Meisenheimer's missing! Anionic σ‐complexes, best known as Meisenheimer complexes, have long been assumed to be intermediates in SNAr reactions. New evidence now suggests that these intermediates may only be formed in select cases and that a concerted pathway is more common. These claims are supported by 12C/13C kinetic isotopes effects, determined using a new method based on 19F NMR, and DFT calculations.
- concerted reactions
- density functional calculations
- kinetic isotope effect
- mechanistic studies
- nucleophilic aromatic substitution