Synthesis, thermal analysis, and spectroscopic and structural characterizations of zinc(II) complexes with salicylaldehydes

In this study, three new zinc(II) complexes with 5-substituted salicylaldehyde ligands (X-saloH) (X = 5-chloro, 5-nitro and 5-methyl) with the general formula [Zn(X-salo)2(CH3OH)n], (n = 0 or 2) were synthesized. An octahedral geometry was found for both the complexes [Zn(5-NO2-salo)2(CH3OH)2] and [Zn(5-Cl-salo)2(CH3OH)2] by single-crystal X-ray diffraction analysis. These complexes were characterized also by spectroscopy (IR and 1H-NMR). Simultaneous TG/DTG–DTA techniques were used to analyze their thermal behavior under inert atmosphere, with particular attention to determine their thermal degradation pathways, which was found to be a multi-step decomposition accompanied by the release of the ligand molecules. Finally, the kinetic analysis of the decomposition processes was performed by applying both the isoconversional Ozawa–Flynn–Wall (OFW) and the Kissinger–Akahira–Sunose (KAS) methods.