Expanding Reductive Chemistry and Oxidation State Diversity Using the Synthetic Chemistry of the Rare-Earth Metals

在化学系化学合成(SYN)计划的支持下，加州大学欧文分校化学系威廉·J·埃文斯教授正在研究稀土元素的七种新氧化态的化学。稀土是重金属，在电子、医药和其他领域发挥着至关重要的作用。稀土金属最常见的氧化态为+3，但也有一些可以有其他值，如+2。这个项目探索了最近发现其+2氧化态的七种稀土元素的化学。具有这种新氧化态的元素具有使其成为通过磁性(世界上最强大的磁体中的钕)和照明(节能照明中的Eu和Tb)以及医学(磁共振成像中的Gd)和催化(汽车催化转换器中的Ce)的应用的理想应用。埃文斯小组正在研究这些新的氧化态如何影响基础化学，同时培训学生学习这些具有战略重要性的金属的科学。埃文斯教授还致力于开发可在分子水平上设计的最小、最有效的磁体，即单分子磁体，并在量子信息科学中制造新型量子比特，即量子比特。该项目提供稀土元素的操作和应用开发方面的培训和教育，并包含一个鼓励初中生继续从事科学研究的扩展部分。正在探索新的+2离子Pr、Gd、Tb、Ho、Er和Ru的化学，以评估它们出人意料的电子构型可能产生的特殊反应活性和物理性质，这些电子构型不仅涉及4f价轨道，还涉及更高能量的5d轨道。这些4fn5d1离子不同于传统的具有4fn+1电子组态的稀土金属的+2氧化态。新的+2稀土离子Y的化学也在研究中，这是一个4d1系统，用于比较。这些离子的新分子络合物的合成导致了关于如何利用这些新离子的快速演变的观点。例如，LU2+的分子络合物被发现具有最大的电子-核超精细耦合常数之一，它提供了一种稳定的跃迁，称为时钟跃迁，可以用作噪声最小的量子比特。该项目还将寻求发现新的小分子活化反应，例如与氮和氮氧化物的反应，以及其他新的氧化态，例如稀土金属的+1离子。除了培训学生开发F-BLOCK化学的技术专长外，该奖项还面向初中生和高中生，并参与加州大学欧文分校化学本科生计划，通过同行指导支持普通化学领域的第一代、低收入和少数族裔学生。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。

With the support of the Chemical Synthesis (SYN) Program of the Chemistry Division, Professor William J. Evans, Chemistry Department, University of California – Irvine is studying the chemistry of seven new oxidation states of rare earth elements. Rare earths are heavy metals that have vital roles in electronics, medicine, and others. The rare earth metals most commonly have an oxidation state of +3, but some can have other values such as +2. This project explores the chemistry of seven rare earth elements for which a +2 oxidation state has recently been discovered. Elements with this new oxidation state have properties which make them ideal for applications in energy conservation through magnetism (neodymium in the world’s most powerful magnets) and lighting (europium and terbium in energy efficient lighting) as well as in medicine (gadolinium in magnetic resonance imaging), and catalysis (cerium in automotive catalytic converters). The Evans group is studying how these new oxidation states can impact fundamental chemistry, while training students in the science of these strategically important metals. Professor Evans is also pursuing applications in the development of the smallest, most efficient, magnets that can be designed at a molecular level, namely single-molecule magnets, and in quantum information science to make new types of quantum bits, i.e. qubits. The project provides training and education in the manipulation and application development of the rare earth elements and contains an outreach component that encourages middle and high school students to continue in science.The chemistry of new +2 ions of praseodymium, gadolinium, terbium, holmium, erbium, and lutetium is being explored to evaluate the special reactivity and physical properties that can arise from their unexpected electron configurations which involve not only the valence 4f orbitals but also the higher energy 5d orbitals. These 4fn5d1 ions differ from traditional +2 oxidation states of the lanthanide metals that have 4fn+1 electron configurations. The chemistry of the new +2 rare earth ion of yttrium, a 4d1 system, is also being studied for comparison. The synthesis of new molecular complexes of these ions has led to a rapidly evolving perspective of how these new ions can be utilized. For example, a molecular complex of Lu2+ has been found to have one of the largest electron-nucleus hyperfine coupling constants that provides a stable transition called a clock transition that could be used as a qubit with minimum noise. The project also will seek to discover new small molecule activation reactions, e.g. with nitrogen and nitrogen oxides, and other new oxidation states, e.g. the +1 ions of the rare earth metals. In addition to training students to develop technical expertise of f-block chemistry there is significant outreach to middle and high school students and participation in a University of California - Irvine Chemistry Undergraduate Scholars Program to support first generation, low income and minority students in General Chemistry through peer mentoring.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.