Investigation of the electric quadrupole reaction field on nuclear magnetic resonance solvent shifts

Abstract

The ¹H and ¹³C nuclear magnetic resonance chemical shifts of a series of non-polar, substituted benzene solutes have been measured in 11 test solvents. The gas-to-infinite-dilution shifts were plotted against the dielectric function (6ε– 6)/(3ε+ 2) and were found to be linear. The reaction-field model, according to Buckingham, predicts the slopes to be proportional to the electric quadrupole moment of the solute molecules. However, the magnitude and direction of the observed slopes are not in accord with the quadrupole moments calculated from quantum theory.