Understanding the Redox Chemistry of β-diketiminate Supported Aluminium Complexes

Recent years have seen a renaissance in main group chemistry, owing in part to the success of some of their lower oxidation species to mimic useful transition metal behaviour. Whilst reversible redox events have been observed within the p-block, discrete redox events that would enable facile bond activations and catalysis is still generally the domain of transition metals. This study reports a combined electrochemical and synthetic investigation probing the redox chemistry available to aluminium supported by the common β-diketiminate ligand. The key finding here is that reduction from Al(III) to Al(I) occurs in a stepwise manner via an Al(II) intermediate. Though the highly reactive nature of Al(I) induces an electrochemical-chemical (EC) reaction, reversible redox processes are observed in the individual steps [Al(III) ↔ Al(II) and Al(II) ↔ Al(I)]. Importantly, this work provides new insight into the electron transfer processes available to aluminium, essential towards building bona fide redox-based catalytic cycles to compete with those of transition metals.