Methane elimination, kinetic energy

In contrast to the results obtained for dehydrogenation reactions, kinetic energy release distributions for alkane elimination processes can usually be fit with phase space theory. Results for the loss of methane from reaction 9 of Co + with isobutane are shown in Figure 10b. In fitting the... 

The first-row transition metal monocations all react with methane some of the pathways found are illustrated in equations 32 -35. The relative importance of each depends on the kinetic energy of the metal ion. For example, goes mostly by equation 34 at low energies and by equation 32 at high energies. The mechanism suggested is oxidative addition followed by a elimination and reductive elimination of H2 at low... 

For platinum and methane on the other hand, the calculated spin-crossing point lies only 1.2 kcal mol above the reactant asymptote (Figure 3). A substantial fraction of collisions at 300 K have at least this much relative kinetic energy. This result is thus consistent with the fact that a reaction is observed experimentally for platinum and methane. It is believed that the final product of this reaction is the strongly bound, collisionally stabilized adduct H-Pt-CH3, which is bound by 32 kcal mol relative to reactants according to the calculations. The H2 elimination product is ruled out because it is endothermic by a calculated value of 7.2 kcal mol . Moreover, the very large a-elimination barrier, calculated at 31 kcal mol , surely prevents H2 elimination. 

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