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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Theoretical study on the ring-opening of 1,3-disilacyclobutane and H 2 elimination
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Theoretical study on the ring-opening of 1,3-disilacyclobutane and H 2 elimination

机译：1,3-二硅环丁烷开环与H 2消除的理论研究

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摘要

The kinetics and thermochemistry of the decomposition pathways for 1,3-disilacyclobutane (1,3-DSCB) in the gas phase were studied using the second-order M?ller-Plesset (MP2) perturbation theory and coupled cluster methods with single, double, and perturbative triple excitations (CCSD(T)). The reactions examined include 2 + 2 cycloreversion to form two silenes by either a concerted or a stepwise mechanism, 1,1-, 1,2-, and 1,3-H_2 elimination, and the ring-opening initiated by 1,2-H shift to form an open-chain 1,3-disilabut-1-ylidene, which undergoes further decomposition to produce two pairs of silene/silylene species. The structures of the transition states for the concerted and the stepwise 2 + 2 cycloreversion pathways are found to resemble closely those reported for the head-to-tail and head-to-head dimerization, respectively. Comparison of the activation barriers demonstrates unambiguously that the stepwise cycloreversion (ΔH_0~? = 66.1 kcal/mol) is favored over the concerted one (ΔH_0~? = 77.3 kcal/mol). A new pathway was established from the 1,4-diradical intermediate in the stepwise cycloreversion to form 1-silylmethylsilene via 1,3-H shift. The concerted 1,1-H_2 elimination is shown to have the lowest activation barrier of all H_2 elimination reactions. Overall, the 1,2-H shift in 1,3-DSCB with concerted ring-opening to form 1,3-disilabut-1-ylidene is the most kinetically and thermodynamically favorable decomposition pathway, both at 0 and 298 K.
机译：使用二阶M？ller-Plesset（MP2）扰动理论和单，双偶的耦合簇方法研究了气相中1,3-二硅环丁烷（1,3-DSCB）分解路径的动力学和热化学。 ，以及扰动三重激发（CCSD（T））。考察的反应包括通过协同或逐步机理进行的2 + 2环还原以形成两个硅烯，1,1-，1,2-和1,3-H_2消除，以及由1,2-引发的开环H移位以形成开链的1,3-二硅氢丁-1-亚烷基，然后进一步分解以生成两对硅烷/亚甲硅烷基。已发现一致的和逐步的2 + 2环还原途径的过渡态结构分别与报道的头对尾和头对头二聚化非常相似。活化势垒的比较清楚地表明，逐步的环还原（ΔH_0〜？= 66.1 kcal / mol）优于一致的环还原（ΔH_0〜？= 77.3 kcal / mol）。从逐步环还原中的1,4-二自由基中间体通过1,3-H转变形成1-甲硅烷基甲基硅烯建立了新的途径。在所有H_2消除反应中，一致的1,1-H_2消除具有最低的活化势垒。总体而言，在1,3-DSCB中发生1,2-H移位并同时开环，形成1,3-二硅氢丁-1-亚烷基是在动力学和热力学上最有利的分解途径，在0和298 K时均如此。

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