Structural phase transition due to the flexible supramolecule of (4-cyanomethylanilinium)([18]crown-6) in [Ni(dmit)2]− crystal

Abstract

A flexible hydrogen-bonding supramolecular cation of 4-cyanomethylanilinium (CMAni+)-[18]crown-6 was introduced into the [Ni(dmit)2]− salt (dmit2− = 2-thioxo-1,3-dithiole-4,5-dithiolate) as a counter cation to form (CMAni+)([18]crown-6)[Ni(dmit)2]−. The rotation of the cyanomethyl group of the CMAni+ cation is associated with the structural phase transition at 153 K, at which temperature the space group was changed from Pbcn (high-temperature phase) to P212121 (low-temperature phase). The temperature dependent dielectric constants and potential energy calculations were consistent with the rotation of the cyanomethyl group of CMAni+.