Synthesis and Study of Non-Keukule Molecules

来自有机动力学项目的这笔赠款支持匹兹堡大学保罗·多德教授的继续工作。本研究旨在合成具有两个未键合电子的活性中间体。该项目将进一步表征这些双自由基的电子状态。人们对双自由基中间体很感兴趣，因为它们涉及到铁磁性和一些生物过程。多德博士的研究将在双自由基化学领域的理论和实验之间架起一座桥梁。在一个项目中，四亚甲基乙烷的电子结构将在一个刚性分子中进行实验探测。以前在柔性体系中的研究表明，这个双自由基是三重态，而分子轨道计算表明是单重态。在这里使用刚性系统将允许与分子轨道计算进行充分的比较。简单分子轨道理论预测非交替双自由基将是基态单重态，但这还没有得到验证。作为对这一理论的检验，这些双自由基将被产生，并用光谱方法和化学捕获方法进行研究。另外两个双自由基体系，半局部双自由基和亚甲基环丁酮双自由基，也将被制备和表征。由于双自由基是几个化学反应中的重要中间体，这项工作应该增加我们理解和预测反应过程的能力。

This grant from the Organic Dynamics Program supports the continuing work of Professor Paul Dowd at the University of Pittsburgh. The research is directed to the synthesis of reactive intermediates which possess two unbonded electrons. The project will further characterize the electronic state of these biradicals. There is an interest in biradical intermediates, since they are involved in ferromagnetism and some biological processes. Dr. Dowd's research will provide a bridge between theory and experiment in the area of biradical chemistry. In one project, the electronic structure of tetramethyleneethane will be probed experimentally in a rigid molecule. Previous studies in flexible systems have suggested that this biradical is a triplet, while molecular orbital calculations indicate a singlet. The use of a rigid system here will allow for an adequate comparison to the molecular orbital calculations. Simple molecular orbital theory predicts that non-alternant biradicals will be ground state singlets, yet this has not been tested. As a test of this theory, these biradicals will be generated and studied by spectrocopic methods and chemical trapping. Two other biradical systems, semilocalized biradicals and methylenecyclobutanone biradical, are to be prepared and characterized as well. Since biradicals are important intermediates in several chemical reactions, this work should add to our ability to understand and predict the course of reactions.