Redox shuttling and catalysis – exploiting novel anionic aluminyl-ligand and aluminyl-d-block metal synergy

催化可能是上个世纪发展起来的化学科学最重要的应用。通过干预在反应结束时再生的化合物来提高化学转化的速度和选择性，是以资源高效的方式组装复杂分子的有力工具。然而，由于其氧化还原的灵活性，这一领域尤其由贵重的过渡金属主导。因此，成型化合物来自丰富的、化学上无害的较轻的p-块元素(例如，Al、Si等)。通过分子设计与工业相关分子以“过渡金属”的方式相互作用，代表着一种令人兴奋的基本化学挑战，提供非常高的潜在回报。铝是地壳中质量最丰富的元素之一(仅次于氧气和硅)。最近，低价铝化合物，具有一个带阴离子电荷的亲核Al中心，即铝基阴离子([R2Al：]-M+)，处于+I氧化态，具有相对较小的HOMO-LUMO能隙，在潜在模拟过渡金属的双亲反应活性方面显示出很好的活性。然而，铝基阴离子在氧化还原催化中的应用仍然具有挑战性，因为与还原消除相关的困难，从而释放了功能化的底物。本项目的愿景围绕着两个相互关联且日益雄心勃勃的科学目标：i)Al(I)/Al(III)催化：本项目的初始目标是通过系统地设计支撑支架来开发具有可用的[n/(n+2)]氧化还原灵活性的新型阴离子铝(I)物种，并利用这一见解建立水合元素化学(如氢化、氢硼化、氢硅化等)的主族氧化还原催化。ii)双金属催化：尽管如此，我们本项目的主要目标是获得基于铝基体系的无Tm催化。然而，双亲铝基配体对Tm的强烈转化作用(源于Al的强σ-给体和Lewis酸性)和铝基-过渡金属的协作性也可能有助于激活更具挑战性的惰性键(例如烷烃的SP3C-H键)。因此，我们假设铝基配体和过渡金属在共价连接的双金属体系中的结合将使具有氧化还原灵活性的表面新的键活化过程能够增强合作的化学计量和催化过程(例如，烷烃的催化脱氢)。

Catalysis is perhaps the most important application of the chemical sciences developed over the past century. Enhancement of the rate and selectivity of a chemical transformation through the intervention of a compound that is regenerated at the end of the reaction represents a potent tool for assembling complex molecules in a resource-efficient manner. However, this field is particularly dominated by the precious transition metal owing to their redox flexibility. Thus, molding compounds derived from the abundant, chemically benign lighter p-block elements (e.g., Al, Si, etc.) through molecular design to interact with industrially relevant molecules in a 'Transition Metal like' fashion represents an exciting fundamental chemical challenge offering very high potential rewards. Aluminium is one of the most abundant elements in the earth's crust by mass (following oxygen and silicon). Recently, low valent aluminium compounds, possessing a nucleophilic Al centre with an anionic charge, namely aluminyl anion ([R2Al:]-M+), which are in the +I oxidation state, with comparatively small HOMO‐LUMO gaps, showed promising activity in potentially mimicking the ambiphilic reactivity of transition metals. Nevertheless, utilization of aluminyl anion in redox-based catalysis remains challenging due to the difficulties associated with reductive elimination, and therefore release of the functionalized substrates. The vision of this project is centered around two inter-related and increasingly ambitious scientific aims:i) Al(I)/Al(III) catalysis: The initial goal of this project is to develop novel anionic aluminium(I) species with usable [n/(n+2)] redox flexibility through the systematic design of supporting scaffold and use this insight to establish main group redox catalysis of hydroelementation chemistry (e.g., hydrogenation, hydroboration, hydrosilylation, etc.).ii) Bimetallic catalysis: Albeit, our prime goal of this project is to procure TM-free catalysis based on aluminyl system. However, the strong transformative effect of the ambiphilic aluminyl ligand to the TM (derived from the strong σ-donation and Lewis acidity of Al) and aluminyl-transition metal cooperativity could also be useful for activation of more challenging inert bonds (e.g., sp3 C-H bond of alkane). Thus, we hypothesize that combining aluminyl ligand and transition metal in a covalently linked bimetallic system will enable the facial novel bond activation processes with redox flexibility to enhance cooperative stoichiometric and catalytic processes (e.g., catalytic dehydrogenation of alkane).