Syntheses and properties of the novel co-catalysts N,N-dimethylanilinium- and trityl{tetrakis[4-(trifluoromethyl)-2,3,5,6-tetrafluorophenyl]borate}

Kaul, Franz A.R.; Puchta, Gerd T.; Schneider, Horst; Grosche, Manja; Mihalios, Dimitrios; Herrmann, Wolfgang A.

doi:10.1016/s0022-328x(00)00860-3

Cited by 13 publications

(4 citation statements)

References 33 publications

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“…Isoprene was purified by distillation over calcium hydride under a nitrogen atmosphere. Azide, [Et 3 NH][BPh 4 ], [Ph 3 C][B(C 6 F 5 ) 4 ] 3 , Lu(CH 2 SiMe 3 ) 3 (THF) 2 , NSN dipp , NPN dipp H, complex 3 were prepared according to the published procedures …”

Section: Methodsmentioning

confidence: 99%

3,4-Polymerization of Isoprene by Using NSN- and NPN-Ligated Rare Earth Metal Precursors: Switching of Stereo Selectivity and Mechanism

Liu

Sun

et al. 2014

Macromolecules

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The rare-earth metal complexes bearing NSN-bidentate β-diimidosulfonate ligands (RNSN dipp )Ln-(CH 2 SiMe 3 ) 2 (THF) n (R = Ph, Ln = Lu (1a), n = 1, Y (1b), n = 2, Sc (1c), n = 1; R = PhNMe 2 , Ln = Lu (1d), n = 1) were synthesized by treatment of the ion-pairs [Ln(CH 2 SiMe 3 ) 2 (THF) x ][BPh 4 ] with equimolar amount of the ligand lithium salts (RNSN dipp )Li(THF) 2 (NSN dipp = S(NC 6 H 4 i Pr 2 -2,6) 2 ). Addition reaction between lutetium tris(alkyl)s, Ln(Z) 3 (THF) n and NSN dipp gave the corresponding dialkyl complexes (ZNSN dipp )Lu(Z) 2 (THF) n (Z = CH 2 SiMe 3 , n = 1 (1e); Z = o-CH 2 C 6 H 4 NMe 2 , n = 0 (1f)). Deprotonation of β-imidophosphonamido ligands H−NPN dipp and H−NPN Et (NPN dipp = Ph 2 P(NC 6 H 3 i Pr 2 -2,6) 2 , NPN Et = PPh 2 (NC 6 H 3 i Pr 2 -2,6)(NC 6 H 4 -Et-2)) with Lu(CH 2 SiMe 3 ) 3 (THF) 2 yielded the corresponding dialkyl complexes (NPN dipp )Lu(CH 2 SiMe 3 ) 2 (THF) ( 2) and (NPN Et )Lu(CH 2 SiMe 3 ) 2 (THF) (3). All the complexes had been structurally well-defined, and 1a, 1b, 1e, 2, and 3 were further characterized by X-ray diffraction analysis where the almost planar NSN rare-earth metal unit is C s (or pseudo C s ) symmetry with the two alkyl groups arranging on both sides and a coordinated THF against it. Upon activation with [PhMe 2 NH][B(C 6 F 5 ) 4 ] and Al i Bu 3 , all these complexes exhibited high 3,4-regioselectivity (ranging from 91% to >99%) for the polymerization of isoprene. Moreover, the excellent isospecific selectivity up to mmmm > 99% have been achieved with complexes 1 depending on the electronics of the sulfur substituents to give crystalline polyisoprene with the highest T m (170 °C) reported to date. The NPN-bidentate β-imidophosphonamide ligated rare-earth metal complexes provide both high syndio-and iso-3,4-selectivities (3,4 > 99%, rr = 66%, mmmm = 96%) depending on the frameworks, steric environment and geometry of the ligands. The regio-and stereo-selective mechanisms proceeded in these systems were explicated by DFT simulation.

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Section: Methodsmentioning

confidence: 99%

3,4-Polymerization of Isoprene by Using NSN- and NPN-Ligated Rare Earth Metal Precursors: Switching of Stereo Selectivity and Mechanism

Liu

Sun

et al. 2014

Macromolecules

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“…However, in terms of anion stability, it was shown that the parent [B(Ar F ) 4 ] − ion with R F =CF 3 is more stable against methanolic sulfuric acid than the modified borate with R F =2‐C 3 F 7 9 in agreement with the greater electron‐withdrawing effect of the CF 3 group compared to the 2‐C 3 F 7 group 9. Also the ‐C 6 F 5 ligand was modified in the 4‐position by a ‐CF 3 ,10 ‐Si( i Pr) 3 ,11 ‐SiMe 2 t Bu,11 or ‐C 6 F 4 {C(F)(C 6 F 5 ) 2 }12 group. Alternatively the ‐C 6 F 5 group was exchanged for fluorinated biphenyl or naphthalene moieties 13.…”

