Synthesis and characterization of 3-amino-5-methylisoxazole Schiff bases and their complexes with copper(II), nickel(II) and cobalt(II)

Abstract

Schiff bases obtained by condensing 3-amino-5-methylisoxazole with salicylaldehyde, 2,3-dihydroxybenzaldehyde, 2,4-dihydroxy-benzaldehyde, 2,5-dihydroxybenzaldehyde or o-hydroxynaphthaldehyde were obtained and characterized by C, H, N analysis, mass, NMR and IR spectra. Copper, nickel and cobalt complexes of the Schiff bases were prepared and characterized using elemental analysis, conductivity measurements, magnetic moments, IR, UV-VIS and ESR spectra, X-ray diffraction, TGA, DTA and DSC thermal analysis. All the complexes are non-electrolytes. ESR spectra show isotropic as well as axial symmetry for the copper complexes. Thermal studies support the formulation of these complexes and showed that they decompose in two or three steps depending on the metal used. Activation energy E _a and enthalpies ΔH associated with the decomposition process were calculated and correlated with the complexed metal used.

Keywords:

• 3-Amino-5-methylisoxazole
• Schiff bases
• Complexes
• Spectral and thermal properties