Ethylenebis zirconium dichloride

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

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...

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. ... 

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. 

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

Mizuno, A. Tsutsui, T. Kashiwa, N. Stereostructure of regioirregular unit of polypropylene obtained with rac-ethylenebis(l-indenyl)zirconium dichloride/methylaluminoxane catalyst system studied by carbon-13-pro ton shift correlation two-dimensional nuclear magnetic resonance spectroscopy. Polymer 1992, 33, 254-258. 

Rieger, B. Mu, X. Mallin, D. T. Chien, J. C. W. Rausch, M. D. Degree of stereochemical control of racemic ethylenebis(indenyl)zirconium dichloride/methyl aluminoxane catalyst and properties of anisotactic polypropylenes. Macromolecules 1990, 23, 3559-3368. 

Tsutsui, T. Kashiwa, N. Mizuno, A. Effect of hydrogen on propene polymerization with ethylenebis (l-indenyl)zirconium dichloride and methylalumoxane catalyst system. Makrvmol. Chem., Rapid Commun. 1990,11, 565-570. 

Piemontesi, F. Camurati, I. Resconi, L. Balboni, D. Sironi, A. Moret, M. Zeigler, R. Pic-colrovazzi, N. Crystal structures and solution conformations of the meso and racemic isomers of (ethylenebis(l-indenyl)(zirconium dichloride. Organometallics 1995,14, 1256-1266. 

Resconi, L. Eait, A. Piemontesi, R Colonnesi, M. Rychlicki, H. Zeigler, R. Effect of monomer concentration on propene polymerization with the rac-[ethylenebis(l-indenyl)]zirconium dichloride/methylaluminoxane catalyst. Macromolecules 1995, 28, 6667-6676. 

With the system ethylenebis(indenyl)zirconium dichloride/methylaluminoxane, 6% of 1,5-hexadiene could be incorporated [499,500]. The copolymerization parameter ri for this reaction is in the range of 14 to 19. The polymerization rate decreases with increasing 1,5-hexadiene concentration in the reaction mixture. The block copolymers are mostly mixtures of the copolymer and both homopolymers [501]. 

Highly isotactic polypropylene is obtained when chiral ethylenebis(4,5,6,7-tetrahydro-l-indenyl)-zirconium dichloride is employed in combination with methylalumoxane (MeAlO) as the... 

The literature describes several cases of the copolymerization of ethylene with cyclopentene [31b], cyclo-heptene [31b], norbornene [31c], 2-methylnorbornene [31c], dicyclopentadiene [31d], dimethanooctahydro-naphthalene [31a,e], and 2-methyldimethanooctahy-dronaphthalene [31a]. When chiral catalysts were employed (e.g., ethylenebis(indenyl)zirconium dichloride associated with methylaluminoxane), the activity was much higher than that of the achiral catalyst. In addition, the ehiral catalyst increased the polymer stereoselectivity and the amount of the cycloolefin incorporated into the copolymer. Materials having exeellent transpareney, thermal stability, and ehemical resistance—properties that are useful for optical disks—may be produced efficiently by this method. 

---