DETERMINATION OF THE H2O-NO2+ AND CH3O(H)-NO2+ BOND STRENGTHS AND THE PROTON AFFINITIES OF NITRIC-ACID AND METHYL NITRATE

The binding energies of water and methanol to NO2+ have been measured to be 14.8 +/- 2.3 and 19.2 +/- 2.3 kcal/mol, respectively, using energy-resolved collision-induced dissociation of H2O-NO2+ and CH3O(H)-NO2+ in a flowing afterglow triple quadrupole apparatus. These values are used with literature thermochemistry to derive proton affinities for nitric acid and methyl nitrate: PA(HONO2) = 177.7 +/- 2.3 kcal/mol and PA(CH3ONO2) = 175.0 +/- 2.5 kcal/mol. These results are in good agreement with recent calculations by Lee and Rice, but only the methyl nitrate result is in agreement with experimental results of Cacace and coworkers.