Structural characterization, thermal, dielectric and vibrational properties of tris(allylammonium) hexabromoantimonate(III), (C3H5NH3)3SbBr6

The novel inorganic-organic hybrid material, allylammonium hexabromoantimonate(III), (C3H5NH3)(3)-SbBr6, has been synthesized and its structure has been determined by means of the single-crystal X-ray diffraction studies at five temperatures (273, 248, 220, 170 and 100 K). At room temperature the compound crystallizes in the monoclinic space group, C2/m. Its crystal structure is composed of the discrete SbBr63- anions and three non-equivalent allylammonium, (C3H5NH3)(+), cations. In (C3H5NH3)(3)SbBr6 three solid-solid structural phase transitions are detected: a continuous one at 260/256 K (on heating-cooling) from phase I to II, a discontinuous one at 227/208 K (II -> III) and another discontinuous at 197/191 K (III -> IV). The electric properties of the compound have been measured in a wide temperature region (150-300 K). Temperature-dependent vibrational properties in the frequency region 3500-500 cm (1) have been reviewed. Possible mechanisms of the phase transitions in (C3H5NH3)(3)SbBr6 are discussed on the basis of the presented results. (C) 2010 Elsevier B.V. All rights reserved.