The rate coefficients, k, for the reactions of N+ ions with the nonpolar molecule trans-1,2-C2H2Cl2 and the polar molecules 1,1-C2H2Cl2 and cis-1,2-C2H2Cl2 have been determined at 27, 68, and 163 K by using the CRESU technique and at 300 K by using the SIFT technique. Also, the SIFT technique has been used to determine the rate coefficients and ion product distributions at 300 K for the reactions of these molecules with H3+ ions. The measured rate coefficient for the N+ reaction involving the nonpolar isomer of C2H2Cl2 is temperature invariant and in close accord with the collisional rate coefficient, kc, calculated by using the Langevin theory. However, although the increase of the rate coefficients with a decrease in temperature for the two N+ reactions involving the polar molecules is consistent with the adiabatic capture centrifugal sudden approximation (ACCSA), the magnitudes of the rate coefficients are less than the kc predicted by that theory, a temperature-invariant reaction probability of ∼0.5 being indicated. An explanation for this low reaction probability is tentatively proposed. © 1988 American Chemical Society.
