COMPARATIVE STUDY BETWEEN N,N'-BIS (ACETYLACETONE)-O-PHENYLENEDIAMINE AND (MONOACETYLACETONE)-O-PHENYLENEDIAMINE SCHIFF BASE COMPLEXES
Co(II) , Ni(II) and Cu(II) complexes formed from the Sciff base (2Z,4Z)-4-[(2-aminophenyl)imino-]pent-2-en-2-ol , were prepared in situ and characterized on the basis of elemental analyses, magnetism, UV-vis., IR and ESR spectra . Thermal analyses of the complexes were studied in order to confirm th...
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| Autores principales: | , |
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| Lenguaje: | English |
| Publicado: |
Sociedad Chilena de Química
2013
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| Materias: | |
| Acceso en línea: | http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072013000200019 |
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| Sumario: | Co(II) , Ni(II) and Cu(II) complexes formed from the Sciff base (2Z,4Z)-4-[(2-aminophenyl)imino-]pent-2-en-2-ol , were prepared in situ and characterized on the basis of elemental analyses, magnetism, UV-vis., IR and ESR spectra . Thermal analyses of the complexes were studied in order to confirm the proposed structures and determine their thermal stability . Comparison between geometries, ESR and thermal studies obtained from direct condensation and in situ preparation of complexes were discussed. The in situ data show that the Schiff base form complexes with 1:1 (metal : ligand) stoichiometry with Cu(II) and Ni(II) ions compared to 2:1 (metal : ligand) formed from direct condensation between schiff base and metal ions. However, the Co(II) in situ complex formed 1:2 (metal: ligand ) stoichiometry. Square-planar geometry was suggested for the Cu(II) and Ni(II) in situ complexes, while, octahedral geometry was suggested for the Co(II) complex. The ESR spectrum of the in situ Cu(II) complex was isotropic to suggest a geometry involving grossly misaligned tetragonal axes .The thermal behavior of the complexes showed good agreement with the formulae suggested from the analytical data . Thermal decomposition of the complexes took place in several stages. The order of stability was [Cu L.(H2O)] 3H2O > NiL.H2O > CoL2.H2O. The thermodynamic parameters , energy of activation ΔE*a , enthalpy of activation ΔH* , order of reaction n and entropy of activation ΔS* of the complexes were calculated. All the reactions were found to be first order. The high values of activation energies reveal the high stability of these complexes. |
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