Group 2: Elements of 21st Century Catalysis

Catalysis, the acceleration of chemical transformation, is the key to realising environmentally friendly and economical processes for the conversion of both conventional (fossil) and alternative (e.g. biomass and carbon dioxide) chemical feedstocks. Catalysts act by reducing the energy required for a reaction to proceed and will, thus, occupy a key role in the world's energy future. Many of the most useful soluble and solid catalysts incorporate precious metals such as rhodium, palladium, platinum and ruthenium. These metals are expensive and their supply is limited. There is, therefore, a need for the development of non-precious-metal catalysts as replacements. This project proposal seeks funding for a joint synthetic/computational study of the emerging area of the application of environmentally benign and non-toxic Group 2 complexes in homogeneous catalysis. Using chemistry that has been developed in the applicants' own laboratories as a starting point, we shall seek to develop the range of available and easily synthesised alkyl and hydride reagents. Tandem experimental and theoretical studies will be employed to interrogate the factors which dictate the reaction chemistry of these superficially simple but understudied derivatives and will apply this knowledge to the development of ever more ambitious catalytic schemes. To this end we shall challenge one of the most pressing chemical scientific challenges of the early 21st Century, viz the low energy transformation of bulk resources with minimum cost in terms of energy and environmental impact.

A major 21st Century challenge for chemists working in both small research laboratories and with large scale industrial processes is the development of new molecular species for the atom-efficient catalysis of chemical transformation. Catalysis addresses a number of pressing issues for the continued advancement of mankind, namely the assembly of useful bulk, fine chemical or pharmaceutical compounds with minimal energy input and negligible impact upon the environment through the minimisation of by-product waste streams. Historically, homogeneous catalytic research has been concentrated upon species derived from the heavier transition metals and exemplified by the award of a Nobel Prize in 2005 for the development of olefin metathesis catalysts based upon elements such as molybdenum and ruthenium. Many of these elements are, however, scarce and, therefore, expensive. They can also represent an environmental hazard without stringent control of waste products and careful product purification steps to ensure the complete removal of residual contamination. In contrast, the entire series of Group 2 elements below, and including, magnesium are completely non-toxic and exist in high abundance. As a result, issues of cost and the threat of environmental contamination through the use of these elements are all but non-existent, while concerns over process and chemical sustainability may be positively emphasised from the outset of any developmental process. The aspiration of this project from an academic standpoint is ambitious and motivated by a desire to effectively rewrite the sections of chemistry textbooks dedicated to the reactivity of Group 2 element complexes. We have put forward a plan to further exploit our hard-earned experience and expertise in the design and catalytic implementation of new molecular compounds based upon the alkaline earth elements. Our previous investigations have garnered world-wide attention and a number of research groups in Europe, the United States and Japan, as well as in the United Kingdom, have followed our lead and have implemented programmes of study that are both complementary as well as competitive with our established researches. It can be seen, therefore, that our previous work has been highly influential in initiating global academic interest in a class of compound that has been hitherto disregarded by the chemical community. An indication of this increasing attention is provided by the prominence of this catalytic chemistry in the finalised programme of a symposium devoted to 'Early Main Group Chemistry' at the Pacifichem Conference in December 2010. Both Hill and Hunt have accepted invitations to present their work, alongside many of the other international players named on page 2 of the Case for Support of this proposal, at this symposium. Although still relatively immature, our researches have also attracted the attention of the pharmaceutical industry and academic researchers actively engaged in the targeted synthesis of natural and pharmaceutically-relevant organic compounds. A component of this research proposal, therefore, is geared directly toward a demonstration of the practicality of this chemistry as a key component of wider, multistep chemical syntheses. A primary and tangible impact will be the incorporation of the compounds, techniques and reactivity developed during this study into the broad palette of reagents available to the practical academic and industrial organic chemist. We will seek to explore the limits of the reactivity which may be derived from the unique character of each alkaline earth element and to elaborate their fundamental reactivity through the utilisation of new feed-stocks and by targeting some of the most pressing and high profile bond activation catalyses. In doing so we shall address not only specific short term impacts upon healthcare development, energy and environment but also less parochial issues of worldwide chemical sustainability.