2175-90-8Relevant articles and documents
6,6-Diphenylfulvene at 140 K
Bolte, Michael,Amon, Michael
, p. 1354 - 1356 (1997)
The title compound, C18H14, crystallizes with two molecules in the asymmetric unit, which differ only in the angle between the phenyl rings and the fulvene moiety. The two double bonds of the cyclopentadiene moiety are shortened [1.352 (2) and 1.353 (2) A] in the title compound compared with the range found in its metal complexes (1.381-1.520 A). The bond joining these two double bonds is generally shorter in the metal complexes than in the title compound [1.467 (2) and 1.468 (2) A], but there are exceptions. A conformational analysis of the title compound with the molecular modelling program MOMO [Bolte, Beck & Egert (1991). Molecular Modelling Program MOMO. University of Frankfurt, Germany] shows only one minimum on the energy hypersurface, where both phenyl rings form an angle of 56.6° with the fulvene moiety.
In Situ Activation: Chances and Limitations to Form Ultrahigh Molecular Weight Syndiotactic Polypropylene with Metallocene Dichlorides
Stieglitz, Lucas,Henschel, Daniel,Pehl, Thomas,Rieger, Bernhard
supporting information, p. 4055 - 4065 (2021/09/30)
Fluorenyl cyclopentadienyl Cs-symmetric ansa-metallocene (M = Zr, Hf) complexes I-IV featuring different bridging motifs (C and Si) were synthesized and subsequently examined in the syndiospecific coordinative polymerization of propylene. All complexes were activated in situ with triisobutylaluminum (TIBA) and [Ph3C][B(C6F5)4] (TrBCF) in order to highlight the benefits of this in situ activation, resulting in a significantly higher molecular weight and a significantly increased productivity in comparison to methylaluminoxane (MAO). The isopropylidene-bridged zirconocene Ia (ZrCl2[Me2C(η5-Flu)( η5-Cp)]) exhibited a high productivity (80000 kgPP (molcat h)-1) and stereoregularity ([rrrr] up to 93%) with a moderate molecular weight of polypropylene (PP), whereas the polymerization with the corresponding hafnocene Ib (HfCl2[Me2C(η5-Flu)( η5-Cp)]) resulted in a lower productivity and stereoregularity but yielded ultrahigh molecular weight polypropylene (Mw = 1100 kg mol-1). The backbone in II (HfCl2[Ph2C(η5-Flu)( η5-Cp)]) was associated with a higher productivity and molecular weight, while the syndiotacticity was not affected. In contrast, SC-XRD revealed a reduced dihedral angle and D value for Si-bridged hafnocenes III (HfCl2[Me2Si(η5-Flu)( η5-Cp)]) and IV (HfCl2[Ph2Si(η5-Flu)( η5-Cp)]), resulting in a more constrained geometry of the catalyst. This led to an increased molecular weight, while the productivity as well as the syndiotacticity decreased due to these structural parameters. Activation of Ib and II-IV with n-octyl-modified methylaluminoxane (MMAO) resulted in a lower molecular weight of the polymer, because the transfer of the growing polymer chain onto the Al center was enhanced. Nevertheless, the stereoregularity of MMAO-activated catalysts was slightly increased, probably due to a coordination of the ill-defined MMAO anion during the polymerization. DSC analysis exposed for syndiotactic polypropylene (sPP) produced by the highly active zirconocene Ia a defined melting transition (Tm up to 145.2 °C), whereas TIBA/TrBCF-activated hafnocenes Ib and II-IV gave polymers with no observable Tm value.
Preparation method of substituted cyclopentadienyl metallocene compound
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Paragraph 0084; 0085; 0086, (2017/11/30)
The invention relates to a preparation method of a substituted cyclopentadienyl metallocene compound. The preparation method comprises the following steps that a cyclopentadienyl compound and an aldehyde-ketone compound are adopted to carry out reaction to produce a fulvene compound, then the fulvene compound is acted with metal hydride to produce substituted cyclopentadienyl salt, and the substituted cyclopentadienyl salt is further reacted with group IV metal halide to produce the metallocene compound. Compared with the prior art, the preparation method has the advantages of high product yield, convenience in operation, good economy and the like and is suitable for industrial production.
Method for producing fulvene
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Paragraph 0037, (2017/03/08)
PROBLEM TO BE SOLVED: To provide a method for producing a fulvene in which the reaction efficiently proceeds regardless of the nature of the substituent group which a raw-material ketone, especially a ketone not having an α-proton, possesses. SOLUTION: Provided is a method for producing a fulvene including a step to condense a ketone not possessing an α-proton, and an alkali metal salt of cyclopentadiene in the presence of a Lewis acid. SELECTED DRAWING: None COPYRIGHT: (C)2016,JPOandINPIT
