University of Jyväskylä

A game-change in aluminium chemistry

A collaborative research effort between the Departments of Chemistry at the University of Oxford (United Kingdom) and University of Jyväskylä (Finland) has resulted in the discovery of a completely new mode of reactivity for compounds of aluminium – one of the most technologically important elements of the Periodic Table. This new capability may find further use in applications involving the formation of new metal-carbon and metal-metal bonds.

Trivalent aluminium compounds – as every chemistry student will tell – are electron deficient and act as Lewis acids (electron acceptors) in their chemical reactions. Numerous synthetic transformations and widely-used industrial processes (e.g. the production of polythene) draw on this characteristic chemical property. Aluminium compounds in the +1 oxidation state are also known, of course, but the reverse polarity ‘umpolung’ strategy of using an aluminium reagent as the nucleophilic partner in Al-E bond-forming substitution reactions (E = H, C etc.) has not been experimentally accessible.

potassium aluminylcomplex

Picture 1: Figure 1. Diagrammatic representation (left) and solid state structure (right) of the potassium aluminyl complex.

First anionic aluminium(I) nucleophile

Researchers now show for the first time that anionic aluminium(I) compounds can be synthesized, that they can be stable at room temperature, and that they can act as nucleophiles. A dimethylxanthene-stabilized potassium aluminyl compound can be synthesized by potassium reduction of the corresponding iodide, and displays unprecedented reactivity: (i) in ‘umpolung’ fashion as an aluminium-centred nucleophile for the formation of Al-E covalent bonds (E = H, C) via substitution chemistry; and (ii) in the C-H oxidative addition of benzene at a single well-defined main group metal centre. As such, the authors believe that these results describe a step-change in the chemistry accessible to one of the most technologically important elements in the Periodic Table – metaphorically, it turns aluminium chemistry on its head.

The research was published in Springer Nature on the 16th of April 2018.

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