X-ray diffraction, vibrational properties, and dielectric studies of 3-ammoniumpropyl imidazolium pentabromoantimonate (III)

A new organic–inorganic material 3-ammoniumpropyl imidazolium pentabromoantimonate (III) was reported. The title compound was synthesized at room temperature by slow evaporation and then characterized by single-crystal and powder X-ray diffraction, spectroscopic measurements, thermal analysis, and dielectric technique. It crystallizes in the non-centrosymmetric space group P2 1 2 1 2 1 with the following unit cell parameters: a = 8.7120(7), b = 12.6608(1), c = 14.3498(1) Å with Z = 4. The crystal is built up of separated SbBr 5 2− polyhedra anions and 3-ammoniumpropyl imidazolium cations. The cohesion of the structure is ensured by network of N–H…Br hydrogen bonds between the 3-ammoniumpropyl imidazolium cations and [SbBr 5 ] 2− anions, in which they may be effective in the stabilization of the crystal structure. The Raman and infrared spectra confirm the presence of both cationic [C 6 H 13 N 3 ] 2+ and anionic [SbBr 5 ] 2− entities. Dielectric data were analyzed using complex permittivity ε * and complex electrical modulus M * for the sample at various temperatures. The conductivity follows the Arrhenius low. The Z ′ and Z ʺ versus frequency plots are well fitted to an equivalent circuit model. The circuits consist of the parallel combination of bulk resistance Rp and constant phase elements CPE. [C 6 H 13 N 3 ]SbBr 5 crystals undergo one endothermic peak at 333 K. This transition was detected by DSC and by dielectric measurements using the impedance and modulus spectroscopy techniques.