Synthesis, crystal structure, vibrational properties and dielectric properties of 1-(2-ammonium-ethyl) pipérazindiium hexachlorobismuthate(III)

Abstract

[C6H18N3]BiCl6 crystallizes at room temperature in the monoclinic space group P21/n. The crystal is built up of separated BiCl63- octahedral anions and 1-(2ammonium-ethyl) piperazindiium cations. Differential scanning calorimetry (DSC) disclosed structural phase transitions of the order-disorder type at 343 and 393 K. Dielectric investigations revealed a step-wise change of the electric permittivity at Ttr1 and Ttr2, characteristic of crystals in the high-temperature phase. Temperature-dependant Raman spectra for polycrystalline samples were taken between 298 and 493 K to clarify the cation dynamics contribution to the mechanism of the phase transition. The modes are assigned to the deformation vibrations of the anionic group and NH+, NH2+ and NH3+ groups in the 1-(2ammonium-ethyl) piperazindiium cations. The 1-(2ammonium-ethyl) piperazindiium cations appeared to be the most sensitive to the phase transition. © 2012 Elsevier Ltd. All rights reserved.