A thermal analysis study of 1,2-dipiperidinoethane complexes of cobalt, nickel, copper, zinc and cadmium by TG–DTG–DTA techniques

Abstract

A number of complexes of the general formula ML(NO 3) 2, (M=Co(II), Ni(II), Cu(II), Zn(II) and Cd(II); L=1,2-dipiperidinoethane (DPE)) were prepared and studied by means of TG–DTG–DTA techniques. Their compositions were investigated by elemental analysis in order to ensure their purity and structural elucidations were based on conductivity measurements. room temperature magnetic measurement, proton NMR, and IR spectra. Thermal decomposition of these distorted tetrahedral complexes and their ligand took place in two distinct steps upon heating up to 720°C with the loss of inorganic and organic fragments and show almost the same mode of decomposition. The thermal degradation of all the complexes in static air atmosphere starts at temperature lower than observed for free ligand degradation. The composition of intermediates formed during degradation was confirmed by microanalysis and IR spectroscopy. The residues after heating above 600°C correspond to metal oxide. It follows from the results that thermal stability of the complexes increases in the following sequence: Ni(II)<Co(II)<Cu(II)<Zn(II)<Cd(II).