Lanthanide complexes with pyridine-2,6-dicarboxylic acid: synthesis, crystal structure, thermal and magnetic properties of [LnPDA)2(PDAH2)] · (DMAH2)2(DMAH0.5)2

Abstract

Mild solvothermal synthesis, structures, thermal and magnetic properties of coordination complexes [Ln(PDA)₂(PDAH₂)] · (DMAH₂)₂(DMAH_0.5)₂(I–IV) (PDA = pyrdine-2,6-dicarboxylate anion, DMAH = dimethylamine, Ln = Ce, Nd, Sm, and Ho) are described. The DMAH molecules in I–IV, generated in situ from hydrolysis of N,N-dimethylformamide, are responsible to assemble three dimensional coordination polymers through N–H···O and C–H···O hydrogen bonds. Distorted tricapped trigonal prismatic LnO₆N₃ geometry having 14 triangular faces is attributed to mean deviation of dihedral angles while nitrogen shows fairly triangular faces having dihedral angle close to 60°C (CIF files CCDC nos. 872065 (I), 872070 (II), 872069 (III), and 872066 (IV)). Curie–Weiss law and the overall magnetic behavior are typical for the presence of antiferromagnetic exchange coupling interactions between lanthanide. Thermal decomposition analyses reveal removal of ammonia and resultant complexes showthermal stability. Complexes have been further characterized by using elemental analyzer and FT-IR spectroscopy.