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

A new tetradentate chiral Schiff base ligand, C16H26N2O2, 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 N1—(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.