Reactions of Dichloroacetyl Fluoride in Superacidic Media

Dichloroacetyl fluoride was investigated in the superacids HF/ M F 5 and DF/ M F 5 ( M =As, Sb). The O ‐hemiprotonated species of dichloroacetyl fluoride is formed in the binary superacidic systems HF/ M F 5 and DF/ M F 5 ( M =As, Sb) as hexafluoridoarsenates and hexafluoridoantimonates. With an excess of the strong Lewis acid SbF 5 dichloroacetyl fluoride reacts under the formation of the oxonium salt [CCl 2 HCF 2 O X 2 ][SbF 6 ] in the superacidic system X F/SbF 5 ( X =H, D) after HF‐ or DF‐addition, respectively. The colorless salts were characterized by low‐temperature vibrational spectroscopy, NMR spectroscopy, and single‐crystal X‐ray diffraction. [CCl 2 HC(OH)F][(CCl 2 HCOF) 2 H][SbF 6 ][Sb 2 F 11 ] and [CCl 2 HCF 2 OH 2 ][SbF 6 ] crystallize in the monoclinic space groups P 2 1 /c and P 2 1 /m, respectively, with two formula units per unit cell each. The crystal structure of the oxonium salt shows strong O(−H)⋅⋅⋅F hydrogen bonds and strong F⋅⋅⋅F interactions. The experimental data are discussed together with quantum chemical calculations at the ωB97XD/aug‐cc‐pVTZ‐level of theory.