SYNTHESIS, SPECTROSCOPIC STUDY AND CRYSTAL-STRUCTURE OF HIS (4,6-DIMETHYL-2-THIOPYRIMIDINIUM) TETRACHLOROZINCATUM(II) MONOHYDRATE AND ITS SOLID-STATE TRANSFORMATIONS

The solid complex [H(2)L],[ZnCl4]. H2O (HL=4,6-dimethyl-2-thiopyrimidi ne) has been obtained and characterized by IR, H-1 and C-13 NMR spectr oscopies and thermal techniques. The molecular structure of this compl ex has been established by single crystal X-ray diffraction. Crystals of the compound are orthorhombic, of space group P2(1)2(1)2(1) with ce ll constants a = 7.153(2), b = 14.624(3), c = 20.499(4) Angstrom, Z = 6 and D-c = 1.572 g cm(-3). The structure was solved and refined to R = 0.049 (R(w) = 0.029). The asymmetric complex unit consists of two 4, 6-dimethyl-2-thiopyrimidinium cations, a [ZnCl4](2-) anion and a water molecule. The Zn(II) centres are tetracoordinated by chloride ions gi ving a tetrahedral arrangement. This asymmetric unit is stacked along the b axis giving rise to a packing of pyrimidine rings and [ZnCl4](2- ) anions which are linked by hydrogen bonds involving chlorine atoms, NH groups and water molecules. The thermal treatment of [H(2)L](2)[ZnC l4]. H2O leads to two different solid complexes [Zn(HL)(2)Cl-2] and [Z nL(2)] which have been previously obtained and characterized by us.