Aluminum learns to ride a redox cycle

Aluminum is the third-most abundant element in Earth’s crust, after oxygen and silicon. The metal is low cost and highly recyclable, thus making it attractive for chemists looking for more sustainable catalysts. But as a group 13 element, aluminum behaves very differently from more traditional transition-metal catalysts like nickel and palladium.Liu Leo Liu of the Southern University of Science and Technology and his former postdoctoral fellow Xin Zhang have now devised an aluminum complex that undergoes a full catalytic cycle. The metal switches between two different oxidation states to assemble substituted benzene rings from alkynes (Nature 2026, DOI: 10.1038/s41586-025-09941-9). Getting an abundant main-group metal to act more like a transition metal “could significantly broaden the toolbox of synthetic chemistry in a way that is more scalable and resource-efficient,” Liu says in an email to C&EN.Many of the most powerful catalytic reactions rely on catalysts that change their oxidation state, but aluminum strongly prefers to be in the +3 oxidation state. Over the past few decades, researchers have figured out how to make aluminum(I) compounds, but once these complexes have the opportunity to shed two electrons and oxidize to Al(III), it tends to be a one-way trip.To get aluminum to switch between both oxidation states, Liu and Zhang designed an Al(I) complex with a bulked-up carbazole ligand. That ligand can slightly change its geometric conformation to stabilize the metal center throughout the catalytic cycle, which starts with the Al(I) oxidatively adding to an alkyne and becoming Al(III). Two more alkynes are