Studies on the thermal behaviour and decomposition mechanism of complexes of rare earth(III) nitrates) with benzo-15-crown-5

Abstract

Thermal dissociation reactions and mechanism of complexes of rare earth(iii) nitrates with the crown ether benzo-15-crown-5 were investigated by means of TG-ISTG, DSC, DTA and IR technique. The results have shown that the dissociation processes of the complexes consist of several steps, one of which is a fast decomposition reaction. The fast decomposition peak temperatures (DSC) of all the complexes of the lanthanides (except Pm and Tm) decrease regularly with increasing atomic number. Moreover, values of the enthalpy change of desolvation, fast and the fourth step of decomposition and the apparent activation energies of fast and the fourth step of decomposition were obtained.There has been considerable interest in the rare earth(III) complexes of crown ethers during the past several years. Their thermal behaviour has been studied in some papers [1][2][3][4], while the decomposition mechanism has been reported in few papers, especially for the complexes of the rare earth nitrates with benzo-15-crown-5. In this paper, we performed detailed investigations on the solid-state thermal behaviour of fifteen complexes of rare earth(III) nitrates (except Pm) with benzol 5-crown-5 (B 15C5) by means of TG-DTG, DSC and DTA and presented their dissociation steps and conceivable mechanism with IR as an assistant method.