Weak interactions involving organic fluorine: analysis of structural motifs in Flunazirine and Haloperidol

The crystal structure of Flunazirine, an anticonvulsant drug, is analyzed i n terms of intermolecular interactions involving fluorine. The structure di splays motifs formed by only weak interactions C-(HF)-F-... and C-H(...)pi. The motifs thus generated show cavities, which could serve as hosts for co mplexation. The structure of Flunazirine displays cavities formed by C-(HF) -F-... and C-H(...)pi interactions. Haloperidol, an antipsychotic drug, sho ws (FF)-F-... interactions in the crystalline lattice in lieu of (ClCl)-Cl- ... interactions. However, strong O-(HN)-N-... interactions dominate packin g. The salient features of the two structures in terms of intermolecular in teractions reveal, even though organic fluorine has lower tendency to engag e in hydrogen bonding and F F interactions, these interactions could play a significant role in the design of molecular assemblies via crystal enginee ring. (C) 2001 Elsevier Science B.V. All rights reserved.