Poly[[diaqua­bis­[μ₄-5-nitro­isophthalato-κ⁴O¹:O¹:O³:O^3′]bis­[μ₃-pyridine-4-carboxyl­ato-κ³O:O′:N]tricobalt(II)] tetra­hydrate]

The title compound, {[Co₃(C₆H₄NO₂)₂(C₈H₃NO₆)₂(H₂O)₂]·4H₂O}_n, exhibits a two-dimensional layer-like structure in which the Co^II ions exhibit two kinds of coordination geometries. One nearly octa­hedral Co^II ion with crystallographic inversion symmetry is coordinated to six carboxyl­ate O atoms from four bridging 5-nitro­isophthalate (NIPH) ligands and two isonicotinate (IN) anions, while the other type of Co^II ion binds with one N atom and one carboxyl­ate O atom from two IN anions, two carboxyl­ate O atoms from two different NIPH anions and one ligated water mol­ecule, displaying a distorted square-pyramidal coordination geometry. Three adjacent Co^II ions are bridged by six carboxyl­ate groups from four NIPH ligands and two IN anions to form a linear trinuclear secondary building unit (SBU). Every trinuclear SBU is linked to its nearest neighbours in the ab plane, resulting in a two-dimensional layer-like structure perpendicular to the c axis. Along the a-axis direction neighbouring mol­ecules are connected through carboxyl­ate and pyridyl units of the IN anions, along the b axis through carboxyl­ate groups of the NIPH ligands. The H atoms of one free water mol­ecule are disordered in the crystal in a 1:1 ratio. Typical O—H...O hydrogen bonds are observed in the lattice, which include the following contacts: (a) between coordinated water mol­ecules and carboxyl­ate O atoms of the NIPH anions, (b) between lattice water mol­ecules and carboxyl­ate O atoms of the NIPH anions, and (c) between coordinated and lattice water mol­ecules. These inter­molecular hydrogen bonds connect the two-dimensional layers to form a three-dimensional supra­molecular structure.

Poly[aqua(μ₃-5-aza­niumylisophthalato)­(μ-oxalato)neodymium(III)]

The title compound, [Nd(C₈H₆NO₄)(C₂O₄)(H₂O)]_n, is a layer-like coordination polymer. The Nd^III ion is coordinated by four carboxyl­ate O atoms from three bridging 5-aza­nium­yl­isophthalate (Haip) ligands, four carboxyl­ate O atoms from two oxalate (ox) anions and one ligated water mol­ecule in a tricapped trigonal–prismatic geometry. The Haip anion acts as a μ₃-bridge, connecting three Nd^III ions through two carboxyl­ate groups; the ox anion adopts a bis-bidentate-bridging mode, linking two Nd^III ions. The layer framework is further extended to a three-dimensional supra­molecular structure through N—H...O and O—H...O hydrogen bonds.

Diethyl 4,4'-(3,6-dioxaoctane-1,8-diyl­dioxy)dibenzoate

The title compound, C₂₄H₃₀O₈, was obtained by reaction of ethyl 4-hy­droxy­benzoate with 1,2-dichloro­ethane. The mol­ecule occupies a crystallographic inversion center, with its central ethyl­ene bridge in an anti conformation. The other ethyl­ene bridge has a gauche conformation, with the corresponding O-C-C-O torsion angle being 74.2 (1)°. The benzene rings are almost coplanar with the adjacent eth­oxy­carbonyl groups, with an r.m.s. deviation of 0.078 Å.