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

描述（由申请人提供）：鉴于这个星球上的资源有限，化学工业必须采取更可持续的做法，以确保未来的经济增长，并保护人类和环境的福利。由于石油供应的不确定性和加工过程中产生的大量污染，我们目前对石油作为燃料和有机原料的依赖是不够的。寻找替代碳源需要：1)确定可靠且自然丰富的化学原料，2)发现将其转化为增值产品的清洁技术。关于这些目标，一个有前途的研究领域是工业利用合成气、CO和H2，它们可以很容易地从煤和生物质中获得。虽然有几家大型制造工厂利用合成气生产碳氢化合物和含氧化合物，但目前依靠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这种反应性的热力学和动力学限制，从而允许CO的选择性偶联。Bercaw和他的同事们已经证明，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通过使用磷化氢负载的金属羰基配合物和H2的异裂解得到的氢化物供体来实现。尽管这些研究成功地实现了两个CO分子的还原偶联，但所得产物太稳定，无法再生，无法进行可行的催化反应。该提案描述了一种新型羰基铼平台的设计，该平台使用合成气作为碳、氢和电子的唯一来源，用于CO的还原偶联。多功能配体为探索第二配位球相互作用（如氢键、路易斯酸活化和静电吸引）对金属羰基对氢化物供体的反应性的影响提供了机会。这项工作的主要目标是确定促进C-H和C-C键形成过程的因素，这些知识将用于设计催化系统，以选择性地将合成气转化为含碳量更高的材料。

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.