Styrene polymerization catalyzed by nickel complexes bearing hydroxyindanone-iminate ligands

Activated by methylaluminoxane, mononuclear bis(hydroxyindanone-iminate)nickel complexes NiArN = CC₂H₃(CH₃)C₆H₂(R)O]₂ (Ar = 2,6-i-Pr₂C₆H₃, R = Me (1), R = Cl (2), and R = H (3)) showed good activity for the styrene polymerization. The effect of many reaction parameters including the Al/Ni ratio, temperature, and reaction time on catalytic activities of catalytic systems and the molecular weights of the obtained polystyrene was ascertained. The highest activity of 1.34×10⁵ g(PS) · mol⁻¹(Ni) · h⁻¹ was obtained under the optimum reaction condition. The ¹³C NMR spectra of the polymers revealed that the polymer was isotactic-rich atactic polystyrene. And the coordination mechanism was confirmed by the analyses of the polymer chain end-groups. Supported by the National Natural Science Foundation of China (Grant Nos. 20531020, 20721063, and 20771028), Shanghai Leading Academic Discipline Project (Grant No. B108), the National Basic Research Program of China (Grant No. 2005CB623800) and Shanghai Science and Technology Committee (Grant No. 06XD14002)