Pd(II) complexes bearing di‐ and monochelate fluorinated β‐ketonaphthyliminato ligand and their catalytic properties towards vinyl‐addition polymerization and copolymerization of norbornene and ester‐functionalized norbornene derivative

Abstract

Fluorinated β‐ketonaphthyliminate ligand CF3C(O)CHC[HN(naphthyl)]CH3 (L1) and Pd(II) complexes with dichelate fluorinated β‐ketonaphthyliminato ligand, {CF3C(O)CHC[N(naphthyl)]CH3}2Pd (C1), as well as with monochelate fluorinated β‐ketonaphthyliminato ligand, {CF3C(O)CHC[N(naphthyl)]CH3}Pd(CH3)(PPh3) (C2), were synthesized and their solid‐state structures were confirmed using X‐ray crystallographic analysis. The Pd(II) complexes were employed as precursors to catalyze norbornene (NB) homo‐ and copolymerization with ester‐functionalized NB derivative using B(C6F5)3 as a co‐catalyst. High activity up to 2.3 × 105 gpolymer molPd−1 h−1 for the C1/B(C6F5)3 system and 3.4 × 106 gpolymer molPd−1 h−1 for the C2/B(C6F5)3 system was exhibited in NB homopolymerization. Moreover, the Pd(II) complexes exhibited a high level of tolerance towards the ester‐functionalized MB monomer. In comparison with the C1/B(C6F5)3 system, the C2/B(C6F5)3 system exhibited better catalytic property towards the copolymerization of NB with 5‐norbornene‐2‐carboxylic acid methyl ester (NB‐COOCH3), and soluble vinyl‐addition‐type copolymers were obtained with relatively high molecular weights (3.6 × 104–7.5 × 104 g mol−1) as well as narrow molecular weight distributions (1.49–2.15) depending on the variation of monomer feed ratios. The NB‐COOCH3 insertion ratio in all copolymers could be controlled in the range 2.8–21.0 mol% by tuning a content of 10–50 mol% NB‐COOCH3 in the monomer feed ratios. Copolymerization kinetics were expressed by the NB and NB‐COOCH3 monomer reactivity ratios: rNB‐COOCH3 = 0.18, rNB = 1.28 were determined for the C1/B(C6F5)3 system and rNB‐COOCH3 = 0.19, rNB = 3.57 for the C2/B(C6F5)3 system using the Kelen–Tüdõs method. Copyright © 2014 John Wiley & Sons, Ltd.