Protonation of Pyruvic Acid – Synthesis of a plain Superelectrophile

The syntheses of [H 3 C(O)CC(OH) 2 ][ M F 6 ] and [H 3 C(OH)CC(OH) 2 ][ M F 6 ] 2 ( M= As, Sb) by reacting pyruvic acid in the superacidic systems HF/AsF 5 and HF/SbF 5 are reported. The salts were characterized by low‐temperature vibrational spectroscopy and in the cases of [H 3 C(O)CC(OH) 2 ][SbF 6 ] and [H 3 C(OH)CC(OH) 2 ][SbF 6 ] 2  ⋅ HF by X‐ray crystal structure analyses. The experimental results are discussed together with quantum chemical calculations. Remarkably, the bond distance and the twisting angle around the central C−C bond are unaffected by the protonations despite increasing coulombic repulsion. The crystal structure reveals short interionic interactions that have a considerable influence on the C−C bond.