REACTIVITY OF NEGATIVE-IONS WITH TRIFLUOROMETHYL HALIDES

The kinetics of reactions of selected anions (A(-)) with the trifluoro methyl halides CF(3)X (X = F, Cl, Br, I) in the gas phase were measure d at 300 K. Reaction rate constants and product branching fractions we re determined using a selected ion flow tube (SIFT) instrument. The ch osen anions were C5F5N-, o-, m-, and p-CF3C6H4CN-, C6F5Br-, C6F5Cl-, C 6F5CF3-, C6F5COCH3-, Fe-, FeCO-, SF6-, SO-, SO2-, NO-, NO2-, and NO3-. The reactivity of these systems varies from unreactive to collisional , and a variety of reaction types was found. The results of our presen t and previous measurements on A(-) + CF(3)X reactions show that, in c ases where nondissociative electron transfer (NDET) is energetically a llowed, the total reactivity tends to be high, approaching collisional . This suggests that reactivity in these cases is initiated and contro lled by electron transfer from the anion. In addition, association rea ctions tend to be preempted when NDET is energetically allowed. A few exceptions to these tendencies were found and are discussed.