Tunneling kinetic isotope effects in the activation of H-H, C-H, and C-C bonds

Tunneling kinetic isotope effects in reactions of oxidative addition of H-2, D-2, CH4, CD4, C2H6, and C2D6 to the Pd atom were considered. The reaction mechanisms were analyzed using the approximation of the Hamiltonian of the reaction path. Thermal rate constants were calculated in terms of the transition state theory with account for tunneling in the quasiclassical approximation. The tunneling rate constants of the C-H bond activation were shown to be close to the activation constants at T approximate to 280 K, and tunneling rate constants of the C-D and C-C bond activation are close to activation constants at T approximate to 200 K.