Experimental and Theoretical Evidence for Nitrogen–Fluorine Halogen Bonding in Silver-Initiated Radical Fluorinations

We report experimental and computational evidence for nitrogen–fluorine halogen bonding in Ag(I)-initiated radical C–H fluorinations. Simple pyridines form [N–F–N]+ halogen bonds with Selectfluor to facilitate single-electron reduction by catalytic Ag(I). Pyridine electronics affect the extent of halogen bonding, leading to notable differences in selectivity between mono- and bis-fluorinated products. Electronic structure calculations show that halogen bonding to various pyridines alters the single-electron reduction potential of Selectfluor, which is consistent with experimental electrochemical analysis. Multinuclear correlation NMR also provides spectroscopic evidence for pyridine halogen bonding to Selectfluor under ambient conditions.