Bispentiptycenyl–Diimine–Nickel Complexes for Ethene Polymerization and Copolymerization with Polar Monomers

Ni²⁺ coordinated within a bowl-shaped diimine ligand with two pentiptycenyl-substituents [(diimine)­NiBr₂] displays excellent activity for the polymerization of ethene (7 atm) with activities of up to 34 × 10³ kg­(mol Ni)⁻¹ h^–1 following activation with Et₂AlCl. The resulting polymer is characterized by high molecular weights (M_n = 150 × 10³ g·mol^–1), low branching (12/1000 C), and a high melting point (T_m = 133 °C). The polymerization of ethene with polar comonomers leads to the formation of the respective polar polymers with very efficient incorporation of comonomer. The activity of the catalyst critically depends on the molar ratio of Et₂AlCl activator and the polar functional group.