Living Libraries of Intermetallic Superatoms

具有非常不同性质（M/E）的丰富金属的金属间化合物可以潜在地替代基于稀有和贵金属的工业催化剂。为了实现这一机会，原子精确/高效的催化剂设计需要在101 nm的尺寸范围内，其中每个金属原子都是“计数”的。我们发现了一种新的方法来产生亚稳定的连接簇[MaEb]（R）n的“活文库”。这些金属间化合物“超原子”是固态M/E材料的分子对应物。电子状态，例如开放与封闭的“超原子壳”，控制稳定性和反应性。设计标准是金属的选择和混合比例、核（大小）、核结构和连接。术语“活的”突出了进化库的特性，其被定义为簇、生长物种和添加剂的动态混合物。一个活的图书馆通常不会达到化学平衡。它的簇的分布是高度敏感的扰动，其中包括与反应物的相互作用被捕获或转换在簇表面。该假设是，库中充满了相互关联的集群，短暂的和高度反应性的，以及更容易访问，但反应性较低的。这些组合是由初始组分和库演化条件的多变量集合生成的，这些因素涉及成核、生长和降解反应的网络，涉及加成缔合、解离，涉及金属原子位点活化（例如通过配体脱保护）以及涉及与簇表面处的小分子（H2、CO2、CH 4、H2O、O2、N2、NH3、NOx、小烃）的反应。该项目的核心方法是探测（组）库，而不是首先靶向和分离特定的簇，然后研究它们的反应性。平行测试的策略使我们能够探索广阔的材料空间，并直接解决化学复杂性。库（图1）允许有效探测与超原子处小分子的催化转化相关的基元反应步骤。实验方法的多因素设计和库进化监测质谱结合计算建模将被应用。风险来自于不可扩展大小机制（大小、结构、异构体、波动、M/E无序、稳定性）中对簇属性的微妙控制。到目前为止，动力学和机制无法预测：因此，我们必须处理库对组分和条件的高敏感性，从而导致要分析的物种的多样性。然而，收益恰恰来自于这种化学丰富性，我们期待一种新的“超原子催化化学”。

Intermetallics of abundant metals of very different properties (M/E) can potentially substitute industrial catalysts based on rare and precious metals. To realize this opportunity, atom-precise/-efficient catalyst design is required at the size regime of  1 nm, where every metal atom ‘counts’. We discovered a novel way to generate ‘living libraries’ of meta-stable, ligated clusters [MaEb](R)n. These intermetallic ‘superatoms’ are molecular counterparts of the solid state M/E materials. The electronic state, e.g. open vs. closed ‘superatom shell’, controls stability and reactivity. The design criteria are metals selection and mixing ratio, nuclearity (size), core structure and ligation. The term ‘living’ highlights the properties of an evolving library, which is defined as a dynamic mixture of clusters, growth species and additives. A living library has typically not reached chemical equilibrium. Its distribution of clusters is highly sensitive to perturbation, which includes the interaction with reactants to be trapped or converted at the cluster surface. The hypothesis is that the libraries are populated with interrelated clusters, transient and highly reactive as well as more accessible but less reactive ones. These portfolios are generated by multivariate sets of initial components and library evolution conditions, which factors relate to networks of nucleation, growth and degradation reactions, to additive association, dissociation, to metal-atom site activation (e.g. by ligand deprotection) and to reactions with small molecules at the cluster surface (H2, CO2, CH4, H2O, O2, N2, NH3 NOx, small hydrocarbons). The central approach of the project is probing (sets of) libraries rather than targeting and isolating specific clusters first and then studying their reactivity. The strategy of parallel testing enables us to explore a wide materials space and it directly addresses chemical complexity. The libraries (Fig. 1) allow for efficient probing elementary reaction steps related to catalytic transformation of small molecules at superatoms. Multi-factor design of experiment methods and library evolution monitoring by mass spectrometry combined with computational modeling will be applied. Risk arises from the subtle control of cluster properties in the non-scalable size regime (size, structure, isomers, fluctuation, M/E disorder, stability). Kinetics and mechanisms cannot be predicted, so far: thus, we have to deal with the high sensitivity of the libraries to components and conditions, leading to a diversity of species to be analyzed. However, the gain arises exactly from this chemical richness and we anticipate a new ‘superatom chemistry for catalysis’.