Cooperative effect on phenolic νO-H frequencies in 1:1 hydrogen bonded complexes of o-fluorophenols with water: A matrix isolation infrared spectroscopic study (original) (raw)

Matrix isolation infrared spectra of 1:1 complexes of two ortho-fluorophenols, 2-fluorophenol (2-FPh) and 2,6-difluorophenol (2,6-DFPh), with water and benzene have been analyzed in combination with electronic structure calculations to investigate cooperative effect in O-H···O-H···F hydrogen bonded linkage, which manifests as large spectral shifts of the phenolic O-H stretching fundamental. Calculation predicts that a nearly planar cyclic geometry is preferred by the binary water complexes of the syn conformer of 2-FPh as well as 2,6-DFPh, and the observed spectral shifts are in good agreement with the predicted shifts for such conformers. On the other hand, for other possible isomeric structures, the molecular plane of water moiety is oriented perpendicular to that of the fluorophenols, and the observed as well as predicted shifts are smaller than those of the ortho substituted fluorophenols, although the total binding energies are predicted to be larger for the former. The observe...