Thermal studies on some transition metal complexes with N,N' -triethylenediaminebis(3-carboxypropenamide)

Department of Chemistry, S. N. College for Women, Kollam-691 001. India E-mail: jaiviswam@yahoo.co.in Department of Chemistry, University College, Trivandrum-695 034, India Manuscript received 17 May 2004. revised 7 January 2005, accepted 19 January 2005 Thermogravimetric studies of manganese(lI), cobalt(ll), nickel(ll) and copper(ll) complexes of N,N'-tricthylcnediaminebis(3- carhoxypropenamide) [TEBCPH2] have been carried out which give valuable information about the temperature of inception, of maximum rate and of complete decomposition. The thermal decomposition of the complexes of manganese(II) and cobalt(II) occurs in three stages whereas that of nickel(ll) and copper(ll) in two stages. These stages of decomposition arc attributed to the removal of the ligand from the complex. The residue is due to the presence of the metal oxide. In addition to this, the kinetic parameters such as energy of activation (E), pre-exponential factor (A) and the entropy of activation (ΔS) have been determined by Coats-Redfern equation. The negative ΔS values of the first stage of decomposition of nickel(II) complex and that of the manganese(lI) complex show that the activated complexes are more ordered than the reactants. The ΔS values for all other stages of decomposition are positive which indicate that the activated complexes are less ordered in structure compared to the reactants