The Ironworks: a mechanistic foundry for iron-catalysed cross-coupling

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The formation of carbon-carbon bonds lies at the very heart of the production of the molecules that society depends on. Prime examples include pharmaceuticals, agrochemicals and fine chemicals such as the oleds in the screen that you are probably looking at. There are many ways of producing C-C bonds, but exploiting catalysis hugely increases the sustainability of a given transformation as it reduces the amount of energy required and waste produced as well as the number of individual steps necessary in the production. Indeed catalysis is used in the manufacture of around 90% of all chemicals. Transition metals play a special role in catalysis and the platinum group metals (PGMs) such as platinum, rhodium and, in particular palladium, are ubiquitous in many carbon-carbon bond-forming processes, especially in so called catalytic cross-coupling reactions. However, like all PGMs, due to its toxicity, palladium is subject to FDA and EAEMP regulatory control, currently to less than 5-10 ppm in pharmaceutical products, reducing its attractiveness in larger-scale manufacture. Furthermore, due to low natural abundance, all PGMs are defined as being at "very high risk" on the British Geographical Society's 2011 Risk List of 52 elements or element groups necessary to maintain our economy and lifestyle (http://www.bgs.ac.uk/mineralsuk/statistics/riskList.html). With ever increasing competition from the automotive and consumer electronics sectors the long-term use of PGMs in catalysis is unsustainable.Therefore there is a major drive to uncover new catalysts based on Earth abundant metals from the first row transition elements: the low toxicity and high availability of iron (fourth most common element in the Earth's crust) make it the ideal candidate to replace palladium. Thus there has been considerable global effort in the use of iron in carbon-carbon bond-formation studies, however the field is about to hit a major impasse: the simplest iron-catalysed cross-coupling reactions have been realised, while many of the more attractive processes, commonly exploited in palladium catalysis, remain elusive. This is because we have at best only a rudimentary grasp of the mechanisms involved in iron catalysis. These mechanisms are far more challenging to study than those based on palladium. Accordingly we propose to launch a detailed mechanistic study exploiting a wide raft of complementary techniques at four different institutions (Bristol, Cardiff, Bath, Princeton) to uncover the detailed nature of the true active catalysts and their modes of catalytic action. Then we intend to use this unique data to deliver iron-based catalysts for highly desirable yet unmet catalytic processes, building them from the bottom up.