RUI-Antiaromatic Hydrocarbon Dications and Hydrocarbon/Heterocylic Dianions: The Relationship between Delocalization and Antiaromaticity

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The Chemical Structure, Dynamics, and Mechanisms Program supports Professor Nancy S. Mills at Trinity University whose proposal describes the evaluation of the antiaromaticity of indenylidene dications through changes in the placement of substituents and changes in the manner in which the ring systems are linked together. The extension to indenyl systems has the potential to provide antiaromatic species with a broader range of antiaromaticity because the indenyl cation has been shown to be more antiaromatic than the fluorenyl cation. In addition, the local antiaromaticity of the 5-membered ring can be probed through 1H NMR shifts, and its inherent antiaromaticity varied through substitution on the 5-membered ring. These two approaches are not possible for the fluorenyl system whose central 5-membered ring possessed neither protons to be used as a probe nor the possibility of substitution. The opportunity to examine the effect of substituents on both 5-and 6-membered rings in the indenyl system, coupled with the potential for enhanced antiaromaticity of an indenyl system makes this an exciting system for examination. Extension of the investigations of antiaromatic hydrocarbon dianions to the dianion of di-and tribenzannulated heptafulvalene and to antiaromatic heterocyclic dianions is also proposed.With the support of the Chemical Structure, Dynamics, and Mechanisms Program in the Chemistry Division at the National Science Foundation, Dr. Mills' research will study aromaticity, a key concept in organic chemistry. This study will help to explain the stability of chemical compounds and guide the design of new molecules. Trinity University has an active undergraduate research program that emphasizes the early exposure of undergraduates to research. Students will be exposed to the theory that explains the key concepts of aromaticity and see how these are validated by experimental observations. In addition, the research will help support the activities of a research/teaching post-doctoral associate, patterned after the Dreyfus Scholar/Fellow program. Because Trinity University has a relatively large cohort of research /teaching post-doctoral fellows, currently four in chemistry, the department is able to implement a series of activities designed to prepare this group for successful academic careers at principally undergraduate institutions (PUIs).