Abstract
Systematic exploration of reaction paths based on quantum chemical calculations revealed the entire mechanism of Knowles’s light-promoted catalytic intramolecular hydroamination via radical processes. Bond formation/cleavage competes with single electron transfer (SET) from the catalyst/substrate to substrate/catalyst. All these processes were theoretically described by reactions through transition states in the same electronic state and non-radiative transitions through the seam of crossings (SX) between different electronic states. This study determined the energetically favorable reaction path by combining the reaction path searches and the SX geometry searches, and then discusses the entire reaction mechanism. Such a calculation was achieved by establishing a novel computational approach that represents SET as a non-adiabatic transition between substrate's PESs for different charge states adjusted based on the catalyst's redox potential. Finally, we uncovered the whole picture of the reaction process, in which N atom of the substrate is oxidized by photoredox catalyst via SET, the resulting aminium radical is added to alkene, and the hydroamination product is produced after SET process accompanying protonolysis with MeOH. The present calculations showed that the reduction and proton transfer proceed concertedly. Also, in the reduction process, there are SET paths leading to both the product and the reactant, and the redox potentials of the catalyst change the contribution of the SET path leading to the product.
Content

Supplementary materials

Supporting Information SI1-3
SI1. Computational details of the conformation search in S0
SI2. Computational details of the conformation search in D0
SI3. Eight initial structures used in the conformation search in D0cation.
Supporting Information SI4
SI4. List of the geometries optimized in D0cation. Cartesian coordinates are shown in Å, and the electronic energies are shown in a.u.
Supporting Information SI5
SI5. List of 71 D0/S0+281.0-SX geometries obtained using the ES/GP/SC-AFIR method. Cartesian coordinates are shown in Å, and the electronic energies are shown in a.u.
Supporting Information SI6
SI6. List of 445 D0/S0+281.0-SX geometries found by the conformation searches. Cartesian coordinates are shown in Å, and the electronic energies are shown in a.u.
Supporting Information SI7
SI7. List of the geometries shown in Figure 7. Cartesian coordinates are shown in Å, and the electronic energies are shown in a.u.
Supporting Information SI8
SI8. List of the geometries for shown in Figure 9. Cartesian coordinates are shown in Å, and the electronic energies are shown in a.u.