Structural investigation of the protonation states of sulfamic acid

Herein, we report on the <i>O</i>-monoprotonated and double <i>O</i>-hemiprotonated species of sulfamic acid in the binary superacidic systems HF/L (L = BF₃, GeF₄, AsF₅, SbF₅). Within the structural studies, differences in the coordination behavior of the weakly coordinating anions MF₆^- (M = As, Sb) were determined. The colorless salts were characterized by low-temperature vibrational spectroscopy and single-crystal X-ray diffraction. The experimental data are discussed together with quantum chemical calculations in the solid state at the DFT-TZVP/PBE0-(D3) level of theory. Furthermore, the decomposition of sulfamic acid in basic milieu was investigated.