Changes in rate constants, equivalent to changes in Gibbs energies of activation ΔG^≠, are commonly referred to as kinetic effects and differentiated from thermodynamic effects (Δ_rG°). Often, little attention is paid to the fact that structural effects on ΔG^≠ are composed of a thermodynamic (Δ_rG°) and a truly kinetic (intrinsic) component (ΔG₀^≠), as expressed by the Marcus equation. Rate and equilibrium constants have been determined for a number of reactions of enamines with benzhydrylium ions (Aryl₂CH⁺), which has allowed the determination of Marcus intrinsic barriers and a differentiated analysis of structure–reactivity relationships. To our knowledge, this is the first report in which the Lewis basicity of a π_CC bond towards carbon‐centered Lewis acids (for example, carbenium ions) has quantitatively been determined. The synthesis, structures, and properties of deoxybenzoin‐derived enamines ArCH=C(Ph)NR₂, which have been designed as reference nucleophiles for the future quantification of electrophilic reactivities, are explicitly described.