Preparation, spectral properties and thermal decomposition of new ternary complexes of La(III), Ce(III), Pr(III) and Nd(III) ions with N-phenylanthranilic acid and 1,10-phenanthroline

The new ternary complexes of the formula Ln2(nfa)5(phen)(OH)·nH2O (where n = 1 or 1.5; nfa - N-phenylanthranilate anion (C13H10NO2), phen - 1,10-phenanthroline (C12H8N2), Ln = La(III), Ce(III), Pr(III) and Nd(III)) were synthesized and characterized by elemental analysis, complexometry, infrared spectroscopy, XRD technique, simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC), evolved gas analysis by TG-DSC coupled with FTIR and MS spectroscopy. The detailed thermogravimetic analysis showed that thermal decomposition of the complexes in nitrogen and air atmosphere occurs in several stages including water elimination, neutral ligand loss and N-phenylanthranilate anion decomposition, respectively. It was found that the thermal stability and the decomposition path of the studied compounds depend on the metal ion and the applied atmosphere. Low values of the dehydration enthalpies indicate that dehydration is connected with the release of crystallization water. By the use of the coupled TG-FTIR-MS techniques the decomposition pathways of the synthesized compounds were examined and the gaseous products released during pyrolysis and thermal oxidation of the complexes were identified.