Transition Metal Alkane Sigma Complexes by Solid-Gas Synthesis Routes: Defining and Exploiting a New Area of Organometallic Chemistry

固-气合成路线的过渡金属烷烃西格玛配合物：定义和开发有机金属化学的新领域

• 批准号: EP/K035908/1
• 负责人: Andrew Weller
• 金额: $ 34.9万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FK035908%2F1
• 关键词: Transition; Metal; Alkane; Sigma; Complexes

Alkanes are cheap and readily available chemicals and a long-term goal of chemical research has been to develop methods to exploit these species directly as chemical feedstocks. This would greatly improve the overall efficiency of chemical synthesis used in the production of commodity and fine chemicals that underpin the chemical and pharmaceutical industries. In order to achieve this goal the means to "activate" (i.e. break) the notoriously unreactive C-H bond is required. While examples of such C-H activation with transition metal complexes have been reported in recent years, much more information on this process is required before the integration of C-H activation into chemical synthesis is fully realised. Much useful insight could be gained by studying the way an alkane interacts with a metal centre prior to actually cleaving the C-H bond. This requires the means to prepare and study such so-called 'transition metal alkane sigma complexes'; however, until recently, examples of such species have been extremely limited due to the lack of straightforward and predictable general methods of preparation. Very recently the Weller (experimental chemistry) and Macgregor (computational modelling) research groups have reported a breakthrough in the synthesis and characterisation of transition metal alkane sigma complexes (see Science 2012, 337, 1648). Our approach was to react a transition metal alkene precursor in the crystalline solid-state with hydrogen gas. This produces the equivalent alkane sigma-complex directly in the crystalline state, allowing for its full characterisation by a variety of experimental and complementary computational techniques. This represents a step-change in current state-of-the-art for the synthesis and characterization of transition metal alkane sigma-complexes, opening up the exciting prospect that, for the first time, such species could be routinely synthesized and their chemistry fully understood.This research proposal seeks support for the Weller and Macgregor groups to fully explore and generalise the new gas-solid synthetic methodology for the synthesis of transition metal alkane sigma-complexes. Our approach will involve experimental synthesis and characterisation allied with the computational modelling; with the latter also providing structural data that are difficult to routinely obtain by experimental means. In addition computational modelling can be used to predict how strong the transition metal-alkane interaction will be. In this way the calculations will be able to target the most promising combinations for further study experimentally, thus significantly enhancing the overall productivity of the project. From our understanding of what makes a transition metal alkane sigma complex stable in the solid state we will then move to develop systems that are also stable in solution in order to provide definitive data on the properties and reactivity (i.e. C-H activation) of such species. Another exciting possibility will be to explore what other chemical transformations occur in the gas-solid regime; for example the commercially important catalytic hydrogenation of alkenes may occur in the solid state, without the need to revert to the use of solvents.The research in this project is fundamental in nature, however it will deliver significant long-term legacy through developing the chemistry of transition metal alkane sigma-complexes and how such species relates to the key C-H activation process. It will also explore the development of solid-state organometallic chemistry, both in terms of making new organometallic supramolecular complexes, but also, more generally, by exploring the potential of new catalytic processes (especially solid-gas reactions) in the solid state.

烷烃是廉价且容易获得的化学品，化学研究的长期目标是开发直接利用这些物种作为化学原料的方法。这将大大提高化学合成的整体效率，用于生产支撑化学和制药工业的商品和精细化学品。为了实现这一目标，需要“激活”（即断裂）臭名昭著的非反应性C-H键的方法。虽然近年来已经报道了用过渡金属络合物进行这种C-H活化的例子，但是在完全实现将C-H活化整合到化学合成中之前，需要关于该过程的更多信息。通过研究烷烃在实际裂解C-H键之前与金属中心的相互作用方式，可以获得许多有用的见解。这需要制备和研究这种所谓的“过渡金属烷烃σ络合物”的手段;然而，直到最近，由于缺乏直接和可预测的一般制备方法，这种物质的实例非常有限。最近，Weller（实验化学）和Macgregor（计算建模）研究小组报道了过渡金属烷烃σ络合物的合成和表征的突破（参见Science 2012，337，1648）。我们的方法是使结晶固态的过渡金属烯烃前体与氢气反应。这直接在结晶状态下产生等价的烷烃σ-复合物，允许通过各种实验和互补计算技术对其进行充分表征。这代表了过渡金属烷烃σ-配合物的合成和表征的当前最新技术水平的一个阶段性变化，开辟了令人兴奋的前景，首次，此类物质可以常规合成，并且它们的化学成分可以被充分理解。这项研究提案寻求支持Weller和Macgregor小组充分探索和概括这种新气体-合成过渡金属烷烃σ-络合物的固体合成方法。我们的方法将涉及实验合成和表征与计算建模结盟，后者还提供了难以通过实验手段常规获得的结构数据。此外，计算模型可用于预测过渡金属-烷烃相互作用的强度。通过这种方式，计算将能够针对最有希望的组合进行进一步的实验研究，从而显着提高项目的整体生产力。从我们对是什么使过渡金属烷烃σ络合物在固态下稳定的理解，我们将转而开发在溶液中也稳定的系统，以便提供有关此类物质的性质和反应性（即C-H活化）的明确数据。另一个令人兴奋的可能性将是探索在气-固状态下发生的其他化学转变;例如商业上重要的烯烃的催化氢化可以在固态下发生，而不需要恢复到使用溶剂。该项目的研究本质上是基础性的，然而，它将通过开发过渡金属烷烃σ-络合物的化学以及这些物质如何与关键的C-H活化过程。它还将探索固态有机金属化学的发展，无论是在制造新的有机金属超分子络合物方面，还是更普遍地通过探索固态新催化过程（特别是固气反应）的潜力。

项目成果

A Rhodium-Pentane Sigma-Alkane Complex: Characterization in the Solid State by Experimental and Computational Techniques.

• DOI: 10.1002/anie.201511269
• 发表时间: 2016-03-07
• 期刊: Angewandte Chemie (International ed. in English)
• 作者: Chadwick FM;Rees NH;Weller AS;Krämer T;Iannuzzi M;Macgregor SA
• 通讯作者: Macgregor SA