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.