(IUCr) Crystallography Journals Online

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Acta Cryst. (2009). E65, o722-o723 [ doi:10.1107/S1600536809008137 ]

A second tricilinc polymorph of 6,6'-diethoxy-2,2'-[propane-1,2-diylbis(nitrilomethylidyne)]diphenol

H.-K. Fun, R. Kia, H. Kargar and A. Jamshidvand

Abstract: The title Schiff base compound, C₂₁H₂₆N₂O₄, is a second triclinic polymorph of a previously reported room-temperature structure [Jia (2009). Acta Cryst. E65, o646]. Strong intramolecular O-HN hydrogen bonds generate S(6) ring motifs. Intermolecular C-HO interactions link neighbouring molecules into dimers with an R₂²(16) ring motif. The mean planes of the two benzene rings are almost perpendicular to each other, making a dihedral angle of 88.24 (5)°. An interesting feature of the crystal structure is the intermolecular short CO [3.1878 (13) Å] contact which is shorter than the sum of the van der Waals radii of the relevant atoms. The crystal structure is further stabilized by intermolecular C-H [pi] and [pi] - [pi] interactions [centroid-centroid distance = 3.7414 (6) Å]. The structure has a stereogenic centre but the space group is centrosymmetric, so the molecule exists as a racemate.

Online 11 March 2009