Source:
Magnetic Resonance in Chemistry, John Wiley & Sons, Ltd., 31:916–919, 1993Abstract
Intermolecular effects are shown to induce a variation of about 5 ppm in the nitrogen NMR shieldings of aromatic nitro groups. The latter turn out to be comparable to those exerted by substituents in nitrobenzene derivatives in solutions in a given solvent. Substituent effects on the NO2 nitrogen shielding in nitro benzenes, in a given solvent, seem to reflect contributions from the so-called field-inductive effects on the electron charge distribution in such systems, and are insensitive to the resonance effects concerned with the delocalized pπ-electron systems involved.