Early Metal Bimetallic Platforms for Controlled, Catalytic Dinitrogen Functionalization

在化学系化学合成计划的支持下，加州大学伯克利分校的波莉·L·阿诺德教授将研究f-块和相关正电分子的结构、成键和反应性，这些分子旨在将大气中的氮素转化为氨和胺。最重要的工业过程之一是将大气中的氮转化为氨--这是几乎所有氮肥的基础。这是通过哈伯博世(HB)工艺实现的，该工艺效率高，但需要高温和压力。HB过程使用石油进行，贡献了全球约2%的碳排放。化学家们花了一百多年的时间试图开发可以在室温/压力下运行的HB工艺的替代品。该项目将使用基于金属的催化剂来促进这些反应，这些金属通常不适用于这一应用。在项目期间，学生将接受这一重要领域的培训，并将包括代表人数不足的群体的成员。合成了S、d和f-嵌段的各种正电性金属和Lewis酸性金属的金属环酚配合物，并对它们的还原小分子活化化学进行了评价。这些配体将被功能化，以便能够分离出可结晶和研究的小而可溶的稀土配合物。与尺寸，刘易斯酸度和单电子氧化还原电位的相关性将被研究。开放的络合物将使复杂的氮官能化反应更易于研究，并将为更容易地研究S-嵌段还原活化化学提供机会。在整个研究过程中，将使用一系列光谱技术来了解从还原电子源到由正电金属中心激活的氮素分子的电子流动路径(S)。这些研究将有助于我们理解通常不能将电子结合或添加到氮素中的正极贱金属如何能够支持其转化为胺。这一裁决反映了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 program in the Division of Chemistry, Professor Polly L Arnold of the University of California, Berkeley, will study the structure, bonding, and reactivity of f-block and related electropositive molecules that are designed to convert atmospheric dinitrogen to ammonia and amines. One of the most important industrial processes is the conversion of atmospheric nitrogen into ammonia – the basis of nearly all nitrogen fertilizers. This is accomplished by the Haber Bosch (HB) process that is efficient but requires high temperatures and pressures. The HB process is carried out using petroleum and contributes about 2% of the worldwide carbon emissions. Chemists have spent over a hundred years trying to develop alternatives to the HB process that can operate at room temperature/pressure. This project will facilitate these reactions using catalysts based on metals that have not normally been applied to this application. During the project students will be trained in this vital field and will include members of underrepresented groups. Metalacyclic phenolate complexes of a variety of electropositive and Lewis acidic metals from the s, d, and f-block will be synthesized and their reductive small molecule activation chemistry will be evaluated. The ligands will be functionalized to enable the isolation of small and soluble dilanthanide complexes that can be crystallized and studied. Correlations with size, Lewis acidity, and one-electron redox potentials will be investigated. Open-faced complexes will make complicated dinitrogen functionalization reactivity amenable to study and will offer the opportunity to study s-block reductive activation chemistry with greater ease. Throughout the studies, a range of spectroscopic techniques will be employed to understand the path of electron flow from the source of reducing electrons to the dinitrogen molecule that activated by the electropositive metal center(s). The studies will aid our understanding of how electropositive base metals, which would not normally be able to bind or add electrons to dinitrogen, are able to support its conversion to amines.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.