Distortions of [Sb2Cl10]4- bioctahedra and phase transitions in the chloroantimonate(III) (C3H5NH3)2[SbCl5] • (C3H5NH3)Cl

Bis(allylammonium)pentachloroantimonate(III)-allylammonium chloride, (C3H5NH3)(2)[SbCl5]center dot(C3H5NH3)Cl, belongs to the chloroantimonate(III) organic-inorganic salts family. The DSC studies of this compound showed two anomalies at 181 K and at 223 K. Both are associated with phase transitions, which mainly occur due to ordering-disordering processes of the organic cations. Between 181 and 223 K the structure is incommensurate. The crystal structure was determined at 298 and 86 K. At both temperatures the crystal structure consists of (C3H5NH3)(+) cations, anionic distorted [Sb2Cl10](4-) units and isolated Cl- ions. In the room-temperature phase two out of three, and in the low-temperature phase two out of six allylammonium cations were found to be disordered. The deformations of the [Sb2Cl10](4-) moieties in both phases are discussed and explained by the deviation of the Sb-III 5s electron tone pair from its spherical symmetry and the influence of N-H center dot center dot center dot Cl hydrogen bonds, which join together the organic and inorganic sublattices.