Catalytic Metal-Mediated Small Molecule Fixation

有了这个奖项，化学部的化学催化项目资助了马里兰州大学的Lawrence Sita博士开发过渡金属催化剂，这些催化剂可用于从容易获得的，安全的和廉价的起始材料（如氮气，二氧化碳，一氧化碳和硫）生产高价值的特种化学品。 随着全球人口预计在未来50年内增加30亿至40亿人，必须在近期内实现高价值工业化学品商业化生产的化学技术进步，以满足自然资源、能源和环境日益增加的负担。 针对这些需求，该项目的主要目标是开发过渡金属催化剂，用于从容易获得、廉价和安全的起始材料，如氮气、二氧化碳、一氧化碳、一氧化二氮和硫，生产增值的特种化学品。 这项工作的更广泛影响是可能开发出更具原子经济性和能源效率的工业规模化学转化，这将有利于世界经济、环境和社会，并可以降低健康和安全风险当前技术需要危险试剂和中间体的生成、运输和现场存储。 本研究的重点是中间价、第二和第三排、第5族（Nb，Ta）和第6族（Mo，W）金属与双胍基（CPAM）和双胍基（CPGU）配体的配合物的合成和表征。 这些配合物适合于研究具有X-Y多重键的小分子的配位和“固定”（例如，N2、O2、N2 O、CO和CO2）。 这些金属络合物和小分子之间的相互作用导致（1）通过形成强M-X和M-Y键合相互作用来补偿的X-Y多重键断裂，和（2）原子经济的、X-和Y-转移到基底的途径，其相对于起始金属络合物完成催化循环。 CPAM和CPGU，分子离散的复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，以及在固态下使用单晶X射线分析，元素分析，IR和EPR光谱进行充分表征。

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.