Synthesis, structure and dielectric property of poly[(cyanomethyltriethylammonium) bis(μ2-chloro)-bis(μ3-chloro)-tri(μ2-bromo)trimercury(II)] and [cyanomethyltriethylammonium][bis(μ2-chloro)-bis(dichloromercury(II))]

An investigation into the reaction of cyanomethyltriethylammonium (CTA) halide salts with HgCl2 afforded into [(CTA)+(Hg3Cl4Br3)−]n (1) and [(CTA)+]2 (Hg2Cl6)2 − (2). The two compounds have same propeller-like quaternary ammonium cations. The anion in compound 1 was a novel two-dimensional architecture and in compound 2 was an isolated centrosymmetrical dimer. Some Csingle bondH⋯N and Csingle bondH⋯X (X = Cl, Br) hydrogen bonds have been found in the two compounds, which assemble the cations and anions into a three-dimensional network. Variable-temperature dielectric properties have been studied for them. There was no dielectric anomaly in 1, whereas an obvious reversible dielectric anomaly was found in 2. The differential scanning calorimetric (DSC) and variable-temperature powder XRD properties have been studied for 2. The combined results showed that compound 2 has a solid–solid phase transition from crystalline to non-crystalline.