The Unusual Role of Aromatic Solvent in Single-Site AluminumI Chemistry: Insights from Theory

The single-site activation of strong sigma bonds (such as that of H-H, P-H, and N-H) remains a significant challenge in main-group chemistry, with only a few cases reported to date. In this regard, recent exciting experiments performed with aluminum(I) complexes hold significance because they have been seen to activate a variety of strong sigma bonds. Such chemistry is generally seen to occur in aromatic solvents. Current computational studies with DFT reveal the interesting reason for this: an explicit aromatic solvent molecule acts as a catalyst by converting the aluminum(I) complex into aluminum(III) during the process. Different cases of sigma-bond activation by aluminum(I) complexes have been investigated and the efficiency of H-X (X=H, NHtBu, PPh2) bond activation in the presence of an explicit benzene solvent molecule is orders of magnitude higher than that in its absence. The current work therefore reveals the chemistry of aluminum(I) complexes to be richer and more complex than that previously realized, and shows it to be dependent on metal-solvent cooperativity; the first known example of its kind in main-group chemistry.