Hydrocarbon activation by f-block complexes

燃烧汽油和其他来自化石燃料的碳氢化合物会破坏环境，浪费资源，否则这些资源可以用来制造提高生活质量的物质。然而，碳氢键的强度，加上选择性进入特定分子上的特定位点的困难，意味着需要高活性的金属化合物来催化这种过程。甲烷是最简单、最丰富的碳氢化合物，它中的单个C-H键可能是选择性功能化的最重要的经济目标，但在更复杂的碳氢化合物中激活C-H键也是所有化学合成领域的科学家非常希望的“工具箱”组件。在未来几年，随着我们的平台化学物质从化石燃料衍生到生物质衍生的变化，这种选择性将变得越来越重要。25年前，镧系元素和锕系元素的有机金属化合物通过选择性切割甲烷中的一个碳氢键，首次展示了它们的潜力，但支持配体的局限性阻碍了任何进一步的功能化步骤。从那时起，在d-和f-金属中心已经证明了各种C-H键活化化学，这增加了我们对该反应的基本理解，但尚未提供有利可图的应用。有机金属f嵌段化学的最新进展（包括学术突破和表征方法），以及寻找不基于稀有和昂贵的铂族金属的C-H活化催化剂的愿望，现在正在推动f嵌段金属回到C-H键活化化学的前沿。我们在有机金属f嵌段化学方面做出了各种贡献，挑战了f嵌段结构和键合的传统观点，例如分离出具有新的极性金属-元素键的f嵌段配合物(J. Am.；化学。Soc. 2007)，以及铀酰化的U=O氧基团对C-Si和N-Si键裂解的空前反应性的证明（Nature, 2008）。拟议的工作计划侧重于碳氢化合物C-H键的选择性活化和功能化，并建立在我们最近在功能有机镧系和锕系化学方面的成功和概念验证结果的基础上。我们已经确定了三种机制上不同的C-H键激活类型，并将它们组合成一个程序，以提供最高的成功机会。该奖学金为PI管理这一密集的国际合作研究项目提供了理想的机会，并为碳氢化合物活化提供了新的f段催化剂。这项工作通过提供催化、原子高效、低能耗的化学途径，将生物质或化石燃料中的碳氢化合物转化为高价值的化学品，从而使工业和社会都受益，从而有助于实现能源优先。对不寻常的f块化合物的反应性和键合性的基本理解提高了我们处理核材料和废物的能力，而这个项目的研究人员将获得锕系元素处理技能，这被认为是英国的关键短缺。最后，贫化铀化合物对重要碳氢化合物化学的证明将有助于在我们未来的核时代提高铀的公众形象。

Burning petrol and other hydrocarbons from fossil fuels is damaging to the environment and wasteful of resources that could otherwise be used to make substances that improve the quality of life. However, the strength of the carbon-hydrogen bond, coupled with the difficulties associated with selectively accessing a specific site on a particular molecule, means that highly reactive metal compounds are needed to catalyse such processes.A single C-H bond in methane, the simplest and most abundant hydrocarbon, is potentially the most financially important target for selective functionalisation, but the activation of C-H bonds in more complex hydrocarbons is also a highly desirable 'toolbox' component for scientists working in all areas of chemical synthesis. This selectivity will become increasingly more important as our palette of platform chemicals changes from fossil fuel-derived to biomass-derived in the coming years.Organometallic compounds of the lanthanides and actinides first gave a tantalising glimpse of their potential with the selective cleavage of one C-H bond in methane some 25 years ago, but the limitations of the supporting ligands precluded any further functionalisation step. Since then, a variety of C-H bond activation chemistry has been demonstrated at d- and f-block metal centres that has increased our fundamental understanding of this reaction, but not yet provided profitable applications. Recent advances in organometallic f-block chemistry (both in terms of academic breakthroughs, and characterisation methods), and the desire to find C-H activation catalysts not based on the rare and expensive platinum group metals, is now pushing f-block metals back to the forefront of C-H bond activation chemistry.We have made a variety of contributions to organometallic f-block chemistry that challenge traditional views of f-block structure and bonding, such as the isolation of f-block complexes with new polar metal-element bonds (J. Am. Chem. Soc. 2007), and the demonstration of unprecedented reactivity of the U=O oxo groups of the uranyl dication towards C-Si and N-Si bond cleavage (Nature, 2008).The proposed programme of work focuses on the selective activation and functionalisation of hydrocarbon C-H bonds, and builds on our recent successes and proof-of-concept results in functional organolanthanide and actinide chemistry. We have identified three mechanistically distinct types of C-H bond activation, and have combined them into one programme, to offer the highest chance of success. A fellowship offers the ideal opportunity for the PI to manage this intensive and internationally collaborative research programme and deliver new f-block catalysts for hydrocarbon activation.This work contributes to the Energy priority, by providing catalytic, atom-efficient, low-energy chemical routes to convert hydrocarbons from biomass or fossil fuels into high-value chemicals, so benefitting both industry and society.The fundamental understanding that comes from the reactivity and bonding studies of unusual f-block compounds improves our ability to handle nuclear materials and wastes, while the researchers on this project will gain actinide handling skills that are identified as a key shortage in the UK. Finally, the demonstration of important hydrocarbon chemistry by depleted uranium compounds would help to enhance the public image of uranium in our future nuclear age.