Messersmith Reid E, Tovar John D
Department of Chemistry , Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States of America.
Department of Materials Science and Engineering , Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States of America.
J Phys Chem A. 2019 Jan 31;123(4):881-888. doi: 10.1021/acs.jpca.9b00125. Epub 2019 Jan 22.
The definition and measurement of local and global aromaticity in fused ring polycyclic aromatic compounds is a complex issue. Historically, these types of molecules have been explored in this capacity by way of experimental (NMR, thermochemistry) and computational (NICS, HOMA) analyses. We previously showed how borepin rings with [ b, f] arene fusions can be used as experimental magnetic aromaticity reporters via the remaining protons attached to the borepin rings. In this report, we describe a joint experimental and computational analysis of several borepin-containing polycyclic aromatic molecules in order to draw conclusions about the influence of ring fusion on aromaticity. We find that the borepin ring within these extended structures is a unique motif with limited σ-contribution to aromaticity while still displaying a wide range of structural and magnetic aromatic character.
稠环多环芳烃中局部和全局芳香性的定义与测量是一个复杂的问题。从历史上看，这类分子一直通过实验（核磁共振、热化学）和计算（核独立化学位移、HOMA）分析来进行这方面的探索。我们之前展示了具有[b, f]芳烃稠合的硼杂环庚三烯环如何通过连接在硼杂环庚三烯环上的剩余质子用作实验性磁芳香性报告分子。在本报告中，我们描述了对几种含硼杂环庚三烯的多环芳烃分子进行的联合实验和计算分析，以便得出关于环稠合对芳香性影响的结论。我们发现，这些扩展结构中的硼杂环庚三烯环是一种独特的结构单元，对芳香性的σ贡献有限，但仍表现出广泛的结构和磁芳香特征。
