Syntheses, spectral and structural characterization of trinuclear and mononuclear Zn(II) complexes of N′-benzoyl hydrazine carboperthioate and 5-phenyl-1,3,4-oxadiazole-2-thione: An approach to DFT calculation, antibacterial and thermal studies

Abstract

Potassium N′-(benzoyl)-hydrazine carbodithioate forms novel complexes [Zn3(μ-bhcp)2(py)4] (1) and [Zn(phot)2(en)2] (2) containing newly generated ligands N′-benzoyl hydrazinecarboperthioate (bhcp)3− and 5-phenyl-1,3,4-oxadiazole-2-thione (phot)− which have been characterized by elemental analyses, m.p, IR, NMR and single crystal X-ray data. During complexation, potassium N′-(benzoyl)-hydrazine carbodithioate is converted to N′-benzoyl hydrazinecarboperthioate (oxidized ligand having a S-S linkage) and 5-phenyl-1,3,4-oxadiazole-2-thione in the presence of pyridine and ethylenediamine (en), respectively which act as secondary ligands. The crystal structure of complex 1 reveals that the ligand is acting as trinegative pentadentate ON2S2, bonded to terminal zinc as ONS dinegative tridentate and to the other as NS uninegative bidentate. In the trinuclear complex 1, both terminal zinc atoms have distorted square pyramidal geometry and the middle zinc has tetrahedral geometry. Complex 2 has distorted octahedral geometry where central atom is bounded to two en and two oxadiazoles anions. The geometry of the complexes has also been optimized by the DFT method and the results of which are presented and compared with the X-ray diffraction data. The ligand has been also optimized and analyzed for its reactive site. In addition to this, frontier molecular orbitals (FMO) were also calculated. Raman analyses give the evidence of the binding of zinc with the newly generated oxadiazole and acyclic perthio ligands and the results corroborate with the IR and XRD data. Solid state electrical conductivity, bactericidal and thermal properties have been analyzed. The bioefficacy of the ligand and complexes has been examined against the growth of bacteria in vitro to evaluate their anti-microbial potential.