ISOMERIC FORMS OF THE PRODUCTS OF THE COLLISIONAL ASSOCIATIONS OF CH3+ WITH CH3OH AND H3O+ WITH C2H4

A selected ion flow tube has been used to study the reactions of C2H7O + generated by the collisional associations of CH3+ with CH3OH and H3O + with C2H4. Reactions with C2H5OCHO, (CH3)(2)CHOH, CH3CO2H, CH3C6H5, CH3CHO, H2CCCH2 (allene), CH3OH, c-C3H6, H2O, and C2H6 were studied to give information on the isomeric forms of the C2H7O+ ions. The data w ere compared with previous data on the reactivity of other isomeric fo rms, (CH3)(2)OH+ and C2H5OH2+, with the same reactant neutrals. The ra te coefficient data show a very strong correlation between the reactiv ities of (CH3)(2)OH+ and the associated ion CH3+/CH3OH and between C2H 5OH2+ and H3O+/C2H4, indicating that the associated ions are similar i n form to these strongly bonded species. This is consistent with concl usions based all potential energy surfaces calculated in the accompany ing paper. The agreement between the product ion distributions is not so conclusive. Generally, where proton transfer is exothermic for the strongly bonded species, it occurs rapidly for the associated ions. Wh ere this proton transfer is very endothermic, association occurs for t he associated ions as it does for the strongly bonded species. In inte rmediate cases, the associated ions show some additional products that are either endothermic for the strongly bonded species in their groun d vibrational state or that can be construed as Ligand switching, indi cating that the associated ions have access to the weak ligand bonded form. The conclusion is that the associated ions are higher energy for ms of protonated (CH3)(2)O and C2H5OH with access to the weak ligand b onded form. The data imply that the reactions of the two types of isom ers are controlled by an early barrier giving a set of rate coefficien ts that are independent of whether the isomer is the strongly bonded f orm or produced in the association reaction, but that the products are more controlled by the energy in the isomer and by the dominant struc tural conformation of that isomer.