Living polymerization of ethylene catalyzed by diene complexes of niobium and tantalum, M(η5-C5Me5)(η4-diene)X 2 and M(η5-C5Me5)(η4-diene) 2 (M = Nb and Ta), in the presence of methylaluminoxane

Kazushi Mashima, Toshiyuki Oshiki, Yoshiyuki Tanaka, Hisao Urata, Toshiyuki Oshiki, Eiji Tanaka, Akira Nakamura

Research output: Contribution to journalArticle

134 Citations (Scopus)

Abstract

Catalyst systems of MX25-C5R5)(η 4-diene) (M = Nb and Ta; R = H and CH3; X = Cl and CH3) in a combination of methylaluminoxane (MAO) are the precursors of the living polymerization of ethylene. Mono-diene complexes MCl25-C5R5)(η 4-diene) [M = Nb, R = CH3 (1); M = Ta, R = CH3 (2); M = Ta, R = H (3); M = Nb, R = H (4); diene = buta-1,3-diene (a), isoprene (b), 2,3-dimethylbuta-1,3-diene (c)] were prepared by the reaction of MCl4-(η5-C5R5) with 2 equiv of the methylated allyl Grignard reagents in THF. Reaction of 2 and 3 with MeMgI afforded dimethyl complexes, Ta(η5-C5R5)(η 4-1,3-butadiene)Me2 [R = CH3 (5); R = H (6)], respectively. The polymerization of ethylene catalyzed by 1/MAO, 2/MAO, and 5/MAO at low temperature (-20°C) gave polyethylene with very narrow polydispersities (Mw/Mn as low as 1.05). The niobium complexes are superior to the tantalum complexes in terms of the catalyst activity and the polydispersity. When the ligand was Cp instead of Cp*, the catalyst activity of 3 for the polymerization of ethylene at -20°C increased but the polydispersity of the obtained polyethylene broadened (Mw/Mn = 1.40). Protolytic reaction of 5b with 1 equiv of TfOH produces TaCp*(η4-isoprene)(CH3)(OSO2CF 3) (7), whose structure is determined by single-crystal X-ray diffractometry. Compound 7 crystallizes in the orthorhombic space group P212121 (No. 19) with a = 13.388(6) Å, b = 16.196(4) Å, c = 9.214(4) Å, Z = 4, V = 1998(1) Å3, Dcalcd = 1.823 g/mL, and R = 0.041 based on 2191 reflections. The molecular structure shows that 7 is not a cationic complex. The tantalum atom is in a chiral center surrounded by four different ligands: η1-triflate, η5-Cp*, η4-isoprene, and methyl. A cationic species derived from 5b and B(C6F5)3 was detected by 1H NMR spectroscopy and found to be active in ethylene polymerization. A system of one of the bis-diene complexes of the type M(η5-C5R5)(η 4-2,3-dimethyl-1,3-butadiene)2 [M = Nb, R = H (8); M = Nb, R = CH3 (9); M = Ta, R = CH3 (10)] in the presence of a large excess of MAO was also found to be an active catalyst for the polymerization of ethylene.

Original languageEnglish
Pages (from-to)2633-2640
Number of pages8
JournalOrganometallics
Volume14
Issue number6
Publication statusPublished - 1995
Externally publishedYes

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Niobium
Tantalum
Living polymerization
dienes
tantalum
niobium
ethylene
polymerization
Polydispersity
Polymerization
Polyethylene
catalysts
Catalyst activity
butadiene
Ligands
polyethylenes
Catalysts
X ray diffraction analysis
Molecular structure
Nuclear magnetic resonance spectroscopy

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Organic Chemistry

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Living polymerization of ethylene catalyzed by diene complexes of niobium and tantalum, M(η5-C5Me5)(η4-diene)X 2 and M(η5-C5Me5)(η4-diene) 2 (M = Nb and Ta), in the presence of methylaluminoxane. / Mashima, Kazushi; Oshiki, Toshiyuki; Tanaka, Yoshiyuki; Urata, Hisao; Oshiki, Toshiyuki; Tanaka, Eiji; Nakamura, Akira.

In: Organometallics, Vol. 14, No. 6, 1995, p. 2633-2640.

