Figure 11.

Schematic representation of the bonding interaction and the evolution of energy of the individual diabatic states and the global adiabatic state associated with the protonation of pyridine at (a) the N site, (b) C_meta, (c) C_para, and (d) C_ortho. Note that the profile associated with Φ_ion,2 is not depicted in this figure due to the significant energy gap between this profile and those associated with Φ_ion,1 and Φ_HL, respectively. Spin-pairing stabilization energies upon bond formation are depicted in italics in blue; resonance energies are shown in magenta. Weights of the individual structures in the adiabatic wave function at the optimal bonding distance are shown at the bottom of each panel.