Immobilization of η 5 -cyclopentadienyltris(dimethylamido)zirconium polymerization catalysts on a chlorosilane- and HMDS-modified mesoporous silica surface: a new concept for supporting metallocene amides towards heterogeneous single-site-catalysts

Schneider, Horst; Puchta, Gerd T.; Kaul, Franz A.R.; Raudaschl‐Sieber, Gabriele; Lefèbvre, Frédéric; Saggio, Guillaume; Mihalios, Dimitrios; Herrmann, Wolfgang A.; Basset, Jean‐Marie

doi:10.1016/s1381-1169(01)00051-6

Cited by 31 publications

(6 citation statements)

References 73 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…According to Table 3, the catalysts immobilized by covalent bonds onto MWCNT surface (C2, C4, and C5) show the higher activities compared to physisorbed ones (C1 and C2). This observation confirms the postulation of Choi [18] and Schneider et al [27] which describe the role of covalent catalyst-support linkage on the formation of the higher active immobilized metal centers for ethylene polymerization. The highest activity among immobilized catalysts has been provided by C5 catalyst (5863 g PE mmol −1 Ni h −1 at 60°C) which supports the highest bonding strength in TGA analysis (Fig.…”

Section: Ethylene Polymerization Results Using Heterogeneous Catalystssupporting

confidence: 91%

Immobilization of α-diimine nickel (II) catalysts on multi-walled carbon nanotube for slurry ethylene polymerization

Talebnezhad

Pourmahdian

2014

Colloid Polym Sci

View full text Add to dashboard Cite

Homogeneous α-diimine nickel (II) catalyst complexes, with and without amino para-aryl position functionality, were synthesized. These complexes were immobilized on carboxyl, hydroxyl, and acyl chloride functionalized multiwalled carbon nanotubes to form five novel heterogeneous α-diiminonickel catalysts. Immobilization was performed by covalent or electrostatic bonding via methylaluminoxane (MAO) linker or amide linkage. All the immobilized catalysts were fully characterized and their structures and supporting efficiencies were determined. Both the nature of α-diimine ligands and the kind of interaction between anchored catalyst complexes and multi-walled carbon nanotube surface influenced the catalytic performance, microstructure, and morphology of obtained polyethylenes. Catalysts immobilized by covalent bonds showed higher activities than physisorbed ones with the trend of activity rising versus temperature. Reaction between ligand amino para-aryl position and multiwalled carbon nanotube acyl chloride functionality resulted in immobilization through amide linkage. This procedure prepared catalyst with the lowest relative weight loss in thermogravimetry analysis and highest activities up to 5863 g PE mmol −1 Ni h −1 . The catalyst produced polyethylene with dense botryoidal morphology, highest molecular weight distributions and highest melting points up to 14.1 at 60°C and 133°C at 30°C in polymerization trials, respectively.

show abstract

Section: Ethylene Polymerization Results Using Heterogeneous Catalystssupporting

confidence: 91%

Immobilization of α-diimine nickel (II) catalysts on multi-walled carbon nanotube for slurry ethylene polymerization

Talebnezhad

Pourmahdian

2014

Colloid Polym Sci

View full text Add to dashboard Cite

show abstract

“…Shimada et al used this kind of reactivity for the immobilization of complex organic functionalities on silica surfaces . Despite the fact that immobilized indenyl groups are widely used as ligands in heterogeneous catalysis, ,− the herein described elimination reaction has not been considered until now.…”

Section: Resultsmentioning

confidence: 99%

Advanced Surface Functionalization of Periodic Mesoporous Silica: Kinetic Control by Trisilazane Reagents