Research output: Contribution to journalArticle

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title = "Living polymerization of ethylene catalyzed by diene complexes of niobium and tantalum, M(η5-C5Me5)(η4-diene)X 2 and M(η5-C5Me5)(η4-diene) 2 (M = Nb and Ta), in the presence of methylaluminoxane",
abstract = "Catalyst systems of MX2(η5-C5R5)(η 4-diene) (M = Nb and Ta; R = H and CH3; X = Cl and CH3) in a combination of methylaluminoxane (MAO) are the precursors of the living polymerization of ethylene. Mono-diene complexes MCl2(η5-C5R5)(η 4-diene) [M = Nb, R = CH3 (1); M = Ta, R = CH3 (2); M = Ta, R = H (3); M = Nb, R = H (4); diene = buta-1,3-diene (a), isoprene (b), 2,3-dimethylbuta-1,3-diene (c)] were prepared by the reaction of MCl4-(η5-C5R5) with 2 equiv of the methylated allyl Grignard reagents in THF. Reaction of 2 and 3 with MeMgI afforded dimethyl complexes, Ta(η5-C5R5)(η 4-1,3-butadiene)Me2 [R = CH3 (5); R = H (6)], respectively. The polymerization of ethylene catalyzed by 1/MAO, 2/MAO, and 5/MAO at low temperature (-20°C) gave polyethylene with very narrow polydispersities (Mw/Mn as low as 1.05). The niobium complexes are superior to the tantalum complexes in terms of the catalyst activity and the polydispersity. When the ligand was Cp instead of Cp*, the catalyst activity of 3 for the polymerization of ethylene at -20°C increased but the polydispersity of the obtained polyethylene broadened (Mw/Mn = 1.40). Protolytic reaction of 5b with 1 equiv of TfOH produces TaCp*(η4-isoprene)(CH3)(OSO2CF 3) (7), whose structure is determined by single-crystal X-ray diffractometry. Compound 7 crystallizes in the orthorhombic space group P212121 (No. 19) with a = 13.388(6) {\AA}, b = 16.196(4) {\AA}, c = 9.214(4) {\AA}, Z = 4, V = 1998(1) {\AA}3, Dcalcd = 1.823 g/mL, and R = 0.041 based on 2191 reflections. The molecular structure shows that 7 is not a cationic complex. The tantalum atom is in a chiral center surrounded by four different ligands: η1-triflate, η5-Cp*, η4-isoprene, and methyl. A cationic species derived from 5b and B(C6F5)3 was detected by 1H NMR spectroscopy and found to be active in ethylene polymerization. A system of one of the bis-diene complexes of the type M(η5-C5R5)(η 4-2,3-dimethyl-1,3-butadiene)2 [M = Nb, R = H (8); M = Nb, R = CH3 (9); M = Ta, R = CH3 (10)] in the presence of a large excess of MAO was also found to be an active catalyst for the polymerization of ethylene.",
author = "Kazushi Mashima and Toshiyuki Oshiki and Yoshiyuki Tanaka and Hisao Urata and Toshiyuki Oshiki and Eiji Tanaka and Akira Nakamura",
year = "1995",
language = "English",
volume = "14",
pages = "2633--2640",
journal = "Organometallics",
issn = "0276-7333",
publisher = "American Chemical Society",
number = "6",

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TY - JOUR

T1 - Living polymerization of ethylene catalyzed by diene complexes of niobium and tantalum, M(η5-C5Me5)(η4-diene)X 2 and M(η5-C5Me5)(η4-diene) 2 (M = Nb and Ta), in the presence of methylaluminoxane

