Pyrolytical characterization of transition metal complexes of cobalt, nickel, copper and zinc with ethylenediamine-N,N′-diacetate

Abstract

Abstract A series of octahedral complexes, [M(EDDA)(H2O)2] · H2O (where, M+2 = Co(II), Cu(II), Ni(II) and Zn(II); EDDA, ethylenediamine-N,N′-diacetate), was prepared and studied by means of thermogravimetry (TG) and differential thermal analysis (DTA). Their compositions were investigated by elemental analysis in order to ensure their purity and structural elucidation was based on spectral and magnetic properties. Thermal decomposition of these distorted octahedral complexes, [Ni(EDDA)(H2O)2], [Co(EDDA)(H2O)2] · H2O, [Cu(EDDA)(H2O)2] · H2O and [Zn(EDDA)(H2O)2] · H2O came of in one, two, three and four steps, respectively, upon heating to 800 °C, with the loss of organic and inorganic fragments. Ligand decomposed in three steps. The thermal degradation of all the complexes in static air atmosphere started at temperatures lower than those observed for the free ligand degradation (Ni-complex being the only exception). The composition of intermediates formed during degradation was confirmed by microanalysis ...