Aqua­(2,9-dimethyl-1,10-phenanthroline-κ(2) N,N′)diformato-κ(2) O,O′;κO-nickel(II) monohydrate

The asymmetric unit of the title compound, [Ni(HCO(2))(2)(C(14)H(12)N(2))(H(2)O)]·H(2)O, contains a mononuclear complex mol­ecule hydrogen bonded to a lattice water mol­ecule. The Ni(II) atom exhibits a distorted octa­hedral coordination geometry formed by the N atoms from a 2,9-dimethyl-1,10-phenanthroline ligand, two O atoms of a chelating formate anion, one aqua O atom and one O atom of a coordinating formate anion. The mol­ecules are assembled into chains extending along [100] through by O—H⋯O hydrogen bonds. The supra­molecular chains are further linked into layers parallel to (011) by weak π–π packing inter­actions [centroid–centroid separation = 3.768 (2) Å]. The resulting layers are stacked to meet the requirement of close-packing patterns.