Phase-Space Theory of Chemical Kinetics. II. Ion—Molecule Reactions

The revised phase‐space (or statistical) theory of chemical kinetics has been used to compute cross sections for simple ion—molecule reactions. Reaction rates and isotope effects were investigated for bimolecular exchange reactions of the types $$\begin{array}{c}{\mathrm{X}}^{+}+\mathrm{HD}\to \begin{array}{cc}{\mathrm{X}}^{+}+\mathrm{HD}& \\ {\mathrm{XH}}^{+}+\mathrm{D},& (\mathrm{X\; is\; He},\mathrm{Ne},\mathrm{Ar},\mathrm{Kr})\\ {\mathrm{XD}}^{+}+\mathrm{H}& \end{array}\\ \mathrm{X}+{\mathrm{HD}}^{+}\to \begin{array}{c}\mathrm{X}+{\mathrm{HD}}^{+}\\ {\mathrm{XD}}^{+}+\mathrm{H}\\ {\mathrm{XH}}^{+}+\mathrm{D}.\end{array}\end{array}$$ Dissociative charge‐transfer reactions of rare‐gas ions with CO were also investigated. Reasonable agreement with experiment, with no adjustable parameters used in the calculations, indicates that the phase‐space theory has considerable predictive value in ab initio calculations of reactive cross sections for low‐energy ion—molecule reactions.