Evaluation of the role of disordered organic fluorine in crystal packing: insights from halogen substituted benzanilidesElectronic supplementary information (ESI) available: IR data, PXRD and simulated Powder X-ray data, 1H NMR data, X-ray crystallographic information files (CIFs) for all the crystal structures have been deposited in CSD. CCDC reference numbers 640039, 640042, 764625-764629, 774717, 774718 and 811042. For ESI and crystallographic data in CIF or other electronic format see DOI: 1

• Main Authors: Nayak, Susanta K, Reddy, M. Kishore, Chopra, Deepak, Guru Row, Tayur N
• Format: Journal Article
• Language: English
• Published: 05.12.2011
• DOI: 10.1039/c1ce05441d

The determination of the crystal and molecular structures of a large number of compounds containing the C(sp 2 )-F bond has been investigated in detail in halogenated benzanilides and also in liquids, namely the fluorinated amines. It has been observed that when the fluorine atom is present in the ortho or meta position with respect to the amide functionality in benzanilides or the amino group in fluorinated amines which are liquids at room temperature, the fluorine atom exhibits positional disorder. This is associated with changes in patterns of intermolecular interactions which affect crystal packing. Furthermore, the presence of a fluorine atom on the benzanilide framework, in the presence of a heavier halogen (chloro, bromo and iodo), meta or ortho to the amide group does not eliminate the disorder associated with these molecules. In this article, we highlight the salient features present in halogenated compounds exhibiting disorder in the position of organic fluorine with concomitant changes in crystal packing. This feature is also compared with related compounds exhibiting similarity in electronic features, namely positional disorder. Amongst all the organic halogens (F/Cl/Br/I), organic fluorine exhibits positional disorder, predominantly on substitution at ortho / meta site of aromatic ring, generating unique packing motifs in the crystal lattice.