Activation of C-H and B-H bonds through sigma-bonding to Cobalt complexes

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By applying knowledge gained from the extensive research into 4d and 5d metal complexes for C-H activation and dehydrocoupling of amino borane, to 3d metals, especially cobalt. A range of novel catalysts will be synthesised, characterised and used in catalysis with a focus upon dehydrocoupling and C-H activation processes and in particular the generation of sigma-alkane complexes. The use of 3d metals in these processes is relatively unexplored and offers many scientific and technological opportunities. Amine boranes have received considerable recent attention due to the range of their potential uses: as a hydrogen storage and transport vector, as precursors for ceramic BN thin-films, and as precursors to polymers with potentially interesting properties. The majority of reported catalysts for dehydrocoupling of amine boranes are based on 4d and 5d metals, with limited research addressed towards finding examples of cobalt complexes. The few cobalt examples investigated have low activity and selectivity for the polyaminoborane target product and are ill defined. By applying previous research into rhodium and iridium based catalysts to cobalt based systems new, highly active, complexes will be isolated, characterised and used in catalysis. Following this with detailed mechanistic studies will lead to insight into this previously under investigated class of catalyst. These same complexes should also display interesting behaviour in C-H activation. Due to its potential applications in the transformation of natural gas into chemical feedstocks, and in natural product synthesis, C-H activation has been the focus of extensive research. Again, most of this work has been carried out using 4d and 5d metal complexes. A focus within the Weller group has been on the isolation of the low valent sigma-alkane complexes as an intermediate in C-H activation processes. The group has carried out single-crystal solid-gas reactions which have led to the isolation of a number of rhodium based sigma-alkane complexes. Application of this same methodology to cobalt could allow the synthesis of 3d sigma-alkane complexes, which would be a significant landmark discovery in the area. This project falls within the EPSRC Physical Science research area, more specifically within the focus of catalysis. It is estimated that catalysis currently contributes over £50 billion/year to the UK economy, and further development is essential for transformation towards a sustainable society.