Complex tellurium salts with supramolecular bidimensional lattices:: Synthesis and X-ray characterization of (2-Br-C5NH5)2[TeX6] (X = Cl, Br)

The reaction of tellurium(IV) tetrahalides with hydrochloric and hydrobromic acid leads to the formation of (H3O)(2)[TeX6], which reacts subsequently with (2-Br-C5NH5)X-+(-) to afford (2-Br-C5NH5)(2)[TeCl6] (1) and (2-Br-C5NH5)(2)[TeBr6] (2). The structure of the complex salts were analysed by X-ray diffractometry affording the centrosymmetric space groups P2(1)/n (monoclinic, 1) and P1 (triclinic, 2). Interionic hydrogen bondings hold their lattices in bidimensional supramolecular arrays not yet described in the literature. The lone electron pair of the AX(6)E-system of the hexahalotellurates [TeX6](2-) (X = Cl, Br) seems to be fully delocalized since only small octahedral deviations were observed for the anionic species. The structures of the title compounds were refined with the Te atoms occupying sites with full point symmetry, approximately m3m. In both cases the Te atoms enclose centers of inversion and the octahedrally dynamic structures are enforced and stabilized along the supramolecular lattices by the crystal field of the 2-Br-pyridinium cations.