How Different are the Diamagnetic and Paramagnetic Contributions to Off‐Nucleus Shielding in Aromatic and Antiaromatic Rings?

Abstract

including the URL of the record and the reason for the withdrawal request.ing, respectively, each ring and its surroundings. The different signs of the most popular aromaticity criterion, the nucleusindependent chemical shift (NICS), in C 6 H 6 and C 4 H 4 are shown to follow from a change in the balance between the respective diamagnetic and paramagnetic contributions. Thus, the different NICS values for antiaromatic and antiaromatic molecules cannot be attributed to differences in the ease of access to excited states only; differences in the electron density, which determines the overall bonding picture, also play an important role.