Ordering of electrophilic fluorinating reagents of the NF class

Abstract

The order of the fluorinating ability of NF reagents as assessed electrochemically is criticized. An alternative thermodynamic ordering, using calculated enthalpy couples [N(−I)/N(−III)] restricted to a closely related set of reagents, agrees with experimental observation. The cation's LUMO energy, rather than the localized electron density on nitrogen or fluorine, correlates with activity. A similar kinetic ordering would be expected if fluorination were controlled by NF bond breaking because the reduction couples are also a measure of NF bond dissociation energies.