Catalytic Metal-Mediated Small Molecule Fixation

凭借该奖项，化学部门的化学催化项目将资助马里兰大学的Lawrence Sita博士开发过渡金属催化剂，该催化剂可用于从易于获得、安全且廉价的起始材料（如氮、二氧化碳、一氧化碳和硫）中生产高价值的特种化学品。由于预计未来50年全球人口将增加30亿至40亿人，因此必须在近期内取得用于高价值工业化学品商业化生产的化学技术的进步，以满足对自然资源、能源和环境日益增加的负担。为了满足这些需求，该项目的主要目标是开发过渡金属催化剂，该催化剂可用于从易于获得、廉价和安全的起始材料（如氮、二氧化碳、一氧化碳、氧化亚氮和硫）中生产增值的特种化学品。这项工作的更广泛的影响是潜在的发展更原子经济和节能，工业规模的化学转化将有利于世界经济，环境和社会，并可以减少当前技术的健康和安全风险，这些技术需要危险试剂和中间体的产生，运输和现场储存。这项建议的工作将进一步为未来几代本科生、研究生和博士后研究人员提供培训的重要工具。本研究的重点是含环戊二烯基氨基酸酯（CPAM）和环戊二烯基胍酸酯（CPGU）配体的中价、第二和第三行5族（Nb, Ta）和6族（Mo， W）金属配合物的合成和表征。这些配合物适合于研究具有X-Y多键的小分子（如N2、O2、N2O、CO和CO2）的配位和“固定”。这些金属配合物与小分子之间的相互作用导致(1)X- y多键断裂，由强M-X和M-Y键相互作用的形成补偿，以及(2)原子经济的途径，X和y转移到底物，这完成了对起始金属配合物的催化循环。CPAM和CPGU，分子离散配合物将在溶液中使用NMR， EPR， UV和IR光谱，电喷雾质谱和电化学进行全面表征，并在固态中使用单晶x射线分析，元素分析，IR和EPR光谱进行全面表征。

With this award, the Chemical Catalysis Program in the Chemistry Division is funding Dr. Lawrence Sita from the University of Maryland to develop transition-metal catalysts that can be used for the production of high-value specialty chemicals from readily available, safe, and inexpensive starting materials, such as nitrogen, carbon dioxide, carbon monoxide, and sulfur. Advances in chemical technologies for the commercial production of high-value, industrial chemicals must be made in the near term in order to meet the increasing burdens placed on natural resources, energy, and the environment as the global population is anticipated to expand by 3 to 4 billion people over the next 50 years. In response to these needs, the primary objective of the project is the development of transition-metal catalysts that can be used to produce value-added, specialty chemicals from readily-available, inexpensive and safe starting materials, such as nitrogen, carbon dioxide, carbon monoxide, nitrous oxide and sulfur. The broader impact of this work is the potential development of more atom-economical and energy-efficient, industrial-scale chemical transformations that will be beneficial to the world economy, the environment, and the society and that can reduce the health- and security-risk of current technologies that require the generation, transportation, and on-site storage of hazardous reagents and intermediates. The proposed work will further provide an important vehicle by which future generations of undergraduates, graduate students, and postdoctoral researchers are trained.The focus of the research is the synthesis and characterization of mid-valent, second- and third-row, group 5 (Nb, Ta) and 6 (Mo, W) metal complexes with cyclopentadienyl amidinate (CPAM) and cyclopentadienyl guanidinate (CPGU) ligands. These complexes are suited for the study of the coordination and "fixation" of small molecules possessing X-Y multiple bonds (e.g., N2, O2, N2O, CO and CO2). The interaction between these metal complexes and the small molecules leads to (1) X-Y multiple bond cleavage compensated by the formation of strong M-X and M-Y bonding interactions, and (2) pathways for atom-economical, X- and Y-transfers to a substrate, which complete the catalytic cycle with respect to the starting metal complex. The CPAM and CPGU, molecularly-discrete complexes will be fully characterized both in solution using NMR, EPR, UV, and IR spectroscopies, electrospray mass spectrometry, and electrochemistry, and in the solid state using single-crystal X-ray analysis, elemental analyses, and IR and EPR spectroscopies.