Ethylenediammonium tetrakis({2,2′-[ethane-1,2-diylbis(nitrilomethylidyne)]diphenolato}nickel(II)) bis(perchlorate) dimethylformamide monosolvate

The title compound, (C2H10N2)[Ni(C16H14N2O2)]4(ClO4)2·C3H7NO, crystallizes with four Ni(salen) molecules {salen is 2,2′-[ethane-1,2-diylbis(nitrilomethylidyne)]diphenolate}, one ethylenediammonium cation (actually two half-cations, each located on a center of inversion), two perchlorate anions and one dimethylformamide solvent molecule in the asymmetric unit. Each NiII cation in the Ni(salen) complex is four-coordinated by two imine N atoms and two phenolate O atoms from the tetradentate ligand. The Ni(salen) units form parallel slipped stacks with Ni⋯Ni separations of 3.4541 (4) and 3.6442 (6) Å. The crystal packing is stabilized by intermolecular hydrogen bonds between the ammonium H atoms and the perchlorate and salen O atoms, which generate a three-dimensional structure.

The work presented here describes the synthesis and structural characterization of Ni II salen complex co-crystallizing with ethylenediammonium perchlorate and N,N'-dimethylformamide presented in Fig. 1. The asymmetric unit contains four neutral Ni(salen) molecules, ethylenediammonium perchlorate (actually two half ethylenediammonium cations lying on centers of inversion), and an N,N'-dimethylformamide solvate molecule. All species are linked together by an extensive series of hydrogen bonds between the ethylenediammonium cations and perchlorate anions, neutral Ni(salen) and N,N'-dimethylformamide molecules. This is a good example of molecular recognition. The Ni-O phenolate bond distances range from 1.8353 (15) to 1.8576 (14) Å and the Ni-N distances range from 1.836 (2) to 1.8497 (18) Å and are comparable to those found in literature for similar neutral Ni(salen) complexes reported earlier (Prabhakar et al. 2006). The coordination around Ni II ions shows a slightly distorted square planer geometry. The Ni(salen) units form parallel slipped stacks with Ni-Ni separations of 3.4541 (4) and 3.6442 (6) Å.

Experimental
The ligand ethylenebis(salicylideneimine) was synthesized by reacting a solution of (5 g, 83.19 mmol) of ethylenediamine in 10 ml ethanol with a solution of (20.32 g, 166.38 mmol) salicylaldehyde in 40 ml ethanol. The mixture was refluxed for 24 hrs. The mixture was then evaporated under reduced pressure and yellow solids were obtained with a yield of 96.6%.
The complex was synthesized by reacting 1.36 g (3.73 mmol) of Ni(ClO 4 ) 2 .6H 2 O in methanol (10 ml) with 1 g (3.73 mmol) of ethylenebis(salicylideneimine) in CH 2 Cl 2 (10 ml) for 24 hours while stirring with magnetic stirrer at room temperature. The mixture was evaporated under reduced pressure and brownish solids were obtained. These solids were dissolved in N,N'-dimethylformamide. The solution obtained was filtered and layered with diethyl ether. Brownish X-ray quality crystals were obtained after slow diffusion of the diethyl ether into the N,N'-dimethylformamide solution of the complex over a period of several days. supplementary materials sup-2 Refinement One DMF molecule was disordered in a manner that was not possible to model successfully. This was removed using the SQUEEZE routine from Platon. The output files from Platon are appended to the cif file and the fcf file has been modified using the Calc-FCF routine from Platon. H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms with a C-H distance of 0.95 and 0.99 Å U iso (H) = 1.2U eq (C) and 0.98 Å for CH 3 [U iso (H) = 1.5U eq (C)].
The H atoms attached to N were idealized with an N-H distance of 0.91 Å. Fig. 1. Showing the contents of the asymmetric unit with complete ethylenediammonium cations (generated by symmetry codes 1-x, 1-y, 1-z and 2-x, -y, 2-z

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.