Al(II) Transfer Harnessing a Well-Defined Cadmium Precursor

Abstract

Low-valent aluminum chemistry continues to expand the boundaries of main-group reactivity, yet the selective generation and transfer of Al(II) fragments remain underexplored. Controlled Al(II) transfer may establish a basis for selective substrate alumination and subsequent functionalization. More broadly, findings in the field offer conceptual guidance for the development of synthetically and potentially catalytically relevant main-group platforms. Here, we now show that heterometals can act as structural templates that tame and direct Al(II) reactivity within covalent Al/Cd frameworks. The trimetallic compound [({N(TMS)₂})(Cp*)Al]₂Cd (1^tri; Cp* = C₅Me₅) proved as an excellent candidate, selectively transferring aluminum complex fragments through cadmium extrusion. This reactivity was verified through reactions with free radicals, dichalcogenides, and benzophenone(-derivatives), the latter representing spin-trapped versions of the fleeting Al(II) radical [({N(TMS)₂})(Cp*)Al]^•. In contrast, [{N(TMS)₂}(Cp*)Al–Cd{N(TMS)₂}] (1^bi) retains cadmium and instead promotes cadmium transfer, i.e. to form chalcogenophenolates, underscoring its nuclearity-dependent reactivity. Corroborating these experimental observations, DFT studies provide insight into the formation pathways, electronic structure, and stability of the resulting compounds.