title: Poly[[tetra-aqua-bis[μ(4)-2,2'-(p-phenyl-ene-di-oxy)diacetato][μ(2)-2,2'-(p-phenyl-ene-di-oxy)diacetato]dierbium(III)] hexa-hydrate].
abstract: The asymmetric unit of the title compound, [Er(2)(C(10)H(8)O(6))(3)(H(2)O)(4)]·6H(2)O, comprises one Er(3+) ion, one and a half 2,2'-(p-phenyl-enedi-oxy)diacetate (hqda) ligands, two coordinated water mol-ecules and three uncoordinated water mol-ecules. The Er(3+) ion is nine-coordinated by seven O atoms from hqda ligands and two O atoms from water mol-ecules. In the title compound, there are two types of crystallographically independent ligands: one with an inversion center in the middle of the ligand is chelating on both ends of the ligand towards each one Er center; the other hqda ligands are bridging-chelating on one side, and bridging on the other end of the ligand. Two adjacent Er(3+) ions are thus chelated and bridged by -COO groups from hqda ligands in three coordination modes (briding-chelating, bridging and chelating). These building blocks are linked by OOC-CH(2)O-C(6)H(4)-OCH(2)-COO spacers, forming two-dimensional neutral layers. Adjacent layers are linked by O-H⋯O hydrogen-bonding inter-actions, forming a three-dimensional supermolecular network.
authors.affiliation: State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo, Zhejiang 315211, People's Republic of China.
authors.forename: Dan-Yi
authors.initials: DY
authors.lastname: Wei
authors.forename: Yan-Guang
authors.initials: YG
authors.lastname: Zhang
authors.forename: Mei-Li
authors.initials: ML
authors.lastname: Wang
authors.forename: Zhen-Ke
authors.initials: ZK
authors.lastname: Zhu