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首页> 外文会议>American Chemical Society National Meeting >Kinetic and Equilibrium Deuterium Isotope Effects for C-H Bond Reductive Elimination and Oxidative Addition Reactions Involving the Ansa-Tungstenocene Methyl-Hydride Complex Me_2Si(C_5Me_4)_2W(Me)H
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Kinetic and Equilibrium Deuterium Isotope Effects for C-H Bond Reductive Elimination and Oxidative Addition Reactions Involving the Ansa-Tungstenocene Methyl-Hydride Complex Me_2Si(C_5Me_4)_2W(Me)H

机译：动力学和均衡氘同位素对C-H键的减少消除和氧化添加反应涉及Ansa-钨烯甲基 - 氢化物复合物ME_2SI（C_5ME_4）_2 W（ME）H.

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The reductive elimination of methane from [Me_2Si(C_3Me_4)_2]W(CH_3)H and [Me_2Si(C_5Me_4)_2]W(CD_3)D is characterized by an inverse kinetic isotope effect (KIE). A kinetics analysis of the interconversion of [Me_2Si(CsMe4)_2]-W(CH_3)D and [Me_2Si(C_5Me_4)_2]W(CH_2D)H) accompanied by elimination of methane, provides evidence that the reductive coupling step in this system is characterized by a normal KIE and that the inverse KIE for overall reductive elimination is a result of an inverse equilibrium isotope effect (EIE), rather than being a result of an inverse KIE for a single step. Calculations on [H_2Si(C_5H_4)_2]W(Me)H support these results and further demonstrate that the interconversion between [H_2Si(C_5H_4)_2]W(Me)H and the c-complex [H_2Si(C_5H_4)_2]-W(o-HMe) is characterized by normal kinetic isotope effects for both reductive coupling and oxidative cleavage. Interestingly, the temperature dependencies of EIEs for coordination and oxidative addition of methane to the tungstenocene fragment {[H_2Si(C_5H_4)_2]W} are calculated to be very different, with the EIE for coordination approaching zero at OK, while the EIE for oxidative addition approaches infinity.
机译：通过[ME_2SI（C_3ME_4）H和[ME_2SI（C_5ME_4）_2] W（CD_3）D的还原消除甲烷来自逆动力学同位素效应（KIE）的特征。 [ME_2SI（CSME4）_2] -W（CH_3）D和[ME_2SI（C_5ME_4）H）的相互互连的动力学分析伴随着消除甲烷，提供了证据表明该系统中的还原耦合步骤以正常的kie为特征，并且对整体还原消除的逆kie是逆平衡同位素效应（eie）的结果，而不是作为单一步骤的逆kie的结果。 [H_2SI（C_5H_4）_2] W（ME）H支持这些结果，并进一步证明[H_2SI（C_5H_4）_2] W（ME）H和C复杂[H_2SI（C_5H_4）_2] -W之间的相互互连（O-HME）的特征在于既具有正常动力学同位素效应，用于还原偶联和氧化切割。有趣的是，计算到钨烯片段的eie的温度依赖性和氧化氧化丙烷片段（[H_2SI（C_2SI（C_5H_4）_2] W}非常不同，EIE用于在OK处接近零的协调，而EIE用于氧化加法接近无限。

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