Study of weak interactions in (4-chlorophenyl)-(4-fluorophenyl)-(4-pyridyl) methanol and bis-(4-fluorophenyl)-(4-pyridyl) methanol

As a part of our investigations on weak interactions involving organic fluorine, we have analyzed two representative compounds, (4-chlorophenyl)-(4-fluorophenyl)-(4-pyridyl) methanol and bis-(4-fluorophenyl)-(4-pyridyl) methanol. In these structures the molecules are linked by strong O-H...N hydrogen bonds to form antiparallel chains along the baxis. In addition, C-F...pi interactions are observed as a consequence of the fluorine atom being flanked by two phenyl rings of the neighboring molecules. The first structure also has a significantly short intermolecular Cl...Cl interaction [type I, Cl...Cl = 3.4213(9) Angstrom, angleC-Cl...Cl' = 127.20(8)degrees] while the second structure though analogous to the first, does not display F...F interaction. The packing modes are rationalized in terms of intermolecular interactions in comparison with the reported structure of diphenyl (4-pyridyl) methanol. (C) 2002 Elsevier Science B.V. All rights reserved.