• A P Mishra

      Articles written in Journal of Chemical Sciences

    • Synthesis and structural investigation of some mixed-ligand selenito complexes of cobalt(II)

      P Chourasia K K Suryesh A P Mishra

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      Two complexes, [Co(An)2(O2SeO)] and [Co(Iso)2(H2O)2(O2SeO)], have been isolated and characterised by elemental analyses, IR spectra, magnetic measurements and thermogravimetric analysis. Their lattice constants have been determined with the help of X-ray powder diffraction data. Kinetic parameters like energy and entropy of activation for the thermal degradation process have been arrived at using Piloyan-Novikova, Coats-Redfern and Horowitz-Metzger equations. The mechanism of non-isothermal decomposition of complexes is by phase boundary nucleation. The probable structure for Co(II) complexes is six-coordinated octahedral in a high-spin electron configuration. The order of the thermal stability of complexes is [Co(An)2(O2SeO)]>[Co(Iso)2(H2O)2(O2SeO)].

    • Thermal, magnetic and X-ray diffraction studies on mixed-ligand dimetavanadato complexes of manganese(II)

      A P Mishra

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      Novel mixed-ligand dimetavandato complexes of Mn(II) of composition [Mn(en)(H2O)2(VO3)2] and [Mn(pz)(H2O)2(VO3)2]H2O (where en=1,2- diaminoethane, pz=hexahydropyrazine) have been synthesized. The probable structures of the complexes have been worked out on the basis of elemental analysis, IR spectra, magnetic measurements and thermogravimetric analysis. X-ray powder diffraction study has been carried out to determine the unit lattice parameters. Magnetic moment values indicate high-spin complexes of manganese. Dynamic thermogravimetric data of the relevant steps of thermal degradation have been analysed for the study of solid-state kinetics. Non-isothermal methods by Piloyan-Novikova, Coats-Redfern and Horowitz-Metzger have been employed for evaluating the kinetic parameters viz. energy of activation, frequency factor and entropy of activation. The mechanism of non-isothermal decomposition of complexes is ‘phase boundary contracting cylinder nucleation’.

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