Organometallic fluorenyl compounds, preparation, and use

Abstract: Benzofluorenyl-containing metallocenes are disclosed along with methods for making the metallocenes. Also disclosed are methods for using the metallocenes as polymerization catalysts. In addition, polymers resulting from such polymerizations are disclosed.

Description: This application is related to the subjects of EP-A-0 524 624, EP-A-0 512 554 and EP-A-0 628, 577. This invention relates to metallocenes containing at least one benzofluorenyl ligand. In another aspect, this invention relates to a process for polymerizing olefins using such organometallic benzofluorenyl compounds. Background of the Invention Since the discovery of ferrocene in 1951, a number of metallocenes have been prepared by the combination of compounds having cyclopentadienyl structure with various transition metals. The term "cyclopentadienyl structure" as used herein refers to the following structure. The term "cyclopentadienyl-type compounds" as used herein refers to compounds containing the cyclopentadiene structure. Examples include unsubstituted cyclopentadiene, unsubstituted indene, unsubstituted fluorene, and substituted varieties of such compounds. Also included is tetrahydroindene. Thus polycyclic cyclopentadiene compounds are included within the term. Many cyclopentadienyl-type metallocenes have been found useful in catalyst systems for the polymerization of olefins. It has been noted in the art that variations in the chemical structure of such cyclopentadienyl-type metallocenes as a polymerization catalyst. For example, the size of and substitutions on cyclopentadienyl-type ligands has been found to affect the activity of the catalyst, the stereoselectivity of the catalyst, the stability of the catalyst, and other properties of the resulting polymer; however, the effects of various substituents is still largely an empirical matter, that is, experiments must be conducted in order to determine just what effect a particular variation will have upon a particular type of cyclopentadienyl-type metallocene. Some examples of some cyclopentadienyl-type metallocenes are disclosed in U.S. Patent Nos. 4,530,914; 4,808,561; and 4,892,851. While there are references in the prior art which have envisioned metallocenes containing fluorenyl groups, only a very limited number of fluorenyl-containing metallocenes have actually been prepared prior to the present invention. The Journal of Organometallic Chemistry, Vol. 113, pages 331-339 (1976) discloses preparing bis-fluorenyl zirconium dichloride and bis-fluorenyl zirconium dimethyl. U.S. Patent 4,892,851 and the New Journal of Chemistry, Vol. 14, pages 499-503, dated 1990, each disclose preparing a metallocene from the ligand 1-(cyclopentadienyl)-1-(fluorenyl)-1,1-dimethylmethylene. The New Journal of Chemistry article also discloses preparing a similar compound in which the cyclopentadienyl radical has a methyl substituent in the 3-position. The term fluorenyl as used herein refers to 9-fluorenyl unless indicated otherwise. EP-A 0 528 287 and 0 549 900 describe similar metallocenes: The former substituted and unsubstituted Fl and Cp-containing metallocenes, the latter those metallocenes exhibiting two benzo-condensed indenyl radicals. An object of the present invention is to provide certain new benzofluorenyl-containing metallocenes. Another object of the present invention is to provide processes for the polymerization of olefins using benzofluorenyl-type metallocene catalyst systems. Summary of the Invention In accordance with the present invention, there are provided new metallocenes of the formula (1-(3,4-benzofluorenyl)-1-cyclopentadienyl-1,1-(dimethyl) methane) zirconium dichloride; (1 -(3,4-benzofluorenyl)- 1-cyclopentadienyl-1,1-(diphenyl) methane) zirconium dichloride; (1,2-di(3,4-benzofluorenyl) ethane) zirconium dichloride. In accordance with another aspect of the present invention, there is provided a process for the polymerization of olefins comprising contacting said olefins under suitable reaction conditions with a catalyst system comprising a benzofluorenyl-containing metallocene as described above