(3-Acetyl-4-methyl-1H-pyrazol-1-ide-5-carboxylato)bis(1,10-phenanthroline)nickel(II) 3.5-hydrate

The title compound, [Ni(C7H6N2O3)(C12H8N2)2]·3.5H2O, crystallizes as a neutral mononuclear complex with 3.5 solvent water molecules. One of the water molecules lies on an inversion centre, so that its H atoms are disordered over two sites. The coordination environment of NiII has a slightly distorted octahedral geometry, which is formed by one O and five N atoms belonging to the N,O-chelating pyrazol-1-ide-5-carboxylate and two N,N′-chelating phenanthroline molecules. In the crystal, O—H...O, N—H...O and O—H...N hydrogen bonds involving the solvent water molecules and pyrazole-5-carboxylate ligands form layers parallel to the ab plane. These layers are linked further via weak π–π interactions between two adjacent phenanthroline molecules, with centroid-to-centroid distances in the range 3.886 (2)–4.018 (1) Å, together with C—H...π contacts, forming a three-dimensional network