Vinyl-type polymerization of norbornene by a nickel-based catalyst with phosphoraneiminato ligands

Abstract

SUMMARY: High molecular weight vinyl-type polynorbornene was obtained in high yields with a highly active nickel-based phosphoraneiminato complex in the presence of methylaluminoxane. This polynorbornene is soluble at room temperature in chlorobenzene and shows no indication of crystallinity in the solid state. Catalyst activity, polymer yield, and polymer molecular weight can be controlled over a wide range by variation of reaction parameters.

The Vinyl Homopolymerization of Norbornene

“…Greiner et al could observe catalyst activities up to 20.5 t N (mol Ni) -1 N h -1 and polymer molar masses up to 3.4 6 10 6 g N mol -1 . [80] The polymer yield or catalyst activity of 35/MAO and the molar mass of the poly(norbornene) could be controlled through the reaction parameters temperature, time and the molar ratios Al : Ni and norbornene : Ni. The molar ratio Al : Ni had a significant impact on the polymer yield, yet, it did not affect the molar mass much.…”

Grafting of Vinyl‐Type Polynorbornene on Polybutadiene and Polyisoprene

“…For polymerization of norbornene (2) 0.5 ml of a 10 % (w/w) triethylaluminium solution in hexane was added per 1 l of toluene as scavenger for oxygen and moisture. [NiBr(NPMe 3 )] 4 (1) was prepared according to a published procedure. [16] 2 (Aldrich) was purified by distillation over potassium.…”

“…[4,8] In this study we have replaced MAO by B(C 6 F 5 ) 3 (3). The replacement of MAO by 3 is well established in metal catalyzed polyinsertions of olefins and has been used before also for Ni-catalyzed polymerization of 2.…”

“…[3] We have recently reported on vinyl-type polymerization of norbornene initiated by the Ni-phosphorane iminato complex [NiBr(NPMe 3 )] 4 /MAO. [4] Phosphorane iminato ligands (NPR 3 À ) gained particular interest since phosphorane iminato ligands are believed to be c-isolobal to cyclopentadienyl ligands. [4][5][6][7] In an extension of this work we have shown that norbornene polymerizations using the system [NiBr(NPMe 3 )] 4 /MAO are terminated upon addition of olefins [8] as also found previously for numerous transition metal complexes (including Ni).…”

“…[4] Phosphorane iminato ligands (NPR 3 À ) gained particular interest since phosphorane iminato ligands are believed to be c-isolobal to cyclopentadienyl ligands. [4][5][6][7] In an extension of this work we have shown that norbornene polymerizations using the system [NiBr(NPMe 3 )] 4 /MAO are terminated upon addition of olefins [8] as also found previously for numerous transition metal complexes (including Ni). [9][10][11][12][13] Chain terminations of polynorbornenes by addition of olefins occur by addition of the olefin to the active chain end and subsequent b-H elimination.…”