Molecular Geometry as a Source of Chemical Information. 5. Substituent Effect on Proton Transfer in Para-Substituted Phenol Complexes with Fluoridea B3LYP/6-311+G Study

The simplified model system [p-X−PhO···H···F]-, where −X are −NO, −NO2, −CHO, −H, −CH3, −OCH3, and −OH, with various O···F distance was used to simulate the wide range of the H-bond strength. Structural changes due to variation of the substituent as well as the H-bond strength are well monitored by the changes in the aromaticity index HOMA and by two empirical measures of the H-bond strengththe 1H NMR chemical shift of proton involved and the C−O bond length. Changes in H-bonding strengths and the position of proton transfer while shortening the O···F distance are well described by the Hammett equation.