Transient Exciplex Formation Electron Transfer Mechanism
Figure 2
Schematic plot of free energy along the reaction pathway (A* + D ⇄ A*⋯D (loose pair of reactants) ⇄ A-z D+z (transition state or exciplex) ⇄ A•-⋯D•+ (solvent separated ion pair) ⇄ A•- + D•+) blue line—for long-range mechanism ((2), eV, eV); and red line—for transient exciplex mechanism ( eV) for isoenergetic ET reaction () in butyronitrile ( eV). Experimental data on , , along the reaction coordinate: green squares—for 9-cyanoanthracene* + 1, 8-dimethylnaphthalene in MeCN ( eV); dark cyan rhombs—in PrCN ( eV); magenta triangles—for 9-cyanophenanthrene + 1, 2-dimethoxylbenzene in PrCN ( eV) [15]; black circles—for 1, 2, 4, 5-tetracyanobenzene* + durene in 1, 2-dichloroetane (according to the experimental data [27, 28], eV).