ZINC(II) AND CADMIUM(II) HALIDE-COMPLEXES WITH 2,6-DIMETHYL-4H-PYRAN-4-THIONE

The thiocarbonyl donor 2,6-dimethyl-4H-pyran-4-thione (DMTP) forms with zinc(II) and cadmium(II) halides complexes of general formulae [M(DMTP)2X2] and [M(DMTP)X2]n (M = Cd or Zn; X = halide). The compounds have been characterized by IR and proton NMR spectroscopy. The crystal structure of [Zn(DMTP)2Cl2] was determined by X-ray crystallography and refined to the final R of 0.060, based on 2073 observed reflections. The crystal is triclinic, P1, with a = 7.955(6), b = 8.599(6), c = 14.098(5) angstrom, alpha = 92.12(3), beta = 110.96(3) and gamma = 108.60(3)-degrees. Zn is tetrahedrally coordinated by two Cl and two S(ligand) atoms. Bond distances (mean values) are Zn-Cl 2.25, Zn-S 2.37, S-C 1.69 angstrom. The IR absorptions due to metal-halide bond vibrations support a distorted tetrahedral structure for all 1:2 complexes. The [Cd(DMTP)Cl2]n adduct has probably a polymeric structure by bridging halides, with the cadmium atom in an octahedral environment, whereas the [M(DMTP)X2]n (M = Zn, X = Br or I; M = Cd, X = I) complexes are dimers by halide bridges. Proton NMR spectra in various deuterated solvents are discussed.