Protonation of γ-Butyrolactone and γ-Butyrolactam.

γ-Butyrolactone and γ-butyrolactam were reacted in the superacidic systems XF/MF (X=H, D; M=As, Sb). Salts of the monoprotonated species of γ-butyrolactone were obtained in terms of [(CH ) OCOH] [AsF ] , [(CH ) OCOH] [SbF ] and [(CH ) OCOD] [AsF ] and the analogous lactam salts in terms of [(CH ) NHCOH] [AsF ] , [(CH ) NHCOH] [SbF ] and [(CH ) NDCOD] [AsF ] . The salts were characterized by low temperature Raman and infrared spectroscopy and for both protonated hexafluoridoarsenates, [(CH ) OCOH] [AsF ] and [(CH ) NHCOH] [AsF ] , single-crystal X-ray structure analyses were conducted. In addition to the experimental results, quantum chemical calculations were performed on the B3LYP/aug-cc-pVTZ level of theory. As in both crystal structures C⋅⋅⋅F contacts were observed, the nature of these contacts is discussed with Mapped Electrostatic Potential as a rate of strength.