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

The title compound, [Ni(C(7)H(6)N(2)O(3))(C(12)H(8)N(2))(2)]·3.5H(2)O, 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 Ni(II) 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.