in combination with a suitable organoaluminum co-catalyst. Detailed Description of the Invention The novel metallocenes provided in accordance with the present invention involve metallocenes in which a benzofluorenyl radical, either substituted or unsubstituted, is bonded to another cyclopentadienyl-type radical by a bridging structure R" and both the benzofluorenyl and the cyclopentadienyl radicals of that bridged ligand are bonded to the metal. These metallocenes are referred to herein as bridged metallocenes. Illustrative examples of bridged metallocenes containing bridged benzofluorenyl ligands include (1 -(3,4-benzofluorenyl)-1-cyclopentadienyl-1,1-(dimethyl) methane) zirconium dichloride; (1-(3,4-benzofluorenyl)-1-cyclopentadienyl-1,1-(diphenyl) methane) zirconium dichloride; (1,2-di(3,4-benzofluorenyl) ethane) zirconium dichloride. The inventive metallocenes as well as related metallocenes can be prepared by reacting an alkali metal salt of the selected benzofluorenyl compounds with a suitable transition metal compound in a suitable solvent under suitable reaction conditions. The bridged benzofluorenyl ligands can be prepared using procedures of the type taught in U.S. Patent No. 5,191,132 and the aforementioned U.S. Patent application Serial No. 08/064,630 and 07/984,054. Some methylene-bridged benzofluorenyl ligands can be made by using 6- or 6,6-substituted fulvenes. Examples of fulvene reactions are disclosed in U.S. Patent No. 4,892,851 and in J. Organomet. Chem. 435 , 299-310 (1992). In general, the technique involves reacting an alkali metal salt of the selected benzofluorene compound with the selected fulvene type compound. The 6,6-diphenyl fulvenes can be prepared by reacting a suitable aryl bromide, i.e. phenyl bromide, p-tolyl bromide, p-fluorenyl bromide, or p-t-butylphenyl bromide, with magnesium to form a Grignard reagent, which is hydrolyzed after the dropwise addition of methyl formate to result in the formation of the corresponding diarylcarbinol. The diarylcarbinol can then be oxidized smoothly to give the correspondingly substituted benzophenone, preferably using sulfuric acid and chromic acid. The resulting substituted benzophenone can then be reacted with cyclopentadiene in ethanol containing sodium ethoxide to yield the 6,6-substituted fluvene. A variation of this technique involves the production of indanyl fulvene (which can also be called indanylidene fulvene) by reacting 1-indanone with cyclopentadiene in the presence of ethanol and sodium ethoxide. The indanyl fulvene is particularly useful in that it can be reacted with the alkali metal salt of a fluorene compound, i.e. a benzofluorene, to yield an indanyl bridged fluorenyl cyclopentadienyl compound. An example would be 1-(3,4 benzofluorenyl)-1-(cyclopentadienyl) indanylidene. The benzofluorenyl compounds needed to make the ligands can be prepared using procedures generally known in the prior art. See for example U.S. Patent No. 3,615,412. Some particularly desirable techniques for forming certain of the benzofluorenyl compounds will be described in further detail in which follows. The term transition metal compound is used herein includes zirconium tetrachloride, cyclopentadienyl zirconium trichloride, fluorenyl cyclopentadienyl zirconium dichloride, and the like. One embodiment of the present invention involves carrying out the reaction of the benzofluorenyl-containing salt and the transition metal compound in the presence of a liquid diluent which is non-halogenated and non-coordinating toward the transition metal compound. Examples of such suitable liquid include hydrocarbons such as toluene, pentane, or hexane as well as non-cyclic ether compounds such a diethylether. It has been found that the use of such non-halogenated non-coordinating solvents generally allows one to obtain large amounts of substantially pure metallocenes and in a more stable form; and also often allows the reaction to be conducted under high temperature conditions, than when dichloromethane is used as the diluent. In an especially preferred embodiment the benzofluorenyl-containing salt used as a ligand is also prepared in a liquid diluent