Linked cyclopentadienyl–amido complexes of zirconium; ligand dependence of cation–anion interactions and ethene polymerisation activity

Sinnema, Piet-Jan; Liekelema, K; Staal, Oetze K.B; Hessen, Bart; Teuben, Jan H.

doi:10.1016/s1381-1169(97)00168-4

Cited by 40 publications

(31 citation statements)

References 21 publications

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“…The half-sandwich complex was obtained by the reaction of Ti[NEt 2 ] 4 and (Cp(CH 2 ) 2 NHEt in toluene as described before by Hughes et al [14] for analogous compounds. The procedure results in [{g 5 :r-C 5 H 4 (CH 2 ) 2 NEt}Ti(NEt 2 ) 2 ] obtained as an orange moisture-sensitive oil, that was purified by fractional distillation under reduced pressure. 1 H NMR spectrum showed signals that are characteristic for these systems.…”

Section: Resultsmentioning

confidence: 99%

“…[1][2][3] These systems are potential catalytic precursors for homogeneous olefin polymerization. [1,[3][4][5] Even though these systems are efficiently activated with MAO, the effect of the MAO/M (M = Ti, Zr, Hf) molar ratio on the polymerization activity and on the polymer properties has only been studied in the case of bis-indenyl, bis-cyclopentadienyl or Cp-fluorenyl systems carrying chlorine and/or alkyl groups as additional ligands. [6,7] Furthermore, the catalytic behaviour of halfsandwich Cp-amido complexes investigated in the homogeneous catalytic polymerization until now contain a dialkylsilanediyl bridge, [1,2,4,8] whereas the systems analysed here contain a hydrocarbon bridge.…”

Section: Introductionmentioning

confidence: 99%

“…[6,7] Furthermore, the catalytic behaviour of halfsandwich Cp-amido complexes investigated in the homogeneous catalytic polymerization until now contain a dialkylsilanediyl bridge, [1,2,4,8] whereas the systems analysed here contain a hydrocarbon bridge. [5,9,10] The new ((cyclopentadienyl)(N-ethylamido)ethylene) titanium di(diethylamino) complex was prepared in the present work. We report the study of its catalytic activity in the ethene polymerization and ethene/propene copolymerization and the effect of the MAO/Ti molar ratio on the catalyst activity and on the polymer properties.…”

Section: Introductionmentioning

confidence: 99%

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Ethene homo- and ethene/propene copolymerization using a MAO activated cyclopentadienyl-amido half-sandwich complex

Chirinos¹,

Rajmankina

Parada

et al. 2000

Macromol. Chem. Phys.

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The half‐sandwich complex [{η5:σ‐C5H4(CH2)2NEt}Ti(NEt2)2] was synthesized and characterized by means of IR‐spectroscopy. This compound was activated by methylaluminoxane (MAO) for homogeneous ethene polymerization and ethene/propene copolymerization. The effect of the Al/Ti molar ratio on the polymerization activity, the molecular masses, and the thermal properties of the polymers was studied. The molecular weight distributions and the DSC measurements of the copolymers show the presence of two different catalytic sites.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ethene homo- and ethene/propene copolymerization using a MAO activated cyclopentadienyl-amido half-sandwich complex

Chirinos¹,

Rajmankina

Parada

et al. 2000

Macromol. Chem. Phys.

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“…The method has been applied in the syntheses of various types of CGCs including ligand variations such as CpC 3 S- [35] or CpBN- [36] patterns. A straightforward entry to dichloro CGCs is accessed when bis(amido)dichloro complexes such as Zr(NMe 2 ) 2 Cl 2 (THF) 2 are employed [37].…”

Section: Metallation (Amine and Alkane Elimination)mentioning

confidence: 99%

How to synthesize a constrained geometry catalyst (CGC) – A survey

Cano

Kunz

2007

Journal of Organometallic Chemistry

105

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“…This phenomenon has been also observed by other groups for related zirconium complexes. 9b, 16 [Zr(Me 2 TACD)(CH 2 SiMe 3 ) 2 ] (1). A solution of (Me 2 TACD)H 2 (500.0 mg, 2.5 mmol) in 5 mL of benzene was added to a solution of [Zr(CH 2 SiMe 3 ) 4 ] (1.098 g, 2.5 mmol) in 5 mL of benzene.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Neutral and Cationic Zirconium Hydrides Supported by a Dianionic (NNNN)-Type Macrocycle Ligand

