- Preparation method of substituted cyclopentadienyl metallocene compound
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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.
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Paragraph 0120; 0121; 0122
(2017/11/30)
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- New syntheses of ansa-metallocenes or unbridged substituted metallocenes by the respective reductive dimerization of fulvenes with Group 4 metal divalent halides or with Group 4 metal dichloride dihydrides
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Two unprecedented syntheses of Group 4 metallocenes from 6-substituted fulvenes have been discovered and developed into high-yielding processes. In the first route the di-n-butylmetal dichlorides of Ti, Zr and Hf are generated in toluene suspensions of LiCl at -78°C from the metal tetrachlorides and 2 equiv. of n-butyllithium. Bringing the Bun2MCl2 to 25°C and then heating at reflux for several hours gave complete conversion to slurries of MCl2 (M = Ti, Zr, Hf). Heating such slurries of MCl2 with 2 equiv. of 6-substituted or 6,6-disubstituted fulvenes gave high yields of ansa-metallocenes or substituted ethylene-bis(cyclopentadienyl)metallocene dichlorides (fulvenes: 6,6-dimethyl-, 6-phenyl-, 6-(1-naphthyl)-, 6-(9-anthryl)-). For 6-substituted fulvenes, both racemic- and meso-1,2-disubstituted ethylene-ansa-metallocene dichlorides are expected to form, but with M = Zr (or Ti), the actual racemic- to meso-ansa-metallocene dichloride ratios observed were: phenyl, 50:50; 1-naphthyl, 83:17; 9-anthryl, 100:0. Apparently for steric reasons 6,6-diphenylfulvene underwent no ansa-metallocene dichloride formation with ZrCl2 but rather produced bis(diphenylmethyl(cyclopentadienyl))zirconium dichloride. The second route to novel metallocenes involves generating Bun2MCl2 at -78°C in toluene slurry, as in the foregoing method, but then adding 2 equiv. of the 6-substituted or 6,6-disubstituted fulvene immediately thereafter at -78°C. Except with Bun2TiCl2, warming the reaction mixture to 25°C and then further heating at 65°C cause a smooth bis-hydrometallation by transfer to occur, giving good to very good yields of bis(substituted cyclopentadienyl)metal dichlorides (M = Zn, Hf). The instability of Bun2TiCl2, even at -78°C, rapidly led to a mixture of TiCl2 and Bun2TiCl2and hence to a mixture of ansa-titanocene dichlorides and unbridged, bis(substituted cyclopentadienyl) titanocene dichlorides. With a detailed study of the attainment and the stereochemistry of the formation of ansa-bridged complexes or metallocenes with acetophenone, benzylideneaniline and 6-arylfulvenes, a mechanistic model is developed involving either a three-membered metallocycle formed from MCl 2 or an open-face sandwich complex of the fulvene and MCl2. Such intermediates offer a rational steric explanation for the observed stereochemistry of ansa-bridge C-C bond formation. Finally, in comparative polymerizations of ethylene by such metallocenes, cocatalyzed by MAO, the superior catalytic activity of ansa-metallocenes in the order, Ti > Zr > Hf and of ansa-metallocenes over unbridged substituted metallocenes is attributed to the hyperconjugative stabilization afforded by the ansa σ C-C bond to the metallocenium cation at the active olefin-polymerization site.
- Eisch, John J.,Owuor, Fredrick A.,Shi, Xian
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p. 1325 - 1339
(2008/10/09)
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- METALLOCENE DERIVATIVES OF EARLY TRANSITION METALS. PART 2. SUBSTITUTED CYCLOPENTADIENYL GROUP 4A DICHLORO-METALLOCENE COMPLEXES (M=Zr OR Hf; R=Me, Et, Pri, But, OR SiMe3), THEIR MONO- AND DI-ALKYL DERIVATIVES (X=Cl OR R';R'= CH2SiMe3 OR CH2CME3...
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The substituted d0 metallocene dichloro-complexes 2 (M = TiIV, ZrIV, or HfIV; R = Me, Et, Pri, But, or SiMe3), (1)-(11), have been prepared from MCl4 and 2Li in tetrahydrofuran (thf).From the appropriate dichloride and either(i) MgR'Cl in CH2Cl2 there was obtained the chloro(alkyl) (R = CH2SiMe3) or , or (ii) akyl-lithium in OEt2 the dialkyl (M'= Zr or Hf; R'' = H, Me, Et, Pri or But; X = C or Si), (13)-(16), was produced; treatment of t)2Cl2> with BBr3 in CH2Cl2 gave t)2Br2>.The 1H n.m.r. spectra of each of the dichlorides (1)-(11) show the ring protons of the C5H4R group as an AA'BB' or A2B2 (R = SiMe3) signal; the dialkyls (13)-(16) show this feature as an A2X2 pattern, whereas in t)2SiMe3)Cl> it appears as ABCD.The 13C n.m.r. spectra show three signals for the corresponding carbon atoms (C5H4R) and the chemical shift data are compared with results on substituted ferrocenes or benzenes, or C6H5R.Treatment of the complex with an equimolar portion of Na in thf at 20 deg C yields an appropriate d1 dialkylmetal(III) complex, which is persistent for M = Ti or Zr but not for M = Hf, and is characterised by its e.s.r. spectrum av., 1.984-1.993; a(1H), 0.175-0.360 mT; a(47/49Ti), 0.720-1.05. mT;a(91Zr),1.000-2.410 mT> showing coupling with the α protons of the alkyl group R'.As each of these (Zr) dialkyls undergoes irreversible one-electron reduction at a Pt electrode in 0.2 mol dm-3 in thf the above d1 complexes are formulated as .Cyclic voltammetry data are provided for several metallocene(IV) complexes: (i) dichlorides -(M = Zr), and E1/2red is nearly 1 V more negative than for Ti>; (ii) chloro(alkyls) (irreversible reduction); and (iii) dialkyls (irreversible reduction).
- Lappert, Michael F.,Pickett, Christopher J.,Riely, Paul I.,Yarrow, Paul I. W.
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p. 805 - 813
(2007/10/02)
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