that is non-halogenated and non-coordinating toward the transition metal. The formation of the alkali metal salt of the bridged or unbridged benzofluorenyl compound can be formed using generally any technique known in the art. For example, such can be prepared by reacting an alkali metal alkyl with the cyclopentadienyl type compounds or the bridged compounds having two cyclopentadienyl-type radicals per molecule. The molar ratio of the alkali metal alkyl to the cyclopentadienyl type radicals present can vary, generally however, the ratio would be in the range of about 0.5/l to about 1.5/l, more preferably about 1/l. Typically, the alkali metal of the alkali metal alkyl would be selected from sodium, potassium, and lithium, and the alkyl group would have 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms. Preferably, if the benzofluorenyl salt is formed using tetrahydrofuran (THF) as the liquid solvent, the salt is isolated, and substantially all of the THF is removed before the salt is contacted with the transition metal halide. The molar ration of the bridged or unbridged benzofluorenyl alkali metal compound to the transition metal compound can vary over a wide range depending upon the results desired. When a bridged benzofluorenyl alkali metal compound is used, the molar ration of the bridged benzofluorenyl alkali metal compound to the transition metal compound is about 1 to 1 when one desires a bridged metallocene. The resulting metallocene can be recovered and purified using conventional techniques known in the art such as filtration, extraction, crystallization, and recrystallization. It is generally desirable to recover the metallocene in a form that is free of any substantial amount of by-product impurities. Accordingly, recrystallization and fractional crystallization to obtain relatively pure metallocenes are desirable. Dichloromethane has been found to be particularly useful for such recrystallizations. Since the stability of the various metallocenes varies, it is generally desirable to use the metallocenes soon after their preparation or at least to store the metallocene under conditions favoring their stability. For example, the metallocenes can generally be stored at low temperature, i.e. below 0°C in the absence of oxygen and water. The resulting benzofluorenyl-containing metallocenes can be used in combination with a suitable co-catalyst for the polymerization of olefins. In such processes the metallocene or the co-catalyst can be employed on a solid insoluble particulate support. Examples of suitable co-catalyst include generally any of those organometallic co-catalysts which have in the past been employed in conjunction with transition metal-containing olefin polymerization catalysts. Some typical examples include organometallic compounds of metals of groups IA, IIA, and IIIB of the Periodic Table. Examples of such compounds have included organometallic halide compounds, organometallic hydrides and even metal hydrides. Some specific examples include triethyl aluminum, tri-isobutyl aluminum, diethyl aluminum chloride, diethyl aluminum hydride, and the like. Other examples of known cocatalysts include the use of a stable non-coordinating counteranion technique such as disclosed in U.S. Patent 5,155,080, e.g. using triphenyl carbenium tetrakis(pentafluorophenyl)boronate. Another example would be the use of a mixture of trimethylaluminum and dimethylfluoroaluminum such as disclosed by Zambelli et al., Macromolecules , 22 , 2186 (1989). In such processes the metallocene or the co-catalyst can be employed on a solid insoluble support. The currently most preferred co-catalyst is an aluminoxane. Such compounds include those oligomeric or polymeric compounds having repeating units of the formula where R is an alkyl group generally having 1 to 5 carbon atoms. Aluminoxanes, also sometimes referred to as poly(hydrocarbyl) aluminum oxides), are well known in the art and are generally prepared by reacting an organo aluminum compound with water. Such preparation techniques are disclosed in U.S. 3,242,099 and 4,808,561. The currently preferred co-catalysts are prepared either from trimethylaluminum