Diacetatobis(propane-1,3-diamine)nickel(II) dihydrate

In the title complex, [Ni(CH3COO)2(C3H10N2)2]·2H2O, the NiII atom resides on a centre of symmetry and is in an octahedral coordination environment comprising four amino N atoms and two carboxylate O atoms. Intermolecular N—H⋯O and O—H⋯O hydrogen bonds produce R 2 1(6), R 2 2(12), R 3 2(8) and R 5 5(16) rings, which generate a two-dimensional polymeric network parallel to (001).


Comment
The 1,3-Diaminopropane (tn) ligand behaves as a strong chelator in its metal complexes due to the formation of a stable six-membered ring. At the same time, it is a good H-bond donor due to the existence of amino groups (Sundberg et al., 2001). Herein, we report the synthesis and structure of the title compound.
The molecular structure and atom-numbering scheme are shown in Fig. 1. The compound crystallizes in the space group P-1 with Z'=1/2. The nickel(II) ion is located on a symmetry center, and is coordinated by two O atoms from two identical carboxylate groups and four N atoms from two 1,3-diaminopropane ligands. The geometry around the nickel(II) ion ( Table   1) is that of a slightly distorted octahedron, of which the equatorial plane (N1/N2/N1 i /N2 i ) is formed by four amino N atoms The amino atom N1 in the molecule at (x, y, z) acts as a hydrogen-bond donor (Table 2) to atom O2 i so forming a C(6) (Bernstein et al., 1995) chain running parallel to the [-100] direction. Amino atom N2 in the molecule at (x, y, z) acts as a hydrogen-bond donor to atom O2 ii so forming a C (6)
Blue blocks were obtained from methanol.

Refinement
All H atoms bound to C atoms were refined using a riding model, with C-H = 0.97Å and U iso (H) = 1.2U eq (C) for methylene C atoms and C-H = 0.96Å and U iso (H) = 1.5U eq (C) for methyl C atom. Water H atoms were located in difference maps and refined subject to a DFIX restraint of O-H = 0.83 (2) Å. Amino H atoms were located in difference maps and refined freely.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq