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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Studies on the Trapping and Detrapping Transition States of Atomic Hydrogen in Octasilsesquioxane Using the Density Functional Theory B3LYP Method
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Studies on the Trapping and Detrapping Transition States of Atomic Hydrogen in Octasilsesquioxane Using the Density Functional Theory B3LYP Method

机译：密度泛函理论B3LYP方法研究八倍半硅氧烷中原子氢的俘获和俘获跃迁态。

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B3LyP level optimizations were performed on the structures of the octasilsesquioxane (SigO12Hg, HT g)double four-ring (D4R)cage and single hydrogen atom-trappedHTg (H@HTg). Moreover, the transition state inthe detrapping process of the hydrogen atom from the D4R cage was examined. The basis sets used were 6-31G** for ~T g and (3 1 1/1 * I*/I *) for the trapped hydrogen. atom. Both HT g and H@HTgwere structure-optimized with Oh molecular symmetry and the resulting cage conformations were similar. The trapped H atom was located at the center of the D4R cage. The weak interaction between the D4R cage and the trapped H atom in H@HTg was determined by examining the singly occupied molecular orbital (SOMO)[8a1g] ofl-I@HT8, TheSOMOwas constructed from an antibonding interaction between the lowest unoccupied molecular orbital' (LUMO) [8aJg] of HTg and the Is orbital of the trapped H atom. For the transition state, the structure was optimized with C4v molecular symmetry. As a result, the position of the Sigcube framework was unchanged, and four O atoms,in a ~ilicon single four-ring were displaced, thereby opening one of the oxygen windows of the D4R cage. Th~ detrapping H atom was located n~a,r the center of the oxygen window and the MO, illustrations showed a change in shape from spherical to ellipsoid. Consequently, it is clear that the detrapping process is not due to the formation of chemical bonding. The calculated activation and reaction energies of this detrapping process were +98.6 and -26.1 kJ/mo1.. respectively. In. addition, single-point calculations at the MP21evel were done for each optimized structure, and the obtained activation and reaction energies were + 128.7 and -9.3 kJ/mol, respectively. Both calculated activation energies were comparable to Stosser's expenmental data ( + 109.6 :!: 3.1 kJ/mol) for H.:SigO1iOSi(CH;3)3)g (QgMg). Furthermore, additional explanations are given on the IR vibrational frequencies ofHTg and H@HTg and the hyperfine coupling constant for caged atomic hydrogen by ESR.
机译：B3LyP水平优化是在八碳倍半硅氧烷（SigO12Hg，HT g）双四环（D4R）笼和单个氢原子捕获的HTg（H @ HTg）的结构上进行的。此外，还研究了氢原子从D4R笼中的去俘获过程中的过渡态。对于〜T g，使用的基本集是6-31G **，对于捕获的氢，使用的基本集是（3 1 1/1 * I * / I *）。原子。 HT g和H @ HTg均通过Oh分子对称性进行结构优化，所得笼构型相似。捕获的H原子位于D4R笼的中心。 D4R笼与H @ HTg中捕获的H原子之间的弱相互作用是通过检查1-I @ HT8的单占据分子轨道（SOMO）[8a1g]确定的。 HTg的（LUMO）[8aJg]和被捕获的H原子的Is轨道。对于过渡态，通过C4v分子对称性优化了结构。结果，Sigcube框架的位置未变，并且在一个硅单四环上置换了四个O原子，从而打开了D4R笼的氧窗口之一。脱氢的H原子位于氧窗口和MO的中心附近，插图显示从球形到椭圆形的形状变化。因此，很明显，脱陷过程不是由于化学键的形成。该脱阱过程的计算活化能和反应能分别为+98.6和-26.1 kJ / mo1..。在。此外，针对每个优化的结构在MP21evel上进行了单点计算，获得的活化能和反应能分别为+ 128.7和-9.3 kJ / mol。对于H.:SigO1iOSi(CH;3)3)g（QgMg），两种计算出的活化能均与Stosser的实验数据（+ 109.6：！：3.1 kJ / mol）相当。此外，通过ESR对HTg和H @ HTg的红外振动频率以及笼形原子氢的超精细耦合常数作了进一步的解释。

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