Journal Article

Physical Properties and Structural Characterization of Ionic Liquids and Solid Electrolytes Utilizing the Carbamoylcyano(nitroso)methanide Anion

Pringle, Jennifer M., Razali, Mohd R., Batten, Stuart R., MacFarlane, Douglas R., Janikowski, Judith, Forsyth, Craig M., Nairn, Kate M.

2013

Overview

The carbamoylcyano(nitroso)methanide (ccnm) anion has been used for the synthesis of eight new salts, two of which are liquid at room temperature. The ionic liquid containing a large phosphonium cation displays the highest thermal stability, while the imidazolium salt is the most fluid and conductive. Analysis of the crystal structures of four of the new materials, containing pyrrolidinium and small phosphonium cations, reveals notably different anion stacking behaviour depending on the nature of the cation. The solid [ccnm] salts all display good ionic conductivities, above 1 mS cm−1 for the four different pyrrolidinium species. This, and their soft appearance, is hypothesized to be a result of the presence of both the syn and anti conformational isomers of the [ccnm] anion. Finally, solid‐state NMR linewidth analysis and second moment calculations have been used to gain further insight into the disorder within one of the pyrrolidinium plastic crystals, revealing significant, quantifiable translational motion of some fraction of the material at temperatures over 0 °C. Plastic fantastic: The first use of the carbamoylcyano(nitroso)methanide anion for the synthesis of ionic liquids produces crystal structures that depend strongly on the nature of the cation. The organic ionic plastic crystals made using this anion display good solid‐state ionic conductivities, consistent with the increasing interest in this type of material as new solid‐state electrolytes.

• Publisher: WILEY-VCH Verlag,WILEY‐VCH Verlag
• Subject: electrolytes / ionic liquids / NMR spectroscopy / plastic crystals / X-ray diffraction