{4,4′,6,6′-Tetraiodo-2,2′-[propane-1,3-diylbis(nitrilomethanylylidene)]diphenolato-κ4 O,N,N′,O′}nickel(II)

The asymmetric unit of the title compound, [Ni(C17H12I4N2O2)], comprises half of a Schiff base complex. The NiII and central C atom of the propyl chain are located on a twofold rotation axis. The geometry around the NiII atom is square planar, supported by the N2O2 donor atoms of the coordinated ligand. In the crystal, there are no significant intermolecular interactions present. The crystal studied was a non-merohedral twin with a refined twin component ratio of 0.944 (1):0.056 (1).

The asymmetric unit of the title compound, [Ni(C 17 H 12 I 4 N 2 O 2 )], comprises half of a Schiff base complex. The Ni II and central C atom of the propyl chain are located on a twofold rotation axis. The geometry around the Ni II atom is square planar, supported by the N 2 O 2 donor atoms of the coordinated ligand. In the crystal, there are no significant intermolecular interactions present. The crystal studied was a non-merohedral twin with a refined twin component ratio of 0.944 (1):0.056 (1).
The asymmetric unit of the title compound, Fig. 1, comprises a Schiff base complex. The bond lengths (Allen et al., 1987) and angles are within the normal ranges and are comparable to the bond lengths and angles of the related ligand (Kargar et al., 2012a) and related Ni-complexes (Kargar et al., 2012b,c,d,e). The Ni II and C9 atom of the propyl segment are located on a two-fold rotation axis. The geometry around Ni II atom is square-planar which is supported by the N 2 O 2 donor atoms of the coordinated ligand.
There are no significant intermolecular interactions in the crystal structure.

Experimental
The title compound was synthesized by adding 3,5-diiodo-salicylaldehyde-1,3-propanediamine (2 mmol) to a solution of NiCl 2 . 6H 2 O (2.1 mmol) in ethanol (30 ml). The mixture was refluxed with stirring for 1h. The resultant solution was filtered. Red single crystals of the title compound suitable for X-ray structure determination were recrystallized from ethanol by slow evaporation of the solvents at room temperature over several days.

Refinement
The H-atoms were included in calculated positions and treated as riding atoms: C-H = 0.93 and 0.97 Å for CH and CH 2 H-atoms, respectively, with U iso (H) = 1.2 U eq (C).

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 > 2sigma(F 2 ) is used only for calculating R-factors(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.