TERMINAL CARBON-ATOMS AS REACTIVE SITES - TRENDS IN THE REACTIVITIES OF LINEAR C4HN-4), AND HNC3O+ (N=0-3) IONS(, HNC3N+ (N=0)

The reactions of the ions HnC3N+ (n = 0-4) and HnC3O+ (n = 0-3) with s everal molecules have recently been studied in a SIFT apparatus at 300 +/- 5 K. Here we compare the reactivities of these ions and the ions C4Hn+ (n = 0-4) (which have been studied independently by other groups ) with the neutrals H-2, CO, C2H2, and HCN. Several authors have previ ously commented that linear hydrocarbon ions containing two or more hy drogen atoms are much less reactive than ions with zero or one hydroge n; our results suggest that this trend applies to ions functionalized by-the heteroatoms nitrogen and oxygen as well as by hydrogen. These o bservations support and extend an existing model in which ions possess ing ''bare'' terminal carbon atoms are particularly reactive.