A new three‐dimensional cobalt(II) coordination polymer with a 4‐connected CdSO4‐like topology

The title cobalt(II) coordination polymer, polydiaquacobalt(II)]‐μ₄‐3,3′‐(p‐phenylene)diacrylato], Co(C₁₂H₈O₄)(H₂O)₂]_n, was obtained by reaction of Co(NO₃)₂·6H₂O and 3,3′‐(p‐phenylene)diacrylic acid (H₂L) under hydrothermal conditions. Each Co^II cation sits on a centre of inversion and is hexacoordinated by six O‐atom donors in an octahedral geometry. The Co^II centres are connected by four centrosymmetric L^2? anions, resulting in a three‐dimensional framework structure. The coordinated water molecules and carboxylate O atoms form hydrogen‐bond interactions, stabilizing the structure of the three‐dimensional framework. Topologically, the framework represents a rare example of the three‐dimensional 4‐connected CdSO₄ network type. The metal cations and the organic ligand both show in‐plane coordination with respect to the extended structure.