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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Gas Phase Structures and Conformational Properties of 1-Silabutane and 2-Silabutane
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Gas Phase Structures and Conformational Properties of 1-Silabutane and 2-Silabutane

机译：1-Silabutane和2-Silabutane的气相结构和构象性质

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摘要

The molecular structures of 1-silabutane 1 and 2-silabutane 2 have been determined by gas electron diffraction (GED). The conformational equilibrium of 1 and 2 was studied experimentally in the gas phase (GED) and by quantum chemical (QC) calculations (HF with 6-31G* basis sets, MP2 with 6-31G* and cc-pVTZ basis sets, and B3LYP with 6-311G* basis sets). The potential function for internal rotation around the central C-C bond in 1 resembles that for n-butane, whereas the rotation around the Si-C bond in 2 has much lower energy barriers. The experimental relative enthalpies ΔH°(gauche-anti) are 0.76(10) and 0.14(18) kcal mol~(-1) for 1 and 2, respectively. The enthalpy difference for 2 is reproduced within the experimental uncertainties by all four QC methods. Only the MP2 method with a large basis set reproduces the enthalpy difference for 1 correctly. Taking the different multiplicities of anti and gauche conformers into account, the conformational composition of 1 was found to be 65(5)% anti and 35(5)% gauche. The conformational composition of 2 was found to be 43(9)% anti and 57(9)% gauche.
机译：1-silabutane 1和2-silabutane 2的分子结构已通过气体电子衍射（GED）确定。在气相（GED）中并通过量子化学（QC）计算（HF具有6-31G *基组，MP2具有6-31G *和cc-pVTZ基组以及B3LYP）对1和2的构象平衡进行了实验研究6-311G *基本集）。 1中围绕中心C-C键的内部旋转的势函数类似于正丁烷，而2中围绕Si-C键的内部旋转的势垒要低得多。 1和2的实验相对焓ΔH°（gauche-anti）分别为0.76（10）和0.14（18）kcal mol〜（-1）。通过所有四个QC方法在实验不确定性范围内再现了2的焓差。只有具有较大基础集的MP2方法才能正确再现1的焓差。考虑到anti和gauche构象异构体的多样性，发现1的构象组成是65（5）％anti和35（5）％gauche。发现2的构象组成是43（9）％抗和57（9）％薄纱。

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