Bis{2-[2,5-bis(pyridin-2-yl)-1H-imidazol-4-yl]pyridinium} tetracyanidoplatinate(II) tetrahydrate

The asymmetric unit of the title hydrated complex salt, (C ₁₈H₁₄N₅)₂[Pt(CN)₄] ·4H₂O, consists of one 2-[2,5-bis(pyridin-2-yl)-1H-imidazol-4- yl]pyridinium cation, half a tetracyanidoplatinate(II) dianion, which is located about a crystallographic inversion center, and two water molecules of crystallization. The Pt^II atom has a square-planar coordination environment, with Pt - CCN distances of 1.992 (4) and 2.000 (4) Å. In the cation, there is an N - H⋯N hydrogen bond linking adjacent pyridinium and pyridine rings in positions 4 and 5. Despite this, the organic component is non-planar, as shown by the dihedral angles of 10.3 (2), 6.60 (19) and 15.66 (18)° between the planes of the central imidazole ring and the pyridine/pyridinium substituents in the 2-, 4- and 5-positions. In the crystal, cations and anions are linked via O - H⋯O, O - H⋯N and N - H⋯O hydrogen bonds, forming a three-dimensional network. Additional π-π, C - H⋯O and C - H⋯N contacts provide stabilization to the crystal lattice.