The reaction of magnesium(II) chloride tetrahydrate with the proton-transfer compound piperazinediium pyridine-2- carboxylate, (pipzH2)(pyc)2 (pipz is pirerazine and pycH is pyridine-2-carboxylic acid) in aqueous solution leads to the formation of the title compound, [Mg(C6H4NO2)2- (H2O)2]0.15H2O. The Mg atom is six-coordinated in a distorted octahedral environment by two bidentate pyridine- 2-carboxylate groups and two O atoms of coordinated water molecules, which are located in cis positions. In the crystal structure, intermolecular O—H O and C—H O hydrogen bonds, and – [– distance = 3.5616 (8) A ˚ for pyridine rings; symmetry code: 2 x; 1 y; 1 z] and C—H stacking, connect the various components into a supramolecular structure.
