Complexes of heterocyclic thiones and group 12 metals: Part VI. Preparation and characterisation of complexes of cadmium(II) halides with 1-methylimidazoline-2(3H)-thione, 1,3-thiazolidine-2-thione and 1,3-benzothiazoline-2-thione. Crystal structures of polymeric (1,3-thiazolidine-2-thione)cadmium(II) chloride, bis(1,3-thiazolidine-2-thione)cadmium(II) iodide and monomeric bis(1-methylimidazoline-2(3H)-thione)cadmium(II) bromide

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Reactions of 1-methylimidazoline-2(3H)-thione (meimz2SH), 1,3-thiazolidine-2-thione (tzdSH) and 1,3-benzothiazoline-2-thione (bztzSH) with cadmium(II) halides in ethanol solutions result in the formation of 1:1 complexes for the chloride, both 1:1 and 2:1 complexes for the bromide, and only 2:1 complexes for the iodide. Spectroscopic evidence confirms the exocyclic sulfur atom to be the donor in all cases. Cadmium(II) acetate and the heterocyclic ligands in the presence of triethylamine form the insoluble deprotonated complexes. The structure of (tzdSH)CdCl 2 consists of double halogen-bridged chains, linked into sheets via NH⋯Cl interactions and with the heterocycle coordinated to the metal via the exocyclic sulfur atom. Thus each cadmium is approximately octahedrally surrounded by one sulfur, 2 two-coordinate and 3 three-coordinate chlorine atoms. In contrast (tzdSH) 2CdI 2 forms chains via I⋯S interactions; the metal is tetrahedrally coordinated by two sulfur and two iodine atoms. The structure of (meimz2SH) 2CdBr 2 consists of discrete complex molecules with essentially tetrahedrally coordinated Cd and no significant intermolecular interactions; the six molecules in the asymmetric unit are related by pseudo-symmetry and are very similar except for variation in the orientation of the heterocyclic substituents.