Dinuclear cationic zirconium complexes with the fulvalene ligand. Synthesis and reactivity

Cuenca, Tomás; Galakhov, Mikhail; Jiménez, Gerardo; Royo, Eva Sáenz; Royo, Pascual; Bochmann, Manfred

doi:10.1016/s0022-328x(97)00212-x

Cited by 28 publications

(20 citation statements)

References 31 publications

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“…Figure 2a). Evidently, even a large excess of MAO is unable to reactivate [(BuCp 2 Zr) 2 (μ‐CH 2 )(μ‐Cl)][MAO(Me)] in agreement with the hypothesis that its formation corresponds to an irreversible deactivation reaction [42] …”

Section: Resultssupporting

confidence: 75%

“…[3d,13b-c] However, this α-CÀ H activation reaction has been observed for cationic fulvalene [41] complexes of zirconium analogous to 2, and is thought to be a possible mechanism for metallocene catalyst deactivation. [42] Moreover, fulvalene complexes analogous to 9 have been prepared and their insertion chemistry studied. [43] They are not reactive towards olefin insertion polymerization.…”

Section: Metallocene Catalyst Activationmentioning

confidence: 99%

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Activation of Substituted Metallocene Catalysts Using Methylaluminoxane

Collins

Linnolahti

2022

ChemCatChem

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Activation of the metallocene complexes (n-C 4 H 9 -(η 5 -C 5 H 4 )) 2 ZrCl 2 (BuCp 2 ZrCl 2 ) and rac-1,2-ethylenebis(1-η 5 -C 9 H 6 )ZrCl 2 (EBIZrCl 2 ) using methylaluminoxane (MAO) was investigated by electrospray ionization mass spectrometry (ESI-MS). Formation of dinuclear complexes at low Al : Zr ratios, which is accompanied by catalyst deactivation, occurs in the former case. In contrast, this behavior was not observed at similar Al : Zr ratios in the case of the EBIZrCl 2 complex. Both active [BuCp 2 ZrMe 2 AlMe 2 ][MAO(Me)] 3 and deactivated [(BuCp 2 Zr) 2 (μ-CH 2 )μ-Cl][MAO(Me)] 9 complexes were detected in leaching experiments using a SiO 2 -MAO-supported BuCp 2 ZrCl 2 catalyst and excess MAO. DFT studies of the structure and UV-Vis spectra calculated for the dinuclear cations 9 detected by ESI-MS suggest that these species may account for long-wavelength absorption seen in experimental spectra of complexes like BuCp 2 ZrCl 2 upon activation with MAO.

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Section: Resultssupporting

confidence: 75%

Section: Metallocene Catalyst Activationmentioning

confidence: 99%

Activation of Substituted Metallocene Catalysts Using Methylaluminoxane

Collins

Linnolahti

2022

ChemCatChem

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“…After 1 h at room tempera- -fragment gives signals at δ = 0.84 and 0.91 ppm for derivatives 12 and 14, respectively, suggesting a certain interaction between the anionic and the cationic centres. [25][26][27][28][29] The signals of the methylene protons of the benzylborate anion [(PhCH 2 )B(C 6 F 5 ) 4 ] -appear at δ = 3.14 and 2.90 ppm for derivatives 13 and 15, respectively. It is not easy to establish a limit to determine the coordination or non-coordination of the anionic and cationic centres by analysing the methylene benzylborate anion resonances.…”

Section: Study Of the Molecularmentioning

confidence: 99%

Alkylmono(cyclopentadienyl)titanium Complexes Containing the 2,2′‐Methylenebis(6‐tert‐butyl‐4‐methylphenoxido) Ligand – Studies on the Nature of the Catalytic Species Present in α‐Olefin Polymerisation Processes

et al. 2006

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The mono(alkyl)bis(phenoxido)titanium complexes [TiRЈ(η 5 -C 5 R 5 )(η 2 -mbmp)] [R = H, RЈ = Me (4), CH 2 Ph (5), Ph (6), CH 2 SiMe 3 (7); R = Me, RЈ = Me (8), CH 2 Ph (9), CH 2 SiMe 3 (10); η 2 -mbmp = 2,2Ј-methylenebis(6-tert-butyl-4-methylphenoxido)] have been prepared in good yields by reaction of the appropriate alkylating reagent with the corresponding chlorido(cyclopentadienyl)bis(phenoxido)titanium derivative. Compound 6 reacts in toluene with traces of water to afford the µ-oxidotitanium complex {Ti(η 5 -C 5 H 5 )(η 2 -mbmp)} 2 (µ-O) (11). Compounds 8, 9 and 11 have been characterised by single-crystal X-ray crystallography, and density functional calculations have been performed in order to elucidate the energetic and structural properties of these compounds. The activity of these complexes in the presence of methylaluminoxane (MAO), B(C 6 F 5 ) 3 or [Ph 3 C][B(C 6 F 5 ) 4 ] as co-catalysts in the polymerisation of propylene and styrene has been studied. In an effort to model the nature of the catalytic species generated from these precursors, the reactions of the mono(cyclopentadienyl)bis(phenoxido)chlorido-and

