(3-Acetyl-4-methyl-1H-pyrazol-1-ide-5-carboxyl-ato)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 mol-ecules. One of the water mol-ecules lies on an inversion centre, so that its H atoms are disordered over two sites. The coordination environment of Ni(II) has a slightly distorted octa-hedral geometry, which is formed by one O and five N atoms belonging to the N,O-chelating pyrazol-1-ide-5-carboxyl-ate and two N,N'-chelating phenanthroline mol-ecules. In the crystal, O-H⋯O, N-H⋯O and O-H⋯N hydrogen bonds involving the solvent water mol-ecules and pyrazole-5-carboxyl-ate ligands form layers parallel to the ab plane. These layers are linked further via weak π-π inter-actions between two adjacent phenanthroline mol-ecules, 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.