Spectroscopic study, thermal investigation and evolved gas analysis (EGA) during pyrolysis and oxidative decomposition of new binuclear complexes of La(III), Ce(III), Pr(III) and Nd(III) with N-phenylanthranilic acid

Abstract

New binuclear complexes of La(III), Ce(III), Pr(III) and Nd(III) ions with N‐phenylanthranilic acid of general formula Ln2(NFA)5(OH)·nH2O (where NFA–N–phenylanthranilic acid) were synthesized and characterized by elemental analysis, infrared spectroscopy, XRD technique and thermogravimetric analysis. The obtained results show that in complexes only the carboxyl group is involved in the coordination of the rare earth ions in the bidentate mode. Coordination does not occur through the nitrogen atom.The detailed TG–DSC analysis provided previously unreported information concerning the thermal behaviour of these binuclear compounds in nitrogen and air atmosphere. Thermogravimetric analysis shows that decomposition processes are multistage and dehydration is the first step of decomposition. The calculated dehydration enthalpies are low for all studied complexes what indicates that it is crystallization water. Moreover, the thermal stability and the decomposition path of these compounds depend on the metal ion and the used atmosphere. The TG–FTIR–MS technique was employed in order to study a decomposition pathway of the obtained compounds. The EGA data allowed for the identification and comparison of gaseous products evolved during pyrolysis and oxidative decomposition of the considered compounds.