Complexes of Zn, Cd and Hg Halides with S and N Polydentate Schiff-Base. Metal Template Effect in the Synthesis of Analogous Oxygenated Base. Crystal Structure of [Zn(btsc)₂Cl₂] and [Cd(btsc)₂Br₂]

Abstract

Zinc, cadmiun and mercury dihalide react with 4-acetylpyridinthiosemicarbazone (4-aptsc) to give complexes with 1:1 and 2:1 ligand/metal stoichiometric ratios. These metals are effective templates for the Schiff-base condensation of 4-acetylpyridine with semicarbazide to give the complexes [M(4-apsc)X 2 ] and [M(4-apsc) 2 X 2 ] where M = Zn, Cd or Hg and X = Cl, Br or I. These compounds were characterized by elemental analyses, conductivities measurements, IR and 13 C, 1 H NMR spectra. The zinc chloride and bromide complexes of benzalthiosemicarbazone (btsc) have been prepared and characterized by X-ray measurements. The compounds Zn(btsc) 2 Cl 2 and Cd(btsc) 2 Br 2 are isostructural and crystallize in the space group P2 1 /n. The crystal structure of the chlorine derivative has been resolved by single-crystal X-ray diffraction. The zinc centre is in a slightly distorted tetrahedral environment. There are intra and intermolecular hydrogen bonds.