Syntheses, structures of manganese/cadmium/ferrous complexes and magnetic property of manganese complex with the ligand 5-hydroxynicotinic acid

Poly[tetra-aqua-(5-hy-droxy-pyridin-1-ium-3-carboxyl-ato-κO (3))tris-(μ-oxalato-κ(4) O (1),O (2):O (1'),O (2'))dieuropium(III)]

In the title compound, [Eu₂(C₆H₅NO₃)₂(C₂O₄)₃(H₂O)₄]_n, the Eu^III atom is bonded to one O atom from a monodentate 5-hy­droxy­pyridin-1-ium-3-carboxyl­ate ligand, six O atoms from three oxalate ligands and two water mol­ecules, exhibiting a highly distorted tricapped trigonal geometry. Three independent oxalate ligands, each lying on an inversion center, bridge the Eu^III atoms, forming a brickwall-like layer parallel to (001), which is stabilized by intra­layer O—H⋯O hydrogen bonds. The layers are further linked through inter­layer O—H⋯O and N—H⋯O hydrogen bonds and π–π inter­actions between the pyridine rings [centroid–centroid distance = 3.5741 (14) Å] into a three-dimensional supra­molecular network.