Acta Crystallographica Section B

Structural Science

Volume 58, Part 5 (October 2002)

research papers

Acta Cryst. (2002). B58, 864-876 [ doi:10.1107/S0108768102009941 ]

Nine isomeric nitrobenzylidene-iodoanilines: interplay of C-HO hydrogen bonds, iodonitro interactions and aromatic stacking interactions

C. Glidewell, R. A. Howie, J. N. Low, J. M. S. Skakle, S. M. S. V. Wardell and J. L. Wardell

Abstract: Nine isomeric nitrobenzylidene-iodoanilines, O₂NC₆H₄CH= NC₆H₄I [(I)-(IX)], have been synthesized and the structures of all except 4-nitrobenzylidene-4'-iodoaniline (IX) have been analyzed. 2-Nitrobenzylidene-2'-iodoaniline (I) contains isolated molecules, while 3-nitrobenzylidene-2'-iodoaniline (II) and 2-nitrobenzylidene-3'-iodoaniline (IV) both contain chains of molecules linked by C-HO hydrogen bonds: similar chains in 4-nitrobenzylidene-2'-iodoaniline (III) are further linked by aromatic [pi] [pi] stacking interactions, forming sheets. In both 3-nitrobenzylidene-3'-iodoaniline and 4-nitrobenzylidene-3'-iodoaniline, (V) and (VI), a combination of C-HO hydrogen bonds and iodonitro interactions generates molecular ladders that are linked into sheets by aromatic [pi] [pi] stacking interactions, while in 2-nitrobenzylidene-4'-iodoaniline and 3-nitrobenzylidene-4'-iodoaniline, (VII) and (VIII), which both crystallize with Z' = 2 in C2/c and P $\bar 1$ , respectively, the combination of C-HO hydrogen bonds and iodonitro interactions generates sheets, which in (VIII) are further linked by [pi] [pi] stacking interactions to form a three-dimensional structure. The 4,4'-isomer (IX) crystallizes in Fdd2 with Z' = 2, but both molecules are intractably disordered.

Keywords: nitrobenzylidene-iodoanilines; hydrogen bonds; iodonitro interactions; stacking interactions.