Mechanism Insights of Ethane C-H Bond Activations by Bare [FeⅢ=O]+:Explicit Electronic Structure Analysis
会议名称：《中国化学会第28届学术年会》
会议日期：2012年
学科分类：081704[工学-应用化学] 07[理学] 08[工学] 0817[工学-化学工程与技术] 070303[理学-有机化学] 0703[理学-化学]
关 键 词：density functional calculations reactivity iron oxo PCET FMO
摘 要：Alkane C-H bond activation by various catalysts and enzymes has attracted considerable attention recently but many issues are still *** conversion of ethane to ethanol and ethene by bare [FeIII=O]+ has been explored using density functional theory and coupled-cluster method *** possible reaction mechanisms are available for the entire reaction,the direct H abstract mechanism and the concerted ***,in the direct H abstract mechanism,a direct H abstraction is encountered in the initial step,going through a collinear transition state C H O-Fe and then leads to the generation of an intermediate Fe-OH bounded to alkyl radical *** final product of the direct H abstract mechanism is ethanol which is produced by the hydroxyl group back transfer to the carbon ***,in the concerted reaction mechanism,the H abstraction process is characterized via overcoming a four/five-centered transition states 6/4TSH5 or *** second step of the concerted mechanism can lead either to product ethanol or ***,the major product ethene can be obtained through two different pathways,the one step pathway and the stepwise *** is the first report that the former pathway starting from 6/4IM to product can be better described as a proton coupled electron transfer(PCET).It plays important role in the product ethene generation according to the CCSD(T)*** spin-orbital coupling(SOC)calculations demonstrate that the title reaction should proceed via two-state reactivity(TSR)pattern that the spin-forbidden transition could slightly lower the rate-determining energy barrier *** thorough theoretical study,especially the explicit electronic structure analysis,may provide important clues for understanding and studying the C-H bond activation promoted by iron-based artificial catalysts.