(2-Amino-7-methyl-4-oxidopteridine-6-carboxyl­ato-κ(3) O (4),N (5),O (6))aqua­(ethane-1,2-diamine-κ(2) N,N′)nickel(II) dihydrate

The Ni(II) atom in the title complex, [Ni(C(8)H(5)N(5)O(3))(C(2)H(8)N(2))(H(2)O)]·2H(2)O, is six-coordinated in a distorted octa­hedral geometry by a tridentate 2-amino-7-methyl-4-oxidopteridine-6-carboxyl­ate (pterin) ligand, a bidentate ancillary ethane-1,2-diamine (en) ligand and a water mol­ecule. The pterin ligand forms two chelate rings. The en and pterin ligands are arranged nearly orthogonally [dihedral angle between the mean plane of the en mol­ecule and the pterin ring = 77.1 (1)°]. N—H⋯O, O—H⋯N and O—H⋯O hydrogen bonds link the complex mol­ecules and lattice water mol­ecules into a three-dimensional network. π–π inter­actions are observed between the pyrazine and pyrimidine rings [centroid–centroid distance = 3.437 (2) Å].