Several phenoxy-imine ligands bearing
o-trityl group in phenoxy moiety RN=CHArOH (Ar = C
6H
2(CPh
3)
tBu,
R = 2,6-Me
2C
6H
3 ( L
1 H ); 2,6-
iPr
2C
6H
3 ( L
2 H ); 3,5-(CF
3)
2C
6H
3 ( L
3 H ); 3,5-(OMe)
2C
6H
3 ( L
4 H ); CHPh
2 ( L
5 H ); CPh
3 ( L
6 H )) were synthesized and characterized by
1H NMR and
13C NMR spectroscopy. The vanadium complexes based on these ligands LVCl
2(THF)
2 ( 1–6 ) were synthesized via conventional transmetalation reaction in moderate to high yields. Complexes 1–6 were fully characterized by FT-IR, elemental analyses and the molecular structures of 1 , 2 ·H
2O, (2 ·H
2O )
2 (
μ-Cl)
2 , 4 , and 5 were confirmed by X-ray crystallographic analysis in which the six-coordinated vanadium centers are in a typical octahedral geometry. Upon activation with Et
2AlCl in toluene, complexes 1–6 showed high activities in ethylene polymerization affording polymers with moderate molecular weight (5.9–11.8 × 10
4 Da). Moreover, in hexane or CH
2Cl
2, 1–6 /Et
2AlCl exhibited enhanced activities. When activated with MAO or MMAO in toluene, these complexes showed relatively low activities but afforded polymers with ultra-high molecular weight (up to 3.30 × 10
6 Da). 1–6 /Et
2AlCl also showed high activities in ethylene/1-hexene copolymerization at room temperature giving moderate molecular-weight polymers (6.5–11.4 × 10
4 Da) with co-monomer incorporation being of 6.0 ~ 7.8%.
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