AU - Mashima, Kazushi

AU - Oshiki, Toshiyuki

AU - Tanaka, Yoshiyuki

AU - Urata, Hisao

AU - Oshiki, Toshiyuki

AU - Tanaka, Eiji

AU - Nakamura, Akira

PY - 1995

Y1 - 1995

N2 - Catalyst systems of MX2(η5-C5R5)(η 4-diene) (M = Nb and Ta; R = H and CH3; X = Cl and CH3) in a combination of methylaluminoxane (MAO) are the precursors of the living polymerization of ethylene. Mono-diene complexes MCl2(η5-C5R5)(η 4-diene) [M = Nb, R = CH3 (1); M = Ta, R = CH3 (2); M = Ta, R = H (3); M = Nb, R = H (4); diene = buta-1,3-diene (a), isoprene (b), 2,3-dimethylbuta-1,3-diene (c)] were prepared by the reaction of MCl4-(η5-C5R5) with 2 equiv of the methylated allyl Grignard reagents in THF. Reaction of 2 and 3 with MeMgI afforded dimethyl complexes, Ta(η5-C5R5)(η 4-1,3-butadiene)Me2 [R = CH3 (5); R = H (6)], respectively. The polymerization of ethylene catalyzed by 1/MAO, 2/MAO, and 5/MAO at low temperature (-20°C) gave polyethylene with very narrow polydispersities (Mw/Mn as low as 1.05). The niobium complexes are superior to the tantalum complexes in terms of the catalyst activity and the polydispersity. When the ligand was Cp instead of Cp*, the catalyst activity of 3 for the polymerization of ethylene at -20°C increased but the polydispersity of the obtained polyethylene broadened (Mw/Mn = 1.40). Protolytic reaction of 5b with 1 equiv of TfOH produces TaCp*(η4-isoprene)(CH3)(OSO2CF 3) (7), whose structure is determined by single-crystal X-ray diffractometry. Compound 7 crystallizes in the orthorhombic space group P212121 (No. 19) with a = 13.388(6) Å, b = 16.196(4) Å, c = 9.214(4) Å, Z = 4, V = 1998(1) Å3, Dcalcd = 1.823 g/mL, and R = 0.041 based on 2191 reflections. The molecular structure shows that 7 is not a cationic complex. The tantalum atom is in a chiral center surrounded by four different ligands: η1-triflate, η5-Cp*, η4-isoprene, and methyl. A cationic species derived from 5b and B(C6F5)3 was detected by 1H NMR spectroscopy and found to be active in ethylene polymerization. A system of one of the bis-diene complexes of the type M(η5-C5R5)(η 4-2,3-dimethyl-1,3-butadiene)2 [M = Nb, R = H (8); M = Nb, R = CH3 (9); M = Ta, R = CH3 (10)] in the presence of a large excess of MAO was also found to be an active catalyst for the polymerization of ethylene.

AB - Catalyst systems of MX2(η5-C5R5)(η 4-diene) (M = Nb and Ta; R = H and CH3; X = Cl and CH3) in a combination of methylaluminoxane (MAO) are the precursors of the living polymerization of ethylene. Mono-diene complexes MCl2(η5-C5R5)(η 4-diene) [M = Nb, R = CH3 (1); M = Ta, R = CH3 (2); M = Ta, R = H (3); M = Nb, R = H (4); diene = buta-1,3-diene (a), isoprene (b), 2,3-dimethylbuta-1,3-diene (c)] were prepared by the reaction of MCl4-(η5-C5R5) with 2 equiv of the methylated allyl Grignard reagents in THF. Reaction of 2 and 3 with MeMgI afforded dimethyl complexes, Ta(η5-C5R5)(η 4-1,3-butadiene)Me2 [R = CH3 (5); R = H (6)], respectively. The polymerization of ethylene catalyzed by 1/MAO, 2/MAO, and 5/MAO at low temperature (-20°C) gave polyethylene with very narrow polydispersities (Mw/Mn as low as 1.05). The niobium complexes are superior to the tantalum complexes in terms of the catalyst activity and the polydispersity. When the ligand was Cp instead of Cp*, the catalyst activity of 3 for the polymerization of ethylene at -20°C increased but the polydispersity of the obtained polyethylene broadened (Mw/Mn = 1.40). Protolytic reaction of 5b with 1 equiv of TfOH produces TaCp*(η4-isoprene)(CH3)(OSO2CF 3) (7), whose structure is determined by single-crystal X-ray diffractometry. Compound 7 crystallizes in the orthorhombic space group P212121 (No. 19) with a = 13.388(6) Å, b = 16.196(4) Å, c = 9.214(4) Å, Z = 4, V = 1998(1) Å3, Dcalcd = 1.823 g/mL, and R = 0.041 based on 2191 reflections. The molecular structure shows that 7 is not a cationic complex. The tantalum atom is in a chiral center surrounded by four different ligands: η1-triflate, η5-Cp*, η4-isoprene, and methyl. A cationic species derived from 5b and B(C6F5)3 was detected by 1H NMR spectroscopy and found to be active in ethylene polymerization. A system of one of the bis-diene complexes of the type M(η5-C5R5)(η 4-2,3-dimethyl-1,3-butadiene)2 [M = Nb, R = H (8); M = Nb, R = CH3 (9); M = Ta, R = CH3 (10)] in the presence of a large excess of MAO was also found to be an active catalyst for the polymerization of ethylene.

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