| PATENT ASSIGNEE'S COUNTRY | CH |
| UPDATE | 04.00 |
| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | 18.04.00 |
| PATENT TITLE |
Olefin polymerization using a catalyst having a bridged cyclopentadienyl-phosphole ligand |
| PATENT ABSTRACT |
An olefin polymerization process uses a catalyst with an organometallic complex of a group 4 metal having a bridged cyclopentadienyl-phosphole ligand, as defined by the formula: ##STR1## wherein: each Sl is a non-interfering spectator ligand; Y is selected from Si, Ge and Sn; Z is 2; R.sub.1, R.sub.2, and R.sub.3 are hydrogen or non-interfering substituents; Cp* is selected from cyclopentadienyl, substituted cyclopentadienyl, indenyl, substituted indenyl, fluorenyl and substituted fluorenyl; M4 is selected from Ti, Zr and Hf; X is an anionic ligand; and n is 1 or 2, depending upon the oxidation state of M4. A catalyst having a fluorenyl ligand and a dimethyl silyl bridge is preferred. This invention may be used to prepare polyethylenes having a broad molecular weight distribution. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | 24.04.98 |
| PATENT FOREIGN APPLICATION PRIORITY DATA | This data is not available for free |
| PATENT REFERENCES CITED | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. A process for polymerizing at least one polymerizable alpha olefin comprising reacting a cocatalyst and a group 4 organometallic complex with said at least one alpha olefin, wherein said group 4 organometallic complex is defined by the formula: ##STR17## 2. The process according to claim 1 wherein said cocatalyst is an alumoxane. 3. The process according to claim 1 wherein said cocatalyst is an ionic activator. 4. The process according to claim 1 wherein said at least one polymerizable alpha olefin comprises a majority of ethylene and a minor portion of at least one of propylene, butene-1, pentene-1, hexene-1, and octene-1. 5. The process according to claim 1 when conducted in a gas phase polymerization reactor. 6. A process for the polymerization of at least one olefin comprising reacting at least one alpha olefin monomer under polymerization conditions with a cocatalyst and a group 4 organometallic complex of the formula: wherein: Flu* is selected from fluorenyl and substituted fluorenyl; each Sl is a non-interfering spectator ligand; Y is selected from Si, Ge, and Sn; R.sub.1, R.sub.2, and R.sub.3 are hydrogen or non-interfering substituents; M4 is selected from Ti, Zr and Hf; X is an anionic ligand; and n is 1 or 2 depending upon the oxidation sate of M4. 7. The process according to claim 6 wherein said cocatalyst is an ionic activator. 8. The process according to claim 6 wherein said at least one alpha olefin comprises a majority of ethylene and a minor portion of at least one of propylene, butene-1, pentene-1, hexene-1 and octene-1. 9. The process according to claim 6 when conducted at a temperature of from 120.degree. C. to 300.degree. C. 10. The process according to claim 6 when conducted in the presence of a solvent for the polymer produced by the process. 11. A medium pressure solution polymerization process comprising reacting an activator and a group 4 metal complex having a bridged fluorenyl phospholyl ligand with at least one polymerizable alpha olefin at a temperature of from 140.degree. C. to 300.degree. C. at a pressure of from 4 to 20 mega Pascals in a solvent for polymer produced by the process. 12. The process according to claim 11 wherein said cocatalyst is an ionic activator. 13. The process according to claim 12 wherein said ionic activator is provided as a carbonium salt of a substantially non-coordinating anion. 14. The process according to claim 11 wherein said group 4 metal complex is defined by the formula: ##STR18## wherein: Flu* is selected from fluorenyl and substituted fluorenyl; each Sl is a non-interfering spectator ligand; Y is selected from Si, Ge, and Sn; R.sub.1, R.sub.2, and R.sub.3 are hydrogen or non-interfering substituents; M4 is selected from Ti, Zr and Hf; X is an anionic ligand; and n is 1 or 2 depending upon the oxidation sate of M4. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
FIELD OF THE INVENTION This invention relates to a new family of phospholes and a process to prepare these phospholes; to a process to use these phospholes to prepare a family of organometallic compounds having a cyclopentadienyl-type ligand which is bridged through a metalloid to a phospholyl ligand ("Cp-bridged-phosphole") and to a process to polymerize olefins using a Cp-bridged-phosphole. BACKGROUND OF THE INVENTION Cyclopentadienyl-type ligands have been used to prepare organometallic complexes which, in turn, are useful in such applications as olefin polymerizations, alkene isomerizations and hydrogenations. More recently, the use of phospholes to prepare phospholyl-type organometallic complexes has been disclosed. The use of phospholyl-type complexes (and "mixed" cyclopentadienyl/phospholyl complexes--i.e. a complex having a cyclopentadienyl and a phospholyl-type ligand) is disclosed in U.S. Pat. No. 5,434,116 (Sone, to Tosoh), published European Patent Office (EPO) applications 617,052 (Aoki et al, to Asahi), and EPO 741,145 (Katayama et al, to Sumitomo) and Patent Cooperation Treaty (PCT) application 95/04087 (de Boer et al, to Shell). It is also known to prepare "bridged and