(1R,2R)-N,N′-Bis[1-(2-pyridyl)ethylidene]cyclohexane-1,2-diamine

In the title compound, C20H24N4, the cyclohexane ring adopts a chair conformation with the two imine groups linked at equatorial positions. The two halves of the molecule are related by a crystallographic twofold rotation axis. The dihedral angle between the pyridine rings is 75.73 (3)°.

In the title compound, C 20 H 24 N 4 , the cyclohexane ring adopts a chair conformation with the two imine groups linked at equatorial positions. The two halves of the molecule are related by a crystallographic twofold rotation axis. The dihedral angle between the pyridine rings is 75.73 (3) .

Comment
The stucture of the title compound is presented in Fig. 1. The cyclohexane ring adopts a chair conformation with the two imines linked at equatorial positions. The two halves of the molecule are realted by a two-fold rotation. The dihedral angel between the two pyridine rings is 75.73 (3)°. The crystal structure is devoid of any inter-or intra-molecular interactions.
The bond distances and angles in the title molecule are in agreement with the corresponding bond distances and angles reported in some related structures (Aslantaş et al., 2007;Glidewell et al., 2005;Liu et al., 2006).

Experimental
A mixture of 2-acetylpyiridine (0.444 g, 4 mmol) and 1,2-diaminocyclohexane (0.224, 2 mmol) was refluxed in ethanol (50 ml) for 2 hours. The solution was then set aside overnight whereupon the yellow crystals of the title compound were formed.

Refinement
Hydrogen atoms were placed at calculated positions (C-H 0.95-1.00 Å), and were treated as riding on their parent atoms with U iso (H) set to 1.2-1.5 U eq (C). Fig. 1. Thermal ellipsoid plot of the title compound at 50% probability level; hydrogen atoms are drawn as spheres of arbitrary radius. Symmetry code for the unlabeled atoms: -x, y, -z+3/ 2.

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.