Theoretical Study on Iridacycle and Rhodacycle Formation via C–H Activation of Phenyl Imines

A computational study with the Becke3LYP DFT functional was carried out on the formation of iridacycles and rhodacycles through C–H activation of phenyl imines in methanol solvent. The whole catalytic pathway was proposed and verified, starting from the catalyst [Cp*MCl2]2 cleavage and ending with the cyclometalated complex. The five most important issues, namely, chloride dissociation and C–H activation precursor formation, aromatic C–H bond activation, the reaction rate difference between the Ir and Rh systems, the nature of regioselectivity, and the role of the protic solvent are discussed. The calculations indicate that the C–H bond activation by the transition metal iridium is kinetically and thermodynamically more favorable than that by rhodium, and the regioselectivity of the reaction has been determined both electronically and sterically.