(3Z,3′E)-3,3′-[Cyclohexane-1,2-diylbis(azanylylidene)]bis(indolin-2-one) N,N-dimethylformamide monosolvate dihydrate

In the Schiff base molecule of the title compound, C22H20N4O2·C3H7NO·2H2O, the cyclohexane ring adopts a chair conformation with the two imine groups linked at the equatorial positions. The two indolin-2-one ring systems make a dihedral angle of 65.63 (5)°. In the crystal, the Schiff base molecules are connected through bifurcated N—H⋯(O,N) hydrogen bonds, forming inversion dimers. The water molecules link the dimers and the dimethylformamide molecules via O—H⋯O, O—H⋯N and N—H⋯O hydrogen bonds. Together with C—H⋯π and π–π [centroid–centroid distance = 3.3889 (10) Å] interactions a three-dimensional supramolecular structure is formed.

In the Schiff base molecule of the title compound, C 22 H 20 N 4 O 2 ÁC 3 H 7 NOÁ2H 2 O, the cyclohexane ring adopts a chair conformation with the two imine groups linked at the equatorial positions. The two indolin-2-one ring systems make a dihedral angle of 65.63 (5) . In the crystal, the Schiff base molecules are connected through bifurcated N-HÁ Á Á(O,N) hydrogen bonds, forming inversion dimers. The water molecules link the dimers and the dimethylformamide molecules via O-HÁ Á ÁO, O-HÁ Á ÁN and N-HÁ Á ÁO hydrogen bonds. Together with C-HÁ Á Á and -[centroid-centroid distance = 3.3889 (10) Å ] interactions a three-dimensional supramolecular structure is formed.
supplementary materials Acta Cryst. (2012). E68, o2107 [doi:10.1107/S1600536812026335]  The title bis-Schiff base is the condensation product of the reaction of 1,2-diaminocyclohexane with 2 eq of isatin. The crystal structure consists of a bis-Schiff base molecule, one DMF and two water solvent molecules. As observed in similar structures (Fonseca et al., 2003;van den Ancker et al., 2006;Zhang et al., 2008), the cyclohexane ring adopts a chair conformation with the imine links at the equatorial positions. The two isatin systems of the molecule are twisted with respect to each other by 65.63 (5)°. In the crystal, the adjacent Schiff bases are connected into a two-dimensionalarray via C-H···π (Table 1) and π-π interactions [Cg1···Cg2 iii = 3.3889 (10) Å, where Cg1 is the centroid of N1/C1/C8/C7/C2 ring and Cg2 iii is the centroid of C2-C7 ring of the symmetry related molecule at -x + 1, -y + 1, -z].
The resulting network is consolidated by intermolecular N4-H···O1 and N4-H···N2 hydrogen bonding (Table 1). The solvent water molecules link the layers via O-H···O, O-H···N and N-H···O hydrogen bonds into a three-dimensional polymeric structure. The DMF solvent molecules are O4-H···O3 bonded to water molecules. An intramolecular C-H···O hydrogen bonding is also observed.

Experimental
An ethanolic solution of 1,2-diaminocyclohexane (1 g, 8.76 mmol) was added slowly to a solution of isatin (3.2 g, 22 mmol) in the same solvent. The mixture was refluxed for 3 hr. The resulting yellow precipitate was filtered, washed with cold ethanol and dried over silica-gel. The title crystals were obtained from a solution of the solid in DMF.

Refinement
The C-bound hydrogen atoms were located in the calculated positions and refined in a riding mode with C-H distances of 0.95 (phenyl), 0.99 (methylene) and 1.00 (methine) Å. The N-bound H atoms were found in a difference Fourier map and refined freely. The water hydrogen atoms were found in a difference Fourier map and refined with a distance restraint of O-H = 0.86 (2) Å. For all hydrogen atoms, U iso were set to 1.2-1.5U eq (carrier atom).   The two-dimensional-array of the Schiff molecules in the ac plane mediated by C-H···π and π···π interactions, shown as dashed lines. The solvent molecules are not shown.  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 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.