Gas-Phase Reactions of ClONO2with Cl-(D2O)n=0-3and NO2-

The reactions of ClONO 2 with the Cl - (D 2 O) n ≤ 3 and NO 2 - ions were studied in a flow-tube apparatus at several temperatures in the range 170−298 K and at a helium buffer gas pressure of 0.28 Torr. Rate constants for these reactions were determined, establishing that all these ions react quite efficiently with ClONO 2 . The product ions observed in reaction sequences are reported, and reaction mechanisms are proposed to account for the findings. In the case of Cl - and NO 2 - the main product ion is NO 3 -, while the hydrates Cl - (D 2 O) n ≤ 1 - 3 lead to production of the hydrated species, NO 3 - (D 2 O) m ≤ n - 1 . The main features of the observed secondary reactions can be described in terms of adduct formation and ligand switching. Limits on the bond energy of (NO 3 ClNO 3 ) -, 14.6 kcal/mol ≤ D (NO 3 - −ClONO 2 ) ≤ 26 kcal/mol, were determined. Finally, implications of these studies to atmospheric chemistry are discussed.