Axial Anagostic Interaction in α-Diimine Nickel Catalysts: An Ultraefficient Occupation Strategy in Suppressing Associative Chain Transfers to Achieve UHMWPEs

• Key Words:MOLECULAR-WEIGHT POLYETHYLENE; OLEFIN POLYMERIZATION; METAL CATALYSTS; ETHYLENE; COPOLYMERIZATION; WALKING; TEMPERATURE; COMPLEXES; PRESSURE; MONOMERS
• Abstract:Axial anagostic bond Mt<middle dot><middle dot><middle dot>H-C can occupy the apical site of d 8 square planar metal complexes, which is highly desired, yet never explored, for olefin polymerization because of its capability to suppress associative chain transfer to access high molecular weight polyolefin products. In this research, we present a method for how such axial anagostic interaction Ni<middle dot><middle dot><middle dot>H-C can be constructed into alpha-diimine NiBr2 complexes, and more importantly, demonstrate its pivotal role in improving the overall ethylene polymerization performance, including (i) ultrahigh efficiency in suppressing associative chain transfer to afford UHMWPEs with M w up to 724.2 x 104 g/mol, (ii) significantly impeded decomposition of the cationic active species that brings in better storage stability, and (iii) higher branched nature of the PE products that guarantee a well-controlled living fashion for the whole polymerization process even when M w reaches ultrahigh levels. With the aid of DFT calculations, the nature of such an anagostic bond and its influence on each step of the polymerization process are also elucidated.
• Volume:58
• Issue:4
• Translation or Not:no