Synthesis and characterization of mono- and poly-nuclear complexes of dithiocarbamate derivative of 2-amino-5-mercapto-1,3,4-thiadiazole

Derivatives of 1,3,4-thiadiazole ring show biological activities against different species of microbes, therefore mono- and poly-nuclear complexes of dithiocarbamate derivatives of 2-amino-5-mercapto-1,3,4-thiadiazole (AMT), have been prepared in an attempt to show the effect of introducing two centers in the structure of the ligand (NaMTD), as well as to investigate the coordination behavior of the ligand toward both transition metals and to compare the biological activity of the complexes with that of the ligand.Dithiocarbamate derivatives of AMT (NaMTD), were prepared by condensation of CS₂ and AMT, which was itself prepared starting from thiosemicarbazide, in alcoholic sodium hydroxide solution, the product was isolated and characterized by FT-IR and U.V.-visible spectroscopy. The Pd(II) complex of  NaMTD  have been prepared using Na₂PdCl₄ in acetone, the product (Pd-MTD) was isolated and used as precursor to prepare a series of heteropolynuclear complexes with  V⁴⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺ and Cd²⁺ metal ions in DMF. Different fine crystalline, colored and stable complexes were isolated and studied using FT-IR and U.V.-visible spectroscopy, magnetic susceptibility and conductivity measurements, the metal content was determined using atomic absorption spectroscopy technique.The complexes exhibit the general formula  [(Pd-MTD)₂ ML₂]ⁿ    where  M = Ni²⁺, Mn²⁺ and  L = H₂O,  n = 0 M = Cu²⁺  and  L =DMF,  n = 0 While the vanadyl ion show complexes of a formula (Pd-MTD)₄ VO]^2- and that  of  Fe(II)   was  [(Pd-MTD)₄ Fe]^2-.2(H₂O).While Co²⁺ and Cd²⁺ have the formula [(Pd-MTD)₂ M] .2L, L = DMF for Co²⁺ and  H₂O for Cd²⁺. A number of structural phenomena have been revealed during the study. The results helped to illustrate the bonding natures between metal ions and the different donor atoms of the ligand. NaMTD was found to coordinate with Pd(II) ion through sulfur of the dithiocarbamate group and the nitrogen of the ring. The thioamide group, on the other side, was left to coordinate to the several metal ions either through sulfur atom only (in case of VO²⁺ and Fe²⁺), or chelating through nitrogen and sulfur (in case of (Ni²⁺, Cu²⁺,Mn²⁺, Co²⁺,  Cd²⁺) ions.The structural formula were either octahedral for (Mn²⁺, Ni²⁺, Cu²⁺) ions, square pyramidal (in case of  VO²⁺ ion), and tetrahedral for Cd²⁺, Fe²⁺, Co²⁺  ions. The antibacterial activity of the NaMTD and it^'s mono- and poly-nuclear complexes were screened against gram (+) and gram (-) bacteria.