Theoretical Studies on Intramolecular C-H Amination of Biaryl Azides Catalyzed by Four Different Late Transition Metals

A systematic DFT study was performed to examine how catalysts with different metals influence the C-H amination mechanism of biaryl azides. The mechanisms of (cod)Ir(OMe), RuCl3(DME) (DME = CH3OCH2CH2OCH3, a solvent molecule), Rh-2(O2CCF3)(4), and ZnI2 were investigated in our study. The calculations indicated that the C-H amination reactions mainly proceeded through a stepwise mechanism regardless of the metal center (Ru, Ir, Rh, or Zn). The energetic span (delta E) model proposed by Shaik et al. has been applied to reveal the kinetic behavior of the four catalytic cycles. The results indicate that the ruthenium species exhibits a higher catalytic performance than the other three. The investigation of magnetic properties suggests that no matter what the metal center was-Ir, Ru, Rh, or Zn-the C-N bond formation step is pseudoelectrocyclization with an orbital disconnection on the nitrogen atom (N-1) in the pseudopericyclic transition structure.