Investigating the physicochemical properties, structural attributes, and molecular dynamics of organic–inorganic hybrid [NH3(CH2)2NH3]2CdBr4·2Br crystals

Abstract

Abstract An in-depth understanding of the physicochemical properties of the organic–inorganic hybrid [NH3(CH2)2NH3]2CdBr6 whose structure corresponds to the formulation [NH3(CH2)2NH3]2CdBr4· 2Br is essential for its application in batteries, supercapacitors, and fuel cells. Therefore, this study aimed to determine the crystal structure, phase transition, structural geometry, and molecular dynamics of these complexes. Considering its importance, a single crystal of [NH3(CH2)2NH3]2CdBr6 was grown; the crystal structure was found to be monoclinic. The phase transition temperatures were determined to be 443, 487, 517, and 529 K, and the crystal was thermally stable up to 580 K. Furthermore, the 1H, 13C, 14N, and 113Cd NMR chemical shifts caused by the local field surrounding the resonating nucleus of the cation and anion varied with increasing temperature, along with the surrounding environments of their atoms. In addition, 1H spin–lattice relaxation time T1ρ and 13C T1ρ, which represent the energy transfer around the 1H and 13C atoms of the cation, respectively, varied significantly with temperature. Consequently, changes in the coordination geometry of Br around Cd in the CdBr6 anion and the coordination environment around N (in the cation) were associated with changes in the N–H···Br hydrogen bond. The structural geometry revealed critical information regarding their basic mechanism of organic–inorganic hybrid compounds.