COPOLYMERIZATION OF ETHYLENE AND CARBON-MONOXIDE BY PHOSPHINITE-MODIFIED PALLADIUM CATALYSTS

Novel palladium complexes with bidentate phosphinite and mixed phosphi ne-phosphinite ligands of the general formula [((PP)-P-Lambda)Pd(Me)Cl ] were prepared. After halide abstraction, these complexes are highly active catalysts for the copolymerization of ethylene and CO, yielding high molecular weight polyketones with activities of up to 30000 mol per mol Pd. The preference of cis- or cans-coordination, depending on the chelate ring size, was investigated. In complexes with up to 11-me mbered chelates, a cis-fixation of the ligands is observed, whereas bi gger chelates afforded catalytically inactive trans-complexes.