Theoretical study on kinetic isotope effects in the C-H bond activation of alkanes by iron-oxo complexes

摘要

The C-H bond dissociation reactions of methane and ethane by the bare FeO~+ complex, diiron and dicopper models of methane monooxygenase, and a compound I model of cytochrome P450 are discussed using density functional theory (DFT) calculations, with an emphasis on their kinetic isotope effects (KIEs). These are possible three types of transition states for the C-H bond dissociation. The first is an oxene insertion mechanism, in which a C-H bond is dissociated and C-O and O-H bonds Are formed in a concerted manner via a three-centered transition state C…H…O-Fe which directly leads to a product alcohol.