Ethylenebis zirconium

Disodium Arsenate Heptahydrate Disodium Ethylenebis (Dithiocarbamate) Disodium Methanearsonate Disodium Methyl Arsonate Disodium Nitrilotriacetate Distillate Flashed Feed Stocks Distillate Straight Run Disulfatozirconic Acid Dithane Sodium Arsenate Nabarn Methanearsonic Acid, Sodium Salts Medianearsonic Acid, Sodium Salts Nitrilotriacetic Acid and Salts Distillate Flashed Feed Stocks Distillate Straight Run Zirconium Sulfate Nabam... 

EBTHI]Zr = [1,2-ethylenebis(r/5 -4,5,6,7-terahydro-1-indenyl)]zirconium dichloride... 

Synthesis of /77eso-Ethylenebis(4,7-dimethyl-1-indenyl)dimethyl Zirconium [75m]... 

An enantioselective version of this allylamine synthesis employs the chiral (S,S)-dimethylzirconium derivative 3, prepared from (S,S)-[l,2-ethylenebis(tetrahydro-l-indenyl]zirconium dichloride.3 Displacement of one methyl group by triflic acid followed by reaction with a lithium anilide results in a zirconaaziridine (a) with loss of methane. Reaction of a with a symmetrical alkyne provides a metallapyrroline (b), which is hydrolyzed to an (S)-allylamine (4) in 90-99% ee. The method tolerates variation in the lithium anilide. Terminal alkynes do not react with a, but 1-trimeth-... 

Both equivalent coordination sites of the C2-symmetric complex are framed by the /i-substituents in such a manner that 7-olefin insertions at the Zr centre occur with equal enantiofacial preference at both sites. It must be emphasised that unilateral coverage of each coordination site is essential for this stereoselectivity this is borne out by the finding that atactic polypropylene is formed if both coordination sites are flanked by two /i-substituents, as in catalysts based on rac.-ethylenebis[l -(3 -methylindenyl)]zirconium dichloride [rac.-(MeIndCH2)2ZrCl2] (Figure 3.39) [112]. 

Figure 3.39 Chiral procatalyst of C2 symmetry containing two -substituents at the cyclopentadienyl rings, rac.-ethylenebis[l-(3-methylindenyl)]zirconium dichloride [rac.-(MeIndCH2)2ZrCl2], which, in combination with [Al(Me)o]x, produces atactic polypropylene. Front side view and side view respectively...

Figure 3.43 Coordination gap aperture angle in rac. -ethylcnchis l -(4,5,6,7-tetrahydroin-denyl)]zirconium dichloride [rac.-(ThindCH2)2ZrCl2] (left) and in rac.-ethylenebis[l -(4,7-dimethyl-4,5,6,7-tetrahydroindenyl)]zirconiumdichloride [rac.-(Me2 ThindCH2),ZrCl2] (right). For the sake of clarity, only the C-C bonds are sketched for the re ligands. 0 - Zr O - CL O C, CH, CH2 or CH3. Side view. Reproduced by permission from Ref. 30. Copyright 1995 Wiley-VCH Weinheim...

Fig. 22. Structural formula of (S)-(l,l-ethylenebis(4,5,6,7-tertahydroindenyl))-zirconium-bis(0-acetyl-(i )-mandelate) (204).

Selectivity Trends Propylene Polymerization with Substituted rizc- l,2-Ethylenebis(iri -mdenyl))zirconium(IV) Catalysts. 

Related Reagents. (—)-[Ethylene-l,2-bis(t -4,5,6,7-tetra-hydro-l-indenyl)]zirconium (/ )- ,l -Bi-2,2 -naphtholate ( )-1, l -Ethylenebis(4,5,6,7-tetrahydro- l-indenyl)zirconium Dichloride. 

Preparative Methods this reagent is an intermediate for the preparation of optically pure ethylenebis(tetrahydro-l-ind-enyl)zirconium dichloride. That is, according to the procedure described for the kinetic resolution of ethylenebis(tetrahydro-1 -indenyl)titanium dichloride with (/ ,/ )- or (S. Sf-binaphtholate, 1 equiv of racemic ethylenebis(tetrahydro- l-indenyl)zirconium dichloride can be resolved with 0.5 equiv of (/ ,7 )-binaphthol in the presence of sodium metal in toluene to yield the optically active (5, 5)-ethylenebis(tetrahydro-l-indenyl)zirconium dichloride and the (—)-[ethylenebis(tetrahydro-l(7 )-indenyl]-zirconium (/ )-binaphtholate. The separated optically pure (—)- [ethy lenebis( tetrahydro-1 (7 )-indenyl]zirconium (7 )-bi-... 

It is also possible to copolymerize ethylene with a-olefins such as propene, 1-butene, 1-pentene, 1-hexene, and 1-octene, forming linear low-density polyethylene (LLDPE). The product of copolymerization parameters V2 obtained by using ethylenebis(l-indenyl)zirconium dichloride (11) indicates random incorporation of the comonomer [38]. 

