A one‐dimensional coordination polymer with a three‐dimensional supramolecular framework: catena‐poly[[[(3,4,7,8‐tetramethyl‐1,10‐phenanthroline)cadmium(II)]‐μ3‐4,4′‐sulfonyldibenzoato] trihydrate]

In the title mixed‐ligand metal–organic polymeric compound, {[Cd(C₁₄H₈O₆S)(C₁₆H₁₆N₂)]·3H₂O}_n, the asymmetric unit contains a crystallographically unique Cd^II atom, one doubly deprotonated 4,4′‐sulfonyldibenzoic acid (H₂SDBA) ligand, one 3,4,7,8‐tetramethyl‐1,10‐phenanthroline (TMPHEN) molecule and three solvent water molecules. Each Cd^II centre is six‐coordinated by two O atoms from a chelating carboxylate group of a SDBA²⁻ ligand, two O atoms from monodentate carboxylate groups of two different SDBA²⁻ ligands and two N atoms from a chelating TMPHEN ligand. There are two coordination patterns for the carboxylate groups of the SDBA²⁻ ligand, with one in a μ₁‐η¹:η¹ chelating mode and the other in a μ₂‐η¹:η¹ bis‐monodentate mode. Single‐crystal X‐ray diffraction analysis revealed that the title compound is a one‐dimensional double‐chain polymer containing 28‐membered rings based on the [Cd₂(CO₂)₂] rhomboid subunit. More interestingly, a chair‐shaped water hexamer cluster is observed in the compound.