Elucidation of the Bonding in Low-Valent Organoactinide Species

在化学系化学合成项目的支持下，普渡大学化学系的Suzanne Bart教授正在研究低价有机锕系化合物的键合。最重的元素是锕系元素，包括铀和钍。尽管这些元素在核能和核废料的处理中非常重要，但人们对它们的化学性质的了解远不如对更轻、更常见的金属的化学性质的了解。甚至连锕系金属能形成的化学键的类型也没有很好地确定。该项目将制备新型铀和钍化合物，其中金属具有异常低的氧化态，并通过多种化学键与其他原子相连。这些知识对于将这些元素与其他金属区分开来以实现化学分离以及发现未来独特的化学物质非常重要。这项研究计划的一个重要目标是将锕系元素的用途和性质整合到高中、大学和研究生的课程中。随着接受处理锕系元素培训的化学家的平均年龄增加，在国家需要的这一领域培养下一代科学家是至关重要的。为此，该项目包括对f元素化学的研究生和本科生进行培训，并向该地区的高中生提供教育。此外，还将开展一系列旨在帮助研究生心理健康的项目。这个项目将探索锕系化合物共价键的程度。该方法是为有机金属过程和小分子活化进行还原铀和钍配合物的合成、表征和反应性。具体目的包括合成具有不同空间和电子性质的取代基的u -烟原（Pn）单键和多键，以及研究软给体配体对锕系元素电子结构和共价的影响。从强还原剂中形成新的钍（III）衍生物也将被探索，因为钍通常处于+4氧化态。这些未被充分研究的化合物有望具有有趣的电子结构，这对于研究了解潜在的应用将是重要的。建议的工作包括合成方法开发，光谱分析，磁化测量和计算方法，以充分了解这些重要的和未开发的低价有机锕系化合物的电子结构和反应性。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。

With support from the Chemical Synthesis Program of the Chemistry Division, Professor Suzanne Bart from the Department of Chemistry at Purdue University, is studying bonding in low valent organoactinide compounds. The very heaviest elements are the actinide elements and include uranium and thorium. Although these elements are very important in nuclear energy and in the handling of, e.g., nuclear waste, their chemistry is not understood nearly as well as that of lighter, more common metals. Even the types of chemical bonds that the actinide metals can form are not well established. This project will prepare new classes of uranium and thorium compounds where the metals have unusually low oxidation states and are attached to other atoms through multiple chemical bonds. This knowledge is important for differentiation of these elements from other metals to enable chemical separations, and for discovering future unique chemistries. An important goal of this research program is to integrate the uses and properties of the actinide elements into the curricula of high school, college, and graduate students. As the average age of chemists trained in handling actinide elements increases, it is essential to prepare the next generation of scientists in this area of national need. Toward this end, the project includes the training of graduate and undergraduate students in f-element chemistry and outreach components to educate high school students in the area. In addition, a series of programs aimed at aiding the mental health of graduate students will be conducted.This project will explore the degree of covalent bonding in actinide compounds. The approach is to perform synthesis, characterization, and reactivity of reduced uranium and thorium complexes for organometallic processes and small molecule activation. Specific aims include synthesizing U-pnictogen (Pn) single and multiple bonds with substituents that have varying steric and electronic properties, and to study the effect of soft donor ligands on actinide electronic structure and covalency. The formation of new thorium(III) derivatives from strong reducing agents will also be explored, as thorium is typically found in the +4 oxidation state. These understudied compounds are expected to have interesting electronic structures that will be important to study to understand potential applications. The work proposed includes synthetic methodology development, spectroscopic analysis, magnetization measurements and computational approaches to fully understand the electronic structure and reactivity of these important and underexplored low valent organoactinide compounds.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.