New calculations on the ion-molecule processes C₂H⁺₂ + H₂ → C₂H⁺₃ + H and C₂H⁺₂ + H₂ → C₂H⁺₄

Abstract

New high-level quantum chemical calculations have been undertaken to understand the rates and mechanisms of the reactive and associative channels for the reactants C2H+2 + H2. The reactive channel, which produces C2H+3 + H, has been shown to be slightly endothermic, confirming earlier calculations at a somewhat lower level and in agreement with some recent experimental work. The associative channel, leading to C2H+4, has been shown to proceed via a transition state with negative energy relative to the reactants, so that association is predicted to be efficient. This result is in conflict with an earlier theoretical study but in agreement with low-temperature experimental measurements. © 1994.