Activation of [Cp2ZrMe2] with New Perfluoroaryl Diboranes: Solution Chemistry and Ethylene Polymerization Behavior in the Presence of MeAl(BHT)2

Williams, V. Clifford; Dai, Chaoyang; Li, Zengmin; Collins, Scott; Piers, Warren E.; Clegg, William; Elsegood, Mark R. J.; Marder, Todd B.

doi:10.1002/(sici)1521-3773(19991216)38:24<3695::aid-anie3695>3.0.co;2-e

Cited by 107 publications

(83 citation statements)

References 7 publications

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“…The Gabbaï group has also reported related derivatives of indium. [52] Both perfluorinated diboryl-(7b) [53] and diboraanthracene (8) [47,53] activate [Cp 2 ZrMe 2 ] to form active ethylene polymerization catalysts. In the case of the former activator, the anion formed upon methide abstraction from the metallocene is an equilibrating mixture of two species (Scheme 5).…”

Section: B(ar F ) 2 Units Bridged By Two Atomsmentioning

confidence: 90%

“…We postulate that this species is able to complex [Cp 2 ZrMe] ϩ in much the same way as AlMe 3 , [54] accounting at least in part for the slightly lower activities observed for catalysts derived from 7b and [Cp 2 ZrMe 2 ] in comparison to the parent B(C 6 F 5 ) 3 / [Cp 2 ZrMe 2 ] system. [53] The bifunctional borane 7b does not appear to abstract two methyl groups when treated with excess [Cp 2 ZrMe 2 ]. In contrast, diboraanthracene (8) will react with one or two equivalents of [Cp 2 ZrMe 2 ] to form the ion pairs shown in Scheme 6.…”

Section: B(ar F ) 2 Units Bridged By Two Atomsmentioning

confidence: 99%

“…The facility with which C 6 F 5 migration occurs in this system is probably related to the magnitude of ion pair association. Our experiments show that 8 is comparable to B(C 6 F 5 ) 3 as a co-catalyst for ethylene polymerization using [Cp 2 ZrMe 2 ], [53] and the Dow/North- Scheme 6 western Patent claims significantly higher performance (an order of magnitude) using 8 vs. B(C 6 F 5 ) 3 in conjunction with a titanium based CGC catalyst. [47] Since the methide anion of 7b exhibits the behavior described above, we have sought to convert it into a weakly coordinating anion with countercations capable of activating neutral organometallic precursors.…”

Section: B(ar F ) 2 Units Bridged By Two Atomsmentioning

confidence: 99%

“…The cation is a µ-F dimer ( 19 F NMR resonance at δ ϭ Ϫ90.4 [59] ) formed from [Cp 2 ZrMe] ϩ and the neutral methyl fluoride [Cp 2 Zr(Me)F] produced in the first step. Similar species appear to be formed in the reaction involving 9؊N 3 , as evidenced by the signature 19 F NMR spectrum for [7b·Me] Ϫ ; [53] the cationic portion of this ion pair has not been rigorously characterized, although the 1 H NMR spectra are consistent with a dimeric µ-N 3 metallocenium ion.…”

Section: B(ar F ) 2 Units Bridged By Two Atomsmentioning

confidence: 99%

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Highly Lewis Acidic Bifunctional Organoboranes

Piers

Irvine

Williams

2000

Eur. J. Inorg. Chem.

132

106

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Chelating Lewis acids have not been developed to the same degree as multidentate Lewis bases. Nonetheless, such compounds have attracted interest due to their potential for the enhanced activation of basic substrates and the selective binding of anions. Organodiboryl compounds form a class of bidentate Lewis acids which have a long, but relatively underdeveloped history. Many examples exist where donor groups on boron serve to stabilize the Lewis acid centers. More recently, advances in the chemistry of diboryls with highly Lewis acidic boron centers substituted with perfluoroaryl groups have been made. In particular, compounds of general formula (F5C6)2B−linker−B(C6F5)2 have been prepared and their chemistry examined. In this Microreview, we survey the classes of bifunctional boron Lewis acids known, including their synthesis, properties and anion binding chemistry. Particular emphasis is placed on the role these Lewis acids play in olefin polymerization catalyst generation from simple metallocene precursors.

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Section: B(ar F ) 2 Units Bridged By Two Atomsmentioning

confidence: 90%

Section: B(ar F ) 2 Units Bridged By Two Atomsmentioning

confidence: 99%

Section: B(ar F ) 2 Units Bridged By Two Atomsmentioning

confidence: 99%

Section: B(ar F ) 2 Units Bridged By Two Atomsmentioning

confidence: 99%

See 2 more Smart Citations

Highly Lewis Acidic Bifunctional Organoboranes

Piers

Irvine

Williams

2000

Eur. J. Inorg. Chem.

132

106

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“…This phenol reacts with AlMe 3 to produce (BHT) 2 AlMe [123] which does not interfere with the active site but can still scavenge unwanted impurities [124,125]…”

Section: Alme 3 and Its Effects On Alkyl Cations And Polymerisationmentioning

confidence: 99%

Group 4 metal complexes for homogeneous olefin polymerisation: a short tutorial review

2015

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The discovery of transition metal-catalysed polymerisation of olefins in the 1950s by Ziegler and Natta was of huge importance. Over the last 30 years, the interest in homogenous polymerisation has not only grown but has changed focus from primarily studying the metallocene complexes of Group 4 to widespread exploration of postmetallocene systems. This is a consequence of extensive patenting of the metallocene catalyst systems, as well as for general interest in the improvement of polyolefin catalysis. The plastics industry produces more than 10 7 tonnes of polyethylene, polypropylene and polystyrene each year worldwide, and the study of well-defined homogenous catalysts is invaluable in uncovering the mechanism of polymerisation and the fundamental properties of the active species. This short Tutorial Review gives an overview of homogenous transition metal Ziegler-Natta catalysis in general as well as an overview of a selection of Group 4 post-metallocene catalysts. An overview of the synthesis and reactions of alkyl cations relevant to olefin polymerisation is also given. Finally, this review summarises recent advances in bimetallic catalysts for olefin polymerisation.

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