Ethylene polymerization by a novel dinuclear heteroligated titanium complex with the ligand of (Salicylaldiminato) (β-enaminoketonato)

Abstract

The condensation of acetylacetone (CH₃COCH₂COCH₃) with benzdine (H₂N-C₆H₄-C₆H₄-NH₂) yielded diimine ligand 1 [HOC(Me)C(H)(Me)C=N(p-C₆H₄)(C₆H₄-p)N=C(Me)C(H)C(Me)OH)], which was converted into sodium salts. And then the sodium salts reacted with monosalicylaldiminato titanium complex 2{[3,5-di-Bu ^t-2-(O)C₆H₂CHN(PH)]TiCl₃(THF)} in dried dichloromethane to give a new benzdine-bridged binuclear complex 3{[3,5-di-Bu ^t-2-(O)C₆H₂CHN(PH)]₂[OC(Me)C(H)(Me)C=N(p-C₆H₄)-(C₆H₄-p)N=C(Me)C(H) C(Me)]Ti₂Cl₄}. The complex 3 was characterize by ¹HNMR and elemental analysis. In the presence of MAO(methylaluminoxane), the complex 3 in toluene was effective to catalyze polymerization, affording moderately high catalytic activity 1.93×10⁵ g PE /(mol·Ti·h)]and high molecular weight polyethylene [5.63×10⁵ g/mol]. The high temperature gel permeation chromatography (GPC) curve of polyethylene obtained revealed a single peak, but the molecular weight distribution (MWD=3.21) is obviously broader than that of the similar mononuclear titanium complex. The melting points of the obtained polyethylene reaches 138 °C, indicating that the polyethylene is of high crystallinity.

Keywords

ethylene polymerization / titanium complex / binuclear

References

[1] Small B. L., Brookhart M., Bennett A. M. A. Highly Active Iron and Cobalt Catalysts for the Polymerization of Ethylene [J]. J. Am. Chem. Soc., 1998, 120(16): 4049-4050.

[2] Gibson V. C., Spitzmesser S. K. Advances in on-metallocene Olefin Polymerization Catalysis [J]. Chem. Rev., 2003, 103(1): 283-316.

[3] Fujita T, Mitani M, Matsui S, . Olefin Polymerization Catalysts, Transition Metal Compounds, Processes for Olefin Polymerization, and Alpha-olefin/Conjugated Diene Coplymers[J]. Eur. Patent, 1998, 0874005: 129331166.1081

[4] Zhang D., Jin G. X. Novel Highly Active Bimuclear 2, 5-Disubstituted Amino-p-benzoquinone Nickel (II) Ethylene Polymerization Catalysts [J]. Organometallics, 2003, 22(14): 2851-2854.

[5] Liu J. Y., Li Y. S., Liu J. Y., . Ethylene Polymerization with a Highly Active and Long-lifetime Macrocycle Trinuclear 2,6-Bis(imino)pyridyliron[J]. Macromolecules, 2005, 38(7): 2559-2563.

[6] Liu X. J., Sun J. Q., Zhang H. Y., . Ethylene Polymerization by Novel Phenylene Dimethylene Bridged Homodinuclear Titanocene/MAO Systems [J]. Euro. Polym. Jnl., 2005, 41(7): 1519-1524.

[7] Sun J. Q., Zhang H. Y., Liu X. J., . Ethylene Polymerization by Novel 4, 4-Bis(methylene) Biphenylene Bridged Homodinuclear Titanocene and Zirconocene Combined with MAO[J]. Euro. Polym. Jnl., 2006, 42(6): 1259-1265.

[8] Pennington D. A., Harrington R. W., Clegg W., . The Synthesis, Structure and Ethylene Polymerization Activity of Octahedral Heteroli gated(salicyladiminato) (β-enaminoketonato) Titanium Complexes: The X-ray Crystal Structure of {3-Bu^t-2-(O)C₆H₃CHN(PH)} {(PH) NC(Me)O}TiCl₂[J]. J.Organ. Chem., 2006, 691: 3183-3188.

[9] Brown N. M. D., Nonhebe D. C. l. NMR Spectra of Intramolecularly Hydrogen-bonded Compounds II Schiff Bases of β-diketones and o-hydroxycarbonyl Compounds [J]. Tetrahedron, 1968, 24(16): 5655-5664.

[10] Nie Y. J., Sun J. Q., Wang L. C. Ethylene Polymerization by Heteroligated (Salicylaldiminato)(β-enaminoketonato) Titanium Complex/MAO[J] J. Materials Science & Engineering, 2007, 25(4): 493-496.

[11] Francis P. S., Cooke R. C. J., Elliott J. H. Fraction of Polyethylene [J]. J. Polym. Sci., 1958, 31(123): 453-466.

[12] Li X F, Dai K, Ye W P, Pan L, et al. New Titanium Complexes with Two β-Enaminoketonato Chelate Ligands: Syntheses, Structure, and Olefin Polymerization Activities[J]. Organometallics, 2004, (23):1223–1230

[13] Bochmann M., Lancaster S. J. Base-free Cationic Zirconium Benzyl Complexes as Highly Active Polymerization Catalysts [J]. Organometallics, 1993, 12: 633-640.

[14] Kaminsky W., Bark A., Steiger R. Sterospecific Polymerization by Metallocene/aluminoxane Catalysts [J]. J. Mol. Catal., 1992, 74: 109-119.

[15] Juengling S., Muelhaupt R., Plenio H. Cooperative Effects in Binuclear Zirconocenes: Their Synthesis and Use as Catalyst in Propene Polymerization [J]. J. Organomet. Chem., 1993, 460: 191-195.

[16] Ushioda T., Green M. L., Haggitt J., . Synthesis and Catalytic Properties of ansa-Binuclear Metallocenes of the Group IV Transition metals[J]. J. Organomet. Chem., 1996, 518(1–2): 155-166.