Cooperative Activation of CO and Pyridine by an Aluminum(I) Complex Ligated with a Silylene–Borane Ligand

A silylene–borane-ligated aluminum(I) complex featuring Si(II)→Al(I) and Al(I)→B(III) donor–acceptor interactions were synthesized and structurally characterized. The ambiphilic ligand- aluminum cooperation enables C≡O bond cleavage and pyridine dearomatization, uncovering new avenues in low-valent aluminum chemistry.

Abstract

Cooperative main-group systems based on alumylenes are highly attractive due to their potential for activating and transforming inert chemical bonds and small molecules. However, their development has been hindered by the scarcity of suitable supporting ligands. Herein, we report the synthesis of an amphiphilic carboranyl silylene–borane ligand (1) and demonstrate its effectiveness in stabilizing an aluminum(I) complex 2. Complex 2 has been unambiguously characterized by spectroscopic analysis, X-ray diffraction analysis, and DFT calculations, which reveals a unique structure featuring both silicon(II)→aluminum(I) and aluminum(I)→boron(III) donor–acceptor bonds. The synergistic interplay between the silylene–borane ligand and the aluminum(I) center in 2 drives its unusual reactivity toward CO and pyridine activation, facilitating cleavage of the C≡O bond and dearomatization of pyridine.

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