Silicon 伪-Effect: A Systematic Experimental and Computational Study of the Hydrolysis of C伪- and C纬-Functionalized Alkoxytriorganylsilanes of the Formula Type ROSiMe2(

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• 作者：Andr茅 Berkefeld ; C茅lia Fonseca Guerra ; R眉diger Bertermann ; Dennis Troegel ; J眉rgen O. Dai脽 ; J眉rgen Stohrer ; F. Matthias Bickelhaupt ; Reinhold Tacke
• 刊名：Organometallics
• 出版年：2014
• 出版时间：June 9, 2014
• 年：2014
• 卷：33
• 期：11
• 页码：2721-2737
• 全文大小：720K
• 年卷期：v.33,no.11(June 9, 2014)
• ISSN：1520-6041

文摘

To understand the silicon 伪-effect in terms of an enhanced reactivity of the Si鈥揙C bond of 伪-silanes of the formula type ROSiMe₂CH₂X compared to analogous 纬-silanes ROSiMe₂(CH₂)₃X (R = Me, Et; X = functional group), a systematic experimental and computational study of the kinetics and mechanisms of hydrolysis of such compounds was performed. For this purpose, a series of suitable model compounds was synthesized and studied for their hydrolysis kinetics in CD₃CN/D₂O under basic and acidic conditions, using ¹H NMR spectroscopy as the analytical tool. To get more information about the reaction mechanisms, the experimental investigations were complemented by computational studies. These investigations demonstrated that the silicon 伪-effect cannot be rationalized in terms of a special single effect. The reactivities observed rather result from a summation of different components, such as electronic and steric effects, pD dependence, and hydrogen bonds between the functional group (or even protonated functional group) and the alkoxy leaving group. Therefore, the term 鈥渟ilicon 伪-effect鈥?should not be used furthermore to explain the hydrolysis reactivity at the silicon atom of alkoxyorganylsilanes with functional groups in 伪- or 纬-position of the organyl groups (so-called 伪- or 纬-silanes).