Protonation of N 2 O and NO 2 in a solid phase

Adsorption of gaseous N2O on the acidic surface Brønsted centers of the strongest known solid acid, H(CHB11F11), results in formation of the N≡N-OH+ cation. Its positive charge is localized mainly to the H-atom, which is H-bonded to the CHB11F11- anion forming an asymmetric proton disolvate of the L1-H+L2 type, where L1 = N2O and L2 = CHB11F11-. NO2 protonation under the same conditions leads to the formation of the highly reactive cation radical NO2H˙+, which reacts rapidly with an NO2 molecule according to the equation N2OH+ + NO2 → [N2O4H+] → N2OH+ + O2 resulting in the formation of two types of N2OH+ cations: (i) a typical Brønsted superacid, N[triple bond, length as m-dash]N-OH+, with a strongly acidic OH group involved in a rather strong H-bond with the anion, and (ii) a typical strong Lewis acid, N[triple bond, length as m-dash]N+-OH, with a positive charge localized to the central N atom and ionic interactions with the surrounding anions via the charged central N atom.