Acridinium (6-carboxypyridine-2-carboxylato)(pyridine-2,6-dicarboxylato)zincate(II) pentahydrate

The reaction of Zn(NO3)2 with pyridine-2,6-dicarboxylic acid (pydcH2) and acridine (acr) in aqueous solution leads to the formation of the title compound, (C13H10N)[Zn(C7H3NO4)(C7H4NO4)]·5H2O or (acrH)[Zn(pydcH)(pydc)]·5H2O. In the title compound, the ZnII atom is coordinated by four O atoms and two N atoms from the tridentate chelating rings of (pydc)2 and (pydcH) anions. The geometry of the resulting ZnN2O4 coordination can be described as distorted octahedral. To balance the charges, one protonated acridine (acrH)+ cation is present. In the crystal structure, extensive O—H...O and N—H...O hydrogen bonds involving acrH+, the complex anion and uncoordinated water molecules form a three-dimensional network.