The reaction of mercury(II) nitrate with the proton-transfer compound (pipzH2)(pydc), where pipz is piperazine and pydcH2 is pyridine-2,6-dicarboxylic acid, in aqueous solution leads to the formation of the title compound, (pipzH2)[Hg- (pydc)2]6H2O or (C4 H12N2)[Hg(C7H3NO4)2]6H2O. The structure features six-coordinate Hg2+ (site symmetry 2) with a distorted octahedral geometry. Extensive intermolecular O—H O, N—H O and C—H O hydrogen bonding involving the (pydc)2 ligand, (pipzH2)2+ (site symmetry 2) as a counter-ion and uncoordinated water molecules forms a three-dimensional network.
