Fig. 8. Computed pathway for diimine formation (M06/6-311G(d,p)/SMD, 25 °C, C6H5Br). All free energies are referenced to IM1 = 0.0 kcal mol−1. (a) Intrinsic bond orbitals (IBOs) showing [4 + 2] cycloaddition between NO π-bond (red) orbital of coordinated PhNO and π-backbone (green orbital) of IM3. (b) IBOs showing rearrangement of IM4 to IM5via retro-[4 + 2] cycloaddition.
