Thermal decomposition of triethanolamine and monoethanolethylenediamine complexes of some transition metal saccharinates

The thermal decomposition behaviour of triethanolamine (TEA) and monoethanolethylenediamine (me-en) complexes of Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) saccharinates was studied under non-isothermal conditions by TG, DTA and DTG in dynamic nitrogen atmosphere. The decomposition of the TEA complexes proceeds via three main stages. The first stage involves exothermic removal of two CH2OH groups, due to degradation of uncoordinated ethanol groups of the TEA molecules, and the second and third stages correspond to formation of metal saccharinates and metals as the end products, respectively. All the me-en complexes show similar decomposition behaviour and, after evolution of two CH2OH groups, they progressively decompose through saccharinate intermediates and subsequently yield metals or metal oxides as the final residue. Tea complexes showed much higher thermal stability than their me-en analogues. A thermal decomposition mechanism for the metal complexes was suggested.