Synthesis and Coordination Chemistry of Novel Multi-dentate Carbenes as Ligands - Initiating Collaboration with University of California at Riverside

这个项目将探索一类特殊的化合物的基本行为的某些方面，这些化合物被称为卡宾，这是一种高活性的碳基(有机)分子。这是如此之多，以至于直到20世纪80年代末的S，它们还被认为只是暂时的中间体，只有在极低的温度下才能使用特殊设备进行分离。卡宾的反应性很大程度上源于它们的结构，R2C(不带电)。这会产生一个“二价”的中心碳原子，而不是“四价”的(大多数碳基化合物的情况)，使其缺乏电子(因此是活性的)。然而，在过去十年左右的时间里，已经制备了三类卡宾，它们可以像任何普通有机化合物一样被分离和操纵。这些所谓的“瓶装卡宾”吸引了化学家的巨大兴趣，不仅在基础水平上，而且在更多的应用化学方面。最重要的是，研究表明，当它们附着在金属上(并通过电子给予或共享)时，所生成的含金属化合物显示出出色的催化剂性能。以高效(反应步骤最少，废物可忽略)、清洁和环境友好的方式合成精细的碳基分子，对于制备新材料和药物具有重要的工业意义。生产这类物种的一种特别有吸引力的方法是使用基于金属的“催化剂”，这种方法：a)使在没有金属的情况下通常无法实现的反应成为可能；b)选择性(只与特定的起始原料实现一种类型的反应)；c)高效(即使用少量的金属催化剂来生成许多所需的产品分子)，副反应很少或没有。这些基于金属的催化剂的成功不仅源于对金属的正确选择，还源于对有助于支撑金属/通常是有机化合物的‘支架’(或‘配体’)的精心设计。因此，催化的持续成功有赖于生产更精细和更可调的配体；卡宾的性质使它们成为此类应用的非常有吸引力的目标。本项目将只关注一种类型的“瓶装卡宾”，即“环(烷基)(氨基)卡宾”(CAAC)，它通过将富电子的氮原子直接与中心碳结合来解决电子太少的问题。这些特殊的卡宾不仅易于制备(并且可以通过各种结构获得/这是“微调”催化剂的基本特征)，而且它们具有许多独特的化学性质，使它们从其他两类中脱颖而出。然而，作为金属的配体，它们几乎没有受到任何关注！该计划将允许申请者访问该领域的世界领先者的实验室，并给他机会学习如何制备这些令人兴奋的卡宾化合物，同时准备有助于控制用于催化剂的金属的反应性和选择性的配体。申请者将把这项“技术”带回英国，并将其用于他的研究小组正在进行的项目中。在访问期间，申请者将花时间与东道主一起撰写建议书，以支持使用这种新开发的配体的合作项目。重要的是，申请者还将有机会向东道主大学及其工作人员展示他自己的研究成果。这不仅将有助于更广泛地消除他自己感兴趣的领域，而且对于促进未来的国际合作也将是极其重要的，这是正在争取的赠款的一个重要特征。

This project will explore certain aspects of the fundamental behaviour of a particular family of compounds called 'carbenes', which are highly reactive carbon-based (organic) molecules. This is so much so that up until the late 1980's they were thought of as only being transient intermediates, which could only be isolated using special equipment at extremely low temperatures. The reactivity of carbenes stems largely from their structure, R2C (uncharged). This gives rise to a central carbon atom that is 'divalent' rather than 'tetravalent' (the situation found for the majority of carbon-based compounds) leaving it short of electrons (and hence reactive). However, over the last decade or so three classes of carbene have been prepared that can be isolated and manipulated in much the same way as any normal organic compound. These so-called 'bottleable carbenes' have attracted huge interest from chemists, not only at a fundamental level, but also in much more applied chemistry. Most importantly, it has been shown that when they are attached to metals (and held by electron-donation or /sharing), the resulting metal-containing compounds show outstanding performance as 'catalysts'.The synthesis of elaborate carbon-based molecules in efficient (minimal reaction steps with negligible waste), clean and environmentally friendly ways is of great importance industrially for the preparation of, for example, new materials and pharmaceuticals. One particularly attractive method for the production of such species is to use metal-based 'catalysts', which: a) make possible reactions that are not normally achievable in the absence of the metal; b) are selective (achieve only one type of reaction with a particular starting material); and c) are efficient, (i.e. a small quantity of metal catalyst is used to generate many of the desired product molecules) with little/no side reactions. The success of these metal-based catalysts results from not only the right choice of metal, but also from the careful design of the 'scaffold' (or 'ligands') that help support the metal / generally organic compounds. Thus, the continued success of catalysis relies upon the production of ever more refined and 'tuned' ligands; the properties of carbenes make them very attractive targets for such applications.This project will focus on just one type of 'bottleable carbene', namely 'Cyclic(Alkyl)(Amino) carbenes' (CAACs), which get round the problems of having too few electrons by having an electron-rich nitrogen atom bound directly to the central carbon. These particular carbenes, are not only readily prepared (and can be obtained with a diverse range of structures / an essential feature for 'fine-tuning' catalysts), but they have a number of unique chemical properties that make them stand out from the other two classes. However, they have received virtually no attention as ligands for metals!The programme will allow the applicant to visit the laboratory of the world leader in this field and give him the opportunity to learn how to prepare these exciting carbene compounds, while at the same time preparing ligands that will be beneficial for controlling the reactivity and selectivity of metals used in catalysis.The applicant will bring this 'technology' back to the UK and use it to input into on-going projects in his research group. During the visit itself, the applicant will spend time with his host writing proposals to support collaborative projects using this newly developed ligands.Importantly, the applicant will also have the chance to present his own research to the host university and its staff. This will not only help diseminate his own areas of interest more widely, but will also be extremely important in fostering future international collaborations, an important feature of the grant being appled for.