Bisulfate

Most evidence suggests that the proton in bisulfite ion is located on sulfur, giving rise to C_3v symmetry. There is, however, some evidence from ₁₇O NMR spectroscopy to suggest that two tautomeric forms of HSO₃ exist in dynamic equilibrium, one having C_3v symmetry (protonated at sulfur) and other C_s symmetry (protonated at oxygen). The C_3v structure is supported by X-ray crystallography and, in aqueous solution, by Raman spectroscopy (ν(S–H) = 2500 cm−1).