Propane-1,2-diaminium bis(pyridine-2,6-dicarboxylato-κ3O2,N,O6)cadmate dihydrate

The reaction of cadmium nitrate dihydrate, propane-1,2-diamine and pyridine-2,6-dicarboxylic acid in a 1:1:2 molar ratio in an aqueous solution resulted in the formation of the title compound, (C3H12N2)[Cd(C7H3NO4)(2)]center dot 2H(2)O or (p-1,2-daH(2))-[Cd(pydc)(2)]center dot 2H(2)O (where p-1,2-da is propane-1,2-diamine and pydcH(2) is pyridine-2,6-dicarboxylic acid). The Cd-II ion is coordinated by four O and two N atoms of two pydc ligands in a distorted octahedral environment. The structure also contains two uncoordinated water molecules. In the crystal, there are several intermolecular N-H center dot center dot center dot O, O-H center dot center dot center dot O and weak C-H center dot center dot center dot O hydrogen bonds. There are also pi-pi stacking interactions between the pyridine rings of pydc units, with centroid-centroid distances of 3.4708 (16) angstrom.