GAS-PHASE ION-MOLECULE ASSOCIATION REACTIONS - STATISTICAL PHASE-SPACE THEORY APPROACH

A theoretical treatment of gas-phase ion-molecule association reactions is presented. The treatment is developed for the energy-transfer model AH+ + A ⇄* (A2H+)*; (A2H+)* + A → A2H+ + A. Explicit distribution functions for the activating reaction and for the steady-state distribution of (A2H+)* are presented. The phase space theory technique utilized rigorously conserves energy and angular momentum. Unimolecular reaction of (A2H+)* is shown to depend strongly on angular momentum. Detailed comparison between theory and experiment is made for A = NH3, CH3NH2, (CH3)2NH, and (CH3)3N over a wide range of temperature and pressure. The phase space theory results give semiquantitative agreement with experiment for all systems except possibly NH3. The mechanism of the reaction is discussed in detail. © 1979, American Chemical Society. All rights reserved.