Crystal structure and thermodynamic properties of phase change material bis(1-dodecylammonium) tetrachlorochromate (C12H25NH3)2CdCl4(s)

Abstract

A novel complex bis(1-dodecylammonium) tetrachlorochromate (C12H25NH3)2CdCl4(s) (abbreviated as C12Cd(s)) was synthesized by liquid phase reaction. Crystal structure and composition of the complex were determined by X-ray crystallography, chemical analysis, and elemental analysis. It is triclinic, the space group is P−1 and Z = 2. Lattice potential energy (LPE) of the complex was calculated to be kJ·mol−1 from crystallographic data. Low-temperature heat capacities were measured by a precise automatic adiabatic calorimeter over the temperature range from 78 to 370 K. The temperature, molar enthalpy, and entropy of the phase transition of the complex were determined to be 331.88 ± 0.02 K, 55.79 ± 0.46 kJ·mol−1, and 168.10 ± 1.38 J·K−1·mol−1, respectively. Two polynomial equations of the heat capacities as a function of temperature were fitted by least-square method. Smoothed heat capacities and thermodynamic functions of the complex were calculated.