et al. 2006

Self Cite

View full text Add to dashboard Cite

The surface reactions of mesoporous silica MCM-41 with a series of new trisilylamines (trisilazanes) (SiHMe2)2NSiMe2R and (SiMe2Vin)2NSiMe2R (R = indenyl, norpinanyl, chloropropyl, 3-(N-morpholin)propyl; Vin = vinyl), disilylalkylamine (SiHMe2)iPrNSiMe2(CH2)3Cl, and monosilyldialkylamines Me2NSiMe2R (R = indenyl, chloropropyl, 3-(N-morpholin)propyl) were investigated. 1H, 13C, and 29Si MAS NMR spectroscopy, nitrogen adsorption/desorption, infrared spectroscopy, and model reactions with calix[4]arene as a mimic for an oxo surface were used to clarify the chemical nature of surface-bonded silyl groups. The trisilylamines exhibited a comparatively slow surface reaction, which allowed for the adjustment of the amount of silylated and nonreacted SiOH groups and led to a stoichiometric distribution of surface functionalities. The 2:1 integral ratio of SiHMe2 and SiMe2R moieties of such trisilazanes was found to be preserved on the silica surface as indicated by microanalytical as well as 13C and 29Si MAS NMR spectroscopic data of the hybrid materials. For example, the reaction of MCM-41 with (SiHMe2)2NSiMe2(CH2)3Cl, (SiHMe2)iPrNSiMe2(CH2)3Cl, and Me2NSiMe2(CH2)3Cl provided bi- and monofunctional hybrid materials with one-third, one-half, or all chemically accessible silanol groups derivatized by chloropropyl groups, respectively. Thus, a molecular precursor strategy was developed to efficiently control the relative amount of three different surface species, SiHMe2 (or SiVinMe2), SiMe2R, and SiOH, in a single reaction step. The reaction behavior of indenyl-substituted monosilazanes and trisilazanes (R = Ind) with calix[4]arene proved that the indenyl substituent can act as a leaving group forming a dimethylsilyl species, which is anchored bipodally on the silica surface, that is, via two Si-O bonds.

show abstract

“…The nature of the M–X bond is also important to their reactivity; for example, selective substitution of these groups with ancillary ligands (LX) provides routes to reactive complexes, including catalysts. While the rich chemistry of surface-supported organometallic compounds indicates that alkyl species are desirable, work with grafted early-metal amides suggests their emerging potential in catalysis. − In rare-earth chemistry, homoleptic organometallic and pseudo-organometallic compounds are particularly important starting materials, but their large ionic radii and low numbers of X-type ligands (either two or three) add to the challenge of preparing reactive monometallic species …”

Section: Introductionmentioning

confidence: 99%

β-SiH-Containing Tris(silazido) Rare-Earth Complexes as Homogeneous and Grafted Single-Site Catalyst Precursors for Hydroamination

et al. 2017

View full text Add to dashboard Cite

A series of homoleptic rare-earth silazido compounds and their silica-grafted derivatives were prepared to compare spectroscopic and catalytic features under homogeneous and interfacial conditions. Trivalent tris-(silazido) compounds Ln{N(SiHMe 2 )tBu} 3 (Ln = Sc (1), Y (2), Lu (3)) are prepared in high yield by salt metathesis reactions. Solution-phase and solid-state characterization of 1− 3 by NMR and IR spectroscopy and X-ray diffraction reveals Ln↼H−Si interactions. These features are retained in solventcoordinated 2·Et 2 O, 2·THF, and 3·THF. The change in spectroscopic features characterizing the secondary interactions (ν SiH , 1 J SiH ) from the unactivated SiH in the silazane HN(SiHMe 2 )tBu follows the trend 3 > 2 > 1 ≈ 2·Et 2 O > 2·THF ≈ 3· THF. Ligand lability follows the same pattern, with Et 2 O readily dissociating from 2·Et 2 O while THF is displaced only during surface grafting reactions. 1 and 2·THF graft onto mesoporous silica nanoparticles (MSN) to give Ln{N(SiHMe 2 )tBu} n @MSN (Ln = Sc (1@MSN), Y (2@MSN)) along with THF and protonated silazido as HN(SiHMe 2 )tBu and H 2 NtBu. The surface species are characterized by multinuclear and multidimensional solid-state (SS) NMR spectroscopic techniques, as well as diffuse reflectance FTIR, elemental analysis, and reaction stoichiometry. A key 1 J SiH SSNMR measurement reveals that the grafted sites most closely resemble Ln·THF adducts, suggesting that siloxane coordination occurs in grafted compounds. These species catalyze the hydroamination/bicyclization of aminodialkenes, and both solution-phase and interfacial conditions provide the bicyclized product with equivalent cis:trans ratios. Similar diastereoselectivities mediated by catalytic sites under the two conditions suggest similar effective environments.

show abstract

Immobilization of η 5 -cyclopentadienyltris(dimethylamido)zirconium polymerization catalysts on a chlorosilane- and HMDS-modified mesoporous silica surface: a new concept for supporting metallocene amides towards heterogeneous single-site-catalysts

Cited by 31 publications

References 73 publications

Immobilization of α-diimine nickel (II) catalysts on multi-walled carbon nanotube for slurry ethylene polymerization

Immobilization of α-diimine nickel (II) catalysts on multi-walled carbon nanotube for slurry ethylene polymerization

Advanced Surface Functionalization of Periodic Mesoporous Silica: Kinetic Control by Trisilazane Reagents

β-SiH-Containing Tris(silazido) Rare-Earth Complexes as Homogeneous and Grafted Single-Site Catalyst Precursors for Hydroamination

Contact Info

Product

Resources

About