Optical, structural characterization and dielectric relaxation of [C2H5NH3]2ZnCl4 compound

Abstract

ABSTRACTThe new organic-inorganic compound [C2H5NH3]2ZnCl4 has been grown by the slow evaporation at room temperature. The zero-dimensional (0-D) structure for this compound was determined by the single X-ray diffraction. It crystallizes at room temperature in the non-centrosymmetric space group Pna21 and consists of ethylammonium cations [C2H5NH3]+ and [ZnCl4]2− tetrahedra anions. That is interconnected by means of hydrogen bonding contacts N-H···Cl. The molecular geometry and vibrational frequencies of [ZnCl4]2− and [C2H5NH3]+ in the ground state was calculated using density functional method (B3LYP) with 6–31G(d) and 6–311G (d,p) basis set. The optimized geometric bond lengths and bond angles, obtained by using B3LYP/6–311G (d,p), show the best agreement with the experimental data. The optical absorbance was measured in order to deduce the absorption coefficient α, optical band gap Eg. The optical band gap is determined by extrapolating the plotted graph of (αhυ)1/2 vs. (hυ). The large value of indirect optical band gap energy indicates the insulating nature of this material. Moreover, the extinction coefficient, refractive index and the dielectric permittivity of [C2H5NH3]2ZnCl4 compound were calculated and the results are discussed. The evolution of the dielectric loss as a function of frequency revealed a distribution of relaxation times, probably ascribed to the reorientational dynamics of alkyl chains in this compound, and then analyzed with the Cole–Cole formalism.