Poly[tetradecaaquatetrakis(μ3-1H-imidazole-4,5-dicarboxylato)tetra-μ3-sulfato-cobalt(II)hexagadolinium(III)]

Abstract

The asymmetric unit of the title compound, [CoGd6(C5H2N2O4)4(SO4)6(H2O)14]n, contains a CoII ion (site symmetry overline1), three GdIII ions, two imidazole-4,5-dicarboxylate ligands, three SO42− anions, and seven coordinated water molecules. The CoII ion is six-coordinated by two O atoms from water molecules, two O atoms and two N atoms from two imidazole-4,5-dicarboxylate ligands, giving a slightly distorted octahedral geometry. The GdIII ions exhibit three types of coordination environments. One Gd ion is eight-coordinated in a bicapped trigonal–prismatic geometry by four O atoms from two imidazole-4,5-dicarboxylate ligands, two O atoms from two SO42− anions and two coordinated water molecules. The other Gd ions are nine-coordinated in a tricapped trigonal–prismatic geometry; one of these Gd ions is bonded to four O atoms from two imidazole-4,5-dicarboxylate ligands, three O atoms from three SO42− anions and two water O atoms and the other Gd ion is coordinated by one O atom and one N atom from one imidazole-4, 5-dicarboxylate ligand, five O atoms from three SO42− anions as well as two coordinated water molecules. These metal coordination units are connected by bridging imidazole-4,5-dicarboxylate and sulfate ligands, generating a three-dimensional network. The crystal structure is further stabilized by N—H...O, O—H...O, and C—H...O hydrogen-bonding interactions between water molecules, SO42− anions, and imidazole-4,5-dicarboxylate ligands.