The reaction of isotope-substituted hydrated iodide I(HO) with ozone: the reactive influence of the solvent water molecule

We report an investigation of the reaction of isotope-substituted hydrated iodide I(H 18 2 O) − with ozone 16 O 3 to examine the involvement of the water molecules in the oxidation reactions that terminate with the formation of IO 3 − . Experimentally, we studied the reaction in the gas phase as elementary reactions using a radio-frequency (RF) ion-trap combined with a quadrupole mass spectrometer (QMS). In approximately 1.2% of the reactions of I(H 18 2 O) − and 16 O 3 , the 18 O atom is found to appear in iodine oxide anions, thus giving evidence for a close involvement of the water molecule in a non-negligible number of the reactions towards IO 3 − . As a part of the experimental investigation, the reaction rate constant for the exchange reaction I(H 18 2 O) − + H 16 2 O → I(H 16 2 O) − + H 18 2 O at 300 K was found to be (1.3 ± 0.1) × 10 −8 cm 3 s −1 . Quantum chemical calculations are exploited to establish the energetic difference between I(H 18 2 O) − and I(H 16 2 O) − . We report an investigation of the reaction of isotope-substituted hydrated iodide I(H 18 2 O) − with ozone 16 O 3 to examine the involvement of the water molecules in the oxidation reactions that terminate with the formation of IO 3 − .