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Uranium-Ligand Multiple Bonds: From Molecules to Materials

铀配体多重键：从分子到材料

基本信息

批准号：
EP/M027015/1
负责人：
Stephen Liddle
金额：
$ 181.29万
依托单位：
University of Manchester
依托单位国家：
英国
项目类别：
Fellowship
财政年份：
2015
资助国家：
英国
起止时间：
2015 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FM027015%2F1
关键词：
Uranium Ligand Multiple Bonds Molecules

项目摘要

Since the 2011 Fukushima disaster, a major priority for the nuclear sector has been to develop accident tolerant fuels (ATFs). A very promising ATF is uranium-nitride (UN). UN has a high thermal conductivity, enabling heat to be transferred efficiently so the fuel is meltdown-resistant. UN has a high fissile content, so more power can be generated than with existing oxide fuels for the same enrichment level. Mixed UN/PuN is a fuel option for Generation IV reactors breeding fissile material and producing less long-lived radioactive waste. So, UN is a safer, more environmentally friendly, and sustainable nuclear fuel. For similar reasons uranium-carbides are also attractive ATFs. However, preparing uranium-nitrides and -carbides by traditional routes presents challenges. An attractive approach is to use molecular uranium-nitride and -carbyne precursors and decompose them to binary nitrides and carbides. Sadly, for decades there were few molecular uranium-nitrides so a molecules-to-materials approach was not realistic. The situation for uranium-carbynes is worse; there are only two spectroscopic reports of uranium-carbynes at ~10 Kelvin. Recently, we prepared the first molecular uranium-nitride triple bonds (Science, 2012, 337, 717; Nature Chemistry, 2013, 5, 482). Metal-ligand multiple-bonding is fundamentally important in chemistry and we have made a number of contributions in this area (e.g. J. Am. Chem. Soc. 2014, 136, 5619; Angew. Chem. Int .Ed. 2014, 53, 4484) and preliminary results show that our molecular nitrides can be controllably decomposed to binary nitrides which opens up a molecules-to-materials approach.This Proposal aims to apply our recent coordination chemistry to the preparation of materials for energy in Grand Challenge and Priority Areas. We will develop a new range of uranium precursors to generate a platform to expand the range of nitrides. This exploits a blend of steric and electronic properties uniquely suited to stabilising uranium-ligand multiple bonds. Using these precursors we have identified four routes to maximise our chance of success to prepare high-value uranium-carbynes which have no precedent. With an expanded range of molecular uranium-nitrides and new uranium-carbynes we will build on preliminary results and investigate their decomposition to binary materials. The availability of new precursors leads to the possibility of exploring high pressure phase transitions to give new polymorphs. This is directly relevant to understanding fuels under extreme conditions in nuclear reactors and these metallic polymorphs are interesting to study as their itinerant vs localised 5f electron behaviour is magnetically fascinating and crucial to designing better ATFs.We will combine synthetic, structural, and materials studies with interdisciplinary magnetometric, computational, and spectroscopic studies with collaborators to give a comprehensive understanding of uranium-nitrogen and -carbon bonding, reactivity, and materials applications. A Fellowship will provide the best opportunity to oversee this complex programme of research, manage an intensive array of collaborations, and make the time to engage with the nuclear industry and translate academic advances on to the next level into industrially relevant applications. The researchers on this project will develop a range of skills in a recognised strategic skills shortage area. Our molecules provide unique opportunities to probe the nature and extent of covalency in uranium bonding; this issue is long-running, still hotly debated, and important because of the nuclear waste legacy in the UK. Spent nuclear fuel is ~96% uranium and the official Nuclear Decommissioning Authority figure for nuclear waste clean-up bill is 70 billion pounds. If we can better understand the chemistry of uranium this may in the future contribute to ameliorating the UK's nuclear waste legacy and provide new routes to ATFs to be developed with the Nuclear Industry.

自2011年福岛灾难以来，核部门的主要优先事项是开发事故耐受燃料（ATF）。一种非常有前途的ATF是氮化铀（UN）。UN具有很高的导热性，使热量能够有效地传递，因此燃料具有抗熔性。UN具有高裂变含量，因此在相同的浓缩水平下，可以产生比现有氧化物燃料更多的电力。UN/PuN混合燃料是第四代反应堆的一种燃料选择，用于增殖裂变材料和产生更少的长寿命放射性废物。因此，UN是一种更安全，更环保，更可持续的核燃料。出于类似的原因，碳化铀也是有吸引力的ATF。然而，通过传统途径制备铀-氮化物和铀-碳化物提出了挑战。一个有吸引力的方法是使用分子氮化铀和碳炔前体，并将它们分解为二元氮化物和碳化物。可悲的是，几十年来，几乎没有分子铀氮化物，因此从分子到材料的方法是不现实的。铀-碳炔的情况更糟;只有两个在~10开尔文的铀-碳炔光谱报告。最近，我们制备了第一个分子铀-氮化物三键（Science，2012，337，717; Nature Chemistry，2013，5，482）。金属-配体多重键合在化学中是根本重要的，并且我们在该领域中已经做出了许多贡献（例如J. Am. 2014，136，5619; Angew. 2014，53，4484），初步结果表明，我们的分子氮化物可以可控地分解为二元氮化物，这开辟了分子到材料的方法。该提案旨在将我们最近的配位化学应用于制备用于Grand Challenge和Priority Areas的能源材料。我们将开发一系列新的铀前体，以产生一个平台来扩大氮化物的范围。这利用了空间和电子性质的混合物，独特地适合于稳定铀-配体多重键。利用这些前体，我们确定了四条路线，以最大限度地提高我们成功制备高价值铀碳炔的机会，这是前所未有的。随着分子铀氮化物和新的铀碳炔的范围扩大，我们将建立在初步结果和研究它们的分解二元材料。新前体的可用性导致探索高压相变以得到新的多晶型物的可能性。这与理解核反应堆中极端条件下的燃料直接相关，并且这些金属多晶型物是有趣的研究，因为它们的巡回与局部5 f电子行为是磁性迷人的，并且对于设计更好的ATF至关重要。我们将联合收割机合成，结构和材料研究与跨学科的磁力学，计算，与合作者进行光谱研究，以全面了解铀-氮和碳键合，反应性和材料应用。奖学金将提供最好的机会来监督这个复杂的研究计划，管理一系列密集的合作，并抽出时间与核工业接触，将学术进步转化为下一个层次的工业相关应用。该项目的研究人员将在公认的战略技能短缺领域开发一系列技能。我们的分子提供了独特的机会来探测铀键合中共价的性质和程度;这个问题是长期存在的，仍然是激烈的争论，并且由于英国的核废料遗产而非常重要。废核燃料含有约96%的铀，核退役管理局的官方数字是700亿英镑。如果我们能够更好地了解铀的化学性质，这可能有助于改善英国的核废物遗产，并为与核工业一起开发ATF提供新的途径。