Hyperconjugation in diethylether cation versus diethylsulfide cation
Hyperconjugation in diethylether cation versus diethylsulfide cation
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二乙醚阳离子与二乙基硫醚阳离子的超共轭
DOI：
10.1039/c5cp03765d
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发表时间：
2015
影响因子：
3.3
通讯作者：
K. Takahashi
中科院分区：
文献类型：
--
作者：
M. Morita;Y. Matsuda;T. Endo;N. Mikami;A. Fujii;K. Takahashi
分子的电离能极大地改变其电子结构和几何结构。在这项合作的实验和理论研究中，我们研究了二乙醚（DEE）和二乙硫醚（DES）电离后超共轭的变化。我们获得了DEE、DES、DEE+、DES+、DEE+-Ar和DES+-Ar在2500 ~ 3600 cm−1波数区域的实验气相振动光谱。对于DEE+和DEE+-Ar，我们在2700 cm−1处观察到一个大大红移的CH伸缩峰，而DEE、DES、DES+和DES+-Ar的最低CH伸缩峰在2850 cm−1附近观察到。对于DEE+，我们计算出在2760 cm−1处的CH伸缩峰发生了剧烈的红移，但对于DEE、DES和DES+，最低的CH伸缩峰分别计算出在2860、2945和2908 cm−1处。此外，对于DEE，在中性状态下的最小（最大）几何形状变成在阳离子状态下的最大（最小）几何形状，而在DES的中性和阳离子状态下看到类似的最小几何形状。这些实验和理论结果是合理的，通过自然键轨道分析，量化的超共轭σCH轨道和电离的单占据的p轨道的氧（硫）在DEE+（DES+）。这项研究表明，电离轨道的取向如何极大地影响相邻CH键的强度和极性，以及系统的几何形状。此外，DEE+和DES+之间的CH键强度的这种变化是从两个阳离子的分子内质子转移的能量量化的。
Ionization of a molecule can greatly alter its electronic structure as well as its geometric structure. In this collaborative experimental and theoretical study, we examined variance in hyperconjugation upon ionization of diethyl ether (DEE) and diethyl sulfide (DES). We obtained the experimental gas phase vibrational spectra of DEE, DES, DEE+, DES+, DEE+–Ar, and DES+–Ar in the wavenumber region of 2500 to 3600 cm−1. For DEE+ and DEE+–Ar, we observed a greatly red shifted CH stretching peak at 2700 cm−1, while the lowest CH stretching peaks for DEE, DES, DES+ and DES+–Ar were observed around 2850 cm−1. For DEE+, we calculated a drastic red shifted CH stretching peak at 2760 cm−1, but for DEE, DES, and DES+ the lowest CH stretching peaks were calculated to be at 2860, 2945, and 2908 cm−1, respectively. In addition, for DEE, the minima (maxima) geometry in the neutral state becomes a maxima (minima) geometry in the cationic state, while similar minima geometries are seen in neutral and cationic states of DES. These experimental and theoretical findings were rationalized through the natural bond orbital analysis by quantifying the hyperconjugation between the σCH orbital and the ionized singly occupied p orbital of the oxygen (sulfur) in DEE+ (DES+). This study showed how orientation with the ionized orbital can greatly affect the neighboring CH bond strength and its polarity, as well as the geometry of the system. Furthermore, this change in the CH bond strength between DEE+ and DES+ is quantified from the energies for intramolecular proton transfer in the two cations.