Highly Active Mechanochemically Generated Main Group and Lanthanide Complexes

该项目由化学部化学合成计划资助。范德比尔特大学化学系的蒂莫西·哈努萨教授探讨了普通金属在各种应用中取代稀土金属的程度。稀土在医药、电子和化学方面有数百种用途。然而，它们价格昂贵，目前在美国没有这些元素的有效来源。这导致了未来稀土供应和可用性的不确定性。因此，努力开发稀土的替代品是一项战略优先事项。该项目的目标是开发含有铝、钙或锶（常见的廉价金属）的化合物，其行为类似于稀土。 这是使用一种称为机械化学的独特技术来制备三种金属的化合物。在机械化学中，试剂在没有溶剂的情况下一起研磨或球磨。由于这些化合物缺乏溶剂，可以在其中诱导类似稀土的行为。然后开发这些作为各种应用中稀土的替代品。机械化学的另一个优点是不需要处理溶剂，因此污染的可能性较小。该项目还为各种学生提供研究机会，包括妇女、代表性不足的少数民族以及初中和高中学生。 学生的这种培训和发展对于培养能够在全球市场上竞争的下一代国内科技人员至关重要。该项目强调使用空间体积庞大的烯丙基配体，这些配体与广泛的金属相容，并具有高构象灵活性。与无溶剂合成结合，这些配体稳定具有低配位数和相应的高反应性的络合物。新化合物的研究与NMR光谱，X射线晶体学，密度泛函理论计算。最有希望的是测试其催化聚合活性。该研究的更广泛影响包括本科生和研究生的培训，以及在学年和夏季参与范德比尔特参与的各种教育和推广计划。这些活动鼓励学生参与现代科学的多个领域。

This project is funded by the Chemical Synthesis Program of the Chemistry Division. Professor Timothy Hanusa of the Department of Chemistry at Vanderbilt University explores the extent to which common metals can replace rare-earth metals in various applications. The rare earths have hundreds of uses in medicine, electronics, and chemistry. However, they are expensive and at present there is no active source of these elements in the United States. This has resulted in uncertainties over the future supply and availability of the rare earths. As a consequence efforts to develop replacements for the rare earths is a strategic priority. This project targets the development of compounds that contain aluminum, calcium, or strontium (common inexpensive metals) and whose behavior resembles that of the rare earths. This is done using a unique technique called mechanochemistry to prepare normally inaccessible compounds of the three metals. In mechanochemistry reagents are ground or ball milled together without solvent. Because these compounds lack solvent, rare earth like behavior can be induced in them. These are then developed as replacements for rare earths in a various applications. An additional advantage of mechanochemistry is that no solvent must be disposed of and, consequently, there is less chance for pollution. The project also provides research opportunities for a variety of students including women, underrepresented minorities, and both middle and high school students. Such training and development of students is critically important for preparing the next generation of domestic science and technology personnel capable of competing in the global marketplace. This project emphasizes the use of sterically bulky allyl ligands that are compatible with a wide range of metals and possess high conformational flexibility. In conjunction with the solventless synthesis, these ligands stabilize complexes with low coordination numbers and corresponding high reactivity. The new compounds are studied with NMR spectroscopy, X-ray crystallography, and density functional theory calculations. The most promising are tested for their catalytic polymerization activity. The broader impact of the research includes the training of undergraduate and graduate students, and participation in various educational and outreach programs involving Vanderbilt during the academic year and summer. These activities encourage the students to participate in multiple areas of modern science.