Radical Cage Effects in Organometallic Chemistry

无机，生物无机和有机化学计划的这个奖项支持俄勒冈州大学的大卫泰勒教授研究自由基反应化学中笼效应的基本原理。 仍然令人困惑的作用，溶剂将探索使用一个新的模型的基础上的“微粘度”的溶剂。 研究的另一部分将集中在光的波长对光生自由基笼对中的笼效应有什么影响。初步结果表明，与理论预测的趋势相反。 其他实验将探测自旋对两个金属自由基复合的影响，这一点到目前为止还没有得到系统的解决。 另一组实验将研究自由基质量、大小和形状对笼子效应的影响。 特别是，它提出的笼逃逸笼重组的速率常数的比率是成比例的质量除以自由基的表面积的平方根。 这个假设将用不同质量和大小的自由基来检验。如果这种关系是普遍的，它将为研究人员提供一个强大的工具来预测笼重组效率。飞秒时间尺度的激光泵浦探测实验将被用来直接观察短寿命的自由基笼对。 在这些实验中，笼效应的两个随机碰撞自由基将研究相对于笼效应的自由基笼对形成的键均裂。 由于前者自由基在笼中相遇时最初具有随机取向，而后者自由基最初是对齐的，因此这种差异可能表现为笼效应和笼对反应性的差异。 研究生将参加成功的实习项目，为博士学位做准备。通过将学生安排在地区公司或大学进行为期一个学期的实习，帮助他们在工业或教学领域取得成功。 本文所述的研究还以合作研究项目的形式与区域公司和学院建立了更密切的联系。 这导致了地区学院的教授在泰勒教授的实验室休假，以及这些学院和公司的学生使用俄勒冈州大学化学系的仪器。

This award in the Inorganic, Bioinorganic and Organometallic Chemistry program supports Professor David Tyler at the University of Oregon to investigate the fundamental, underlying principles of the cage effect in radical reaction chemistry. The still-confusing role of the solvent will be explored using a new model based on the "microviscosity" of the solvent. Another part of the research will focus on what effect the wavelength of light has on the cage effect in photogenerated radical cage pairs. Preliminary results show a trend opposite to that predicted by theory. Other experiments will probe spin effects on the recombination of two metal radicals, which has not been systematically addressed until now. Another set of experiments will examine the effects of radical mass, size, and shape on the cage effect. In particular, it is proposed that the ratio of the rate constants for cage escape to cage recombination is proportional to the square root of the mass divided by the surface area of the radical. This hypothesis will be tested with radicals of various masses and sizes. If this relationship is general, it will give researchers a powerful tool for predicting cage recombination efficiencies. Femtosecond timescale laser pump-probe experiments will be used to directly observe the shortlived radical cage pair. In these experiments, the cage effect for two randomly colliding radicals will be studied relative to the cage effect for a radical cage pair formed by bond homolysis. As former radicals initially have a random orientation when they meet in a cage, whereas the latter radicals are initially aligned, this difference may show up as a difference in the cage effect and in the reactivity of the cage pair. Graduate students will participate in successful internship programs, which prepare Ph.D. students for successful careers in industry or teaching by placing them in regional companies or in colleges for a one-term internship experience. The research described herein has also fostered closer ties to regional companies and colleges in the form of collaborative research projects. This has led to professors at regional colleges taking sabbatical leaves in the Professor Tyler's laboratory and to students at such colleges and companies using the instrumentation in the University of Oregon Department of Chemistry.