{4,4'-Dimeth-oxy-2,2'-[1,1'-(ethane-1,2-diyldinitrilo)diethyl-idyne]diphenolato}nickel(II) hemihydrate

In the title complex, [Ni(C(20)H(22)N(2)O(4))]·0.5H(2)O, the Ni(II) ion is in a slightly distorted square-planar geometry involving an N(2)O(2) atom set of the tetra-dentate Schiff base ligand. The asymmetric unit contains one mol-ecule of the complex and half a water solvent mol-ecule. The solvent water mol-ecule lies on a crystallographic twofold rotation axis. An inter-molecular O-H⋯O hydrogen bond forms an R(2) (1)(4) ring motif involving a bifurcated hydrogen bond to the phenolate O atoms of the complex. In the crystal structure, mol-ecules are linked by π-π stacking inter-actions, with centroid-centroid distances in the range 3.5310 (11)-3.7905 (12) Å, forming extended chains along the b axis. In addition, there are Ni⋯Ni and Ni⋯N inter-actions [3.4404 (4)-4.1588 (4) and 3.383 (2)-3.756 (2) Å, respectively] which are shorter than the sum of the van der Waals radii of the relevant atoms. Further stabilization of the crystal structure is attained by weak inter-molecular C-H⋯O and C-H⋯π inter-actions.