Poly[[diaqua(μ3-3-nitrophthalato)calcium(II)] monohydrate]

The title 3‐nitrophthalate–calcium coordination polymer, {[Ca(C8H3NO6)(H2O)2]·H2O}n, crystallizes as a one‐dimensional framework. The CaII centre has a distorted pentagonal–bipyramidal geometry, being seven‐coordinated by five O atoms from three different 3‐nitrophthalate groups and by two water molecules, resulting in a one‐dimensional zigzag chain along the a‐axis direction by the interconnection of the four O atoms from the two carboxylate groups. There is a D3 water cluster composed of the coordinated and the solvent water molecules within such chains. Adjacent chains are aggregated into two‐dimensional layers via hydrogen bonds in the c‐axis direction. The whole three‐dimensional structure is further stabilized by weak O—H...O hydrogen bonds between the O atoms of the nitro group and the water molecules.