Chopra Deepak, Mohan T P, Vishalakshi B, Guru Row T N
Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012, Karnataka, India.
Acta Crystallogr C. 2006 Sep;62(Pt 9):o540-3. doi: 10.1107/S010827010602378X. Epub 2006 Aug 11.
The crystal structures of the title compounds, viz. C24H14F2N2O2, (I), and C25H17FN2O2, (II), respectively, have been determined in order to unravel the role of an ordered F atom in generating stable supramolecular assemblies. On changing the substitution from fluorine to a methyl group, C-H...F interactions are replaced by C-H...pi interactions, revealing the importance of such weak interactions when present alongside N-H...O and C-H...O hydrogen bonds. The dihedral angle between the planes of the 4-fluorophenyl ring and the pyridine ring is 26.8 (1) degrees in (I), while that between the planes of the 4-methylphenyl and pyridine rings is 29.5 (1) degrees in (II).
为了阐明有序氟原子在生成稳定超分子聚集体中的作用，分别测定了标题化合物即C24H14F2N2O2（I）和C25H17FN2O2（II）的晶体结构。当取代基从氟变为甲基时，C-H...F相互作用被C-H...π相互作用所取代，这揭示了此类弱相互作用与N-H...O和C-H...O氢键共存时的重要性。在（I）中，4-氟苯基环与吡啶环平面之间的二面角为26.8（1）°，而在（II）中，4-甲基苯基与吡啶环平面之间的二面角为29.5（1）°。