or triethylaluminum, sometimes referred to as poly(methyl aluminum oxide) and poly(ethyl aluminum oxide), respectively. It is also within the scope of the invention to use an aluminoxane in combination with a trialkylaluminum, such as disclosed in U.S. Patent No. 4,794,096. The fluorenyl-containing metallocenes in combination with the aluminoxane co-catalyst can be used to polymerize olefins. Generally, such polymerizations would be carried out in a homogenous system in which the catalyst and co-catalyst were soluble; however, it is within the scope of the present invention to carry out the polymerizations in the presence of supported forms of the catalysts and/or co-catalyst in a slurry or gas phase polymerization. It is within the scope of the invention to use a mixture of two or more fluorenyl-containing metallocenes or a mixture of an inventive fluorenyl-containing metallocenes with one or more other cyclopentadienyl-type metallocenes. The fluorenyl-containing metallocenes when used with aluminoxane are particularly useful for the polymerization of mono-unsaturated aliphatic alpha-olefins having 2 to 10 carbon atoms. Examples of such olefins include ethylene, propylene, butene-1, pentene-1, 3-methylbutene-1, hexene-1, 4-methylpentene-1, 3-ethylbutene-1, heptene-1, octene-1, decene-1, 4,4-dimethyl-1-pentene, 4,4-diethyl-1-hexene, 3,4-dimethyl-1-hexene, and mixtures thereof. The catalysts are particularly useful for preparing copolymers of ethylene or propylene and generally a minor amount, i.e. about 20 to 10 mole percent, more commonly about 12 mole percent, still more typically less than about 10 mole percent, of a higher molecular weight olefin. The present invention thus also relates to a process for polymerizing an olefin, said olefin preferably being ethylene or propylene, the process comprising the step of contacting said olefin under suitable polymerization conditions with a catalyst system comprising a fluorenyl-containing metallocene selected from the group consisting of: (1-(3,4-benzofluorenyl)-1-cyclopentadienyl-1,1-(dimethyl) methane) zirconium dichloride; (1-(3,4-benzofluorenyl)-1-cyclopentadienyl-1,1-(diphenyl) methane) zirconium dichloride; (1,2-di(3,4-benzofluorenyl) ethane) zirconium dichloride. and a suitable co-catalyst, the co-catalyst preferably comprising an alkylaluminoxane. In a further embodiment of the process according to the invention, the olefin is ethylene and said metallocene is a rac/meso mixture of (1,2-di(3,4-benzofluorenyl)ethane)zirconium dichloride. In still another embodiment of the invention, the olefin is propylene and said metallocene is preferably (1-(3,4-benzofluorenyl)-1-cyclopentadienyl-1,1-(diphenyl) methane) zirconium dichloride or (1-(3,4-benzofluorenyl)-1-cyclopentadienyl-1-1-(dimethyl)methane) zirconium dichloride. In yet another embodiment of the invention, ethylene is polymerized in the presence of another alpha-olefin having 4 to 8 carbon atoms. The polymerizations can be carried out under a wide range of conditions depending upon the particular metallocene employed, and the results desired. Examples of typical conditions under which the metallocenes can be used in the polymerization of olefins include conditions such as disclosed in U.S. Patents 3,242,099; 4,892,851; and 4,530,914. It is considered that generally any of the polymerization procedures used in the prior art with any transition metal-based catalyst systems can be employed with the present fluorenyl-containing metallocenes. Generally, the molar ratio of the aluminum in the aluminoxane to the transition metal in the metallocene would be in the range of about 0.1:1 to about 10 5 :1, and more preferably about 5:1 to about 10 4 :1. As a general rule, the polymerizations would be carried out in the presence of liquid diluents which do not have an adverse effect upon the catalyst system. Examples of such liquid diluents include propane, butane, isobutane, pentane, hexane, heptane, octane, cyclohexane, methylcyclohexane, toluene, xylene, and the like. The polymerization temperature can vary over a wide range, temperatures typically would be in the range of about -60° to about 