A new salen ligand: 2,2′-[(spiro[4.4]nonane-1,6-diyl)dinitrilomethylidyne]bis(4,6-dichlorophenol).

The title compound, C23H22Cl4N2O2, was synthesized by the reaction of 1,1′-spiro[4,4]nonane-1,6-diamine and 3,5-dichlorosalicylaldehyde. It is a new Schiff base containing a spirocyclic backbone and an approximate non-crystallographic C2 axis. Two intramolecular O—H...N hydrogen bonds determine the relative orientation of the two benzene rings. Intermolecular π–π stacking interactions between the phenyl rings and weak intermolecular C—H...Cl hydrogen bonds stabilize the structure. Cp1 and Cp2 are the centroids of the planes defined by atoms C11–C16 and C18–C23. The angle between the planes is only 0.8° and interplanar distances are Cp1...Cp2( x, y, z + 1) = 4.023 Å and Cp1...Cp2( x + 1, y, z + 1) = 4.032 Å. [ABSTRACT FROM AUTHOR]