A catalytic cycle for C-H amination from an organoazide complex was analyzed using DFT to give insight into how geometric factors may influence enantioselectivity and the thermodynamic profile of the reaction. All intermediates and transition states were analyzed at the ONIOM(B3LYP/6-31+G(d):UFF) level of theory. From the calculations, the imide and amide intermediate structures were found to possess a T-shaped geometry about the nickel center. The imide to the amide transformation was exergonic and occurred through a H-atom abstraction transition state (TS), which favors the R-configuration, ΔG[CT1] [CL2] ^‡ = 21.3 kcal/mol. The transformation from the amide to the amine product is also exergonic and proceeds through a radical recombination TS to form the S-enantiomer, ΔΔG[CT3] [CL4] ^‡ ~ 2 kcal/mol. The final S-amine product is thermodynamically favored with a ΔG of -17.6 kcal/mol (relative to the initial iminyl structure). The greater stability of the S-enantiomer was attributed to reduced steric clashes with the bulky CPh₃ substituent. In further work, the transition from organoazide complexes to nitride intermediates is being analyzed using different 3d metals.

<b>Figure 1:</b> Catalytic cycle for C-H amination and transition state structures. a) Catalytic cycle for selective C-H amination of a N-heterocyclic amine. b) H-atom abstraction transition state structure. c) Radical recombination transition state structure. structures have hydrogen atoms and Ph<sub>3</sub> groups omitted for clarity with reactive portion of interest highlighted in red.

Figure 1: Catalytic cycle for C-H amination and transition state structures. a) Catalytic cycle for selective C-H amination of a N-heterocyclic amine. b) H-atom abstraction transition state structure. c) Radical recombination transition state structure. structures have hydrogen atoms and Ph₃ groups omitted for clarity with reactive portion of interest highlighted in red.

Yuyang Dong

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