Shapeshifting Ligand Masks Lewis Acidity of Dicationic Palladium(II)

Supporting ligands reduce the Lewis acidity of transition metal ions, limiting the degree of electrophilic activation for any substrate. Here, we demonstrate that L1 and L2 mask the Lewis acidity of dicationic Pd(II) via a reversible C–N bond formation. These shapeshifting complexes catalyze electrophilic olefin isomerization, even in the presence of a polar functional group. The equilibrium between two coor-dination modes allows the system to access an electrophilic state that is comparable to a “naked” Pd(II) Lewis acid. However, because these shapeshifting systems are not sub-ject to the same rate determining step (via interconversion with a second less electrophilic state), they are also faster catalysts than the benchmark Pd(II) Lewis acid. Overall, we demonstrate that catalytic systems featuring reversible dy-namics can be advantaged relative to structurally static counterparts.