Transition-state energy and position along the reaction coordinate in an extended activation strain model

We investigate palladium-induced activation of the C-H, C-C, C-F, and C-Cl bonds in methane, ethane, cyclopropane, fluoromethane, and chloromethane, using relativistic density functional theory (DFT) at ZORA-BLYP/TZ2P. Our purpose is to arrive at a qualitative understanding, based on accurate calculations, of the trends in activation barriers and transition state (TS) geometries (e.g. early or late along the reaction coordinate) in terms of the reactants' properties. To this end, we extend the activation strain model (in which the activation energy ΔE