Plots of proton magnetic shielding density in the benzene molecule, obtained via accurate coupled Hartree-Fock calculations, are reported. They unequivocally show that proton deshielding is due to local effects arising in the adjacent carbon atom and C--- H bond. Therefore downfield chemical shifts observed in proton magnetic resonance spectroscopy can be entirely explained in terms of magnetic anisotropy of the carbon environment. This shows the unphysical character of the ring current model and the reliability of Musher's model.
The validity of the Musher's model for the magnetic properties of aromatic molecules / Lazzeretti, Paolo; R., Zanasi. - In: CHEMICAL PHYSICS LETTERS. - ISSN 0009-2614. - STAMPA. - 100:(1983), pp. 67-69.