Semiempirical method for examining asynchronicity in metal–oxido-mediated C–H bond activation
Suman K. Barman, Meng-Yin Yang, Trenton H. Parsell, Michael T. Green, A. S. Borovik
Abstract
Significance There is considerable interest in understanding the role that asynchronicity plays in metal–oxido-mediated C–H bond activation. A semiempirical method is presented for gauging the relative importance of the free energies for proton transfer (PT) and electron transfer (ET) in determining the rate constants for C–H bond cleavage. The method deviates from traditional Bell–Evans–Polanyi analyses by examining the behavior of log ( k ) vs. a linear combination of PT and ET terms, rather than bond strengths. The appropriate combination of free energy terms is determined by the linearity of plots vs. log ( k ). We developed the approach by examining substrate oxidations by a Mn IV –oxido complex and applied it to data for other M–O(H) systems, indicating it has general applicability to other proton-coupled electron transfer (PCET) processes.