Synthesis, structural and spectral characterization of Zn(II) complexes, derived from thiourea and thiosemicarbazide

Novel mono- and binuclear complexes of Zn(II) with thiourea derivatives (H2L) (N-2-propenyl-N′-2-pyridinylthiourea) and thiosemicarbazide, H3L (2-[(2-hydroxyphenyl)methylene]hydrazine-N-(2-propenyl)carbothioamide, (2-[(2-hydroxyphenyl)methylene]hydrazine-N-phenylcarbothioamide) have been synthesized. The possibility of mono- or tridentate coordination to the central metal ion of these ligands both in neutral and in monodeprotonated thionic tautomeric form with the stoichiometric ratios Zn:L = 1:1 and 1:2 has been shown. The synthesized complexes Zn(CH3COO)2(H2L)2 (I), Zn2(CH3COO)2(H2L)2·Zn2(CH3COO)(H2O)(H2L)2 (II), Zn(H2L)2 (III), Zn2(CH3COO)2(H2L)2 (IV) have been studied by IR, UV–Vis, 1H, 13C NMR spectroscopy and single crystal X-ray diffraction (I, II, IV). It has been established that in compound (I) the central Zn atom forms a strongly distorted tetrahedral ZnS2O2 coordination, while in (II) and (IV) it forms a square-pyramidal ZnSNO3 environment. In the case of complex (II) the asymmetric unit contains two molecules of binuclear complex compounds, which are slightly differ by coordination in vertex direction of Zn polyhedron. The square-pyramidal geometry of Zn(II) ions from the first molecule completed by two acetate anions, which is similar to compound (IV). In the second molecule, the Zn(II) coordination polyhedrons are completed by one acetate anion and one water molecule.

Four novel Zn(II) complexes with thiourea and thiosemicarbazones have been yielded under different synthesis conditions. The structure and spectral characteristic of obtained compounds have been discussed.Figure optionsDownload as PowerPoint slideHighlights
► Four new Zn(II) coordination compounds obtained from thiourea and thiosemicarbazone derivatives.
► Zn displays different coordination geometry depending on synthesis conditions and ligand nature.
► Regulation of pH in reaction mixture led to formation of different products.