The first chiral bridged zirconocene synthesized in 1984 by Brintzinger and used as an isospecific polymerization catalyst was racemic ethylenebis-(4,5,6,7-tetrahydro-l-indenyl)zirconium dichloride (see Structure 9) [45]. Ewen showed that the analogous ethylenebis(l-indenyl)titanium dichloride (a mixture of the meso form and the racemate) produces a mixture of isotactic and atactic polypropylene [46]. The chiral titanocene as well as the zirconocene were shown to work by enantiomorphic site control in the case of the titanocene, the achiral meso structure causes the formation of atactic polymer. 

Kioka, M. Mizuno, A. Tsutsui, T. Kashiwa, N. 1-Butene Polymerization with Ethylenebis-(l-Indenyl)Zirconium Dichloride and Methylaluminoxane Catalyst System. In Catalysis in Polymer Synthesis, ACS Symposium Series Vandenberg, E. J., Salamone, J. C., Eds. American Chemical Society Washington, DC, 1992 Vol. 496, p 72. 

Cyclic olefin copolymer (COC, poly(norbomene-co-ethylene)) catalyzed by ansa-ethylenebis-(indenyl)zirconium dichloride (Et[Ind](2)ZrCl2)/methyl-aluminoxane (MAO) gives rise to phenomenal increase of Tg upon annealing. Unaveraged solid-state NMR resonance of the CH carbons in the norbor-nene (53 and 49 ppm) evidenced the different conformation conversions. ... 

Chiral metallocene complex [(5 )-l,2-ethylenebis(j7 -tetrahydroindenoyl)]Ti(OTf)2 422a and its zirconium analog 422b efficiently catalyzed the cycloadditions of 1,3-oxazolidin-2-one based dienophiles 17a and 404 with cyclopentadiene which gave 421 and 405, respectively . The endo selectivity was highest in dichloromethane, whereas the enan-tioselectivity was higher in nitroalkane solvents (equation 127, Table 24). 

Racemic [1,r-ethylenebis(4,5,6,7-tetrahydro-l-indenyl)]zirconium dichloride and methylalu-moxane as cocatalyst promote the formation of highly isotactic polymers from propene and longer a-alkenes1 3. While with a pure enantiomer of this zirconium complex the polymerization of linear terminal alkenes cannot be expected to give optically active products (see Section 1.5.8.3.2.), the oligomers should display measurable optical activities4. 

A new type of enantioselective diene polymerization is found with cyclopolymerization of 1,5-hexadiene which leads to polymers with a saturated chiral main chain28,58>109. As catalyst, (—)-(7 )-[l,T-ethylenebis(4,5,6,7-tetrahydro-l-indenyl)]zirconium (/ )-binaphtholate is used in the presence of methylalumoxane to give optically active poly(methylene-1,3-cyclopentane) (3) with 68% trans configuration in the five-membered ring (diisotacticity). If the (S)-enantiomer of the ansa-metallocene with (ft)-binaphthol is used as catalyst then the opposite rotation of the polymer is observed58. 

Chiral zirconocene complexes have also been studied as catalysts for the hydrogenation of nonfunctionalized olefins115. Using homogeneous Ziegler Natta-type catalyst systems derived from [ethylenebis(4,5.6,7-tetrahydro-l-indenyl)]zirconium complexes and methyl aluminoxane [A1(CH3)0] , 2-phenyl-l-butene was hydrogenated in 36% optical yield (20 bar H2, benzene, 25 °C). Under the same conditions, the reaction of styrene with D2 gave optically active 1,2-dideuteroethylbenzene with 65% ee. 

The X-ray structures of ethylenebis(indenyl) and bis(tetrahydroindenyl) hafnium dichloride have been determined and compared to Zr and Ti complexes. The ligand-metal distances decrease in the order Zr > Hf Ti. The hafnium complex activated by methylaluminoxane catalyzes the polymerization of propene at 50-80 °C. Indenyl complexes are more active and give higher molecular weight products, but are less stereospecific than tetrahydroindenyls. Racemic zirconium... 

Asymmetric synthesis cyclopolymerization of 1,5-pentadiene (261) was performed with an optically active metallocene catalyst. The polymer (262) obtained by (S)-ethylenebis(tet-rahydroindenyl)zirconium (S)-binaphtholate ([a] 435+1848°) in the presence of methyl aluminoxane (MAO) showed molecular rotation [(p] 4os-49.3°, and NMR analysis showed that the polymer had -68% tram structure. An optically active copolymer consisting of cyclic 262 units and linear units formed by 1,2-insertion shows LC phases. ... 

Chemical composition distribution Biscyclopentadienyl titanium dichloiide Biscydopentadienyl zirconium dichloride Ethylenebis(indenyl)zirconium dichloride Ethylenebis(tetrahydroindenyl)zirconium dichloride Ethylidene(l-tetramethylcyclopentadienylKindenyl) titanium dichloride... 

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