Thermal,spectral and magnetic properties of 2-hydroxy-1,4-naphthoquinone monoximates of Ho(III), Er(III) and Yb(III) |
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Authors: | Jagtap S B Chikate R C Yemul O S Ghadage R S Kulkarni B A |
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Institution: | (1) Department of Chemistry, PDEA's Annasaheb Magar Mahavidyalaya Hadapsar, Pune-411 028, India;(2) Department of Chemistry, Post-graduate and Research Center, MES Abasaheb Garware College, Karve Road, Pune-411 004, India E-mail;(3) Polymer Science & Engineering Group, Chemical Engineering Division, National Chemical Laboratory Pashan, Pune-411 008, India;(4) Department of Chemistry, University of Pune, Pune-411 007, India |
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Abstract: | Ho(III), Er(III) and Yb(III) complexes of 2-hydroxy-1,4-naphthoquinone-1-oxime derivatives having ML3(H2O)2] are characterized using spectral and thermal decomposition studies. The thermolytic patterns suggested that they are decomposed
in three distinct stages; 1ststage is related to the loss of two coordinated water molecules while one of the coordinated ligands and remaining two ligands
are lost during subsequent 2nd and 3rd stages of degradation. After the 2nd stage, the structure of these complexes is reorganized reflecting that the structural associations through intermolecular
hydrogen bonding network is essential for thermal stability. The kinetic parameters computed for 2nd step using the non-isothermal procedures of Coats-Redfern are applied to the respective differential thermogravimetric plots
to ascertain the thermal degradation mechanism in air. The order of thermal decomposition reaction is found to be between
1-2 indicating that more than one intermediate might have simultaneously been formed. It also reveals the intermixing of 1st and 3rd stages of decomposition with the predominant 2nd stage leading to more gradual degradation. Energy of activation for 2nd stage of decomposition for these complexes is comparatively lower than those observed earlier for similar types of complexes.
Other spectral data indicate oximino nitrogen and phenolato oxygen as coordination sites of 2-hydroxy-1,4-naphthoquinone monoximates.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | thermal degradation Coats-Redfern energy of activation lanthanides complexes quinone oximes |
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