Polymerization of 1,3-butadiene using (salen)Ni(II) and (salphen)Ni(II) complexes in combination with methyl-aluminoxane

Abstract

Eight nickel complexes with various imino-backbones and substituents at ortho- and para-positions on the aromatic ring of the salicylaldehyde are prepared and characterized. Activated by MAO, the precursors have been investigated for 1,3-butadiene polymerization. All the complexes display high cis-1,4 selectivity (cis-1,4 contents: 90.4 to 93.4 %), while the catalytic activity strongly depends on the position of bulky group located. Introduction of t-butyl at 3,3'-position on the aromatic ring of the ligands remarkably increases catalytic activity, while that at the 5,5'-position decreases the activity. Relatively, variation of imino-backbone shows little influence on catalytic performance. Effects of [Al]/[Ni] molar ratio and temperature on catalytic activity and stereo-selectivity are also investigated.