Development of Organopalladium(IV) Chemistry: Fundamental Aspects and Systems for Studies of Mechanism in Organometallic Chemistry and Catalysis

Palladium is one of the most widely studied elements in organometallic chemistry, partly owing to the important role of palladium complexes in organic synthesis and catalysis. Since the initial report of PdIMe3(bpy), a rich and diverse organopalladium(IV) chemistry has evolved, including reaction systems that are ideal for studying topics of contemporary interest, e.g., mechanisms of oxidative addition and reductive elimination reactions, selectivity in reductive elimination, and studies of alkyl group exchange between metal centers. An account of each of these topics is presented here, followed by an assessment of some of the possible roles of Pd(IV) in organic synthesis and catalysis. Palladium(IV) chemistry has developed rapidly since 1986 to include the isolation of alkyl-, benzyl-, (eta-l-allyl)-, and arylpalladium complexes. It is providing new comparisons of structure, solution dynamics, and reactivity among the nickel triad elements and is providing new systems for mechanistic studies.