Nonredox Metal-Ion-Accelerated Olefin Isomerization by Palladium(II) Catalysts: Density Functional Theory (DFT) Calculations Supporting the Experimental Data

Redox metal-ion-catalyzed olefin isomerization represents one of the important chemical processes. This work illustrates that nonredox metal ions can sharply accelerate Pd(II)-catalyzed olefin isomerization, while Pd(II) alone is very sluggish. Nuclear magnetic resonance (NMR) and ultraviolet visible light (UV-vis) characterizations disclosed that the acceleration effect originates from the formation of heterobimetallic Pd(II) species with added nonredox metal ions, which improves the C-H activation capability of the Pd(II) moiety. Density functional theory (DFT) calculations further confirmed the sharp decrease of the energy barrier in C-H activation by the heterobimetallic Pd(II)/Al(III) species.