Section: The Candidatesmentioning

confidence: 99%

Noncoordinating Anions—Fact or Fiction? A Survey of Likely Candidates

2004

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Is there anything resembling a truly noncoordinating anion? Would it not be great to be able to prepare any crazy, beautiful, or simply useful cationic species that one has in mind, or has detected by mass spectroscopy? In condensed phases the target cation has to be partnered with a suitable counteranion. This is the moment when difficulties arise and many wonderful ideas end in the sink owing to coordination or decomposition of the anion. However, maybe these counteranion problems can be overcome by one of the new weakly coordinating anions (WCAs). Herein is an overview on the available candidates in the quest for the least coordinating anion and a summary of new applications, available starting materials, and general strategies to introduce a WCA into a system. Some of the unusual properties of WCA salts such as high solubility in low dielectric media, pseudo gas-phase conditions in condensed phases, and the stabilization of weakly bound and low-charged complexes are rationalized on thermodynamic grounds. Limits of the WCAs, that is, anion coordination and decomposition, are shown and a quantum chemical analysis of all types of WCAs is presented which allows the choice of a particular WCA to be based on quantitative data from a wide range of different anions.

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“…Dies ist in Übereinstimmung mit dem größeren elektronenziehenden Effekt der CF 3 ‐Gruppe im Vergleich zur 2‐C 3 F 7 ‐Gruppe 9. Auch der C 6 F 5 ‐Ligand wurde in der 4‐Position durch CF 3 ‐,10 Si i Pr 3 ‐,11 SiMe 2 t Bu‐11 und C 6 F 4 {C(F)(C 6 F 5 ) 2 }‐Substituenten12 modifiziert. Des Weiteren wurde der gesamte C 6 F 5 ‐Ligand gegen fluorierte Biphenyl‐ oder Naphthalinliganden ersetzt 13.…”

Section: Die Kandidatenunclassified

Nichtkoordinierende Anionen – Traum oder Wirklichkeit? Eine Übersicht zu möglichen Kandidaten

2004

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Gibt es so etwas wie ein wirklich nichtkoordinierendes Anion? Wäre es nicht großartig, jede verrückte, schöne oder einfach nur nützliche kationische Spezies herstellen zu können, sei es, weil sie einen gerade interessiert oder weil man sie vielleicht schon einmal im Massenspektrum entdeckt hat? Um dieses Ziel in kondensierter Phase zu erreichen, müssen die Zielkationen mit einem geeigneten Gegenion versehen werden – dies ist der Moment, bei dem häufig Schwierigkeiten auftreten und viele gute Ideen wegen einer Koordination oder Zersetzung des Anions im Abguss enden. Zur Lösung des Problems bietet sich womöglich eines der neuen schwach koordinierenden Anionen (WCAs) an, die Gegenstand dieses Aufsatzes sind. Vorgestellt werden neue Entwicklungen, Anwendungen, Ausgangsmaterialien und allgemeine Strategien zur Einführung von WCAs in ein System. Einige der ungewöhnlichen Eigenschaften von WCA‐Salzen wie hohe Löslichkeit in unpolaren Medien, Pseudo‐Gasphasenbedingungen in der kondensierten Phase oder die Stabilisierung von schwach gebundenen und niedrig geladenen Komplexen werden anhand thermodynamischer Betrachtungen plausibel gemacht. Die Grenzen bei der Verwendung von WCAs – durch Koordination und Zersetzung – werden aufgezeigt, und eine quantenchemische Analyse der WCA‐Typen wird vorgestellt. Dies ermöglicht es, die Entscheidung für ein spezielles WCA auf der Basis von harten quantitativen Daten aus einer Vielzahl von Anionen zu gründen.

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Syntheses and properties of the novel co-catalysts N,N-dimethylanilinium- and trityl{tetrakis[4-(trifluoromethyl)-2,3,5,6-tetrafluorophenyl]borate}

Cited by 13 publications

References 33 publications

3,4-Polymerization of Isoprene by Using NSN- and NPN-Ligated Rare Earth Metal Precursors: Switching of Stereo Selectivity and Mechanism

3,4-Polymerization of Isoprene by Using NSN- and NPN-Ligated Rare Earth Metal Precursors: Switching of Stereo Selectivity and Mechanism

Noncoordinating Anions—Fact or Fiction? A Survey of Likely Candidates

Nichtkoordinierende Anionen – Traum oder Wirklichkeit? Eine Übersicht zu möglichen Kandidaten

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