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，化学品行业是英国经济的主要贡献者，每年为该国经济增加近200亿英镑的价值，年营业额约为600亿英镑，维持了超过50万个就业岗位。在该领域，大多数化学品的制造都涉及使用催化剂，催化剂通常基于地壳中最稀有的元素，例如贵金属（钯、铑或铱）。这些特殊金属的供应有限。 ，连同他们的巨大的环境足迹（例如，获得 1 公斤纯金属铑会产生近 32 吨二氧化碳），这阻碍了真正可持续工艺的发展，这促使化学家发现基于廉价、丰富且良性的贱金属（例如镍、然而，BM中心的反应通常通过单电子事件进行，导致难以控制和维持催化剂功能，从而阻碍了可持续、高效和可预测的催化剂的开发。为了控制贱金属的化学，我们被化学金属-配体合作所吸引，其中演员配体参与成键和断裂事件，基于此，我们的策略是驾驭双电子催化循环并开发可预测的催化方法。 BM 将利用低价铝基配体，因此，我们的目标是提供能够 (1) 将底物结合到高亲电子 Al 中心和 (2) 激活的两亲性 Al-BM 单元。使用亲核贱金属中心并不是随机选择：这种第 13 族元素不仅是良性的，而且是地壳中最丰富的金属。此外，其 +1 氧化态具有以下有趣的特性。配体，成为具有空且可接近的p轨道的强大的σ供体，这些特性最近已在贵金属催化领域得到利用。与另一种地球丰富的金属配对仍处于探索之中，目前仅限于小分子的化学计量活化，然而，在这些例子中，Al-BM键的完整性丧失，这对其在催化过程中的实施构成了重大挑战。 ，因为配体解离会导致其协同活化能力的破坏，从而导致催化失活。为了克服这个问题并获得刚性和稳定的结构和Al-BM键，我们将建立合理的设计策略来获得定制的Al-BM配合物。将通过精心选择配体主链、锚臂和贱金属中心（Co、Ni、Fe）来构建这些配合物，并将使用基于化学计量催化策略的自下而上方法进行研究：采用从化学计量活化研究中收集的知识，以催化方式向 Al-BM 单元注入贵金属将是可以实现的，与贵金属相比，Coop-NBM 的实施将代表一种更环保、更便宜的有机分子功能化替代方案。总体而言，这项研究提案的重要性在于其提供基于地球上最丰富的元素（例如铝和铁）的催化剂的潜力。贱金属与亚价铝配体的结合仍然是一个未知的领域，也是建立一个新的化学空间的绝佳机会，可以大大减少目前由贵金属催化进行的无数有机转化的环境足迹，这肯定会让英国受益。成为可持续技术开发的中心舞台，旨在让贵金属不再是化学工业的主力。

项目成果

Cooperation towards nobility: equipping first-row transition metals with an aluminium sword.

与贵族合作：为第一排过渡金属配备一把铝剑。

• DOI: http://dx.10.1039/d3dt02722h
• 发表时间: 2023
• 期刊: 2003)
• 作者: Fernández S