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

鉴于地球上的资源有限，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料的依赖是不够的，因为石油供应不确定，而且石油加工造成大量污染。寻找替代碳源需要：1）确定可靠且天然丰富的化学原料，2）发现清洁技术将其转化为增值产品。关于这些目标，一个有前途的研究领域是合成气（合成气）、CO和H2的工业应用，它们可以很容易地从煤和生物质中获得。尽管几个大规模的制造工厂利用合成气来生产烃和含氧化合物，但是目前依赖于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。 介导来自合成气的C-H和C-C键形成反应的均相催化剂可以通过规避传统上阻碍这种反应性的热力学和动力学限制来允许CO的选择性偶联。Bercaw及其同事已经证明，在涉及CO的可能的催化循环中的一些关键反应步骤可以使用膦负载的金属羰基络合物和从H2的异裂解获得的氢化物供体来实现。虽然这些研究导致两个CO分子的成功还原偶联，但所得产物太稳定而不能再生用于可行的催化反应。 该提案描述了一种新的双羰基平台的设计，用于使用合成气作为碳、氢和电子的唯一来源来还原性偶联CO。一个多功能的配体提供了一个机会，探索第二配位圈的相互作用，如氢键，刘易斯酸活化，和静电吸引，对金属羰基物质对氢化物供体的反应性的影响。这项工作的主要目标是确定哪些因素促进C-H和C-C键形成过程，这些知识将用于设计催化系统，用于将合成气选择性转化为含高碳的材料。 公共卫生相关性：如果不立即采取行动纠正工业化对我们生态系统的有害影响，对我们生境的进一步破坏也将威胁人类健康。迈向更可持续的未来的一个积极步骤是开发更绿色的技术，利用地球丰富的燃料和材料产品资源。这项工作的目的是发现新的合成方法，将可以从煤和生物质中容易获得的合成气转化为具有低环境足迹的更有价值的商品。

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. PUBLIC HEALTH RELEVANCE: If immediate actions are not taken to remedy the harmful effects of industrialization on our ecosystems, further damage to our habitat will also threaten human health. One positive step toward a more sustainable future is to develop greener technologies to utilize earth abundant resources for fuel and material goods. This work aims to discover new synthetic methods to convert synthesis gas, which can be readily obtained from coal and biomass, into more valuable commodities with a low environmental footprint.