English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The A2MX4 structures have been of interest for a long time because of their structural properties, phase transitions and thermochromic behavior in the solid state. The thermochromic behavior of copper(II) chloride complexes have been divided at least into two classes [1]. In one class the compounds show a phase transition involving a change in the coordination geometry around the copper ion. In the other class, the thermochromism is associated only with the temperature dependence of the line widths of the electronic absorption bands. It has also been observed that the trans Cl-Cu-Cl angle is less than 132° when there is no possibility of hydrogen bonding between the cation and the CuCl4 2anion. When N-H ...Cl hydrogen bonding exists, the trans Cl-Cu-Cl angle is greater than 132° [1]. In some cases the anion can even have a planar configuration (Cl-Cu-Cl angle of 180°). The new R2R’2N X type quaternary ammonium halides [2-3] have enabled us to crystallize and characterise a new kind of (R2R’2N)2MX4 compounds and examine their thermal behavior in the solid state. Bis[dibenzyldimethylammonium] CuX4 (X = Br or Cl) were crystallized from acetonitrile and dilute HX solutions. When the acetonitrile solution was used, the acetonitrile molecule co-crystallized into the crystal structure. As a result, the isomorphic structures of Bis[dibenzyldimethylammonium]CuX4*0.5CH3CN (X = Br or Cl) in the monoclinic space group P21/n were obtained. Interestingly, while a dilute HX solution was used, the Bis[dibenzyldimethylammoniumUuX4 (X = Br or Cl) crystallized without solvent molecules and the formed crystals were not isomorphous with each other. The tetrabromocuprate structure crystallized in the triclinic space group P-1 and the tetrachlorocuprate structure in the monoclinic space group P21/c. In all cases the CuX4 anion appeared in a distorted tetrahedral geometry as the average of the two large X-Cu-X angles was about 123-133° depending on the structure. The powder diffraction measurements showed that every compound has the same structure both at room temperature and at the temperature of -100°C. Thermal behavior of these compounds was examined by TG/DTA and DSC measurements. In all cases the primary decomposition of the compounds occurred in two stages. Based on the DSC measurements these compounds had a melting peak or a melting-crystallizationmelting peak clearly before or just before the decomposition started. In general, these crystals showed to be exceptionally stable compounds having no phase transitions between -100°C and the melting point. Thus, no marks of any thermochromic behavior were seen in contrast to the general behavior of similar A2MX4 compounds. In addition, these crystals are very stable in the air at ambient temperature as they can be stored in the air for several weeks without any marks of the decomposition.

acta crystallographica. section a, foundations of crystallography/acta crystallographica. section a

Crystal structures and thermal behavior of bis[dibenzyldimethylammonium]CuBr4and bis[dibenzyldimethylammonium]CuCl4crystallized from acetonitrile and dilute HXsolutions