Poly[[tetraaquadi-μ4-glutarato-μ2-terephthalato-dineodymium(III)] heptadecahydrate

Abstract

The title compound, [Nd(2)(C(5)H(6)O(4))(2)(C(8)H(4)O(4))(H(2)O)(4)]·17H(2)O, obtained via hydrothermal reaction of Nd(2)O(3) with glutaric acid and terephthalic acid, assembles as a three-dimensional open framework with ten-coordinate Nd-O polyhedra. The asymmetric part of the unit cell contains half a glutarate anion, a quarter of a terephthalate dianion, half an Nd(III) cation, one coordinated water molecule and 4.25 solvent water molecules. Each [NdO(10)] coordination polyhedron is comprised of six O atoms originating from four glutarate anions, two others from a terephthalate carboxylate group, which coordinates in a bidentate fashion, and two from water molecules. The Nd-O distances range from 2.4184 (18) to 2.7463 (18) Å. The coordination polyhedra are interconnected by the glutarate anions, extending as a two-dimensional layer throughout the bc plane. Individual two-dimensional layers are interlinked via terephthalate anions along the a axis. This arrangement results in rectangular-shaped cavities with interstices of approximately 3.5 × 6 × 6.5 Å (approximately 140 Å(3)), which are occupied by water molecules. The Nd(III) cations, terephthalate anions, glutarate anions and one of the interstitial water molecules are located on special crystallographic positions. The Nd-terephthalate-Nd units are located across twofold rotation axes parallel to [100], with the Nd(III) cations located directly on these axes. In addition, the terephthalate anion is bisected by a crystallographic mirror plane perpendicular to that axis, thus creating an inversion centre in the middle of the aromatic ring. The glutarate ligand is bisected by a crystallographic mirror plane perpendicular to (001). One of the solvent water molecules lies on a site of 2/m symmetry, and the symmetry-imposed disorder of its H atoms extends to the H atoms of the other four solvent water molecules, which are disordered over two equally occupied and mutually exclusive sets of positions.