Regioselective chain‐straightening polymerization of α‐olefins through 2,ω‐enchainment using amine–imine nickel catalysts

Abstract

AbstractThe control of the regioselectivity of metal‐catalyzed α‐olefins polymerization is of everlasting interest. Most nickel and palladium catalysts show high regioselectivity involving 2,1‐insertion of α‐olefins and 1,ω‐enchainment chain‐straightening, especially α‐diimine nickel catalysts. In this contribution, we report extremely rare regioselective chain‐straightening polymerization of α‐olefins through 2,ω‐enchainment using unsymmetrical amine–imine nickel catalysts. The polymerizations of α‐olefins (1‐hexene, 1‐octene, and 1‐decene) were studied in detail, and the effects of catalyst structure, reaction temperature, and monomer concentration on the polymerization activity and the regioselectivity were examined. The unsymmetrical N‐substituents of the amine–imine nickel catalysts play a crucial role in the regioselectivity. High regioselectivity involving 80.4% 1,2‐insertion and 84.5% 2,ω‐enchainment is realized to produce amorphous polyolefins without melting temperatures.