Structural and dielectric properties of thiazolium chlorobismuthate(III) and chloroantimonate(III)

The crystal structures of [C3H4NS](6)]M4Cl18]center dot 2H(2)O (M = Sb, Bi) consist of three nonequivalent thiazolium cations and discrete centrosymmetric anions [M4Cl18](6-). The title compounds appear to be isomorphous and crystallize in the triclinic space group, P (1) over bar (at 100 K). One of three thiazolium cations was found to be disordered (two-site model). [C3H4NS](+) cations are hydrogen bonded to [M4Cl18](6-) units and water molecules. The water molecules (O-w) via the O-H center dot center dot center dot Cl hydrogen bonds are involved in the one-dimensional polymeric chains, which extend along the c-axis. The dielectric dispersion studies on two thiazolium analogs in the audio-frequency region disclosed complex relaxation processes. The dielectric response indicates the presence of two independent relaxators, which are characterized by polydispersive nature. The relaxation processes taking place in the both studied crystals are due to the motion of dipolar thiazolium cations. (C) 2008 Elsevier B.V. All rights reserved.