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。在这个由化学部化学合成计划资助的项目中，德克萨斯州立大学圣马科斯分校化学和生物化学系的托德·哈德纳尔教授试图制备违反每碳四键原则的物质。具体地说，制备了一种称为卡宾的化合物，它含有只有两个键的碳。由于卡宾的键数异常低，因此非常活泼，具有重要的电子性质。开发的制备卡宾的方法被扩展到相关元素，锗和锡。这些合成方法具有潜在的实用价值，是获得亚稳合金的低温途径。除了培养本科生和研究生外，该项目可能最终会发现新材料，这些材料可能会在从量子计算到单分子磁体再到催化剂的各种应用中造福社会。哈德诺教授与麦肯纳儿童博物馆保持着一项名为“实验室工作站”的合作推广计划。这项计划吸引3-10岁的孩子在模拟手套盒中进行动手简单的化学实验，也包括来自峡谷高中的当地化学学生。德克萨斯州立大学是一所西班牙裔服务机构。这个项目为在科学中代表性不足的群体的学生提供研究经验。本项目的目的是制备亲电的卡宾配体和相关的主族类似物。卡宾的亲电性和伴随的pi-酸性可以通过降低它们各自的最低未占据分子轨道(LUMO)能级来系统地增加，通过计算来确定目标。制备了这些化合物以及具有非常小的单态-三态间隙的相关的锗和锡物种。其中包括二氨基硅烯、锗、锡烯和阳离子杂环卡宾。一个被研究的问题是，为什么二氨基卡宾可以被光解到三重态激发态，而其他卡宾不能。探索了卡宾的光化学，并开发了其作为亲电的卡宾负载主族催化剂和作为主族合金低温生成的先驱体的应用。该计划通过将学生纳入研究项目并通过面向K-12学生的外展计划来服务于未被充分代表的群体的学生。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.