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

Lead Research Organisation: Durham University
Department Name: Chemistry


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.


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