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“…For X = Cl, complex 2 with m/z = 31 which is expected to be much less active or inactive in olefin polymerization. 32 In addition, the anions formed at low Al:Zr ratios in the case of Cp 2 ZrCl 2 are extensively chlorinated by a process which involves net exchange of bound Me 3 Al for Me 2 AlCl, the byproduct of catalyst alkylation. 31 It has been demonstrated in the literature that chlorination of MAO (by Me 2 AlCl) can be detrimental for catalyst activation, 21,33 though a recent theoretical study suggests an opposite conclusion for insertion involving chlorinated anions.…”

Section: ■ Introductionmentioning

confidence: 99%

“…The heterodinuclear Me 3 Al adduct 4 predominates at highest Al:Zr ratios with unhindered metallocenes. For X = Cl, complex 2 with m / z = 505 is unstable with respect to CH 4 elimination in solution forming [(Cp 2 Zr) 2 (μ-Cl)(μ-CH 2 )][MAO(Me)] which is expected to be much less active or inactive in olefin polymerization …”

Section: Introductionmentioning

confidence: 99%

Activation of Cp₂ZrX₂ (X = Me, Cl) by Methylaluminoxane As Studied by Electrospray Ionization Mass Spectrometry: Relationship to Polymerization Catalysis

Collins

Linnolahti

Zamora³

et al. 2017

Macromolecules

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Activation of Cp2ZrCl2 and Cp2ZrMe2 by methylaluminoxane (MAO) in toluene is largely complete at Al:Zr ratios of 100:1 to 200:1 as revealed by electrospray ionization mass spectrometry (ESI MS). The anions present undergo chlorination in the case of Cp2ZrCl2. DFT calculations reveal that chlorination of MAO is favorable and involves dissociation of Me3Al, followed by association of Me2AlCl. Ethylene polymerizations were conducted using these catalyst precursors in toluene. The activity vs [Zr] data are essentially identical, while higher MW polyethylene is formed with a narrower MWD at lower Al:Zr ratios in the case of Cp2ZrMe2. The activity vs [Zr] data could be fit to a model which invokes bimolecular deactivation of growing chains. ESI MS reveals that a dinuclear Zr2 cation with m/z 557 is formed on exposure of [Cp2Zr(μ-Me)2AlMe2]+ to ethylene, in addition to other cations that are dinuclear with respect to Zr. Labeling experiments using ethylene-d 4 indicate that these dinuclear cations are derived from ethylene, either through direct incorporation in the case of m/z 557, or indirectly through incorporation of deuterium following e.g. β-H elimination. These experiments shed light on the need for high Al:Zr ratios for ethylene polymerization using soluble metallocene catalysts. The active catalyst [Cp2ZrR][MAO(Me)] (R = H, Et or a higher homologue) suffers a second order deactivation, and thus activity improves upon dilution of the catalyst precursor at constant [Al].

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Dinuclear cationic zirconium complexes with the fulvalene ligand. Synthesis and reactivity

Cited by 28 publications

References 31 publications

Activation of Substituted Metallocene Catalysts Using Methylaluminoxane

Activation of Substituted Metallocene Catalysts Using Methylaluminoxane

Alkylmono(cyclopentadienyl)titanium Complexes Containing the 2,2′‐Methylenebis(6‐tert‐butyl‐4‐methylphenoxido) Ligand – Studies on the Nature of the Catalytic Species Present in α‐Olefin Polymerisation Processes

Activation of Cp₂ZrX₂ (X = Me, Cl) by Methylaluminoxane As Studied by Electrospray Ionization Mass Spectrometry: Relationship to Polymerization Catalysis

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Dinuclear cationic zirconium complexes with the fulvalene ligand. Synthesis and reactivity

Cited by 28 publications

References 31 publications

Activation of Substituted Metallocene Catalysts Using Methylaluminoxane

Activation of Substituted Metallocene Catalysts Using Methylaluminoxane

Alkylmono(cyclopentadienyl)titanium Complexes Containing the 2,2′‐Methylenebis(6‐tert‐butyl‐4‐methylphenoxido) Ligand – Studies on the Nature of the Catalytic Species Present in α‐Olefin Polymerisation Processes

Activation of Cp2ZrX2 (X = Me, Cl) by Methylaluminoxane As Studied by Electrospray Ionization Mass Spectrometry: Relationship to Polymerization Catalysis

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Activation of Cp₂ZrX₂ (X = Me, Cl) by Methylaluminoxane As Studied by Electrospray Ionization Mass Spectrometry: Relationship to Polymerization Catalysis