280°C, more preferably in the range of about 20°C to about 160°C. Typically, the pressure would be in the range of 100-50000 kpa (about 1 to 500 atmospheres) or greater. The polymers produced with this invention have a wide range of uses that will be apparent to those skilled in the art from the physical properties of the respective polymer. A further understanding of the present invention, its various aspects, objects and advantages will be provided by the following examples. In the following examples, where information is given about the microstructure of polymers as determined by 13 CNMR, the spectra were taken using standard accepted spectroscopy techniques. The polymer was dissolved in trichlorobenzene and the spectrum was taken with respect to an internal standard relative to hexamethylsiloxane which has a known reference point relative to tetramethyl silane. From the observed integrals of the relevant peaks, the details regarding the microstructure are calculated. Meso Content = (mm) + ½ (mr) Racemic Content = (rr) + ½ (mr) Isotacticity = % (mm) Heterotacticity = % (mr) Syndiotacticity = % (rr) Randomness Index = (mr)100 2(m)(r) Average Isotactic Block Length = 1 + 2(mm) (mr) Average Syndiotactic Block Length = 1 + 2(rr) (mr) For more details regarding the determination of these values, reference can be made to Chapter 3 of the "Chain Structure and Conformation of Macromolecules" by France A. Bovey (Academic press, 1982). Examples Example I Synthesis of 3,4-benzofluorene A Gringard solution was prepared in a two liter two-necked flask from 13.6 g of magnesium powder, 1,000 ml of diethylether, and 123 g of distilled 1-bromo-2-methylnaphthalene. Then 0.5 g of Ni(TPP) 2 Cl 2 was added and 114 g of iodobenzene was added dropwise with stirring. The light brown suspension became hot and was heated for further 10 hours under reflux. The resulting reaction product was hydrolyzed and then extracted with ether, dried and freed from the solvent. By vacuum distillation, an orange liquid was obtained which was determined to be 2-methyl-1-phenylnaphthalene. Then 97.8g of that product were combined with 81.9 g of n-bromosuccinimide and 4.2g of α,α-azo bis isobutyronitrile in 300 ml of carbon tetrachloride and then heated under reflux for 8 hours. The resulting product was filtered off from the succinimide. Then after the solvent is removed in a vacuum, a pale yellow solid was obtained which was determined to be 2-bromoethyl-1-phenylnaphthalene. The 15.3 g of the 2-bromoethyl-1-phenylnaphthalene were heated with 23g of calcium carbonate in a mixture consisting of 250 ml of an equal volume of a mixture of water and dioxane for 10 hours under reflux. The reaction mixture was carefully poured into diluted hydrochloric acid and then extracted with ether and dried and freed of solvent. The resulting product, 2-hydroxymethyl-1-phenylnaphthalene, in an amount of about 0.45 mol, was dissolved in 200 ml of acetone and added dropwise to a hot suspension of 207 g of KMnO 4 , 280 ml of water and 1000 ml of acetone. The suspension was poured into a large glass beaker containing 1000 ml of water to dissolve the manganese dioxide by the portion-wise addition of dilute HCl and Na 2 SO 3 . The product 1-phenylnaphthalene-2-carboxylic acid was isolated by extraction with ether together with extraction of the organic phase with aqueous carbonate solution. This carboxylic acid product was then reacted with polyphosphoric acid. Specifically, 250 g of polyphorsphoric acid were heated to 100-120°C in a 1000 ml flask. Then 23.9 g of the 1-phenylnaphthalene-2-carboxylic acid were added in portions, and the mixture allowed to stand for 1 hour at that temperature. The mixture was then allowed to cool and diluted to 750 ml by the careful addition of ice water. The sticky crude product was extracted with hot toluene and washed with warm aqueous sodium bicarbonate solution. The organic phase was dried and filtered over silica gel. In a cooling cabinet, dark red crystals of the benzo(c) fluorenone separated from the deep red solution. 