Poly[[tetra­aqua­bis­(μ₃-5-carboxybenzene-1,2,4-tri­carboxyl­ato)tricadmium] tetra­hydrate]

There are three independent Cd^II ions in the title complex, {[Cd₃(C₁₀H₃O₈)₂(H₂O)₄]·4H₂O}_n, one of which is coordinated by four O atoms from three 5-carboxybenzene-1,2,4-tri­carboxyl­ate ligands and by two water mol­ecules in a distorted octa­hedral geometry. The second Cd^II ion is coordinated by five O atoms from four 5-carboxybenzene-1,2,4-tri­carboxyl­ate ligands and by one water mol­ecule also in a distorted octa­hedral geometry while the third Cd^II ion is coordinated by five O atoms from three 5-carboxybenzene-1,2,4-tri­carboxyl­ate ligands and by one water mol­ecule in a highly distorted octa­hedral geometry. The 5-carboxybenzene-1,2,4-tri­carboxyl­ate ligands bridge the Cd^II ions, resulting in the formation of a three-dimensional structure. Intra- and inter­molecular O—H...O hydrogen bonds are present throughout the three-dimensional structure.

Poly[[diaqua­(μ₈-benzene-1,2,4,5-tetra­carboxyl­ato)calciumzinc] monohydrate]

In the title complex, {[CaZn(C₁₀H₂O₈)(H₂O)₂]·H₂O}_n, the Zn^II ion is coordinated by four O atoms from four benzene-1,2,4,5-tetra­carboxyl­ate anions in a distorted tetra­hedral geometry. The Ca^II ion is eight-coordinated by six O atoms from four benzene-1,2,4,5-tetra­carboxyl­ate anions and by two water mol­ecules in a distorted square-anti­prismatic geometry. The Ca^II and Zn^II ions and the lattice water mol­ecule are located on twofold rotation axes; the centroid of the benzene-1,2,4,5-tetra­carboxyl­ate anion is located on a centre of inversion. The μ₈-bridging mode of the anion results in the formation of a three-dimensional structure with channels extending along [100] in which lattice water mol­ecules are situated. Inter­molecular O—H...O hydrogen bonds involving the coordinating and lattice water mol­ecules as donors and the carboxyl­ate O atoms and lattice water mol­ecules as acceptors are present in the structure.