Bond activation by group-11 transition-metal cations

We have computationally explored C–X bond activation by the group-11 transition-metal cations Cu + , Ag + , and Au + , and, for comparison, Pd, using relativistic density functional theory (DFT) at ZORA-BLYP/TZ2P. Oxidative insertion of the second-row transition-metal species Ag + and Pd leads, for a given bond, to the highest overall reaction barriers. On the other hand, if we compare the different bonds oxidative insertion into the C–F bond is associated with (one of the) highest overall barriers whereas insertion into the C–Cl bond leads to the lowest overall barrier for any transition metal. The main trends in reactivity are rationalized using the activation strain model of chemical reactivity, which is an extension of the fragment approach to reaction profiles. In this model, the shape of the reaction profile ΔE(ζ) and the height of the overall reaction barrier ΔE ≠ = ΔE(ζ=ζ TS ) are interpreted in terms of the strain energy ΔE strain (ζ) associated with deforming the reactants along the reaction coordinate ζ plus the interaction energy ΔE int (ζ) between these deformed reactants: ΔE(ζ) = ΔE strain (ζ) + ΔE int (ζ).