Novel Electrophilic Carbene Architectures and Related Main Group Analogs

碳是构成生命元素的建筑材料。一个基本原理是碳形成四个化学键。在这个由化学部门化学合成项目资助的项目中，德克萨斯州立大学圣马科斯分校化学和生物化学系的Todd Hudnall教授试图制备违反每碳四键原理的物质。具体地说，碳烯化合物只含有两个键的碳。由于碳烯的键数非常少，所以碳烯具有很强的反应性和重要的电子性质。将制备碳烯的方法扩展到相关元素锗和锡。这些合成方法在低温下获得亚稳态合金具有潜在的实用价值。除了培养本科生和研究生外，这个项目最终可能会导致新材料的发现，这些材料可能会在从量子计算到单分子磁铁到催化剂的应用中造福社会。哈德纳尔教授与麦肯纳儿童博物馆保持着一个名为“实验室工作站”的合作推广项目。这个项目让3-10岁的孩子们在模拟手套箱里动手做简单的化学实验，也包括当地峡谷高中的化学学生。德克萨斯州立大学是一所西班牙裔服务机构。该项目为来自科学界代表性不足的群体的学生提供研究经验。本课题的目的是制备亲电羰基配体及相关的主基类似物。通过计算，我们确定了一组碳烯，它们的亲电性和伴随的pi-酸度可以通过降低它们各自的最低未占据分子轨道（LUMO）能级而系统地增加。制备了这些化合物和相关的锗和锡种，它们具有极小的单线态-三重态间隙。其中包括二聚硅烯、二甲苯、乙烯烯和阳离子杂环碳烯。研究的一个问题是，为什么二胺碳烯可以被光解成三态激发态，而其他碳烯却不能。探讨了羰基化合物的光化学性质，并开发了其作为亲电羰基负载主基催化剂和低温制备主基合金前驱体的应用。该项目通过将弱势群体的学生纳入研究项目，并通过向K-12学生提供外展项目，为他们提供服务。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Carbon is the building material upon which the elements of life are constructed. A basic tenet is that carbon forms four chemical bonds. In this project, funded by the Chemical Synthesis Program of the Chemistry Division, Professor Todd Hudnall of the Department of Chemistry and Biochemistry at Texas State University - San Marcos seeks to prepare substances that violate the four-bonds per carbon principle. Specifically, compounds called carbenes that contain carbon with only two bonds are prepared. Because of the unusually low number of bonds, carbenes are very reactive and have important electronic properties. The methods that are developed to prepare the carbenes are extended to the related elements, germanium and tin. These synthetic methods potentially useful, low temperature ways to access metastable alloys. In addition to training undergraduate and graduate students, this project may ultimately result in the discovery of novel materials that may benefit society in applications ranging from quantum computing to single molecular magnets to catalysts. Professor Hudnall has maintained a collaborative outreach program with the McKenna Children’s Museum called “Laboratory Workstations.” This program engages children, ages 3-10, in hands-on simple chemistry experiments in mock gloveboxes, and is also inclusive of local chemistry students from Canyon High School. Texas State University is an Hispanic Serving Institution. This project provides research experiences to students from groups underrepresented in science. The aim of this project is to prepare electrophilic carbene ligands and related main group analogs. Sets of carbenes, whose electrophilic character and attendant pi-acidity can be systematically increased by a lowering of their respective Lowest Unoccupied Molecular Orbital (LUMO) energy levels, are targeted using computations. These compounds and related germanium and tin species with exceptionally small singlet-triplet gaps are prepared. Among these are diamidosilylenes, germylenes, stannylenes, and cationic heterocyclic carbenes. One question that is investigated is why diamidocarbenes can be photolyzed to a triplet excited state where other carbenes cannot. The photochemistry of the carbenes is explored and applications as electrophilic carbene-supported main group catalysts and as precursors for the low-temperature generation of main group alloys are developed. The program serves students from underrepresented groups by their inclusion in the research project and though outreach programs to K-12 students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.