Shifang Yuan

Synthesis, characterization, and ethylene polymerization of 1-[2,4-bis(bis(4-fluorophenyl)methyl)naphthylimino]-2-aryliminoacenaphthylnickel bromides: influences of polymerization parameters on polyethylenes

A series of 1-[2,4-bis(bis(4-fluorophenyl)methyl)naphthylimino]-2-aryliminoacenaphthylene derivatives (L1–L5) was prepared and used to react with (DME)NiBr2 to form the title complexes (C1–C5). The organic compounds were characterized by 1H/13C NMR measurements, FT-IR spectra and elemental analysis. Meanwhile, the nickel complexes were analyzed by FT-IR spectra, elemental analysis, and single-crystal X-ray diffraction of the representative complex C1, which indicated a distorted tetrahedral geometry around the nickel center. Upon activation with diethylaluminum chloride (Et2AlCl), all the title nickel complexes were highly active for ethylene polymerization, resulting in polyethylenes with high molecular weights ranging from 0.86–5.58 × 105 g mol−1 and narrow polydispersity (1.22–1.99). Moreover, significant influences of polymerization parameters on the resultant polyethylenes were examined and are discussed.

Synthesis and structural study of an unsymmetrical aliphatic benzamidinato ligand and its use in the formation of selected Cu(I), Mg(II) and Zr(IV) complexes

The reaction of a Et2O solution of LiN(Cy)SiMe3 (Cy = cyclohexyl) with PhCN in the presence of the Lewis-base donor tetrahydrofuran (THF) or Me2N(CH2)2NMe2 (TMEDA) gave the THF- or TMEDA-solvated unsymmetrical aliphatic lithium benzamidinato compound [{PhC(NCy)(NSiMe3)}Li(THF)]2 (1) or [{PhC(NCy)(NSiMe3)}Li(TMEDA)] (2). Treatment of LiN(Cy)SiMe3 with PhCN in diethyl ether, and further with CuCl, MgBr2(THF)2 or ZrCl4 at a ratio of 1:1, 2:1 and 3:1 allowed the formation of novel metal complexes [{PhC(NCy)(NSiMe3)}Cu]2 (3), [{PhC(NCy)(NSiMe3)}2Mg(OEt2)] (4) and [{PhC(NCy)(NSiMe3)}3ZrCl] (5), respectively. The X-ray structures of complexes 1–4 are presented. Complex 5/MAO system allows the moderate polymerization of ethylene.

Group IV compounds bearing a novel tridentate N-donor ligand: synthesis, structures and ethylene polymerization

Treatment of the mixed amidinate-amido-lithium, [PhN(CH2)3NC(Ph)NSiMe3]2Li4·2Et2O, with group IV metal chlorides yields the corresponding compounds 3–5. Their structures were confirmed by X-ray diffraction analysis, showing a distorted octahedral geometry. The catalytic behaviors of compounds 3–5 were investigated in the presence of MAO as a co-catalyst. Compounds 3 and 4 showed high activities for ethylene polymerization.

Zirconium complexes based on an ethylene linked amidinate–amido ligand: synthesis, characterization and ethylene polymerization

The dimer lithium complex 3 and zirconium complexes 4–6 were synthesized and characterized. Monomer/dimer zirconium complexes 4–6 were synthesized by changing the molar ratio of ZrCl4 : ligand. Their structures were confirmed by X-ray diffraction analysis, which showed a distorted octahedral geometry. Complexes 5 and 6 were zirconium trichloride compounds, while complex 4 was not a zirconium chloride species. The catalytic behaviors of complexes 4–6 were investigated in the presence of MAO as a cocatalyst. It was found that the catalytic activities of these zirconium complexes toward ethylene polymerization were closely related to the bonding patterns (η3:η1, η3 or η1), the number of chlorine atoms in the procatalysts and the availability of the coordination site in the molecule. Zirconium trichloride complex 5 showed the highest catalytic activity mainly because of its η1 bonding pattern.

Arylimido zirconium and titanium complexes: characteristic structures and application in ethylene polymerization

Abstract Dimeric anilidolithium (ArHNLi·Et2O)2 (Ar=2,6-iPr2C6H3) reacted with zirconium tetrachloride in THF to give the heterometallic zirconium–lithium complex [(Et2O)2Li(μ-Cl)2(ArHN)(ArN=)Zr(μ-Cl)]2 (C1) and with titanium tetrachloride in toluene to give the titanium complex [(ArN=)TiCl2·(Et2O)2] (C2) each in good isolated yields. Their molecular structures in the solid state were confirmed by X-ray diffraction analysis. Upon activation with methylaluminoxane, both arylimido zirconium and titanium complexes exhibited good catalytic activities toward ethylene polymerization.