Aqua­(1,10-phenanthroline)(pyridine-2,6-dicarboxyl­ato)nickel(II) pyridine-2,6-di­carboxylic acid solvate tetra­hydrate

The title compound, [Ni(C(7)H(3)NO(4))(C(12)H(8)N(2))(H(2)O)]·C(7)H(5)NO(4)·4H(2)O or [Ni(pydc)(phen)(H(2)O)].pydcH(2)·4H(2)O, was obtained by the reaction of nickel(II) nitrate hexa-hydrate with the proton-transfer compound (phenH)(2)(pydc) (phen is 1,10-phenanothroline and pydcH(2) is pyridine-2,6-dicarboxylic acid) in aqueous solution. Both the cationic and anionic portions of the starting proton-transfer compound are involved in the complexation. The Ni(II) atom has a distorted octa-hedral geometry and is hexa-coordinated by three O atoms and three N atoms from one phen fragment (as a bidentate ligand), one (pydc)(2-) unit (as a tridentate ligand) and one water mol-ecule. In the crystal structure, extensive O-H⋯O, O-H⋯N and C-H⋯O hydrogen bonds with D⋯A distances ranging from 2.573 (2) to 3.385 (2) Å, π-π inter-actions between the phen ring systems [with centroid-centroid distances of 3.4694 (12), 3.4781 (11) and 3.8310 (11) Å] and inter-molecular C-O⋯π inter-actions [C⋯π distances of 3.4812 (17), 3.5784 (16) and 3.5926 (16) Å] connect the various components together.