2014

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Hydrogenation of bis(trimethylsilylmethyl) zirconium complex [Zr(Me 2 TACD)(CH 2 SiMe 3 ) 2 ] (1), prepared by reacting [Zr(CH 2 SiMe 3 ) 4 ] with 1,7-dimethyl-1,4,7,10-tetraazacyclododecane (Me 2 TACD)H 2 , gave dinuclear alkyl hydride complex [Zr(Me 2 TACD)(CH 2 SiMe 3 ) 2 (μ-H) 2 Zr-(Me 2 TACD)] (2). According to NMR spectroscopic and single-crystal X-ray diffraction studies, 2 exhibits a C s -symmetrical structure with two distinct zirconium centers, one eight-and the other seven-coordinate, bridged by an amido donor and two hydrides. Abstraction of the trimethylsilylmethyl groups by the weak Brønsted acid [NEt 3 H][B(3,5-C 6 H 3 Cl 2 ) 4 ] gave the monocationic mono(alkyl) dihydride [Zr(Me 2 TACD)(CH 2 SiMe 3 )(μ-H) 2 Zr(Me 2 TACD)][B(3,5-C 6 H 3 Cl 2 ) 4 ] (3) and the dicationic hydride complex [Zr(Me 2 TACD)(THF) 2 (μ-H) 2 Zr(Me 2 TACD)][B(3,5-C 6 H 3 Cl 2 ) 4 ] 2 (4). X-ray crystallography of the cationic complexes 3 and 4 revealed a C s -symmetrical dinuclear structure derived from that of 2. ■ INTRODUCTIONZirconium hydride complexes are important reagents in organic synthesis, 1 reduce small molecules such as carbon monoxide, 2 and activate dinitrogen. 3 They exhibit a polarized metal hydride bond at a relatively strong Lewis acidic and oxophilic metal center that can be modulated by the ancillary ligand set. Whereas zirconocene hydrides 4 and their derivatives have been extensively used, 2a,i,3a,5 zirconium hydrides supported by hard donor ligand sets still remain relatively unexplored. They could be expected to exhibit reactivity patterns distinct from those reported for zirconocene hydrides. 6 Recently, Fryzuk, Martins, et al. have introduced dianionic macrocyclic ligands based on cyclam 7 as supporting ligands for neutral hydride complexes. 3a We have reported (di)cationic zirconium hydride complexes that contain formally monoanionic (NNNN)-type macrocyclic ligands based on cyclen. 6 Here we report the synthesis and characterization of a neutral dinuclear zirconium hydride complex stabilized by the dianionic macrocycle (Me 2 TACD) 2− derived from 1,7-dimethyl-1,4,7,10-tetraazacyclododecane, (Me 2 TACD)H 2 . This L 4 X 2 -type or 12-electron-donor ligand has previously been shown to effectively support Lewis base free rare-earth metal alkyl and hydride compounds. 8a−c ■ RESULTS AND DISCUSSION Solvent-free bis(trimethylsilylmethyl) complex 1 was prepared in good yield by reacting light-and temperature-sensitive [Zr(CH 2 SiMe 3 ) 4 ] with (Me 2 TACD)H 2 at room temperature in benzene and crystallized from pentane as relatively robust yellow crystals (Scheme 1). 1 was characterized by NMR spectroscopy and by single-crystal X-ray diffraction. The NMR spectra in benzene-d 6 are consistent with C 2v -symmetry. Both methyl groups of the Me 2 TACD ligand appear as a sharp singlet at δ 2.29 ppm, and the CH 2 CH 2 protons as multiplets of an ABCD spin pattern centered at δ 3.47, 2.41, and 2.23 ppm. The resonance for ZrCH 2 was recorded at δ 0.16 and 41.6 ppm in the 1 H and 13 C NMR spectrum, respectively.Ac...

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Linked cyclopentadienyl–amido complexes of zirconium; ligand dependence of cation–anion interactions and ethene polymerisation activity

Abstract: Linked cyclopentadienyl-amido complexes of zirconium; ligand dependence of cation-anion interactions and ethene polymerisation activity Sinnema, P.J; Liekelema, K.; Staal, O.K.B.; Hessen, B.; Teuben, J.H

Cited by 40 publications

References 21 publications

Ethene homo- and ethene/propene copolymerization using a MAO activated cyclopentadienyl-amido half-sandwich complex

Ethene homo- and ethene/propene copolymerization using a MAO activated cyclopentadienyl-amido half-sandwich complex

How to synthesize a constrained geometry catalyst (CGC) – A survey

Neutral and Cationic Zirconium Hydrides Supported by a Dianionic (NNNN)-Type Macrocycle Ligand

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