Syntheses, Structure, and Reactivity of Chiral Titanium Compounds: Procatalysts for Olefin Polymerization

Sobota, Piotr; Przybylak, Katarzyna; Utko, Józef; Jerzykiewicz, Lucjan B.; Pombeiro, Armando J. L.; Silva, M. Fátima C. Guedes da; Szczegot, Krzysztof

doi:10.1002/1521-3765(20010302)7:5<951::aid-chem951>3.0.co;2-f

Cited by 81 publications

(54 citation statements)

References 42 publications

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“…The [Ti 4 (maltolato) 8 4 ] showed an irreversible cathodic wave at a potential of (E red ) −1.36 V, suggesting irreversible reduction of Ti(IV) to Ti(III), while no anodic wave was detected up to the solvent-electrolyte discharge potential. If we compare this potential with previously reported Ti(IV)-maltol and Ti(IV)-guaiacol complexes [29], it resembles to reduction potentials of monomeric species such as Ti(maltolato) 2 4 ] by cyclic voltammetry failed due to the lack of solubility in CH 2 Cl 2 and, in solvents such as DMSO or water no anodic/cathodic waves were detected up to the solvent-electrolyte discharge potential.…”

Section: Resultssupporting

confidence: 52%

Synthesis, solution and solid state structure of titanium–maltol complex

Lamboy

Pasquale

Rheingold

et al. 2007

Inorganica Chimica Acta

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The reaction of Cp 2 TiCl 2 with two equivalents of maltol (3-hydroxy-2-methyl-4-pyrone) in water, at room temperature and pH of 5.4, leads to a complete replacement of Cp and chloride ligands affording, Ti(maltolato) 2 (OH) 2. The complex has been characterized by IR, NMR and ESI-MS spectroscopic and cyclic voltammetry methods. In DMSO-d 6 solution, the complex shows two isomers in a ratio of 4:1, in which one OH signal can be identified per isomer. This suggests that in solution the complex is monomeric, most likely a chiral cis-Ti(maltolato) 2 (OH) 2 and trans-Ti (maltolato) 2 (OH) 2 . The monomeric nature of the complex (in water/methanol 1:1) was verified by ESI-MS spectroscopy, showing a parent peak at 329 m/z. Electrochemical behavior of Ti (maltolato) 2 (OH) 2 using cyclic voltammetry experiments showed the complex undergoes irreversible reduction in aprotic solvents. In D 2 O solution, at pH of 8.4, the 1 H NMR spectrum of the complex shows a mixture of monomer and tetramer Ti(IV)-maltol complexes in a ratio of 1:1. The crystallization of Ti (maltolato) .686(7) Å, β= 97.678(4)° and V = 6824(4) Å 3 for Z = 4. Solid state structure determination of the Ti-maltol complex showed to be tetrameric, containing two bridging oxides (in cis position) and two bidentate maltol ligands per titanium in a pseudo-octahedral coordination geometry.

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Section: Resultssupporting

confidence: 52%

Synthesis, solution and solid state structure of titanium–maltol complex

Lamboy

Pasquale

Rheingold

et al. 2007

Inorganica Chimica Acta

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“…Published online 28 This is the first book of a series of forthcoming publications on this field by this publisher. The reader can enjoy both a classical printed version on demand for a small charge, as well as the online version free for download.…”

Section: Publisher Sciyomentioning

confidence: 99%

Alkoxide Molecular Precursors for Nanomaterials: a One Step Strategy for Oxide Ceramics

John¹,

Sobota²

2010

Ceramic Materials

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“…[8][9][10][11][12] Maltolate complexes appear attractive to catalyze olefin polymerization reaction as well. In 2001, Sobota et al 13 synthesized and characterized titanium complexes of methylmaltol and verified their catalytic activity in ethylene and propylene polymerization. Subsequently, our research group has synthesized several Ti and Zr complexes analogous based in maltolate ligands.…”

Section: Introductionmentioning

confidence: 99%

A New Post-Metallocene-Ti Catalyst with Maltolate Bidentade Ligand: an Investigation in Heterogeneous Polymerization Reactions in Different Mesoporous Supports

Gheno¹,

Basso²,

Livotto³

et al. 2016

Journal of the Brazilian Chemical Society

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A new titanium catalyst easily synthesized from ethylmaltol bidentate chelator ligand was studied in homogeneous and heterogeneous ethylene polymerization. The dichlorobis(3-hydroxy-2-ethyl-4-pyrone)titanium(IV) complex was characterized by 1 H and 13 C NMR (nuclear magnetic resonance), UV-Vis and elemental analysis. Theoretical study by density functional theory (DFT) showed that the complex chlorines exhibit cis configuration, which is important for the activity in olefin polymerization. The complex was supported by two methods, direct impregnation or methylaluminoxane (MAO) pre-treatment, in five mesoporous supports: MCM-41 (micro and nano), SBA-15 and also the corresponding modified Al species. All the catalytic systems were active in ethylene polymerization and the catalytic activity was strongly influenced by the method of immobilization of the catalyst and the type of support. Keywords: catalysis, synthesis, mesoporous support, immobilization, polyethylene IntroductionPolyethylene (PE) has a broad application in different segments of the everyday life, from food packaging to resistant pieces for engineering. Due to the polymer industrial demands, continuous development of new technologies and synthetic methods for obtaining this material are necessary. Existing processes, involving polyethylene synthesis in industrial and/or research scale, use Ziegler-Natta, metallocene, and more recently, postmetallocene catalysts. Our research group has studied the synthesis of different post-metallocene catalysts and tested these complexes in ethylene polymerization. Organometallic complexes of Ti and Zr were obtained from bidentate chelator ligands as naphthoquinone, methylpyrone, ethylpyrone and 3-hydroxyflavone. [1][2][3][4][5] All the synthesized complexes were active in homogeneous ethylene polymerization at different reaction conditions. 3-Hydroxy-2-methyl-4-pyrone (methylpyrone or maltol) is a non-toxic compound of natural occurrence in many plants, 6 while 3-hydroxy-2-ethyl-4-pyrone (ethylmaltol) is a synthetic commercial product. These organic compounds are commonly used in food industries as flavor ingredients. Both hydroxypyrones are characterized by their synthetic versatility and they easily coordinate with transition metals of group IV to give L 2 MCl 2 complexes.7 Bis(maltolate) metal(IV) complexes are extensively used in medical studies to assess their therapeutic value as active agents against diabetes, as agents for controlling metal levels in the body and as contrast agents in imaging applications. [8][9][10][11][12] Maltolate complexes appear attractive to catalyze olefin polymerization reaction as well. In 2001, Sobota et al. 13 synthesized and characterized titanium complexes of methylmaltol and verified their catalytic activity in ethylene and propylene polymerization. Subsequently, our research group has synthesized several Ti and Zr complexes Gheno et al. 2083 Vol. 27, No. 11, 2016 analogous based in maltolate ligands. The synthesized complexes were shown to be active in the ethylene...

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Syntheses, Structure, and Reactivity of Chiral Titanium Compounds: Procatalysts for Olefin Polymerization

Cited by 81 publications

References 42 publications

Synthesis, solution and solid state structure of titanium–maltol complex

Synthesis, solution and solid state structure of titanium–maltol complex

Alkoxide Molecular Precursors for Nanomaterials: a One Step Strategy for Oxide Ceramics

A New Post-Metallocene-Ti Catalyst with Maltolate Bidentade Ligand: an Investigation in Heterogeneous Polymerization Reactions in Different Mesoporous Supports

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