Aqua(propanedioato-κ2 O 1,O 3)[2-(1H-pyrazol-1-yl-κN 2)-1,10-phenanthroline-κ2 N,N′]nickel(II) trihydrate

In the title mononuclear complex, [Ni(C3H2O4)(C15H10N4)(H2O)]·3H2O, the metal center is coordinated in a distorted NiN3O3 geometry. In the crystal structure, intermolecular O—H⋯O hydrogen bonds link the components into a two-dimensional network. In addition, there are weak π–π stacking interactions between symmetry-related phenanthroline rings, with a centroid–centroid distance of 3.6253 (17) Å.

In the title mononuclear complex, [Ni(C 3 H 2 O 4 )(C 15 H 10 N 4 )-(H 2 O)]Á3H 2 O, the metal center is coordinated in a distorted NiN 3 O 3 geometry. In the crystal structure, intermolecular O-HÁ Á ÁO hydrogen bonds link the components into a twodimensional network. In addition, there are weakstacking interactions between symmetry-related phenanthroline rings, with a centroid-centroid distance of 3.6253 (17) Å .

Experimental
A 5 ml H 2 O solution of hydrated nickel perchlorate (0.1606 g, 0.439 mmol) was added to an ethanol solution containing 2-(1H-pyrazol-1-yl)1,10-phenanthroline (0.1025 g, 0.416 mmol) and the solution was stirred for a few minutes. A 5 ml H 2 O solution of sodium propanedioate (0.0714 g, 0.482 mmol) was then added dropwise into the above solution. The solution was stirred for another a few minutes. Blue single crystals were obtained after the filtrate had been allowed to stand at room temperature for two weeks.

Refinement
H atoms of water molecules were located in a difference Fourier map and refined as riding in their as-found positions, with U iso (H) = 1.5U eq (O). All other H atoms were placed in calculated positions, and refined as riding, with C-H = 0.97 Å for methylene and C-H = 0.93 Å for other H atoms, U iso (H) = 1.2 eq (C).
supplementary materials sup-2 Figures Fig. 1. The molecular structure of (I) showing the atom numbering scheme with thermal ellipsoids drawn at the 30% probability level.

Special details
Geometry. All e.s. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.