Structural phase transition in catena-(1,2,3,6-tetrahydropyridine tris(μ2-chloro)-cadmium(II))

• A phase transition compound has been synthesized.
• DSC and dielectric analyses confirm the phase transition at about 197 K.
• The order–disorder transition of the 1, 2, 3, 6-tetrahydropyridinium cation is the driving force.

The title compound, catena-(1,2,3,6-tetrahydropyridine tris(μ2-chloro)-cadmium(II)), has a hexagonal perovskite-type structure with formula AMX3. It undergoes a reversible dielectric transition at about 197 K. The transition was accompanied by significant dielectric anomaly, and was confirmed by DSC measurements. The variable-temperature single crystal X-ray diffraction analysis reveals that the transition is a process of the doubling of the cell volume from P21/m to P21/a. The transition is caused by the order–disorder change of the 1,2,3,6-tetrahydropyridinium cation.

A phase transition compound, {[Thpy]·[CdCl3]} (1), has been synthesized. Differential scanning calorimetry measurement shows a pair of sharp peaks at 196.4 K (heating) and 183.1 K (cooling), indicating the phase transition is first-order. The phase transition is derived from the order-disorder transition of the 1,2,3,6-tetrahydropyridinium cation.Figure optionsDownload as PowerPoint slide