Aromatic Solvent-induced Shifts (ASIS). II. Interpretation of Benzene and Hexafluorobenzene Induced Shifts by Means of the Electrostatic Interaction Model

The relationships between the ASIS in proton magnetic resonance and charge distribution in the solute and solvent molecules were studied. The results obtained are as follows. Protons lying in the positive charge-region of the solute dipole showed an up-field shift in C6H6 and a down-field shift in C6F6, while protons lying in the negative charge-region showed a down-field shift in C6H6 and an up-field shift in C6F6. There exists a linear relationship between the ASIS and the solute dipole moments of monosubstituted methanes, t-butyl derivatives, and para substituted toluenes. Shifts of para substituted toluenes and 4-methyl-4′-nitrobiphenyl are in good agreement with those expected from the electrostatic interaction model.