Is the H₂OCl⁺ Ion a Viable Intermediate for the Hydrolysis of ClONO₂ on Ice Surfaces?

The involvement of the H₂OCl⁺ ion in the ClONO₂ hydrolysis on an ice surface is shown to be unlikely via quantum chemical calculations and comparative analysis of infrared spectra of low temperature mixtures of H₂O with HNO₃, N₂O₅ or ClONO₂. For the ClONO₂ hydrolysis on ice, the reaction path involving H₂OCl⁺ is estimated to be ∼10-14 kcal/mol higher in energy than the one involving H₃O⁺ via proton transfer in the ice lattice. An analysis of literature infrared spectra, complemented by quantum chemical calculations of the vibrational frequencies of the relevant species, indicates that the spectral feature previously assigned to H₂OCl⁺ should instead be assigned to molecular HNO₃.