الفهرس 
EXPERIMENTALOnly 14 pages are availabe for public view
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Abstract
A large number of hydrazons and their metal complexes have been studied because of their interesting and important properties. S-alkyldithiocarbazate, and their corresponding hydrazone ligands and their metal complexes have been studied over past few decades. This field increased considerably because of the attractive observation that different ligands show different biological properties including antifungal, antibacterial, antimalarial, antitumoral, antiviral and antioxidant activities. For these applications, we are extending this field in synthesis of novel dimeric hydrazone complexes.
In the present work, the hydrazone ligands were prepared by the condensation of S-methyldithiocarbazate as starting material, with salicylaldehyde, 2-hydroxyacetophenone, 4,6-diacetylresorcinol and 5-acetyl-4-hydroxy-2H-1,3-thiazine-2,6(3H)-dione in the molar ratio 1:1 to afford the corresponding hydrazone ligands; H2La, H2Lb, H3Lc and H2Ld, respectively. The structures of the ligands were elucidated by elemental analyses, IR, mass, 1H-NMR and electronic spectra. Molecular orbital calculations of the ligands were obtained using hyperchem 7.5 program. Also, the dissociation constants (pKa) of the ligands using potentiometric titrations in 75% (v/v) dioxane-water
The reactions of these hydrazone ligands with copper(II), nickel(II), cobalt(II), cadmium(II), zinc(II), iron(III), chromium(III), vanadyl(IV) and uranyl(IV) ions in a molar ratio (1:1, ligand: metal ion) were studied.. All reactions afforded dimer complexes, except uranyl(IV) where the reaction gave the unreacted starting materials.
The newly prepared metal complexes of these ligands were identified by elemental analyses, infrared, electronic, mass, 1H-NMR and ESR spectra as well as magnetic susceptibility measurements, molar conductance and thermal gravimetric (TGA) analysis.
Copper(II) and nickel(II) complexes exhibit a square planar geometry except nickel(II) complex for H2Ld exhibited an octahedral geometry. Cobalt(II), vanadyl(IV), iron(III) and chromium(III) complexes exhibit an octahedral geometry, except vanadyl(IV) complex for H3Lc ligand give square pyramidal geometry around each metal ion. Zinc(II) and cadmium(II) complexes showed tetrahedral geometry. The bonding sites are the azomethine nitrogen atom, the phenolic oxygen atom and the thiol sulfur atom.
Thermal gravimetric analysis (TGA) was performed for four complexes of each ligand (16 complexes). Thermodynamic parameters (ΔG, ΔH, ΔS and Ea) of the metal complexes were calculated using Coats-Redfern method and standard thermodynamic equations, and this was performed using the thermal degradation of the solid complexes using TGA curves.
The prepared ligands and their transition metal complexes were screened for sensitive organisms which are: two strain Gram-positive bacteria (Staphylococcus aureus and Streptococcus pyogenes, Gram-negative bacteria (Pseudomonas fluorescens and Pseudomonas phaseolicola and fungus (Fusarium oxysporum and Aspergillus fumigatus).