Piperazinium bis(pyridine-2,6-dicarboxylato)-mercurate(II) hexahydrate

The reaction of mercury(II) nitrate with the proton- transfer compound (pipzH(2))(pydc), where pipz is piperazine and pydcH(2) is pyridine-2,6-dicarboxylic acid, in aqueous solution leads to the formation of the title compound, (pipzH(2))[Hg-(pydc)(2)]center dot 6H(2)O or (C4H12N2)[ Hg(C7H3NO4)(2)]center dot 6H(2)O. The structure features six- coordinate Hg2+ (site symmetry 2) with a distorted octahedral geometry. Extensive intermolecular O-H center dot center dot center dot O, N-H center dot center dot center dot O and C-H center dot center dot center dot O hydrogen bonding involving the (pydc)(2-) ligand, (pipzH(2))(2+) (site symmetry 2) as a counter-ion and uncoordinated water molecules forms a three-dimensional network.