N-H versus C-H activation of a pyrrole imine at {Cp*Ir}: A computational and experimental study

Reaction of a pyrrole imine with [IrCl₂Cp*] ₂/NaOAc leads to N-H activation in preference to C - H activation at the pyrrole; however, with the N-methylated ligand C-H activation occurs. Density functional calculations show that N-H bond activation is both kinetically and thermodynamically preferred to C-H activation. Both reactions occur with relatively low energy barriers by an electrophilic agostic interaction with the metal with simultaneous intramolecular hydrogen bonding with acetate leading to deprotonation via a six-membered transition state.