Poly[[tetraaquabis(5-carboxypyridine-2-carboxylato-κ2N,O)bis(μ4-pyridine-2,5-dicarboxylato-κ5N,O:O:O′:O′′)dilanthanum(III)] dihydrate

Abstract

The title compound, {[La2(C7H4NO4)2(C7H3NO4)2(H2O)4]·2H2O}n, was prepared by a hydro­thermal reaction at 433 K. The asymmetric unit contains two LaIII ions. Each LaIII ion is nine-coordinated in a slightly distorted tricapped trigonal–prismatic coordination geometry, formed by two N atoms from 5-carboxy­pyridine-2-carboxyl­ate (Hpydc) and pyridine-2,5-dicarboxyl­ate (pydc) ligands, five O atoms from carboxyl­ate groups of one Hpydc and four pydc ligands, and two water mol­ecules. Adjacent LaIII ions are linked together through single bridging carboxyl­ate O atoms and carboxyl­ate groups in a syn–anti mode, forming a two-dimensional layered polymeric structure. Extensive O—H⋯O hydrogen bonding connects adjacent layers into an infinite three-dimensional supra­molecular network structure. The crystal studied was an inversion twin.