POSSIBLE INTRAMOLECULAR VAN DER WAALS CONTRIBUTIONS TO PROTON AND CARBON-13 SHIFTS IN ALIPHATIC AND AROMATIC HALOGEN COMPOUNDS

Abstract

The chemical shifts of protons and carbon-13 nuclei in aliphatic and aromatic halogen compounds are considered on the basis of inductive, magnetic anisotropy, and intramolecular dispersion effects. It is suggested that a model based on all three effects is more consistent with experiment than a model based on the first two effects only. The dispersion effects in general cause a low-field shift and seem to outweigh magnetic anisotropy effects in some cases.