Hemicarcerand ligands for the systematic investigation of sigma-alkane complexes

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The selective functionalisation of alkanes is an area of contemporary importance - motivated by the desire to make efficient and effective use of these inexpensive and abundant hydrocarbons in organic synthesis and as feedstocks for the chemical industry. Such objectives are encumbered by the chemical inertness of alkanes, conferred upon them by the strong constituent C-C and C-H bonds. Through the action of soluble transition metal catalysts, progress has been made in overcoming these limitations although many substantial challenges remain for large-scale practical implementation. One of the key stumbling blocks has proven to be establishing the fundamental mechanistic chemistry of these processes: encumbered by their transient and extremely reactive nature, metal-based intermediates involved in alkane activation processes are exceedingly difficult to investigate using conventional approaches. Such information constitutes vital prerequisite knowledge for the rational development of useful catalytic systems.The proposed research project involves the development of an unprecedented supramolecular approach for systematically investigating the transition metal mediated activation of alkanes, in particular elusive sigma-alkane intermediates. The approach entails the preparation and use of well-defined macromolecular cavitand ligands, which both promote and stabilise the formation of transition metal sigma-alkane complexes through encapsulation of the alkane within the interior of the macromolecule. The inclusion of the alkanes within these supramolecular systems effectively circumvents detrimental problems associated with conventional strategies and allows effective interrogation of the metal-alkane interaction. Ultimately, this approach will generate a definitive body of fundamental chemistry that will enable a step change in understanding of alkane activation methods.