9.8 g of the benzo(c) fluorenone were dissolved in 200 ml of tetrahydrofuran and hydrogenated in the presence of 0.5 g of a palladium/carbon-catalyst containing 10 wt% palladium under atmospheric pressure and room temperature. The resulting product was dried over Na 2 SO 4 , the solvent removed and the residue extracted with pentane and filtered over silica gel. Colorless platelets of 3,4-benzofluorene, also sometimes referred to as benzo(c) fluorene, were recovered. Example II Preparation of 1,2-di -(9 -(3,4-benzofluorenyl)) ethane and Metallocene 3 g of 3,4-benzofluorene were dissolved in 100 ml of ether and reacted with 8.7 ml of a 1.6 molar hexane solution of n-butyllithium. Then 0.6 ml of 1,2-dibromoethane were added to the orange solution after 3 hours, and the mixture was stirred for four more hours. Then a little water was added to carry out hydrolysis, the solid product was filtered off, washed with water, then with ether and pentane, and then recrystallized from toluene. A mixture of the rac/meso isomers of bis 1,2-(3,4-benzofluorenyl) ethane was obtained. The isometric mixture of the 1,2.ethylene bridged-bis 3,4-benzofluorene ligand was dissolved in diethyl ether and stirred with two molar equivalents of the n-butyllithium for at least 8 hours at room temperature. Then one molar equivalent of zirconium tetrachloride was added. The mixture was stirred for several more hours. The complex was extracted with dichloromethane and filtered over Na 2 SO 4 . A solid precipitates at about -25°C to yield an approximately equal mixture of the rac- and meso-forms of the 1,2-bis-(3,4-benzofluorenyl) ethane zirconium dichloride. Example III Ethylene Polymerization Ethylene homopolymerization was carried out using the metallocene of Example II. The polymerization was conducted in a 1-liter autoclave using 0.04 mg of the 1,2-di-(9-(3,4-benzofluorenyl)) ethane zirconium dichloride in 300 ml of hexane with 1 ml of a 30 wt% toluene solution of methylaluminoxane. After this, an ethylene pressure of 1000 kpa (10 bar) was applied and the reaction mixture stirred for 1 hour at 60°C. The recovered polymer was dried using a vacuum. A yield of 27.3 g of polymer was obtained. This translates to an activity of 4.2 x 10 5 g of polyethylene/mol zirconium-hour. A comparable polymerization was carried out employing the metallocene 1,2-bis(fluorenyl) ethane zirconium dichloride. The activity was only 5 x 10 4 g polyethylene/mol Zr-hr. It is theorized that perhaps the benzo substituents keep the aluminoxane counterion away from the active site without hindering the monomer from coordination and insertion. Example IV 1-(3,4-benzofluorenyl)-1,1-dimethyl-1-(cyclopentadienyl) methane zirconium dichloride A metallocene was prepared by dissolving 5 g 3,4-benzofluorene in 100 ml ether. Then a molar equivalent of n-butyllithium in hexane was slowly added. The liquid was stirred for several hours at room temperature. Then a molar equivalent quantity of 6,6-dimethylfulvene was added and stirring was continued at room temperature. Decoloration of the solution occurred quickly. Then approximately 1 molar equivalent of n-butyllithium was added in order to transform any possible excess fulvene into a readily soluble colorless derivative. The mixture was stirred for further 30 minutes and then hydrolyzed with a little water. The resulting dimethylmethylene-bridged ligand was isolated and purified by dissolving in a solvent, filtering over silica gel and crystallization. The 1 g of the bridged benzofluorenyl ligand was added to 30 ml diethylether and stirred with exactly 2 molar equivalents of n-butyllithium for about 8 hours at room temperature. After the liquid became well colored, 1 molar equivalent of zirconium tetrachloride was added and the mixture was stirred for several more hours. The resulting metallocene was then recovered and purified. Example V 1-(3,4 benzofluorenyl)-1,1 diphenyl-1-(cyclopentadienyl) methane zirconium dichloride 1-(3,4 benzofluorenyl)-1,1-diphenyl-1-(cyclopentadienyl) methane was prepared using a procedure similar to that used in Example IV but starting with 6,6-diphenylfulvene. In this preparation it was necessary to stir the reaction mixture overnight to obtain the desired degree of reaction. The resulting