Experimental

R factor = 0.038; wR factor = 0.107; data-to-parameter ratio = 11.2. In the title compound, [Mn2(C8H3NO6)2(C12H8N2)2(H2O)4], the MnII atom in the centrosymmetric binuclear unit has a distorted octahedral geometry and is coordinated by a chelating 1,10-phenanthroline ligand, two monodentate carboxylate anions from two 4-nitrophthalates and two coordinated water molecules. The two MnII ions in the molecule are bridged by two 4-nitrophthalate anions, both in a bis-monodentate mode, which finally leads to the formation of the binuclear unit. Intramolecular O—H O hydrogen bonds between the coordinated and uncoordinated O atoms of one monodentate carboxylate group and the corresponding coordinated water molecules result in an eight-membered and two six-membered rings. In the crystal structure, inter-molecular O—H O hydrogen bonds link the dinuclear molecules into supramolecular chains propagating parallel to [100]. Related literature For general background to self-assembly coordination complexes with metal ions and 4-nitrophthalic acid, see: Guo & Guo (2007); Qi et al. (2008)