Main-group element compounds possessing multiple reaction centers - Systems between cooperativity, synergy and emergence

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Catalysis is one of the most powerful strategies to convert both conventional and alternative resources to valuable chemicals in environmentally friendly and economical processes. Current industrial catalysts almost exclusively incorporate precious and non-precious transition-metals, which are scarce (and correspondingly expensive) and often problematic with regard to (eco)toxicity. Thus, there is a need for alternative concepts that incorporate abundant and more environmentally friendly main-group elements as active sites. However, mechanistic scenarios operative in transition-metal catalysis are so far not fully applicable in catalysis by main-group element compounds. The catalytically most relevant sequence of oxidative addition and reductive elimination has not yet been achieved for main-group element compounds. Consequently, the development of new modes of small molecule activation and transformation as well as the enhancement of complementary strategies are worthy of pursuit. This project is centered around the activation and catalytic functionalisation of small molecules and inert chemical bonds by means of polynuclear environmentally benign main-group element compounds incorporating aluminium, calcium, gallium, germanium, magnesium, silicon and tin. We are interested in both the cooperative and the emergent effects that arise when a ligand frame hosts two active sites in close proximity. Cooperativity or synergism describes the enhanced reactivity of a multi-site catalyst compared to an equivalent mixture of single-site catalysts. In contrast, emergent effects are irreducible, i.e., the observed chemical transformations are not accessible by using single-site catalysts. We do not necessarily seek to establish immediate substitutes for transition-metal catalysts, but rather to develop new concepts for bond breaking and making mediated by main-group element compounds.