Poly[hexaaquahexakis(μ-pyridine-2,4-dicarboxylato)tricopper(II)-dieuropium(III)]

The asymmetric unit of the title heterometallic coordination polymer, [Cu3Eu2(C7H3NO4)(6)(H2O)(6)](n), contains one Eu-III and two Cu-II atoms, three pyridine-2,4-dicarboxylate (pdc)(2-) anions and three water molecules. One Cu-II atom is located on an inversion center and is N, O-chelated by two pdc(2-) anions in the equatorial plane and further coordinated by two carboxylate O atoms from another two pdc anions in the axial positions, with an elongated octahedral geometry [Cu-O = 2.409 (3) angstrom in the axial direction]; the other Cu atom is N, O-chelated by two pdc anions in the coordination basal plane and coordinated by a carboxyl O atom at the apical position with a distorted square-pyramidal geometry [Cu-O = 2.359 (3) angstrom in the apical direction]. The Eu atom is eight-coordinated with a distorted square-antiprismatic geometry formed by five carboxylate O atoms from five pdc anions and three water molecules. The carboxylate anions bridge adjacent Eu and Cu atoms, forming the coordination polymer. Inter- and intramolecular O-H center dot center dot center dot O hydrogen bonding occurs in the structure. pi-pi stacking further consolidates the crystal structure, the centroid-centroid distance between parallel pyridine rings being 3.367 (2) angstrom.