Ring current effects on nuclear magnetic shielding of carbon in the benzene molecule

The differential Biot–Savart law of classical electrodynamics was applied to develop a ring current model for the magnetic shielding of the carbon nucleus in benzene. It is shown that the local effect of the π currents, induced by a magnetic field normal to the molecular plane, on the $\sigma_{\|}^{\rm C}$ out‐of‐plane shielding tensor component vanishes. However, approximately 10% of $\sigma_{\|}^{\rm C}$ is due to the shielding contributions from π current density in the region of the other carbon atoms. Magnetic shielding density maps obtained via quantum mechanical procedures confirm the predictions of the classical model. Copyright © 2004 John Wiley & Sons, Ltd.