Cyclopentadienyl zirconium

The submitters used dich1orobis(n -cyclopentadienyl)zirconium available from Aldrich Chemical Company. This chemical is sufficiently air-stable to be handled in air. 

Zirconocene dichloride (bis[cyclopentadienyl]zirconium dichloride) [1291-32-3] M 292.3, m 242-245 , 248 . Purified by recrystn from CHCI3 or xylene, and dried in vacuum. H NMR (CDCI3) 8 6.52 from MeaSi. Store in the dark under N2 as it is moisture sensitive. [IR, NMR, MS Aust J Chem 18 173 7965 method of J Am Chem Soc 81 1364 7959 and references in the previous entry.]... 

Bis(cyclopentadienyl)zirconium 1,3-alkadiene complexes19-20 show interesting stepwise double insertion reactions to carbonyl compounds, exploration with respect to their stereochemical features has only just begun21-23. 

A convenient method for the preparation of 2-alkenylbis(cyclopentadienyl)zirconium(IV) alkoxides and -trialkylsilyloxides is the reductive metalation of the appropriate alkyl or silyl ethers by means of in situ generated bis(cyclopentadienyl)zirconium(II) 124. 

MOCVD of Zirconia. Yttria-stabilized zirconia is also deposited by MOCVD.Deposition can be accomplished by the codecomposition of the tetramethyl heptadiones of zirconium and yttrium, Zr(CjjHj902)3 and Y(CjjHj902)3, at 735°C. Deposition is also achieved by the decomposition of the trifluoro-acetylacetonates in a helium atmosphere above 300°C.P 1 Other potential MOCVD precursors are bis(cyclopentadienyl)zirconium dichloride, (C5H5)2ZrCl2, and zirconium (IV) trifluoroacetylacetonate,... 

Also known are the bis(cyclopentadienyl) zirconium formamidinates Cp2ZrCl[HN(NR)2] and CpzZrMelHNfNRlzl (R = Cy, Ph). The latter could be... 

The crystal structure of a mono(cyclopentadienyl)zirconium complex containing a novel Me2Si-linked bis(amidinate) ligand was reported (Scheme 203). In this compound the central Zr atom is octahedrally coordinated with the bis(amidi-nate) acting as a tridentate ligand. ... 

The ability to control the polymer from the design of the catalyst, coupled with high catalytic efficiency has led to an explosion of commercial and academic interest in these catalysts. Exxon started up a 30 million lb/5rr ethylene copol3rmer demonstration plant in 1991 using a bis-cyclopentadienyl zirconium catalyst of structure 1. The Dow Chemical Company (Dow) began operating a 125 million Ib/yr ethylene/l-octene copolymer plant in 1993 and has since expanded production capacity to 375 million Ib/yr. This paper will focus on the structure / property relationships of the catalysts used by Dow to produce single-site ethylene a-olefin copolymers. 

Schwartz s Reagent Bis(cyclopentadienyl)zirconium chloride hydride Zirconium, chlorodi-B-cyclopentadienylhydro- (8) Zirconium, chlorobis(ii5-2,4-cyclopentadien-1-yl)hydro- (9) (37342-97-5)... 

Synthesis of 8,8-Bis(cyclopentadienyl)-7,9-bis(trimethylstannyl)-8-zirconabicyclo[4.3.0]nona-1 (9),6(7)-diene 109 (Scheme 7.31) [172] To a solution of bis(cyclopentadienyl)zirconium dichloride (585 mg, 2.0 mmol) in THF (10 mL) at — 78 °C was added dropwise a solution of w-butyllithium in hexane (2.4 mL, 4.0 mmol). After the reaction mixture had been stirred at — 78 °C for 1 h, a solution of l,8-bis(trimethylstannyl)-l,7-octadiyne (863 mg, 2.0 mmol) in THF (2 mL) was added at the same temperature. The temperature was then allowed to rise to ambient, and the mixture was stirred for a further 3 h. The solvent was then removed under reduced pressure and the product was extracted with toluene. The extracts were filtered and the filtrate was concentrated and kept at 0°C to afford the product 109 (723 mg, 55% yield). 

Bis(cyclopentadienyl)phenylvanadium, 3705 Bis(cyclopentadienyl)titanimn, 3295 Bis(cyclopentadienyl)titanium selenate, 3293 Bis(cyclopentadienyl)zirconium, 3296 Bis(dicarbonylcyclopentadienyliron)-bis(tetrahydrofuran)magnesium, 3835... 

In the 1980s, researchers introduced bis-cyclopentadienyl zirconium dichloride, catalysts that maintained their high level of activity for long periods of time. These catalysts became the favorites for copolymerizing ethylene with alpha olefms to produce LLDPE. 

In a similar manner to that described for bicyclic lactams (Section 1.1.1.3.3.4.1.5.I.). alkylation reactions of tricyclic lactams, which contain a fused benzene ring adjacent to the carbon undergoing alkylation, have been exploited14. The first alkylation of the benzo-annulated bicyclic lactam 1 gives a mixture of diastereomers, which is then further alkylated. In the second alkylation step, the counterion on the alkoxide, which is formed prior to enolate formation, proved to be crucial for the diastereoselectivity of the subsequent alkylation reaction. The best diastcrcoselectivity was obtained when either dichlorobis(ij5-cyclopentadienyl)zirconium or triisopropoxytitanium chloride was added to the preformed alkoxide, followed by enolization and alkylation. Using this method the second alkylation step gives a satisfactory diastereoselectivity. Hydride reduction of the purified major diastereomer 2, followed by acid treatment of the product, furnishes chiral naphthalenones 414. 

An efficient synthesis of ethers involves hydrozirconation of thioketones with hydrochlorobis(cyclopentadienyl)zirconium [251]. 

The metallocene complexes are only used in catalytic amounts and may be recovered from the reaction mixture. Bis() 5-cyclopentadienyl)zirconium(TV) chloride (Cp2ZrCI2) and fluoride (Cp2ZrF2) in the presence of magnesium/mercury(II) chloride are equally effective. 

Interestingly, the metallocene-activated C-F activation is not limited to tertiary C F bonds (in contrast to the Na/benzophenone system). Perfluorocyclohexane has been defluorinated in the presence of bis(r/5-cyclopentadienyl)zirconium(IV) chloride or bis(t/5-cyclopentadienyl)-titanium(IV) chloride. This reaction is accompanied by hydrogen transfer from the solvent onto the substrate yielding 1,2,4,5-tetrafluorobenzene as product.210... 

Zinc iodide, 88, 112, 280, 349, 350 Zinc-Silver-Graphite, 348 Zirconium Compounds Chlorobis(cyclopentadienyl)hydrido-zirconium(IV)-Magnesium, 351 Chlorocrotylbis(cyclopentadienyl)-zirconium, 46... 

Triphenylsilyl zirconium and hafnium derivatives have been prepared from the silyl lithium species. Triphenylsilyl bis(cyclopentadienyl) zirconium chloride undergoes carbonyl insertion under pressure of carbon monoxide (100 psi) to give the corresponding acyl zirconium species which, upon treatment with anhydrous hydrogen chloride in a benzene matrix at —196 °C and warming to room temperature, gives rise to formyl triphenylsilane55. 

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