Synthesis, characterization and thermal studies of nickel (II), copper (II), zinc (II) and cadmium (II) complexes with some mixed ligands

Dichloro-(DCA) and trichloroacetate(TCA) -cyclic ligand morpholine (Morph)/thiomorpholine (Tmorph)/methylmorpholine (Mmorph)/dimethyl-piperazine (DMP) complexes of nickel (II), copper (II), zinc (II) and cadmium (II) with the compositions [Ni(tmorph)2(DCA)2], [Ni(tmorph)2 (TCA)2].2H2O, [Cu(DMP)2 (TCA)2],[ML2X2].nH2O where M=ZnII or CdII, L=Morph, DMP or tmorph and X=DCA or TCA and n=O except in case of [Cd (Morph)2 (TCA)2] where n=1 have been synthesised. Some intermediate complexes have been isolated by temperature arrest technique (pyrolysis) and characterised. Configurational and conformational changes have been studied by elemental analyses, IR and electronic spectra, magnetic moment data (in the case of Ni(II) and Cu(II) complexes) and thermal analysis. Ea*, ΔH, and ΔS for the decomposition reaction of these complexes are evaluated and the stability of the complexes with respect to activation energy has also been compared. The linear correlation has been found between Ea* and ΔS for the decomposition of the complexes. (author)