(2Z,2′Z,4E,4′E)-4,4′-(Cyclo­hexane-1,2-diyldinitrilo)dipent-2-en-2-ol

A new tetra­dentate chiral Schiff base ligand, C(16)H(26)N(2)O(2), has been synthesized by the reaction of acetyl­acetone with (1R,2R)-(−)-1,2-diamino­cyclo­hexane. Both of the mol­ecules 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-diamino­cyclo­hexane. The six-membered cyclo­hexane ring is in a chair conformation, and the substituents are equatorial in the most stable conformation (trans-cyclo­hexyl). 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 mol­ecules in the asymmetric unit have almost the same structure, with slight differences in the torsion angles between the substituents and the cyclo­hexane ring; the corresponding N(1)—(C—C—C)(cyclo­hexa­ne) torsion angles are −177.2 (3) and 179.3 (4)° in one mol­ecule and −176.5 (3) and 178.4 (4)° in the other. Two intra­molecular O—H⋯N hydrogen bonds exist in each mol­ecule.