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 rho dacycles 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.