catena-Poly[[tetra­aqua­nickel(II)]-μ-(9,10-dioxo-9,10-dihydro­anthracene-1,4,5,8-tetra­carboxyl­ato)-κ²O¹:O⁸-[tetra­aqua­nickel(II)]-μ-4,4′-bipyridine-κ²N:N′]

In the crystal of the title polymeric complex, [Ni₂(C₁₈H₄O₁₀)(C₁₀H₈N₂)(H₂O)₈]_n, each Ni^II cation is coord­in­ated by four water mol­ecules in the equatorial plane, and is further bridged by an 9,10-dioxo-9,10-dihydro­anthracene-1,4,5,8-tetra­carb­oxy­l­ate anion and a 4,4′-bipyridine ligand in the axial directions, forming a distorted octa­hedral geometry. The 9,10-dioxo-9,10-dihydro­anthracene-1,4,5,8-tetra­carboxyl­ate anion is centrosymmetric with the centroid of the quinone ring located about an inversion center; the 4,4′-bipyridine ligand is also centrosymmetric with the mid-point of the C—C bond linking two pyridine rings located about another invertion center. The 9,10-dioxo-9,10-dihydro­anthracene-1,4,5,8-tetra­carboxyl­ate anion and bypiridine ligand bridge the Ni^II cations, forming a polymeric chain along the b axis. π–π stacking is observed between pyridine and benzene rings [centroid–centroid distance = 3.705 (2) Å]. All of the coordinating water mol­ecules are involved in O—H...O hydrogen bonding.

Poly[[aqua­(μ₂-4,4′-bipyridine-κ²N:N′)[μ₃-3-bromo-2-(carboxyl­atometh­yl)­benzoato-κ³O¹:O^1′:O²]cadmium] monohydrate]

In the title compound, {[Cd(C₉H₅BrO₄)(C₁₀H₈N₂)(H₂O)]·H₂O}_n, the Cd^II atom has a distorted octa­hedral coordination geometry. Two N atoms from two 4,4′-bipyridine (bipy) ligands occupy the axial positions, while the equatorial positions are furnished by three carboxyl­ate O atoms from three 3-bromo-2-(carboxyl­atometh­yl)benzoate (bcb) ligands and one O atom from a water mol­ecule. The bipy and bcb ligands link the Cd^II atoms into a three-dimensional network. O—H...O hydrogen bonds and π–π inter­actions between the pyridine and benzene rings [centroid–centroid distance = 3.736 (4) Å] are present in the crystal.