High molecular weight PE elastomers through 4,4-difluorobenzhydryl substitution in symmetrical α-diimino-nickel ethylene polymerization catalysts

N , N -Diaryl-2,3-dimethyl-1,4-diazabutadiene-nickel complexes appended with 4,4-difluorobenzhydryl groups can efficiently mediate the formation of polyethylene elastomers with molecular weights approaching one million g mol −1 .