Unraveling the role of counter-cations in Pd-catalyzed carboxylic acid C–H activation

The roles of the counter-cation effect were unveiled: promoting the depolymerization of palladium polymers into monomers, reversing the coordination mode from κ 2 to κ 1 and assisting in the C–H activation step. A Pd–Ag–K catalytic model was proposed.