الفهرس 
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Abstract
serves as precursor for the formation of different Schiff base ligands. The condensation of 5-acetyl-4-hydroxy-2H-1,3-thiazine-2,6(3H)-dione with ethylenediamine, 1,3 diaminopropane or diethylenetriamine yield the corresponding tetradentate and pentadentate Schiff base ligands, abbreviated as HR2RLRaR, HR2RLRbR and HR2RLRc, Rrespectively. Reaction of the Schiff base ligands with copper(II), nickel(II), cobalt(II), zinc(II), cadmium(II), iron(III), chromium(III), cerium(III), vanadyl(IV) and dioxouranium(VI) ions in a molar ratio 1:1 afforded the corresponding complexes. The structures of these ligands and their newly prepared complexes were elucidated by elemental analyses, infrared, electronic, mass, P1PH-NMR and ESR spectra as well as molar conductance, magnetic susceptibility measurements and thermal gravimetric analysis (TGA). The Schiff base ligands behave as dibasic or monobasic tetradentate or pentadentate chelating sites via azomethine and amino group, nitrogen and phenolic oxygen atoms for HR2RLRa Rand HR2RLRbR and chelating sites. The metal complexes exhibit monomeric structures with different geometrical arrangements such as square planar, square pyramidal, octahedral, pentagonal bipyramid and octa-coordinated arrangements. Activation parameters (ΔG, ΔH, ΔS and ERaR) of the metal complexes were calculated using Coats-Redfern method. Molecular orbital calculations of the ligands and their metal complexes were calculated using hyperchem 7.5 program. The prepared ligands and their metal complexes were screened for their antimicrobial activity.