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.