RUI-Antiaromaticity of Indenylidene Dications and the Aromaticity/Antiaromaticity Continuum

芳香性和反芳香性的概念在有机化学中起着核心作用。虽然有些难以捉摸的概念，但实验和计算工具的结合可以通过分析磁性、结构和能量标准来评估芳香性和反芳香性。单酰基指示可以通过五元环和六元环上质子的顺性来评估磁性，从而可以通过与核无关的化学位移值来评估抗芳香性。由于独立乙烯基阳离子的环戊二烯环可以通过变形对抗芳性的增加做出反应，因此可以评估其结构性质。可以通过电化学氧化和氧化还原电位与非抗芳模型体系的比较来评估其能量特性。通过对芳香族和反芳香族体系中各种标准的相互比较，将揭示出最有效地定义芳香族/反芳香族体系的标准。自从人们最初认识到苯和相关的“芳香族”碳氢化合物表现出异乎寻常的高稳定性以来，造成这种稳定性的因素就引起了极大的兴趣。“芳香性”及其对应的“反芳香性”在定义有机化学结构和反应性方面起着核心作用，其中化合物的稳定性低于预期。在有机和大分子化学项目的本科院校研究（RUI）资助下，三一大学化学系的Nancy S. Mills教授正在探索有望显示抗芳香性的新分子体系。通过合理设计和合成合适的有机分子，并分析其磁性、结构和能量特性，米尔斯教授正在定义最有效地定义芳香性和反芳香性的标准。大量的本科生研究助理将参与这些研究，为他们提供宝贵的研究经验和各种实验、仪器和理论技术的教育。

The concepts of aromaticity and antiaromaticity play central roles in organic chemistry. Although somewhat elusive concepts, a combination of experimental and calculational tools may be used to assess aromacity and antiaromaticity through analysis of magnetic, structural, and energetic criteria. Indenylidene dications allow the assessment of magnetic properties through the paratropicity of protons on both the five- and six-membered rings, allowing evaluation of the antiaromaticity suggested by the nucleus independent chemical shift values. Because the cyclopentadienyl ring of the indenylidene cation can respond to increased antiaromaticity through deformation, structural properties can be assessed. Energetic properties can be assessed by electrochemical oxidation and comparison of redox potentials with those of non-antiaromatic model systems. By playing the various criteria against each other in aromatic and antiaromatic systems, the criteria that most effectively define aromatic/antiaromatic systems will be exposed.Ever since the initial realization that benzene and related "aromatic" hydrocarbons display unusually high stability, the factors responsible for this stability have been of great interest. "Aromaticity" and its counterpoint, antiaromaticity, in which compounds display lower than anticipated stability, play central roles in defining organic chemical structure and reactivity. With the support of a Research at Undergraduate Institutions (RUI) grant from the Organic and Macromolecular Chemistry Program, Professor Nancy S. Mills, of the Department of Chemistry at Trinity University, is exploring new molecular systems expected to display antiaromaticity. Through the rational design and synthesis of appropriate organic molecules and analysis of their magnetic, structural, and energetic properties, Professor Mills is defining the criteria that most effectively define aromaticity and antiaromaticity. A large number of undergraduate research assistants will participate in these studies, providing them with valuable research experience and education in a variety of experimental, instrumental, and theoretical techniques.