Influence of the Steric Demand of Coligands on the Catalytic Activity of Nickel(II) Complexes in the Copolymerization of Ethene and Carbon Monoxide

The copolymerization of ethene and carbon monoxide can be catalyzed with square planar arenidotriphenylphosphane nickel(II) complexes containing an N,O -chelate ligand. To examine the influence of the phosphorus ligand on the catalytic activity, five new nickel(II) complexes with P -ligands of different basicities and different steric demands were synthesized and fully characterized including the determination of the crystal structures of three of the complexes. The investigation of the catalytic activity of the new compounds showed a decisive influence of the steric properties of the P -ligand. A minimum steric demand is essential to ensure catalytic activity.