Isotactic and atactic copolymerization of styrene and carbon monoxide using cationic palladium-phosphino(dihydrooxazole) complexes

Cationic palladium complexes 2 containing coordinated phosphino(dihydrooxazole) ligands 1 give catalytic systems which allow the production of alternating styrene-carbon monoxide copolymers. Depending on the symmetry of the ligand, the copolymers are produced either with a highly isotactic or with an essentially completely atactic microstructure. Termination of the polymeric chain is mainly due to a beta-H-elimination reaction. Both linear ((E)-PhCH=CHCO-) and branched (CH2=C(Ph)CO-) unsaturated end groups were identified.