Neutral and cationic yttrium alkyl complexes with linked 1,4,7-triazacyclononane-amide monoanionic ancillary ligands: synthesis and catalytic ethene polymerisation

Bambirra, Sergio; Leusen, Daan van; Meetsma, Auke; Hessen, Bart; Teuben, Jan H.

doi:10.1039/b101012n

Cited by 148 publications

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“…Only a limited number of fully characterized mono-and dicationic alkyl complexes of the rare-earth metals has been described, [36,41,42] and the potential of such species in olefin polymerization catalysis remains unexplored. [36,42,54,60,61,65,68,75] For other organic transformations, two instructive examples have recently appeared in the literature. [77,90] Cationic lanthanide alkyl derivatives as homogeneous catalysts appear to be generally superior to their neutral precursors due to their increased electrophilicity towards substrate molecules.…”

Section: Resultsmentioning

confidence: 99%

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Cationic Alkyl Complexes of the Rare‐Earth Metals: Synthesis, Structure, and Reactivity

2005

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This contribution is dedicated to Dick Schrock on the occasion of his 60th birthday.Abstract: Cationic alkyl complexes of the rare-earth metals [LnR m ; L ¼ Lewis base) were virtually unknown species until recently. Because of their increased Lewis acidity/electrophilicity they should have considerable potential as homogeneous catalysts in olefin polymerization and in organic transformations. They can be generated by treating the neutral rare-earth metal precursors containing at least two alkyl groups R with suitable Lewis or Brønsted acids in the presence of weakly coordinating anions. Not only monocationic but also dicationic alkyl derivatives have been shown to be accessible. In the context of modeling homogeneous ethylene polymerization using a mixture consisting of LnR 3 /AlR 3 /[NMe 2 HPh][B(C 6 F 5 ) 4 ], such dications were discovered. Some thermally robust examples of mono-and dicationic alkyl complexes have been structurally characterized as solvent-separated ion pairs. Neutral and monoanionic macrocycles such as crown ethers or aza-crown ethers as well as amidinato, b-diketiminato, and substituted cyclopentadienyl ligands are suitable ancillary ligands to stabilize the cationic alkyl fragments.

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Section: Resultsmentioning

confidence: 99%

“…As compiled in Ta . [65] Interestingly, the yttrium precursor appears to provide the most effective catalyst for ethylene polymerization, as both larger and smaller metals show lower activity under standardized conditions. [42] Activation of the triazacyclononane derivative [Sc(L-1)-(CH 3 , M w /M n ¼ 1.3).…”

Section: Polymerization Of Ethylene and A-olefinsmentioning

confidence: 99%

Cationic Alkyl Complexes of the Rare‐Earth Metals: Synthesis, Structure, and Reactivity

2005

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“…Two of the equatorial THF ligands are pushed out of the plane by their proximity to an o-F atom of the C 6 F 5 groups as shown by C(1)-Eu(1)-O angles > 100 8 ( Table 1). The coordination geometry closely resembles that of the neutral analogue [Eu(C 6 F 5 ) 2 (thf) 5 ], [19] with a THF ligand replacing one of the C 6 F 5 À groups. However, the EuÀC bond of 1¥THF (2.735(2) ä) is shorter (0.087 ä) than that in the neutral complex (2.822(2) ä) [19] emphasizing the bond lengthening caused by the trans disposition of the two C 6 F 5 À groups in the latter.…”

mentioning

confidence: 94%

“…The structure of 2 reveals three similar ion pairs in the asymmetric unit, each having a [Yb(C 6 F 5 )(thf) 5 ] + ion and BPh 4 À ion. The major distinctions between the crystallographically independent units are derived from relative rotations of the THF and phenyl ring planes as well as some variation in the constituent bond lengths (of greater than 3s in the extremes).…”

mentioning

confidence: 98%

“…The longest (significantly) EuÀO distance in 1¥THF is for an equatorial ligand and this must arise from local crowding. Considerable steric stress in the related series 1¥THF, [Eu(C 6 F 5 ) 2 (thf) 5 ], and [EuI 2 (thf) 5 ] is indicated by the respective sums of the steric coordination numbers [28] of the ligands (assuming C 6 F 5~P h), namely 8.5, 8.6, and 8.3, respectively.…”

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Synthesis and Structures of the First Cationic Perfluoroaryllanthanoid(II) Complexes

Deacon¹,

Forsyth²

2004

Chemistry A European J

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Tetraphenylborate salts of solvated pentafluorophenyllanthanoid(II) cations [Ln(C(6)F(5))(thf)(n)](+) (Ln=Eu, n=6 (1); Ln=Yb, n=5 (2)) were readily synthesized in high yield by reactions of ytterbium or europium with HgPh(C(6)F(5)) and Me(3)NHBPh(4) in THF. The structures of 1.THF and 2 confirmed the existence of well-separated ions and both 1 and 2 show notable thermal stability at room temperature. The cation in 2 was also observed in the remarkable mixed-valent complex [Yb(II)(C(6)F(5))(thf)(5)][Yb(III)(C(6)F(5))(2)[N(SiMe(3))(2)](2)] (3), fortuitously isolated in low yield from a reaction of ytterbium metal, HgPh(C(6)F(5)), and HN(SiMe(3))(2) in THF, and which additionally has an unusual bis(pentafluorophenyl)bis[bis(trimethylsilyl)amido)]ytterbate(III) anion. (171)Yb-(19)F coupling has been observed in the low-temperature (171)Yb NMR spectra of 2 and [Yb(C(6)F(5))(2)(thf)(4)].

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Oligomerization & Polymerization by Homogeneous Catalysis

Hlatky¹

2005

Encyclopedia of Inorganic Chemistry

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The metal‐catalyzed oligomerization and polymerization of alkenes by homogeneous metal complexes has not only provided extraordinary insights into the chain‐growth process, it has also become of increasing commercial importance in delivering products of greater purity or improved properties. Novel materials not accessible using conventional heterogeneous catalysts can now be synthesized. Metals are no longer constrained to certain functions (titanium for polymerization, nickel for oligomerization) but span the range of molecular weights and polymer structures. This review discusses the fundamentals of chain‐growth polymerization catalyzed by homogeneous complexes and new developments in the field.

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Neutral and cationic yttrium alkyl complexes with linked 1,4,7-triazacyclononane-amide monoanionic ancillary ligands: synthesis and catalytic ethene polymerisation

Abstract: Neutral and cationic yttrium alkyl complexes with linked 1,4,7-triazacyclononane-amide monoanionic ancillary ligands: synthesis and catalytic ethene polymerisation de Araujo Bambirra, S.; van Leusen, D.; Meetsma, A.; Hessen, B.; Teuben, J.H

Cited by 148 publications

References 10 publications

Cationic Alkyl Complexes of the Rare‐Earth Metals: Synthesis, Structure, and Reactivity

Cationic Alkyl Complexes of the Rare‐Earth Metals: Synthesis, Structure, and Reactivity

Synthesis and Structures of the First Cationic Perfluoroaryllanthanoid(II) Complexes

Oligomerization & Polymerization by Homogeneous Catalysis

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