用三甲基衍生物探测保利排斥和伦敦分散之间的微妙平衡
Sören Rösel1, Jonathan Becker2, Wesley D Allen
1Institute of Organic Chemistry , Justus Liebig University , Heinrich-Buff-Ring 17 , 35392 Giessen , Germany.
Journal of the American Chemical Society
|October 6, 2018
概括
伦敦分散相互作用显著稳定了六乙烯 (HPE) 衍生物. 像阿达曼提尔这样的大型,刚性碳化合物组通过有利的几何适配和强大的分子内分散力来增强HPE的稳定性,即使在溶液中.
科学领域:
- 物理有机化学
- 超分子化学
- 计算化学
背景情况:
- 伦敦分散 (LD) 相互作用是化学中基本的,无处不在的力量.
- 六乙烯 (HPE) 衍生物因其固有的不稳定性而闻名.
- 了解HPE稳定性的因素对于分子设计至关重要.
研究的目的:
- 研究伦敦分散相互作用在稳定六乙烯衍生物中的作用.
- 合成和描述全甲基基替代三甲基 (TPM) 的新型衍生物.
- 量化不同替代剂对HPE稳定性的稳定作用.
主要方法:
- 一系列全甲基碳化合物替代TPM衍生物的合成.
- 单晶X射线衍射 (SC-XRD) 用于结构特征.
- 核磁共振 (NMR),电子磁共振 (EPR) 和紫外线光谱.
- 温度依赖解离常数分析和计算建模 (B3LYP-D3 ((BJ) /def2-TZVPP ((C-PCM)).
主要成果:
- 在二元HPE结构中,SC-XRD发现了超替代物之间的优秀几何匹配,特别是对于特-丁和阿达曼等体积较大的组.
- 谱学数据表明全元基替代对三基支架的边缘电子效应.
- 热力学分析给出了全甲基三乙烯 (0.3(5) 千卡mol-1和全甲基亚达曼乙烯 (2.1(6) 千卡mol-1的实验分离自由能量 (ΔGd298).
- 计算研究证实了实验结果,显示了随着替代物大小的增加而稳定的趋势.
结论:
- 伦敦分散相互作用是六乙烯衍生物的主要稳定因素.
- 大,刚性和对称的碳化合物部分是有效的分散能量捐赠者.
- 最佳的几何适配使这些分子能够通过强烈的分子内 LD 相互作用稳定 HPE,甚至在溶液中持续存在.
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