Hydrothermal investigation of the lanthanide (Ln=La, Ce, Pr, Nd, Sm) 2,6-pyridinedicarboxylate system

In this paper, two new dipicolinate complexes, Ln2(dipic)3(H2O)3 (1) with Ln=La, Ce, Pr, Nd, Sm and Ce3(dipic)5(H2O)2 (2), are described. Hydrothermal synthesis, crystal structure and thermal behaviour of both compounds are described, as well as the magnetic behaviour of the trinuclear complex (2). The structures consist of LaO7N2, LaO7N (1) and CeO7N, CeO6N3 (2) polyhedra linked to form three-dimensional networks. The magnetic study of 2 confirms that it corresponds to a Ce(III)–Ce(IV) molecular compound and that the magnetic interaction is certainly antiferromagnetic. According to the thermogravimetric analysis, thermal decomposition of compounds 1 starts at about 100–130 °C, when 2 is thermally stable up to 250 °C.