Synthesis and Structural Studies of Multinuclear Metal Chelates Derived From a New Hetrocyclic Chelating Ligand
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Date
2007-03
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Addis Ababa Universty
Abstract
2,4-dihydroxy-5-acetylacetophenone(DAAP), 2,4-dihydroxy-5-acetylacetophenone dihydrazone (DAAD), and 4,6-Bis-(1-[(4,6-dichloro-[1,3,5]-triazine-2-yl)-hydrazono]-ethyl)-benzene-1,3-diol (BDTHEBD) as starting materials were synthesized and characterized by physical and spectral studies.4,6-Bis-(1-[(4,6-disemicarbazino-[1,3,5]-triazine-2-yl)-hydrazono]-ethyl)-benzene-1,3-diol (BDSTHEBD) was prepared by the reaction of 4,6-Bis-(1-[(4,6-dichloro-[1,3,5]-triazine-2-yl)-hydrazono]-ethyl)-benzene-1,3-diol(BDTHEBD) with semicarbazide hydrogen chloride in a 1:4 molar ratio in ethanol/methanol/nitromethane(being 1:1:8). The synthesis of complexes with transition metal (II) ions (Co2+and Ni2+) were undertaken and the resulting complexes were characterized by 1H NMR, IR, UV-Vis, and AAS spectroscopic techniques. In addition, thermal analysis, Magnetic susceptibility, conductivity measurements and chloride estimation were also through.
Syntheses of the metal complexes were carried out using methanol/triethyl amine (being 1:5) mixture as a solvent. Analytical results reveal that the complexes have 1:4 ligand and metal ratio. Furthermore, based on spectroscopic results (NMR, IR, UV-Vis, and AAS), analytical data and Magnetic moments, enolization and deprotonation of BDSTHEBD were concluded. Four chelating sequences per ligand (NNN, NNO, NNO, and NNN) were identified through which four metal ions (Co2+ and Ni2+) were coordinated. Subnormal magnetic moments at room temperature suggest metal-metal interactions in the complexes. Octahedral geometry was proposed for the complexes.
Keywords: Heterocyclic compounds, Triazines, Cyanuric chloride, Hydrazine hydrate semicarbazide hydrogen chloride, Multidentate ligand, Multinuclear metal complex.
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Keywords
Heterocyclic compounds; Triazines; Cyanuric chloride; Hydrazine hydrate semicarbazide hydrogen chloride; Multidentate ligand; Multinuclear metal complex