Synthesis of titanium(IV) complexes containing 2,6-dimethylaniline substituted amino alcohols and their utilization in ethylene polymerizations

Abstract

Two new Ti(IV) complexes of the type [(OCHRCH 2N-2,6-Me 2Ph)Ti(NMe 2) 2] 2 (where R=H, or t butyl) have been synthesized by protonolysis of Ti(NMe 2) 4 with the corresponding N-substituted amino alcohol ligand. The two complexes were studied as Ziegler–Natta type polymerization catalysts in the presence of an excess of methylaluminoxane (MAO). It was found that ethylene polymerization activity for both catalysts increased by increasing the polymerization temperature from 25 to 70°C. If the catalysts were pretreated with trimethylaluminum, the activities increased at 25°C, but slightly decreased at 70°C. Both complexes were found to be ineffective for the polymerization of propylene. An X-ray crystal structure of [(OCH 2CH 2N-2,6-Me 2Ph)Ti(NMe 2) 2] 2 shows the complex to be dimeric in the solid state, with bridging through the amino alcohol oxygen atoms. This complex crystallizes in the monoclinic system space group, P2 1/ n with a=9.181(6), b=13.766(3), c=13.002(3), β=93.08(3) and Z=4.