Start date: 01 May 2008,
End date: 30 Apr 2010
The metal-hydrogen exchange reaction (metallation) is one of the most fundamental synthetic tools. Traditionally, bases such as lithium alkyls have been used for the deprotonative metallation of aromatic rings; however, their high nucleophilicity restrict their use with certain sensitive functional groups. Professor Mulvey’s group have shown that special synergic effects can be induced by mixing an alkali metal base with certain magnesium or zinc reagents, leading to revolutionary new mixed-metal reagents that can perform reactions impossible with traditional single metal reagents; introducing the new concepts of alkali-metal-mediated magnesiation (AMMM) and alkali-metal-mediated zincation (AMMZ). For example, toluene can be regioselectively twofold deprotonated at the 2,5-ring positions in a reaction with a mixed-metal Na/Mg compound, that is outside the scope of conventional organometallic bases, which generally attack the more acidic Me group. Recently, this novel chemistry has been extended to a transition metal (manganese) thus pioneering the idea of alkali-metal-mediated manganation (AMMMn). This project will investigate the AMMMn of a variety of organic substrates and the extension of this synergic methodology to other transition metals (cobalt, chromium, iron and nickel) or indeed other main group metals such as tin. Some of these synergic complexes have been described as “inverse crowns”, most of them involving alkali metal-magnesium partnerships. New chemical opportunities can be opened (redox chemistry, catalysis, magnetochemistry and anion complexation) if inverse crowns could be synthesised in which magnesium is replaced by any divalent transition metal. The final aim of this project will therefore be to synthesise and structurally characterise a series of transition metal host inverse crowns. The project will provide an excellent training (air- and moisture- sensitive synthesis) combining aspects of inorganic, organic and supramolecular chemistry.
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