(2Z,2'Z,4E,4'E)-4,4'-(Cyclo-hexane-1,2-diyldinitrilo)dipent-2-en-2-ol.

A new tetra-dentate chiral Schiff base ligand, C(16)H(26)N(2)O(2), has been synthesized by the reaction of acetyl-acetone with (1R,2R)-(-)-1,2-diamino-cyclo-hexane. Both of the mol-ecules in the asymmetric unit are of the same chirality (R configuration), since the absolute configuration was determined by the starting reagent (1R,2R)-(-)-1,2-diamino-cyclo-hexane. The six-membered cyclo-hexane ring is in a chair conformation, and the substituents are equatorial in the most stable conformation (trans-cyclo-hexyl). At the ring substituents, large conjugated -C=N-CH=C-OH systems exist, resulting from the original ketone converted into the enol form. With H atoms excluded, the atoms of each substituent lie in the same plane. The two mol-ecules in the asymmetric unit have almost the same structure, with slight differences in the torsion angles between the substituents and the cyclo-hexane ring; the corresponding N(1)-(C-C-C)(cyclo-hexa-ne) torsion angles are -177.2 (3) and 179.3 (4)° in one mol-ecule and -176.5 (3) and 178.4 (4)° in the other. Two intra-molecular O-H⋯N hydrogen bonds exist in each mol-ecule.