Mercury Takes the Stage: Multifaceted Reactivity of Al/Hg Heterometallics

<jats:p>Despite the long-standing history and remarkable stability of low-valent mercury compounds, their use in molecular reduction chemistry has remained largely unexplored. In particular, the ability of mercury to participate directly in molecular small-molecule reduction has remained elusive. Here, we address this gap through the synthesis of heterometallic compounds combining low-valent mercury and aluminum. Aluminylene insertion into Hg{N(TMS)2}2 affords the bi- and trimetallic mercury aluminyls 1 and 2, respectively, featuring covalent Al–Hg bonds. The cooperative Al–Hg–Al framework of 2 exhibits remarkable stability, enabling further ligand exchange to afford a mere amide substituted derivative 3. Compounds 2 and 3 undergo sequential carbodiimide insertion (4–7) through formally mercury-centered nucleophilic reactivity and promote the reduction of chalcogens to afford 8Ch (Ch = S, Se, Te). These transformations reveal the Al–Hg–Al framework as a source of either nucleophilic mercury or latent Al(II)-type reactivity, depending on the substrate. Quantum-chemical calculations elucidate the electronic structures of selected compounds and provide insight into the mechanism of heterocumulene insertion. Overall, we present Al/Hg heterometallics as isolable, multitalented reagents that enable cooperative main-group/transitionmetal reactivity.</jats:p>