Pd(II) Complexes with Bidentate Nitrogen-Donor Chelating Ligands: Very Versatile and Active Catalyst Precursors for the CO/Olefin Co- and Terpolymerization Reactions

The perfect alternating CO/olefin copolymers constitute an important class of new materials. Their synthesis requires a catalyst; in general, the applied catalytic systems are formed by a palladium(II) salt, modified by diphosphine or dinitrogen chelating ligands, in the presence of a BrØnsted acid as cocatalyst and, frequently, an oxidant such as 1,4-benzoquinone. Alcoholic medium is generally preferred. This overview will report on the main catalytic systems based on bidentate nitrogen-donor chelating ligands; particular attention will be dedicated to the CO/styrene copolymerization. A detailed analysis of several parameters influencing the yield and the quality of CO/styrene polyketone will be presented, together with the discussion of the control of the stereochemistry of the insertion of styrene in the growing chain.