Ionic Solid-State Dimers and Polymers Derived from Imidazolium Dicarboxylic Acids

• Published in: Chemistry : a European journal 2006-05, Vol.12 (15), p.4014-4020
• Main Authors: Fei, Zhaofu, Ang, Wee Han, Geldbach, Tilmann J., Scopelliti, Rosario, Dyson, Paul J.
• Format: Article
• Language: English
• Subjects: Brønsted acids; coordination polymers; hydrogen bonds; ionic liquids; solid-state structures
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200500944

A series of imidazolium dicarboxylic acids have been prepared from the reaction of the 1,3‐bis(carboxymethyl)imidazolium zwitterion with the Brønsted acids HX (X=F, Br, Cl, ClO4). The structures of these acids have been established in the solid state by single‐crystal X‐ray diffraction, which revealed that the cations and anions form strong hydrogen bonds through OH⋅⋅⋅X interactions, leading to the formation of dimeric and polymeric networks. These acids react with elemental zinc and cobalt to form stable polymeric coordination complexes, some of which have also been characterised by X‐ray diffraction. Size matters! A series of imidazolium dicarboxylic acids have been prepared, the crystalline structures of which are found to be largely dependent on the size of the anion; small anions (F−, Cl−) favouring long linear polymeric chains, and large anions (Br−, ClO4−), favouring dimeric units. These acids react with elemental zinc and cobalt to form stable polymeric coordination complexes, some of which have also been characterised by X‐ray diffraction (see picture).