Ni(II) and Pd(II) complexes bearing novel bis(β‐ketoamino) ligand and their catalytic activity toward copolymerization of norbornene and 5‐norbornene‐2‐yl acetate combined with B(C6F5)3

Abstract

AbstractTwo complexes Mt{C10H8(O)C[N(C6H5)]CH3}2 [Mt = Ni(II); Mt = Pd(II)] were synthesized, and the solid‐state structures of the complexes have been determined by single‐crystal X‐ray diffractions. Homopolymerization of norbornene (NB) and copolymerization of NB and 5‐norbornene‐2‐yl acetate (NB‐OCOCH3) were carried out in toluene with both the two complexes mentioned above in combination with B(C6F5)3. Both the catalytic systems exhibited high activity toward the homopolymerization of NB (as high as 2.7 × 105 gpolymer/molNi h, for Ni(II)/B(C6F5)3 and 2.1 × 105 gpolymer/molPd h for Pd(II)/B(C6F5)3, respectively.). Although the Pd(II)/B(C6F5)3 shows very lower activity toward the copolymerization of NB with NB‐OCOCH3, Ni(II)/B(C6F5)3 shows a high activity and produces the addition‐type copolymer with relatively high molecular weights (MWs; 1.80–2.79 × 105 g/mol) as well as narrow MW distribution (1.89–2.30). The NB‐OCOCH3 content in the copolymers can be controlled up to 5.8–12.0% by varying the comonomer feed ratios from 10 to 50%. The copolymers exhibited high transparency, high glass transition temperature (Tg > 263.9 °C), better solubility, and mechanical properties compared with the homopolymer of NB. The reactivity ratios of the two monomers were determined to be rNB‐OCOMe = 0.08, rNB = 7.94 for Ni(II)/B(C6F5)3 system, and rNB‐OCOMe = 0.07, rNB = 6.49, for Pd(II)/B(C6F5)3 system by the Kelen‐Tüdõs method. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011