Nine isomeric nitrobenzylidene-iodoanilines: interplay of C-H center dot center dot center dot O hydrogen bonds, iodo center dot center dot center dot nitro interactions and aromatic pi center dot center dot center dot pi stacking interactions

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-H...O 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-H...O hydrogen bonds and iodo...nitro 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 (1) over bar 1, respectively, the combination of C-H...O hydrogen bonds and iodo...nitro 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.