In the title compound, [Ni(C2H8N2)3][O2P(OCH3)2]2, the NiII atom is six-coordinated in a distorted octa­hedral geometry by six N atoms from three ethyl­enediamine ligands. The P atoms of the anions adopt a distorted tetra­hedral geometry. In the crystal, inter­molecular N—H⋯O and C—H⋯O hydrogen bonds link the cations and anions into a three-dimensional network.

Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.003 Å; R factor = 0.017; wR factor = 0.041; data-to-parameter ratio = 19.9.In the title compound, (C 3 H 12 N 2 )[Hg(C 7 H 3 NO 4 ) 2 ]Á2H 2 O, the Hg II ion is coordinated by four O and two N atoms of two pyridine-2,6-dicarboxylate (pydc) ligands in a distorted octahedral environment. The structure contains two uncoordinated water molecules. In the crystal, N-HÁ Á ÁO, O-HÁ Á ÁO and weak C-HÁ Á ÁO hydrogen bonds and -stacking interactions between the pyridine rings of the pydc ligands, with a centroid-centroid distance of 3.4582 (18) Å , stabilize the structure. Related literature