Synthesis and Characterization of Titanium(IV) Complexes Bearing Monoanionic [O^-NX] (X = O, S, Se) Tridentate Ligands and Their Behaviors in Ethylene Homo- and Copolymerizaton with 1-Hexene

Abstract

A series of novel titanium(IV) complexes bearing monoanionic [O-NX] (X = O, S, Se) ligands is designed by sidearm approach. These complexes were synthesized, characterized, and employed as catalysts in ethylene homo- and copolymerization. X-ray diffraction studies on these new compounds reveal a distorted octahedral coordination of the central metal with the three chlorine ligands in a mer disposition. In the presence of modified methylaluminoxane (MMAO), they exhibit moderate to high activity and afford highly linear polyethylene. Variation of the sidearm, including different heteroatom and substituents, proves to modulate both the catalytic activity and the molecular weight of the resulting polyethylene. The complexes also show excellent capability in copolymerization of ethylene with 1-hexene.

Synthesis and Characterization of NiII and PdII Complexes Bearing N,N,S Tridentate Ligands and Their Catalytic Properties for Norbornene Polymerization

“…Nickel and palladium complexes 1-6 were fully characterized by 1 H NMR and IR spectroscopy, MS, and elemental analyses. The 1 H : S1-C1 1.782(2), S1-C7 1.785(2), C13-N1 1.383(3), N1-C12 1.410(2), C19-C18 1.460(3), N2-C19 1.273(3), N2-C20 1.436(2), C1-S1-C7 102.03(9), C13-N1-C12 124.81(17), C19-N2-C20 117.25 (17), N2-C19-C18 125.04 (18).…”

“…100°) of all complexes suggest that the S atom is sp 3 hybridized. [17] The five-membered S,N chelate ring is coplanar, and the metal atom lies out of the SCCN plane 0.5029 Å for 1, 0.5404 Å for 2, 0.2255 Å for 4, 0.2839 Å for 5, 0.5755 Å for 6. The six-membered N,N chelate ring has a boat conformation with the metal atom lying out of the NCCCN plane (slightly twisted coplanar).…”

“…(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) search has been carried out to elucidate the influence of the sterics of the ligands and the electronic effects of the ligands on polymerization reactions. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] In addition, the sidearm approach had also proven to be an efficient strategy for the design of organometallic catalysts in olefin polymerization, [15][16][17][18][19][20][21] and the sidearm effect of the extra donor had a strong influence on catalytic polymerization. In particular, metal complexes with N, P, O, and S atoms in the sidearm were mainly reported.…”

“…In particular, metal complexes with N, P, O, and S atoms in the sidearm were mainly reported. Chromium, [15] titanium, [16,17] and nickel [18] complexes containing salicylaldiminate ligands with pendant donors had higher catalytic activities than the corresponding complexes without sidearm donors. For the complexes containing relatively hard nitrogen-and oxygen-coordinated atoms, a sidearm containing the soft S or P donor atoms, for understandable reasons, was usually introduced into the ligand backbone.…”

Olefin Polymerization with Non-metallocene Catalysts (Early Transition Metals)

“…[ [61]. Titanium trichloride complexes containing monoanionic tridentate ligands (12,13) exhibited moderate to high catalytic activities for ethylene polymerization (Scheme 3.6) [62,64]: 12 showed better catalyst performance for ethylene copolymerization with 1-hexene and norbornene [62]. In contrast, complex 14 showed remarkable selectivity in ethylene trimerization in the presence of MAO, and second order dependence of activity on ethylene pressure (suggesting the metallacycle mechanism) was observed [65].…”