Using Second Coordination Sphere Interactions of Rhenium(I) Complexes to Promote

描述(申请人提供)：鉴于地球上的资源有限，化学工业必须采用更可持续的做法，以确保未来的经济增长以及保护人类和环境的福利。我们目前对石油作为燃料和有机原材料的依赖是不够的，因为石油供应的不确定性和与其加工相关的巨大污染。寻找替代碳源需要：1)确定可靠的、自然丰富的化学原料，2)发现清洁技术，将其转化为增值产品。关于这些目标，一个有希望的研究领域是合成气(合成气)、一氧化碳和氢气的工业使用，这些气体可以很容易地从煤和生物质中获得。尽管几家大型制造厂利用合成气生产碳氢化合物和含氧物，但目前依赖费托化学的合成方法是非选择性的。分离合成气产品所需的额外步骤大大降低了其整体合成效率。催化合成气中C-H和C-C键形成反应的均相催化剂可以绕过传统上阻碍CO选择性偶联反应的热力学和动力学限制，从而允许CO选择性偶联。Bercaw和他的同事已经证明，在一个可能涉及CO的催化循环中，一些关键的反应步骤可以使用磷化氢支撑的金属羰基络合物和氢化物供体来实现，这些给体是从H2的异源裂解中获得的。尽管这些研究成功地将两个CO分子还原偶联，但生成的产物太稳定，无法再生，无法进行可行的催化反应。这项建议描述了一种新型的利用合成气作为碳、氢和电子的唯一来源来进行一氧化碳还原偶联的Re羰基平台的设计。一个多功能的配体提供了一个机会来探索第二配位球相互作用，如氢键，Lewis酸活化和静电吸引，对金属羰基物种对氢化物给体的反应活性的影响。这项工作的主要目标是确定哪些因素促进了C-H和C-C键的形成过程，这些知识将被用于设计催化系统，将合成气选择性转化为含碳更高的材料。

DESCRIPTION (provided by applicant): Given the limited resources on this planet, it is imperative that chemical industries adopt more sustainable practices to ensure future economic growth as well as to protect the welfare of people and the environment. Our current reliance on petroleum as fuel and organic raw materials is inadequate due to uncertainty in its supply and the enormous amount of pollution associated with its processing. Finding an alternative carbon source requires: 1) identifying a reliable and naturally abundant chemical feedstock, and 2) discovering clean technologies to convert it into value-added products. With regard to these goals, a promising area of research is in the industrial use of synthesis gas (syngas), CO and H2, which can be readily obtained from coal and biomass. Although several large-scale manufacturing plants utilize syngas to produce hydrocarbons and oxygenates, current synthetic methods that rely on Fischer-Tropsch chemistry is non-selective. The additional steps needed to separate syngas products greatly reduce its overall synthetic efficiency. Homogeneous catalysts that mediate C-H and C-C bond forming reactions from syngas may allow selective coupling of CO by circumventing the thermodynamic and kinetic restrictions that have traditionally hindered such reactivity. Bercaw and coworkers have demonstrated that some of the key reaction steps in a possible catalytic cycle involving CO can be achieved using phosphine-supported metal carbonyl complexes and hydride donors obtained from heterolytic cleavage of H2. Although these studies led to successful reductive coupling of two CO molecules, the resulting product was too stable to be regenerated for a viable catalytic reaction. This proposal describes the design of a novel rhenium carbonyl platform for reductive coupling of CO using syngas as the exclusive source of carbon, hydrogen, and electrons. A multi-functional ligand provides an opportunity to explore the influence of second coordination sphere interactions, such as hydrogen bonding, Lewis acid activation, and electrostatic attraction, on the reactivity of metal carbonyl species toward hydride donors. The primary goal of this work is to determine what factors promote C-H and C-C bond forming processes, knowledge of which will be used to design catalytic systems for selective transformation of syngas into higher-carbon containing materials.