Bespoke Bimetallics for Chemical Cooperativity

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The importance of the UK's chemical and pharmaceutical sector can be seen in the statistic that it supplies £60M of added value each working day (that equates to £15bn a year) to our Gross Domestic Product (the total value of goods and services provided by a country in one year). Cutting edge research, innovation and sustainability lie at the heart of this project. The research is in organometallic chemistry, a core area of chemistry that is utilised in a myriad of real world applications, spanning chemistry and other disciplines such as biochemistry and material science. Organometallic compounds, comprising an organic moiety and a metal moiety are essential tools for constructing molecules big and small. A large proportion of known chemical processes depend on the metal moiety of organometallic compounds being a precious transition metal (commonly palladium, platinum, rhodium, iridium, ruthenium, and osmium), which are essential for the manufacture of numerous specialty chemicals from agrochemicals through to pharmaceuticals (especially anticancer drugs).Base (non-precious) metals are generally much cheaper (due to their higher natural abundance) and reflecting this high abundance in the earth's crust they have less toxicity concerns than their precious metal counterparts. The problem is their chemistry (their ability to carry out useful reactions efficiently) is rather limited by comparison so more often than not they are inefficient in many chemical processes. If base metal chemistry could be developed to the status of precious transition metal chemistry or better still to go beyond this status, then sustainability would be significantly improved and reliance on less environmentally benign precious transition metals would be reduced.Recent advances by the research team have demonstrated that base chemistry can be made orders of magnitude more efficient by preparing organometallic compounds that contain two base metal elements instead of one. The metal common to all of these metal pairs is an alkali metal (lithium, sodium or potassium), while the second metal is magnesium, zinc, aluminium or the earth-abundant transition metals iron and manganese. By forming mixed-metal bimetallic structures impossible in single-metal systems, cooperative effects are induced which transform the reactivity of the base metals opening up a vast number of novel reactions that are currently inaccessible to base metals on their own. Cooperativity will be especially important in our targeted C-C bond formations and C-F bond activations through alkali metal -Fe or -Mn partnerships as currently these reactions are generally the domain of precious transition metal catalysis. Realising this escalation of sustainable base metal chemistry will be a major breakthrough in itself but this project will take on an additional ambitious challenge. Alkali metal organometallic chemistry invariably needs to be performed under anaerobic conditions as the compounds involved rapidly decompose with even traces of air or moisture. However, the team recently made the extraordinary finding that certain organoalkali metal reactions could be run under aerobic conditions by using Deep Eutectic Solvents (DES) as opposed to industry standard classical organic solvents. DES are more cost-effective, greener and biorenewable than organic solvents and switching to them would also do away with the need for costly inert atmosphere protocols. The proof of concept results with DES have been with single base metals, so the challenge is to develop this new bimetallic chemistry in DES. Success will impact the practice of organometallic chemistry worldwide.