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))]

•A compound (1) contains a novel 2-D anion is synthesized•A solid-solid phase transition compound (2) is synthesized•DSC, dielectric and powder X-ray diffraction analyses confirm the phase transition at 384 K.

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 CH⋯N and CH⋯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.

Graphical abstractTwo novel compounds :[(CTA)+(Hg3Cl4Br3)−]n (1) and [(CTA)+]2 (Hg2Cl6)2– (2) (CTA = (Et3NCH2CN) are determined. 1 has a novel 2-D architecture inorganic anion. 2 undergoes a crystalline to non-crystalline phase transformation at 384 K.Figure optionsDownload full-size imageDownload as PowerPoint slide