REGIOSELECTIVE AND STEREOSELECTIVE ALTERNATING COPOLYMERIZATION OF CARBON-MONOXIDE WITH PROPENE

Compounds of palladium with ten different chelated bisphosphine ligand s were investigated for their catalysis of alternating copolymerizatio n of propene with carbon monoxide. The bisphosphine structure and chel ate ring size influence strongly the activity, regio- and stereoselect ivity of the catalysts. Molecular mechanics calculations on the pi-ole fin complex showed that the non-bonded interaction between propene and the ligands on Pd is both regio- and stereoselective. Primary inserti on is about seven times more probable than secondary insertion for the Pd complex of bis(diphenylphosphino)butane ligand. The enantioselecti ve catalysts favor the meso enchainment of propene. Gas chromatography /mass spectrometry (GC-MS) of oligomers showed that most chains are in itiated by Pd-H species with less frequent initiation by Pd-OCH3 compl exes; beta-hydrogen elimination is the dominant chain termination proc ess.