New chemistry of η3-allenyl/propargyl complexes of palladium and platinum

The chemistry of allenylpalladium and propargylpalladium has been developed to construct useful catalytic reactions in organic synthesis. However, the reaction mechanism has not been understood well due to the lack of the systematic studies on the allenyl and propargyl complexes of palladium. Thus, the correlation between the coordination mode and the reactivity of eta(1)-allenyl, eta(1)-propargyl, eta(3)-allenyl/propargyl and mu-eta(3)-allenyl/propargyl ligand on palladium or platinum was revealed. Moreover, these coordination modes can be interconverted one another very easily under certain conditions. This easy interconversion generates an intermediate having different coordination mode, which can not be observed but plays a very important role in the key reactions in catalytic cycles, such as isomerization, oxidative addition, and racemization.