Poly[tetradecaaquatetrakis-(μ 3-1H-imidazole-4, 5-dicarboxylato)tetra-μ 3-sulfatocobalt(II)hexagadolinium(III)]

Abstract

The asymmetric unit of the title compound, [CoGd 6(C 5H 2N 2O 4) 4(SO 4) 6(H 2O) 14] n , contains a Co II ion (site symmetry ), three Gd III ions, two imidazole-4,5-dicarboxyl-ate ligands, three SO 42- anions, and seven coordinated water molecules. The Co II ion is six-coordinated by two O atoms from water molecules, two O atoms and two N atoms from two imidazole-4,5-dicarboxyl-ate ligands, giving a slightly distorted octa-hedral geometry. The Gd III 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-dicarboxyl- ate ligands, two O atoms from two SO 42- 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-dicarboxyl-ate ligands, three O atoms from three SO4 2- 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-dicarboxyl-ate ligand, five O atoms from three SO 42- anions as well as two coordinated water molecules. These metal coordination units are connected by bridging imidazole-4,5-dicarboxyl-ate 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, SO 42- anions, and imidazole-4,5-dicarboxyl-ate ligands.