Structural characterization, thermal, dielectric and spectroscopic properties of di(n-pentylammonium) pentabromoantimonate(III): [n-C5H11NH3]2[SbBr5]

The di(n-pentylammonium) pentabromoantimonate(III) compound has been synthesized and studied by means of a single-crystal X-ray diffraction, differential scanning calorimetry, thermal expansion, dielectric and IR techniques. Two solid–solid phase transitions of first order: at 416/388 K and 225/224 K (heating/cooling) have been revealed. The crystal structure of [n-C5H11NH3]2[SbBr5] has been solved at 298 K, Pna21 (phase II) and at 86 K P212121 (phase III). The crystal structure is composed of the SbBr 5 2 - anions which form an infinite chain and four independent n-pentylammonium cations. The dielectric studies have been made in the frequency range 500 Hz–1 MHz between 160 and 430 K. The dielectric relaxation process, taking place over the low temperature phase III, has a polydispersive character. The infrared measurements carried out between 11 and 300 K indicate a significant role of the organic cations in the mechanism of the phase transition from the intermediate to the low temperature at 225 K.