A Systematic Evaluation of the N-F Bond Strength of Electrophilic N-F Reagents: Hints for Atomic Fluorine Donating Ability

The recent discovery of the radical reactivity of a few traditionally-electrophilic N-F reagents has sparked a renaissance of radical fluorination. A knowledge of the N-F bond dissociation enthalpies (BDE) of electrophilic N-F reagents is essential for understanding of their reactivities. However, a thorough literature survey revealed that such information is extremely sparse. This prompted us to carry out the first systematic computation on the N-F BDEs of electrophilic N-F reagents. The calculated N-F BDE scale of 88 electrophilic N-F reagents ranges from 49.3 to 80.0 kcal mol(-1) in acetonitrile. The large variety of N-F reagents and wide span of N-F BDEs make the scale a useful tool not only for the future rational design of novel reagents but also for judicious selection of appropriate ones to explore new radical fluorinations.