Thermal Investigation and Stereochemical Studies of Methylamine, Diethylamine and Triethylamine Complexes of Copper(II)

Abstract

Methylamine, diethylamine and triethylamine complexes of copper(II) were synthesized. The complexes were characterized by elemental and thermal analysis, infrared and electronic spectra and magnetic moment measurement. They were found to have the following compositions: [CuL¹₂Cl₂]·5H₂O, [CuL²(H₂O)Cl₂]·3H₂O, [CuL³(H₂O)Cl₂]·3H₂O, [CuL¹₂Br₂·2H₂O and [CuL²₂Br₂]·4H₂O, where L¹ = methylamine (MeA), L² = diethylamine (DEtA) and L³ = triethylamine (TEtA). The complexes were found to be four coordinated and appear to possess square planar geometry. Thermal investigation was carried out and stereochemical changes which occurred during thermal investigations, were studied. Thermodynamic parameters such as activation energy (E_a*), enthalpy change (DH) and entropy change (DS) for dehydration and decomposition reactions of the complexes were evaluated by using some standard methods. The order of stability of the complexes (with respect to E_a* from TGA curve) follows the trend: TEtA > DEtA > MeA. The probable mechanistic path of dehydration and decomposition reactions is also shown.