气候变化领域集成服务门户(CCPortal): Semiempirical method for examining asynchronicity in metal-oxido-mediated C-H bond activation

CCPortal

DOI	10.1073/pnas.2108648118
	Semiempirical method for examining asynchronicity in metal-oxido-mediated C-H bond activation
	Barman S.K.; Yang M.-Y.; Parsell T.H.; Green M.T.; Borovik A.S.
发表日期	2021
ISSN	0027-8424
卷号	118 期号:36
英文摘要	The oxidation of substrates via the cleavage of thermodynamically strong C-H bonds is an essential part of mammalian metabolism. These reactions are predominantly carried out by enzymes that produce high-valent metal-oxido species, which are directly responsible for cleaving the C-H bonds. While much is known about the identity of these transient intermediates, the mechanistic factors that enable metal-oxido species to accomplish such difficult reactions are still incomplete. For synthetic metal-oxido species, C-H bond cleavage is often mechanistically described as synchronous, proton-coupled electron transfer (PCET). However, data have emerged that suggest that the basicity of the M-oxido unit is the key determinant in achieving enzymatic function, thus requiring alternative mechanisms whereby proton transfer (PT) has a more dominant role than electron transfer (ET). To bridge this knowledge gap, the reactivity of a monomeric MnIV-oxido complex with a series of external substrates was studied, resulting in a spread of over 104 in their second-order rate constants that tracked with the acidity of the C-H bonds. Mechanisms that included either synchronous PCET or rate-limiting PT, followed by ET, did not explain our results, which led to a proposed PCET mechanism with asynchronous transition states that are dominated by PT. To support this premise, we report a semiempirical free energy analysis that can predict the relative contributions of PT and ET for a given set of substrates. These findings underscore why the basicity of M-oxido units needs to be considered in C-H functionalization. © 2021 National Academy of Sciences. All rights reserved.
英文关键词	C-H bond activation; Metal-oxido complexes; PCET
语种	英语
scopus关键词	9,10 dihydroanthracene; anthracene derivative; carbon; cytochrome P450; fluorene; hydrogen; metal oxide; unclassified drug; xanthene; acidity; adsorption kinetics; Article; chemical bond; chemical structure; complex formation; concentration (parameter); electron transport; enzyme activity; oxidation; oxidation reduction potential; phase transition; proton coupled electron transfer; proton transport; thermodynamics
来源期刊	Proceedings of the National Academy of Sciences of the United States of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/238405
作者单位	Department of Chemistry, University of California, Irvine, CA 92697, United States; Department of Molecular Biosciences and Biochemistry, University of California, Irvine, CA 92697, United States
推荐引用方式 GB/T 7714	Barman S.K.,Yang M.-Y.,Parsell T.H.,et al. Semiempirical method for examining asynchronicity in metal-oxido-mediated C-H bond activation[J],2021,118(36).
APA	Barman S.K.,Yang M.-Y.,Parsell T.H.,Green M.T.,&Borovik A.S..(2021).Semiempirical method for examining asynchronicity in metal-oxido-mediated C-H bond activation.Proceedings of the National Academy of Sciences of the United States of America,118(36).
MLA	Barman S.K.,et al."Semiempirical method for examining asynchronicity in metal-oxido-mediated C-H bond activation".Proceedings of the National Academy of Sciences of the United States of America 118.36(2021).