Thermal stability of new formazan complexes derived from thiophene-2-carboxaldehyde

Abstract

Novel formazan ligand was prepared from the condensation of p-phenylenediamine and thiophene-2-carboxaldehyde, with diazonium salt of 4-chloro aniline and its derived metal transition complexes of Co (II), Cu (II) and Ni (II) have been synthesized by reaction of metal chlorides with formazan ligand in the molar ratio 1:1 (M: L). The formazan ligand and its metal complexes were identified by different spectroscopic and analytical techniques, these studies result propose that the metal complexes have tetrahedral geometry. Thermal decomposition of the complexes has been studied by thermogravimetry analysis. The results showed that all values of ∆G are positive which indicate that all steps are non-spontaneous, the decomposition processes were endothermic from the positive rate of ∆H and the complexes more ordered than the reactants from the negative rate of ∆S .Thermodynamic data (∆H, ∆S, ∆G) were calculated by using the Coats-Redfern.