Mechanistic Probes in Main Group Chemistry Employing Highly Reactive Species Containing Electron-Deficient Atoms

化学结构、动力学和机制计划(CSDM)支持圣路易斯华盛顿大学的彼得·加斯帕教授在研究较重元素中的共价键时使用物理有机化学概念。现代有机合成和材料化学被用来研究在元素周期表第一行以下含有主族元素的分子。无论是获得天然产品、电子材料、药物输送系统的新的立体选择路线，还是生物启发的硅基材料纳米制造--这些努力的成功取决于主基团机械性化学的演变，通过理解更重元素的键的形成和断裂。这项拟议的研究协同结合了离子化学的质谱学解释、化学反应的气相和溶液相研究以及计算模型。其策略是研究缺电子和多键物种的重元素类似物，其结构和反应活性可以用有机化学的机理思想很好地描述。母体物种，如卡宾和硝烯，以一种独特的方式反应，机械变化很容易在它们较重的类似物中识别出来。这些观察到的变化不仅将拓宽我们的机理思想，而且还将导致新的合成有用试剂的发现。在将要研究的物种中，有一类极端缺乏电子的离子和分子，它们的外壳中只有四个电子。这些化合物有可能参与同时形成三个新键的反应，这一过程以前从未观察到，也很少有人提出。它们代表了周环反应的三维延伸，具有相当大的合成兴趣。这项工作的更广泛影响包括发现基本原理的前景，这些基本原理将有助于我们更好地了解共价键及其在整个元素周期表中的形成和反应活性，并利用这些知识来发现有用的新化学物质，并制造新分子。对于接受这个项目培训的同事来说，他们的经历提供了不同的背景，鼓励他们培养多才多艺和自信，为他们解决广泛的问题和开始多样化的职业生涯做好准备。在加斯帕的整个职业生涯中，他参与了研究生、本科生、博士后和高中各级代表性不足群体的培训。这些人包括荣获罗兹学者、辉瑞夏季研究员以及NSF和NIH研究生奖学金获得者的本科生。加斯帕集团的研究生在竞争博士后奖学金方面取得了相当大的成功，博士后在工业、研究机构和学术界获得了出色的任命。

The Chemical Structure, Dynamics and Mechanism Program (CSDM) supports Professor Peter Gaspar of Washington University in Saint Louis to use physical organic chemistry concepts in the study of covalent bonds in the heavier elements. Modern organic synthesis and materials chemistry are used to study molecules incorporating main group elements below the first row of the periodic table. Whether it is new stereoselective routes to natural products, electronic materials, drug delivery systems, or bio-inspired nanofabrication of silicon-based materials - success in these endeavors depends on the evolution of main-group mechanistic chemistry through the understanding of the making and breaking of bonds to heavier elements. The proposed research synergistically combines mass spectrometric elucidation of ion chemistry, gas- and solution-phase study of chemical reactivity, and computational modeling. The strategy is to study heavier-element analogs of electron-deficient and multiply bonded species whose structure and reactivity are well described by the mechanistic ideas of organic chemistry. The parent species, such as carbenes and nitrenes, react in such a distinctive manner that mechanistic changes can readily be recognized in their heavier analogs. The observed changes will not only broaden our mechanistic ideas, but also lead to the discovery of new synthetically useful reagents. Among the species to be studied is a family of extremely electron-deficient ions and molecules with only four electrons in their outer shells. These have the potential for participating in reactions that form three new bonds simultaneously, processes never previously observed and rarely suggested. They represent a three-dimensional extension of pericyclic reactions with considerable synthetic interest. Included in the broader impacts of this work are the prospects for discovery of basic principles that will help us to better understand the covalent bond, its formation and reactivity throughout the periodic table, and to use that knowledge to find useful, new chemistry, and to make new molecules. For the coworkers trained on this project, their experience provides a diverse background, encouraging them to develop a versatility and confidence that prepares them to tackle a broad range of problems and launch diverse careers. Throughout his career, Gaspar has been involved in the training of under-represented groups at the graduate, undergraduate, postdoctoral and high school levels. These have included undergraduates honored as Rhodes Scholars, Pfizer Summer Research Fellows, and as winners of NSF and NIH graduate fellowships. Graduate students in the Gaspar group have had considerable success in competing for postdoctoral fellowships, and postdoctorals have secured excellent appointments in industry, research institutes, and academia.