diphenylmethane-bridged benzofluorenyl ligand was then reacted with zirconium tetrachloride in the same manner as used in Example IV. Example VI Propylene Polymerization The dimethylmethane-bridged benzofluorenyl metallocene of Example IV was evaluated for the polymerization of propylene. Polymerization grade propylene was condensed into a 1-liter autoclave reactor. It was stirred for 15-30 min with 10 ml of a 30 wt% methylaluminoxane solution at 20°C and then cooled down to a temperature in the range of 0 to -2°C. A catalyst solution was prepared by combining the metallocene of Example IV with 1 ml of a 30 wt% solution of methylaluminoxane in toluene. The catalyst solution was forced into the cool stirred autoclave using argon pressure. The temperature was then brought to 60°C and maintained at that temperature for 120 min. Then the polymerization was terminated by draining the unconsumed propylene. The polymerization demonstrated an activity of 34.9 x 10 3 kg of propylene per mol Zr-hr. The polymer had a nominal molecular weight of 37.5 x 10 3 g/mol. This was determined using a precision capillary viscometer in decalin at 135°C. For the determination, calibration curves were available for three different polymer concentrations. From 13 C-NMR it was determined that the polymer had a racemic content of 93.7, i.e., it would be viewed as a syndiotactic polymer. Example VII Bulk polymerization of propylene using the diphenylmethane bridged benzofluorenyl metallocene of Example V was carried out using the same technique as described in Example VI. This polymerization demonstrated an activity of 42.9 x 10 3 kg of polypropylene/mol Zr-hr. The nominal molecular weight was 330 x 10 3 mol. The presence of the phenyl groups appears to be effective in increasing the molecular weight of the polymer without causing any significant reduction in the activity of the catalyst. Example VIII Propylene polymerization using the metallocene of Example II, i.e. the bis(benzofluorenyl) ethylene-bridged zirconium dichloride, was carried our using conditions substantially the same as those used in Examples VI and VII. The resulting polypropylene had an isotacticity of 34.3%, a heterotacticity of 39.7%, and a syndiotactivity of 25.9% as determined by 13C-NMR. The polymer has a melt flow of 204. The molecular weight as determined by size exclusion chromatography was 39,000. The nominal molecular weight was 5,000.

Claims: A metallocene selected from the group consisting of: (1-(3,4-benzofluorenyl)-1-cyclopentadienyl-1,1-(dimethyl) methane) zirconium dichloride; (1-(3,4-benzofluorenyl)-1-cyclopentadienyl-1,1-(diphenyl) methane) zirconium dichloride; (1,2-di(3,4-benzofluorenyl) ethane) zirconium dichloride. A process for polymerizing an olefin, said olefin preferably being ethylene or propylene, the process comprising the step of contacting said olefin under suitable polymerization conditions with a catalyst system comprising a fluorenyl-containing metallocene selected from the group consisting of: (1-(3,4-benzofluorenyl)-1-cyclopentadienyl-1,1-(dimethyl) methane) zirconium dichloride; (1-(3,4-benzofluorenyl)-1-cyclopentadienyl-1,1-(diphenyl) methane) zirconium dichloride; (1,2-di(3,4-benzofluorenyl) ethane) zirconium dichloride and a suitable cocatalyst, the cocatalyst preferably comprising an alkylaluminoxane. The process according to claim 2, wherein the olefin is ethylene and said metallocene is a rac/meso mixture of (1,2-di(3,4-benzofluorenyl) ethane) zirconium dichloride. The process according to claim 2, wherein the olefin is propylene and said metallocene is preferably (1-(3,4-benzofluorenyl)-1-cyclopentadienyl-1,1-(diphenyl) methane) zirconium dichloride or (1-(3,4-benzofluorenyl)-1-cyclopentadienyl-1,1-(dimethyl) methane) zirconium dichloride. The process according to claim 2, wherein ethylene is polymerized in the presence of another alpha-olefin having 4 to 8 carbon atoms.

Inventors: ALT HELMUT G, WELCH M BRUCE, ZENK ROLAND, ALT, HELMUT G., WELCH, M. BRUCE, ZENK, ROLAND
Applicants: PHILLIPS PETROLEUM CO, PHILLIPS PETROLEUM COMPANY
Application year: 1995
Main classification: C07F17
IPC codes: C07F17, C08F10, C07C13, C08F4