Gas-Phase Studies of Charged Aromatic Radicals and Biradicals

有机和大分子化学项目通过这一更新奖支持印第安纳州西拉斐特普渡大学化学系的Hilkka I. Kenttamaa博士的工作。本工作的目的是在气相中生成芳香双自由基（1，n-芳烃），并研究它们在与原子供体、亲电试剂、亲核试剂和稳定自由基反应时的产物分支比和速率常数。每个双基携带一个化学惰性的带电取代基，使得它和它的反应产物可以被傅里叶变换离子回旋共振质谱（FT-ICR）研究。双基的结构特征是不同的，包括两个自由基的距离和方向、带电基团的类型以及是否存在额外的取代基。研究的反应性控制参数包括双自由基的单重态-三重态间隙和过渡态的极性。分子轨道计算将作为实验研究的补充。提出的研究是在质谱研究的前沿短寿命反应中间体。要获得的基本信息可能对使用自由基和双自由基进行合成的有机和有机金属化学家非常感兴趣。PI拥有大量本科生和研究生，其中约一半是女性或来自代表性不足的群体。对他们来说，这项研究有望提供宝贵的教育经验。

With this renewal award the Organic and Macromolecular Chemistry Program supports the work of Dr. Hilkka I. Kenttamaa of the Department of Chemistry at Purdue University in West Lafayette, Indiana. The purpose of this work is to generate aromatic biradicals (1,n-arynes) in the gas phase, and study their product branching ratios and rate constants in reactions with atom donors, electophiles, nucleophiles, and stable radicals. Each biradical carries a chemically inert charged substituent that allows it and its reaction products to be studied by Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR). Structural features of the biradicals will be varied, including the distance and orientation of the two radical sigma-orbital lobes, the type of charged group, and the presence of additional substituents. Reactivity-controlling parameters to be investigated include the biradicals' singlet-triplet gaps and the polarity of their transition states. Experimental studies will be complemented by molecular orbital calculations.The proposed research is at the frontiers of mass spectrometry in studies of short-lived reaction intermediates. The fundamental information to be obtained is likely to be of great interest to organic and organometallic chemists who use radicals and biradicals in synthesis. The PI has a large group of undergraduate and graduate students, about half of whom are female or from underrepresented groups. For them the research is expected to provide a valuable educational experience.