Role of Electron-Withdrawing Remote Substituents in Neutral Nickel(II) Polymerization Catalysts
作者:Anna Osichow、Inigo Göttker-Schnetmann、Stefan Mecking
DOI:10.1021/om400757f
日期:2013.9.23
The novel neutral kappa(2)-N,O-salicylaldiminato Ni-(II) complex, [kappa(2)-N,O-2,6-(3',5'-R2C6H3)(2)C6H3-N=C(H)-(3,5-I-2-2-O-C6H2)}NiCH3(pyridine)] (1a-pyr, R = NO2), with four nitro substituents on the N-terphenyl motif is a catalyst precursor for ethylene polymerization to yield linear higher molecular weight polyethylene (e.g., M-n 2.1 x 10(5) g mol(-1) and only 2 methyl branches per 1000 carbon atoms). A comparison with other known catalyst precursors at various polymerization conditions shows that the catalytic properties in terms of linearity and molecular weight are similar to the fluorinated catalyst precursor with R = CF3, showing that the latter is not singular, but rather suppression of chain transfer and branch formation by beta-hydride elimination can also be brought about by nonfluorinated electron-withdrawing remote substituents.