Protonation of N2O and NO2 in a solid phase

Abstract

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, NN–OH⁺, with a strongly acidic OH group involved in a rather strong H-bond with the anion, and (ii) a typical strong Lewis acid, NN⁺–OH, with a positive charge localized to the central N atom and ionic interactions with the surrounding anions via the charged central N atom.