Su Ming-Der
School of Chemistry, Kaohsiung Medical University, Kaohsiung 80708, Taiwan, R.O.C.
J Am Chem Soc. 2002 Oct 16;124(41):12335-42. doi: 10.1021/ja020515l.
The potential energy surfaces for the abstraction reactions of silylenes with oxirane and thiirane have been characterized in detail using density functional theory (B3LYP) as well as the ab initio method (QCISD), including zero-point corrections. Five silylene species including SiH(2), Si(CH(3))(2), Si(NH(2))(2), Si(OH)(2), and SiF(2) have been chosen in this work as model reactants. All the interactions involve the initial formation of a donor-acceptor ylide-like complex followed by a heteroatom shift via a two-center transition state. The complexation energies, activation barriers, and enthalpies of the reactions were used comparatively to determine the relative silylenic reactivity, as well as the influence of substituents on the reaction potential energy surface. As a result, our theoretical investigations suggest that, irrespective of deoxygenation and desulfurization, the alkyl-substituted silylene abstractions are much more favorable than those of the pi donor-substituted silylenes. Moreover, for a given silylene, while both deoxygenation and desulfurization are facile processes, the deoxygenation reaction is more exothermic as well as more kinetically favorable. Furthermore, a configuration mixing model based on the work of Pross and Shaik is used to rationalize the computational results. The results obtained allow a number of predictions to be made.
利用密度泛函理论（B3LYP）以及从头算方法（QCISD），包括零点能校正，详细表征了硅烯与环氧乙烷和硫杂环丙烷的抽象反应势能面。在这项工作中，选择了包括SiH₂、Si(CH₃)₂、Si(NH₂)₂、Si(OH)₂和SiF₂在内的五种硅烯物种作为模型反应物。所有相互作用都涉及供体 - 受体类叶立德配合物的初始形成，随后通过双中心过渡态进行杂原子迁移。通过比较反应的络合能、活化能垒和焓来确定相对硅烯反应活性，以及取代基对反应势能面的影响。结果表明，我们的理论研究表明，无论脱氧和脱硫情况如何，烷基取代的硅烯抽象反应比π供体取代的硅烯抽象反应更有利。此外，对于给定的硅烯，虽然脱氧和脱硫都是容易进行的过程，但脱氧反应放热更多，动力学上也更有利。此外，基于Pross和Shaik的工作的构型混合模型用于合理解算结果。所得结果允许进行一些预测。
