IR spectrum of the ethyl cation:: Evidence for the nonclassical structure
IR spectrum of the ethyl cation:: Evidence for the nonclassical structure
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DOI：
10.1002/anie.200704163
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发表时间：
2008-01-01
影响因子：
16.6
通讯作者：
Dopfer, Otto
中科院分区：
文献类型：
--
作者：
Andrei, Horia-Sorin;Solca, Nicola;Dopfer, Otto
乙基阳离子（C2H5+）是碳氢化合物化学中的基本碳阳离子。它是由烯烃家族中最小的成员乙烯的质子化作用产生的。C2H5+是一种普遍存在于地球和地外碳氢化合物等离子体[1]和许多碳氢化合物分子质谱中的离子。[2,3]此外，C2H5+是化学电离质谱中常用的质子化剂。从理论角度来看，C2H5+是一个基准离子，因为它的非经典结构1和经典结构2（图1）的能量被预测接近。尽管大量的理论和实验研究与非经典平衡结构一致，但仍缺乏令人信服的实验证实。本文报告了C2H5+的红外光谱，这提供了第一个明确的实验证据，证明1确实是这个基本碳正离子中最稳定的结构。
The ethyl cation (C2H5+) is a fundamental carbocation in hydrocarbon chemistry. It results from protonation of ethene, the smallest member of the alkene family. C2H5+ is a ubiquitous ion in terrestrial and extraterrestrial hydrocarbon plasmas [1] and mass spectra of many hydrocarbon molecules.[2, 3] In addition, C2H5+ is a popular protonating agent in chemical-ionization mass spectrometry. From a theoretical viewpoint, C2H5+ is a benchmark ion, because its nonclassical and classical structures, 1 and 2 (Figure 1), are predicted to be close in energy. Although a plethora of theoretical and experimental studies are consistent with a nonclassical equilibrium structure, convincing experimental confirmation is still lacking. Herein we report the IR spectrum of C2H5+, which provides the first clear experimental evidence that 1 is indeed the most stable structure of this fundamental carbocation.