Structures and properties of the mono- and diprotonated species of acetylenedicarbonyl fluoride

In this study, the first crystal structure of acetylenedicarbonyl fluoride is reported. Furthermore, the title compound was investigated in the superacidic media XF/SbF5 (X = H, D) which led to the formation of the monoprotonated species. Sur-prisingly, the diprotonated species was only formed by employing the monoprotonated species in 1,1,1,2-tetrafluoroethane whereas attempts at its synthesis in anhydrous hydrogen fluoride were unsuccessful. The vibrational spectroscopy is discussed together with quantum chemical calculations on the DFT/aug-cc-pVTZ level of theory. The stability of the Z-conformation of protonated acyl fluorides is calculated on the MP2/aug-cc-pVTZ level of theory.