Synthesis, structures and thermal stabilities of five copper(II) coordination polymers based on 2,4,6-tris(pyridyl)-1,3,5-triazine and 1,2,4,5-benzenetetracarboxylate ligands

A novel three-dimensional SrII coordination polymer based on benzene-1,2,4,5-tetracarboxylate: hydrothermal synthesis, crystal structure and spectroscopic and thermal studies

Coordination of the anions of benzenecarboxylic acids with metal cations leads to coordination polymers with various structural features. Very few examples of strontium-based structures have been reported. A new three-dimensional coordination polymer, namely poly[aqua(μ12-benzene-1,2,4,5-tetracarboxylato)distrontium(II)], [Sr2(C10H2O8)(H2O)] n , has been synthesized under hydrothermal conditions and characterized by thermal analysis, vibrational spectroscopy (Raman and IR), single-crystal X-ray diffraction and powder X-ray diffraction. The coordination geometries around the two independent SrII ions can be described as a distorted dodecahedron and a distorted monocapped square antiprism. The compound features a three-dimensional structure containing inorganic motifs, with two-dimensional layers connected through organic linkers, and possesses a topologic structure of a binodal (6,12) connected alb net with the Schläfli symbol {415}2{448.618}. The final product of thermal decomposition is strontium oxide (SrO).

The layered structure of poly[[hexaaqua(μ4-benzene-1,2,4,5-tetracarboxylato)dicopper(II)] tetrahydrate]

In the structure of the title compound, {[Cu2(C10H2O8)(H2O)6]·4H2O}n, the benzene-1,2,4,5-tetracarboxylate ligand, (btec)(4-), is located on a crystallographic inversion centre in a μ4-coordination mode. The coordination environment of each pentacoordinated Cu(II) centre is square pyramidal (SBP), formed by three water molecules and two carboxylate O atoms from two different (btec)(4-) ligands. The completely deprotonated (btec)(4-) ligand coordinates in a monodentate mode to four Cu(II) atoms. The alternation of (btec)(4-) ligands and SBP Cu(II) centres leads to the formation of a planar two-dimensional covalent network of parallelograms, parallel to the ab plane. Hydrogen bonds between a basal water molecule and an apical one from an adjacent [Cu(btec)0.5(H2O)3] unit exist in the intralayer space. Hydrogen bonds are also present between the two-dimensional network and the water molecules filling the channels in the structure.

Disodium dihydrogen pyridine-2,3,5,6-tetra-carboxyl-ate trihydrate

In the title compound, 2Na⁺·C₉H₃NO₈²⁻·3H₂O, the asymmetric unit consists of two Na⁺ cations, one dihydrogen pyridine-2,3,5,6-tetra­carboxyl­ate dianion (H₂pdtc²⁻) and three water mol­ecules coordinated to the Na⁺ cations. The configuration of the anion is stabilized by intramolecular O—H⋯O hydrogen bonding between vicinal carboxylate/carboxy groups. The Na⁺ cations are bridged by the H₂pdtc²⁻ dianions, generating layers extending infinitely in sheets parallel to (001), and further pillared by the water mol­ecule linkers to build up a three-dimensional framework.