STRUCTURE AND PHASE TRANSITIONS IN [C(NH2)3]SbCl6 CRYSTALS

Abstract The crystal structure of [C(NH2)3]SbCl6 at 298 K (monoclinic, C2/m) and 240 K (monoclinic, P21/a) has been determined. The structure consists of isolated SbCl6− anions and guanidinium cations. Differential scanning calorimetry, dilatometric and dielectric studies revealed two structural phase transitions; a first-order one at 351 K and a second-order one at 265 K. One of the two crystallographically non-equivalent anions, SbCl6−(1), disordered in the room temperature phase is postulated to contribute to the phase transition mechanism at 265 K. A ferroelastic domain structure is found below 351 K.