解开N-异环碳化合物和循环 (基) ((氨基) 碳化合物稳定低主群物种之间的显著电结构差异
Eileen Welz1, Julian Böhnke2,3, Rian D Dewhurst2,3
1Institute for Physical and Theoretical Chemistry , Julius-Maximilians-Universität Würzburg , Am Hubland , 97074 Würzburg , Germany.
Journal of the American Chemical Society
|September 6, 2018
概括
循环 (基) 氨基) 碳化合物 (CAAC) 和N-异环碳化合物 (NHC) 在稳定性方面因单环三环间隙而不同,而不仅仅是硬质或电子效应. 分子轨道的考量揭示了这些差距是理解它们独特行为的关键.
科学领域:
- 有机金属化学
- 连接物设计
- 理论化学
背景情况:
- 循环 (基) 氨基) 碳酸 (CAAC) 和N-异环碳酸 (NHC) 是化学中的关键配体.
- 现有的解释对它们的不同属性是不完整的,缺乏明确的分辨体和电子影响.
研究的目的:
- 解开影响CAAC和NHC属性的硬体和电子效应.
- 为了研究独特的化合物 (E) ((L) BB ((L) ((E)),其中L是NHC (I) 或CAAC (II),E是SPh.
- 提供NHC和CAAC捐赠者之间的差异的准确理解.
主要方法:
- 利用分子轨道 (MO) 考量分析研究化合物的电子结构.
- 基于NHC和CAAC的系统的性能进行了比较,并注意到基态 (单元与三元) 和分子几何 (平面与扭曲) 的差异.
主要成果:
- 单元-三元 (S-T) 差距的大小被确定为NHC和CAAC系统之间的差异的主要决定因素.
- S-T 间隙的变化源于最高占有 (HOMOs) 和最低无占有分子轨道 (LUMOs) 的不同抗键效应.
- 这项研究的结果挑战了这些碳化合物的HOMO和LUMO变异的一般科学共识.
结论:
- 单体-三体间隙对于理解CAAC和NHC连接体行为是一个比以前更重要的因素.
- 这种方法通过与Kekulé biradicaloids进行比较来验证,这表明其适用性更广泛.
- 这项工作提供了对循环碳化合物结构影响的联体设计和化学反应的精细视角.
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