Highly Active Mechanochemically Generated Main Group and Lanthanide Complexes

本项目由化学学部化学合成项目资助。范德比尔特大学化学系的Timothy Hanusa教授探索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、电子和化学领域有数百种用途。然而，它们是昂贵的，目前在美国没有这些元素的有效来源。这导致了稀土未来供应和可得性的不确定性。因此，开发稀土的替代品是一项战略重点。这个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。这是通过一种称为机械化学的独特技术来制备通常难以接近的三种金属化合物。在机械化学中，试剂在没有溶剂的情况下被研磨或球磨在一起。由于这些化合物缺乏溶剂，可以在其中诱发类似稀土的行为。然后，它们被开发成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了研究机会，包括女性，代表性不足的少数民族以及中学生和高中生。这种对学生的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学和技术人员至关重要。该项目强调使用立体体积庞大的烯丙基配体，这些配体与多种金属兼容，并具有高构象灵活性。与无溶剂合成相结合，这些配体稳定配合物具有低配位数和相应的高反应活性。用核磁共振光谱、x射线晶体学和密度泛函理论计算对新化合物进行了研究。最有希望的是测试它们的催化聚合活性。这项研究的广泛影响包括对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大学的各种教育和推广项目。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.