Acta Cryst. (2007). C63, o207-o211 [ doi:10.1107/S0108270107006233 ]
Abstract: Two isomeric pairs of Schiff bases, N,N'-bis(2-methoxybenzylidene)-p-phenylenediamine, C22H20N2O2, (I), and 2,2'-dimethoxy-N,N-(p-phenylenedimethylene)dianiline, C22H20N2O2, (II), and (E,E)-1,4-bis(3-iodophenyl)-2,3-diazabuta-1,3-diene (alternative name: 3-iodobenzaldehyde azine), C14H10I2N2, (III), and N,N'-bis(3-iodophenyl)ethylenediimine, C14H10I2N2 [JAYFEV; Cho, Moore & Wilson (2005). Acta Cryst. E61, o3773-o3774], differ pairwise only in the orientation of their imino linkages and in all four individual cases occupy inversion centers in the crystal, yet all four compounds are found to assume unique packing arrangements. Compounds (I) and (II) differ substantially in molecular conformation, possessing angles between their ring planes of 12.10 (15) and 46.29 (9)°, respectively. Compound (III) and JAYFEV are similar to each other in conformation, with angles between their imino linkages and benzene rings of 11.57 (15) and 7.4 (3)°, respectively. The crystal structures are distinguished from each other by different packing motifs involving the functional groups. Intermolecular contacts between methoxy groups define an R22(6) motif in (I) but a C(3) motif in (II). Intermolecular contacts are of the II type in (III), but they are of the NI type in JAYFEV.
Formula: C22H20N2O2 and C14H10I2N2
Structure factor file (CIF format) (76.1 kbytes)
Structure factor file (CIF format) (78.1 kbytes)
Structure factor file (CIF format) (79.6 kbytes)
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