Palladium(II) catalysts for living alternating copolymerization of olefins and carbon monoxide

Abstract

Several Pd(II) catalyst systems have been reported which effect prefectly alternating copolymerization of olefins with carbon monoxide to yield polyketones [C(O)CH(R)CH{sub 2}]{sub n}. There has been increasing interest in these polymers, particularly the C{sub 2}H{sub 4}/CO copolymer (T{sub m} = 257{degree}C), due to their unusual properties, the low cost of monomers, the present of the carbonyl functionality, and the potential for further functionalization. The catalyst systems used have typically employed Pd(II) salts in methanol or chloroform. We report here the synthesis of well-defined Pd(II) catalysts that operate in aprotic solvents to yield living alternating copolymers of olefins and CO. In situ spectroscopic studies have established mechanistic details including the identity of the catalyst resting state.