A novel three‐dimensional CdII coordination polymer: poly[[aquabis(2,2′‐bipyridine)(μ5‐pyrazol‐1‐ide‐3,5‐dicarboxylato)(μ4‐pyrazol‐1‐ide‐3,5‐dicarboxylato)(μ3‐pyrazole‐3,5‐dicarboxylato)tetracadmium(II)] dihydrate]

The title compound, {[Cd₄(C₅H₂N₂O₄)(C₅HN₂O₄)₂(C₁₀H₈N₂)₂(H₂O)]·2H₂O}_n, crystallized in the monoclinic space group P2₁/n and displays a three‐dimensional architecture. The asymmetric unit is composed of four crystallographically independent Cd^II centres, two triply deprotonated pyrazole‐3,5‐dicarboxylic acid molecules, one doubly deprotonated pyrazole‐3,5‐dicarboxylic acid molecule, two 2,2′‐bipyridine ligands, one coordinated water molecule and two interstitial water molecules. Interestingly, the Cd^II centers exhibit two different coordination numbers. Two Cd^II centres adopt a distorted octahedral arrangement and a third a trigonal–prismatic geometry, though they are all hexacoordinated. However, the fourth Cd^II center is heptacoordinated and displays a pentagonal–bipyramidal geometry. The three anionic ligands adopt μ₃‐, μ₄‐ and μ₅‐bridging modes, first linking Cd^II centers into a one‐dimensional wave‐like band, then into a wave‐like layer and finally into a three‐dimensional coordination framework, which is stabilized by hydrogen bonds.