquids: The Importance of Basicity. Issue 40 (18th August 2014)

• Record Type: Journal Article
• Authors: Kelemen, Zsolt; Péter‐Szabó, Barbara; Székely, Edit; Hollóczki, Oldamur; Firaha, Dzmitry S.; Kirchner, Barbara; Nagy, József; Nyulászi, László
• Is Part Of: Chemistry. Volume 20:Issue 40(2014)
• Page Start: 13002
• Page End: 13008
• Publication Date: 2014-08-18
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201402912
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>In the reaction of 1‐ethyl‐3‐methylimidazolium acetate [C₂C₁Im][OAc] ionic liquid with carbon dioxide at 125 °C and 10 MPa, not only the known N‐heterocyclic carbene (NHC)–CO₂ adduct <bold>I</bold>, but also isomeric aNHC‐CO₂ adducts <bold>II</bold> and <bold>III</bold> were obtained. The abnormal NHC‐CO₂ adducts are stabilized by the presence of the polarizing basic acetate anion, according to static DFT calculations and ab initio molecular dynamics studies. A further possible reaction pathway is facilitated by the high basicity of the system, deprotonating the initially formed NHC‐CO₂ adduct <bold>I</bold>, which can then be converted in the presence of the excess of CO₂ to the more stable 2‐deprotonated anionic abnormal NHC–CO₂ adduct via the anionic imidazolium‐2, 4‐dicarboxylate according to DFT calculations on model compounds. This suggests a generalizable pathway to abnormal NHC complex formation.</p> </abstract>