An Unusual Hydrogen-Bonded Network Associated with Metal-Organic Chains: Structure and Crystal Packing of the Coordination Polymer [Cd(terephthalate)(H₂O)₃].4H₂O

Single crystals of [Cd(terephthalate)(H₂O)₃].4H₂O (1), triaquo(1,4-benzenecarboxylato-κO)cadmium tetrahydrate, are grown in a silica gel column. Crystal structure analysis shows that (1) is a polymer with metal-organic chains stacked along the a axis forming layers parallel to the ab plane. These layers are linked by an unusual hydrogen-bonded network formed by the water molecules (both `free' and coordinated ones) and the carboxylate O atoms. This network comprises tridymite-like O<sub>8</sub> cages which `propagate' in the direction of the a axis, mimicking the way they `propagate' along the c axis in hexagonal ice.

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