Cover Feature: Strengthening of the C-F Bond in Fumaryl Fluoride with Superacids (Chem. Eur. J. 15/2022) Fluorides, quantum chemical calculations, R effect, superacids, vibrational spectroscopy, X-ray structure analyses Keywords: fluorides; quantum chemical calculations; R effect; superacids; vibrational spectroscopy; X-ray structure analyses EN fluorides quantum chemical calculations R effect superacids vibrational spectroscopy X-ray structure analyses 1 1 1 03/14/22 20220310 NES 220310 B The C-F bond of fumaryl fluoride b is strengthened by protonation of the oxygen atom in a sea of superacid.