团中的芳香性经历了根本性的结构变化
Jordi Poater1,2, Clara Viñas3, Ines Bennour3
1Departament de Quı́mica Inorgànica i Orgànica & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain.
Journal of the American Chemical Society
|April 24, 2020
概括
像C2B10H12这样的碳酸的稳定性与碳原子的位置有关,而不是芳香度. 集中的芳香性在结构变化中持续存在,甚至在碳酸中.
科学领域:
- 无机化学
- 计算化学
- 材料科学
背景情况:
- 碳酸 (C2B10H12) 呈现同质性,甲碳酸 (m-C2B10H12) 由于后者更容易去氧化,因此比正碳酸 (o-C2B10H12) 稳定.
- 克洛索和碳因其芳香特性而闻名,这种特性通常与它们的稳定性有关.
- 传统观点将三明治金属与三明治金属等同,表明它们具有相似的电子和结构性质.
研究的目的:
- 研究碳酸异构体中脱难度,热力学稳定性和芳香度之间的关系.
- 探索集群中的芳香性持久性,包括碳酸,并与传统的芳香系统进行比较.
- 为了区分三明治金属和金属的芳香性特征.
主要方法:
- 涉及加热o-C2B10H12以诱导向m-C2B10H12和除的实验研究.
- 用密度函数理论 (DFT) 计算分析热力学稳定性和电子结构.
- 核磁共振 (NMR) 光谱 (1H和11B) 用于探测核碳酸中的电子电流和芳香度.
主要成果:
- m-C2B10H12的增强热力学稳定性归因于碳原子的特定排列,而不是芳香度的差异.
- 有证据表明,nido-carboranes中存在芳香性,这表明它对集群内的重大结构修改具有弹性.
- 金属体 (二化物) 具有全球芳香度,与三明治金属体的局部芳香度形成鲜明对比.
- 使用NMR光谱的热流在[C2B9H12]-中的实验证据证实了这些中的芳香性.
结论:
- 集群中的芳香性是一种坚固的特征,可以在结构性变化中存活下来,包括从closo过渡到nido框架.
- 碳酸的稳定性主要取决于原子的位置,而不仅仅取决于芳香度.
- 在金属和金属之间存在着明显的芳香度 (全球和本地).
- 支持集群的电子需求范式,解释了密闭物种和巢状物种的芳香性质.
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