Mechanistic Features in Al(I)-Mediated Oxidative Addition of Aryl C-F Bonds: Insights From Density Functional Theory Calculations

The oxidative addition of a range of robust aryl C-F bonds to a single Al(I) center supported by a (NacNac)(-) bidentate ligand ((NacNac)(-) = [ArNC(Me)CHC(Me)NAr](-) and Ar = 2,6-(Pr2C6H3)-C-i) have been explored by density functional theory calculations. Our calculations demonstrate that the Al(I) center-mediated C-F insertion generally proceeds via the concerted mechanism that involve both the donation (n(Al) -> sigma*(C-F)) and back-donation (sigma(F(p)) -> pi*(Al(P))) interactions. In addition, the predicted free energy barriers for the C-F bond activation show good agreement with the experimental information available. Finally, the comparative studies show that B(I) is the most active among group III metals (B, Al, Ga), thus supplying a testable prediction for experiments.