溶液中的两个乙醇中的键对称性
1Department of Chemistry and Biochemistry , University of California-San Diego , La Jolla , California 92093-0358 , United States.
Journal of the American Chemical Society
|February 9, 2019
概括
研究人员使用同位素标记和NMR研究了结对称性. 一种乙醇表现出不对称的键,而胺乙醇在溶液中表现出罕见的对称结构.
科学领域:
- 化学学
- 物理化学
- 光谱学
背景情况:
- 键在分子结构和反应性中起着至关重要的作用.
- 了解键对称是阐明化学过程的关键.
- 同位素扰动是一种强大的探测分子对称性的技术.
研究的目的:
- 研究特定的化合物的键对称性.
- 确定这些乙醇是否存在于溶液中的对称或不对称结构中.
- 使用同位素标记和NMR光谱来区分分类型.
主要方法:
- 制备由4--2,2,6,6-四甲基-3,5-二和胺衍生的同位素 (18O n,n=0,1,2).
- 使用13CO核磁共振 (NMR) 光谱的电子对称性同位素扰动 (IPES) 的应用.
- 对NMR信号模式进行分析,以推断键对称性和分体组合.
主要成果:
- 4 - -2,2,6,6-四甲基-3,5-二的乙醇显示了四个CO NMR信号,表明由于内在和扰动同位素转移而具有不对称键的混合物.
- 尼托马洛纳米德的乙醇仅表现出两个CO NMR信号,这归因于固有的同位素转移.
- 这表明,在溶液中存在单一的对称结构,这是中性物种的罕见特征.
结论:
- 溶液中的4--2,2,6,6-四甲基-3,5-二以具有不对称键的复合体的混合物形式存在.
- 胺乙醇代表了第一个中性物种,与FHF-离子相比,表现出一种与溶液中集中的单一对称结构.
- 这项研究强调了同位素扰动NMR在溶液中分子细微结构特征的有用性.
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