Thermal properties, crystal structures, and phase diagrams of ionic plastic crystals and ionic liquids containing a chiral cationic sandwich complex.

To investigate the effects of chirality on the phase behavior of ionic plastic crystals and ionic liquids, salts of a chiral sandwich complex with various anions were synthesized. The synthesized salts have the general chemical formula [Ru(C5H5)(C6H5CHCH3OCH3)]X (X = CB11H12, CF3BF3, PF6, CPFSA (= [double bond, length as m-dash]CF2(SO2CF2)2N)), where the ruthenium complex possesses a chiral substituent. The racemates of the salts with the CB11H12, CF3BF3, and PF6 anions crystallized as a solid solution, racemic compound, and conglomerate, respectively. The (S)-enantiomer and the racemate of the CB11H12 salt exhibited phase transitions to the ionic plastic phase and melted at high temperatures. Further, this salt exhibited polymorphism, as crystallographically investigated. Most of the other salts were ionic liquids exhibiting no plastic phase. The CPFSA salt was liquid and exhibited glass transition at low temperatures.