Arene C–H Functionalization by p-Block Metal Tl(III) Occurs at the Borderline of C–H Activation and Electron Transfer

详细信息    查看全文

• 作者：Clinton R. King ; Samantha J. Gustafson ; Benjamin R. Black ; Steven K. Butler ; Michael M. Konnick ; Roy A. Periana ; Brian M. Hashiguchi ; Daniel H. Ess
• 刊名：Organometallics
• 出版年：2017
• 出版时间：January 9, 2017
• 年：2017
• 卷：36
• 期：1
• 页码：109-113
• 全文大小：350K
• ISSN：1520-6041

文摘

M06 density functional theory calculations reveal that arene C–H functionalization by the p-block main-group-metal complex Tl^III(TFA)₃ (TFA = trifluoroacetate) occurs by a C–H activation mechanism akin to transition-metal-mediated C–H activation. For benzene, toluene, and xylenes a one-step C–H activation is preferred over electron transfer or proton-coupled electron transfer. The proposed C–H activation mechanism is consistent with calculation and comparison to experiment, of arene thallation rates, regioselectivity, and H/D kinetic isotope effects. For tetramethyl- and pentamethyl-substituted arenes, electron transfer becomes a competitive pathway and thermodynamic and kinetic calculations correctly predict the experimentally reported electron transfer crossover region. These calculations show that p-block metals activate strong hydrocarbon C–H bonds through organometallic intermediates and changes in arene functional groups can result in a shift from C–H activation to electron transfer.