Cooperative Noble Base Metal Catalysis

协同贵贱金属催化

• 批准号: EP/X019306/1
• 负责人: Oriol Planas
• 金额: $ 60.51万
• 依托单位: Queen Mary University of London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FX019306%2F1
• 关键词: Cooperative; Noble; Base; Metal; Catalysis

In the UK, the chemicals sector is a key contributor to the UK economy. It adds close to £20 billions of value to the country's economy every year and has an annual turnover of approximately £60 billion, sustaining more than half a million jobs. Within this sector, the manufacture of most chemicals involves the use of a catalyst, which is usually based on the rarest elements on the Earth's crust, such as noble metals (Pd, Rh or Ir). The limited supply of these group of privileged metals, together with their huge environmental footprint (e.g. obtaining 1 kg of pure metallic Rh produces near 32t of carbon dioxide) blocks the development of truly sustainable processes. This is pushing chemists towards the discovery of catalysts based on inexpensive, abundant, and benign base metals (e.g. Ni, Co and Fe). However, reactivity on BM centres often proceeds through one-electron events, resulting in difficulties controlling and maintaining the catalyst function, thus preventing the development of sustainable, efficient, and predictable catalysts. Among all the strategies employed to control the chemistry of base metals, we were attracted by chemical metal-ligand cooperation, in which actor ligands participate in bond-forming and breaking events. Based on this, our strategy to tame two-electron catalytic cycles and develop predictable catalytic methods with BM will exploit low-valent aluminium-based ligands. Thus, our aim will be furnishing ambiphilic Al-BM units that are capable of (1) binding substrates to the highly electrophilic Al centre and (2) activate them using a nucleophilic base metal centre. Using Al as binding site is not a random choice: this group 13 element is not only benign, but the most abundant metal in the Earth's crust. Furthermore, in its +1 oxidation state presents interesting properties as ligand, becoming a powerful sigma-donor with an empty and accessible p-orbital. These properties have been recently exploited in the field of noble metal catalysis. Nonetheless, heterobimetallic complexes in which Al(I) is paired with another earth-abundant metal remain under-explored and currently limited to stoichiometric activation of small molecules. In these examples, however, the integrity of the Al-BM bond is lost. This represents a major challenge for their implementation in catalytic processes, as ligand dissociation leads to disruption of their cooperative activation ability, resulting in catalytic deactivation. To overcome this issue and achieve rigid and stable structures and Al-BM bonds, we will establish a rational design strategy to obtain bespoke Al-BM complexes that will be built by a delicate selection of ligand backbone, anchor arms, and base metal centre (Co, Ni, Fe). These complexes will be studied using a bottom-up approach based on a stoichiometric-to-catalytic strategy: employing the knowledge gathered from stoichiometric activation studies, infusing nobility to Al-BM units in a catalytic fashion will be within reach. The implementation of Coop-NBM will represent a greener and cheaper alternative to functionalise organic molecules compared to noble metal catalysis, allowing the achievement of environmentally friendly approaches with potential to be applied at industry.Overall, the importance of this research proposal lies in its potential to provide catalysts based on the most abundant elements of our planet, e.g. Al and Fe. Catalytic use of base metals combined with subvalent Al ligands remains an uncharted territory and an exceptional opportunity to establish a new chemical space that could lead to a dramatic reduction of the environmental footprint of countless organic transformations currently performed by noble metal catalysis. This will certainly make the UK take centre stage in the development of sustainable technologies aiming at retiring noble metals as workhorses of chemical industry.

在英国，化学部门是英国经济的关键因素。它每年为该国的经济增加了近200亿英镑的价值，每年的营业额约为600亿英镑，拥有超过50万个就业机会。在该领域，大多数化学物质的生产涉及使用催化剂，该催化剂通常基于地壳上的罕见元素，例如贵金属（PD，RH或IR）。这些特权金属的供应有限，以及它们巨大的环境足迹（例如，获得1千克纯金属RH产生32T二氧化碳的产生），阻止了真正可持续的过程的发展。这将化学家推向基于廉价，丰富和良性碱金属（例如Ni，Co和Fe）的催化剂。但是，BM中心的反应性通常是通过单电子事件进行的，从而导致控制和维持催化剂功能的困难，从而阻止可持续，高效和可预测的催化剂的发展。在控制碱金属化学的所有策略中，我们被化学金属配体合作所吸引，其中演员配体参与键合和破坏事件。基于此，我们驯服两电子催化循环并使用BM开发可预测的催化方法的策略将利用低价值的基于铝的配体。这是我们的目标是提供能够（1）结合高度亲电的AL中心的弹性AL-BM单元，并使用核philic碱金属中心激活它们。使用Al作为结合位点不是一个随机的选择：该组13元素不仅是良性的，而且是地球上最丰富的金属。此外，在其+1氧化状态中，呈现出有趣的特性，成为配体，成为一个强大的Sigma-Donor，具有空的且易于访问的p轨道。这些特性最近在贵金属催化领域进行了探索。尽管如此，Al（i）与另一种土壤丰富的金属配对的异金属复合物仍然不足，目前仅限于小分子的化学计量激活。但是，在这些示例中，al-BM键的完整性丢失了。这是它们在催化过程中实施的主要挑战，因为配体解离会导致其合作激活能力的破坏，从而导致催化失活。为了克服这个问题并实现刚性和稳定的结构和AL-BM键，我们将建立一个合理的设计策略，以获取Al-BM综合体，该综合体将通过精致的配体骨干，锚固臂和基准金属中心（CO，NI，FE）来构建。这些复合物将使用基于化学计量到催化策略的自下而上的方法进行研究：采用从化学计量激活研究中收集的知识，以催化方式将贵族注入AL-BM单位。与高贵的金属催化相比，Coop-NBM的实施将代表一种更绿，更便宜的有机分子的替代品，从而实现了在行业上实现具有潜力的环境友好方法。此外，这项研究的重要性在于该研究的重要性在于其潜力，其潜力在于基于我们星球最丰富元素的催化剂。 al和fe。将碱金属与亚果Al配体结合使用的催化使用仍然是一个未知的领域，也是建立新的化学空间的非凡机会，这可能导致贵族金属催化目前执行的无数有机转化的环境占地面积。这肯定会使英国成为可持续技术发展旨在退休贵族金属作为化学工业的工作主手的中心阶段。