Reactivity of vinyl and alkynyl zirconium complexes with the di-ansa-[1,1′,2,2′-bis(dimethylsilanediyl) dicyclopentadienyl] ligand

Fernández, Francisco J.; Galakhov, Mikhail; Royo, Pascual

doi:10.1016/s0022-328x(99)00633-6

Cited by 4 publications

(2 citation statements)

References 18 publications

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“…To explore the influence of ancillary ligands on zirconocene coupling, various bis(cyclopentadienyl) substituents were also examined. Zirconacycles containing the ancillary ligands Me 2 C(η 5 -C 5 H 4 ) 2 and CpCp* are of particular interest since most reported zirconacyclopentadienes feature the Cp 2 or Cp* 2 ligand sets. − …”

Section: Resultsmentioning

confidence: 99%

“…Zirconacycles containing the ancillary ligands Me 2 C(η 5 -C 5 H 4 ) 2 and CpCp* are of particular interest since most reported zirconacyclopentadienes feature the Cp 2 or Cp* 2 ligand sets. [42][43][44][45][46] Synthesis of Zirconacyclopentadiene and Zirconacyclopropene Complexes. The starting compounds used in this study were synthesized by reduction of the appropriate zirconocene dichloride in the presence of an alkyne, with either butyl lithium in THF (Negishi protocol) 47 or magnesium amalgam 48 as the reductant.…”

Section: Resultsmentioning

confidence: 99%

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Mechanism of Reversible Alkyne Coupling at Zirconocene: Ancillary Ligand Effects

2008

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The mechanism of reversible alkyne coupling at zirconium was investigated by examination of the kinetics of zirconacyclopentadiene cleavage to produce free alkynes. The zirconacyclopentadiene rings studied possess trimethylsilyl substituents in the alpha-positions, and the ancillary Cp2, Me2C(eta(5)-C5H4)2, and CpCp* (Cp* = eta(5)-C5Me5) bis(cyclopentadienyl) ligand sets were employed. Fragmentation of the zirconacyclopentadiene ring in Cp2Zr[2,5-(Me3Si)2-3,4-Ph2C4] with PMe3, to produce Cp2Zr(eta(2)-PhC[triple bond]CSiMe3)(PMe3) and free PhC[triple bond]CSiMe3, is first-order in initial zirconacycle concentration and zero-order in incoming phosphine (k(obs) = 1.4(2) x 10(-5) s(-1) at 22 degrees C), and the activation parameters determined by an Eyring analysis (DeltaH(double dagger) = 28(2) kcal mol(-1) and DeltaS(double dagger) = 14(4) eu) are consistent with a dissociative mechanism. The analogous reaction of the ansa-bridged complex Me2C(eta(5)-C5H4)2Zr[2,5-(Me3Si)2-3,4-Ph2C4] is 100 times faster than that for the corresponding Cp2 complex, while the corresponding CpCp* complex reacts 20 times slower than the Cp2 derivative. These rates appear to be largely influenced by the steric properties of the ancillary ligands.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Mechanism of Reversible Alkyne Coupling at Zirconocene: Ancillary Ligand Effects

2008

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Synthesis of double silylene‐bridged binuclear zirconium complexes and their use as catalysts for olefin polymerization

Jia

Huang

2007

J. Polym. Sci. A Polym. Chem.

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New double silylene‐bridged binuclear zirconium complexes [(η5‐RC5H4)ZrCl2]2[μ,μ‐(SiMe2)2(η5‐C5H3)2] [R = H (1), Me (2), nPr (3), iPr (4), nBu (5), allyl (6), 3‐butenyl (7), benzyl (8), PhCH2CH2 (9), MeOCH2CH2 (10)] were synthesized by the reaction of (η5‐RC5H4)ZrCl3·DME with [μ,μ‐(SiMe2)2(η5‐C5H3)2]2− (L2−) in THF, and they were all well characterized by 1H NMR, MS, IR, and EA. The binuclear structure of Complex 3 was further confirmed by X‐ray diffraction, where the two zirconium centers are located trans relative to the bridging [μ,μ‐(SiMe2)2(η5‐C5H3)2] moiety. When activated with methylaluminoxane (MAO), this series of zirconium complexes are highly active catalysts for the polymerization of ethylene even under very low molar ratio of Al/Zr (Complex 7, 5.41 × 105 g‐PE/mol‐Zr·h, Al/Zr = 50) and linear polyethylenes (PEs) with broad molecular weight distribution (MWD, Mw/Mn = 7.31–27.6) was obtained. The copolymerization experiments indicate that these complexes are also very efficient in the incorporation of 1‐hexene into the growing PE chain in the presence of MAO (Complex 6, 3.59 × 106 g‐PE/mol‐Zr·h; 1‐hexene content, 3.65%). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4901–4913, 2007

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Olefin poly/oligomerizations by metal precatalysts bearing non–heterocyclic N–donor ligands

Budagumpi

Keri

Biffis

et al. 2017

Applied Catalysis A: General

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Reactivity of vinyl and alkynyl zirconium complexes with the di-ansa-[1,1′,2,2′-bis(dimethylsilanediyl) dicyclopentadienyl] ligand

Abstract: Vinylation of the chloro-ethyl and dichloro zirconium complexes [Zr(CpSi 2 Cp)ClX] (CpSi 2 Cp =1,1%,2,2%-(SiMe 2 ) 2 (h 5

Cited by 4 publications

References 18 publications

Mechanism of Reversible Alkyne Coupling at Zirconocene: Ancillary Ligand Effects

Mechanism of Reversible Alkyne Coupling at Zirconocene: Ancillary Ligand Effects

Synthesis of double silylene‐bridged binuclear zirconium complexes and their use as catalysts for olefin polymerization

Olefin poly/oligomerizations by metal precatalysts bearing non–heterocyclic N–donor ligands

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