Thermoanalytical, magnetic and structural study of Co(II) complexes with substituted salicylaldehydes and neocuproine

In this study, simultaneous TG/DTG-DTA technique was used for two cobalt(II) complexes with neocuproine(neoc) and the anion of a substituted salicylaldehyde ligand (X-salo) (X = 3-OCH 3 , or 5-CH 3 ) with the general formula [Co(X-salo) 2 (neoc)], to determine their thermal degradation in inert atmosphere, which was found to be a multi-step decomposition related to the release of the ligand molecules. The solid material at 1300 °C (verified with PXRD) was a mixture of carbonaceous metal cobalt. Evolved gas analysis by coupled TG-MS verified the elimination of a formaldehyde molecule in the first decomposition stage, initially proposed by the percentage mass loss data. By single-crystal X-ray diffraction analysis an octahedral geometry of the complex [Co(3-OCH 3 -salo) 2 (neoc)] was found. The variable temperature magnetic susceptibility measurements showed a paramagnetic nature of the complexes, in accordance with their molecular structure. Finally, for the determination of the activation energy ( E ) two different methods (the isoconversional methods of Ozawa, Flynn and Wall (OFW) and Friedman) were used comparatively.