substituted" cyclopentadienyl-type ligands--as disclosed, for example, in U.S. Pat. Nos. 5,563,284; 5,565,396, and 5,554,795 (Frey et al), U.S. Pat. No. 5,324,800 (Welborn). These "bridged" cyclopentadienyls form catalyst systems for olefin polymerization when activated by a "substantially non-coordinating anion" (as disclosed by Hlatky and Turner in U.S. Pat. Nos. 5,153,157 and 5,198,401) or an alumoxane. However, there is no known teaching of any process to prepare ligands having a cyclopentadiene-type group which is bridged to a phosphole. SUMMARY OF THE INVENTION An object of the present invention is to provide a new family of phospholes and a process to prepare the phospholes. Another object of the invention is to use the new phospholes to prepare a family of new organometallic complexes having a bridged ligand with a metalloid "bridge" between a cyclopentadienyl group and a phospholyl group. Another object of the invention is to provide processes for olefin polymerization using a catalyst system which includes these new organometallic complexes and an activator. Thus, in one embodiment of the invention there is provided a phosphole characterized by having at least two substituents (a) and (b) where substituent (a) is a leaving group bonded to the phosphorus atom in the phosphole ring and substituent (b) is bonded to one carbon atom in the phosphole ring and is defined by the formula: ##STR2## wherein Cp* is selected from cyclopentadienyl; substituted cyclopentadienyl; indenyl; substituted indenyl; fluorenyl and substituted fluorenyl; each Sl is a non-interfering spectator ligand; Y is a metalloid bridging atom selected from Si, Ge, Sn, N, P, B and Al; and Z is one, two or three depending upon the valence of atom Y. For example, if Y is Si or Ge (which are four valent), then Z is 2. Similarly, if Y is three valent nitrogen, then Z is 1. In another embodiment, this invention provides a process to prepare a phosphole as described above wherein the process comprises the reaction of a reactive organometallic cyclopentadienyl reagent with a halogenated phosphole defined by the formula: ##STR3## wherein: R.sub.1, R.sub.2, and R.sub.3, are hydrogen or non-interfering substituents; Sl is a spectator ligand; Y is Si, Ge, Sn, N, P, B and Al; Z is one, two or three depending upon the valence of Y; L is a leaving group; and Hal is a halogen or pseudohalogen. In another embodiment, the invention provides a process to prepare group 4 metal complexes of the above-described phospholes. In another embodiment, the invention provides a process for polymerizing at least one polymerizable alpha olefin comprising reacting an activator and a group 4 organometallic complex of the present, inventive phospholes. In a preferred embodiment, there is provided a high temperature olefin polymerization process using an activator and catalyst in which the catalyst is a group 4 organometallic complex defined by the formula: ##STR4## wherein: Flu* is selected from fluorenyl and substituted fluorenyl; each Sl is a non-interfering spectator ligand; Y is selected from Si, Ge, and Sn; R.sub.1, R.sub.2, and R.sub.3 are hydrogen or non-interfering substituents; M4 is selected from Ti, Zr and Hf; and each X is an anionic ligand and n is 1 or 2 depending upon the oxidation state of M4. DETAILED DESCRIPTION PART I Novel Phospholes The novel phospholes of the present invention are characterized by having (a) a substituent which is a leaving group (to facilitate further manipulations of the phosphole molecule); and (b) a substituent which includes a cyclopentadienyl structure and a metalloid bridge between the phosphole and the cyclopentadienyl structure. A discussion of each of the features of these novel phospholes is provided below. The term "phosphole" is meant to convey its conventional meaning, namely a cyclic dienyl structure having four carbon atoms and one phosphorus atom in the ring. The simplest phosphole is illustrated below: ##STR5## It will be readily appreciated by those skilled in the art that the hydrogen atoms shown in the above formula may be replaced with other substituents. The novel phospholes of this invention contain a cyclopentadiene-type group. As used herein the term "cyclopentadiene-type" is meant to convey its conventional meaning and to include indene and fluorene ligands. The simplest (unsubstituted) cyclopentadiene, indene and fluorene structures are illustrated below. ##STR6## It will be readily appreciated by those skilled in the art that the hydrogen atoms shown in the above formula may be replaced with substituents to provide the "substituted" analogues. Thus, in the broadest sense, the inventive phospholes contain a cyclopentadienyl structure which may be an unsubstituted cyclopentadienyl, unsubstituted indenyl, substituted indenyl, unsubstituted fluorenyl or substituted fluorenyl. A description of permissible substituents on these cyclopentadienyl type structures is provided in the aforementioned Welborn '800 reference. An illustrative list of such substituents for cyclopentadienyl groups includes C.sub.1 -C.sub.20 hydrocarbyl radicals; substituted C.sub.1 -C.sub.20 hydrocarbyl radicals wherein one or more hydrogen atoms is replaced by a halogen radical, an amido radical, a phosphido radical, an alkoxy radical or a radical containing a Lewis acidic or basic functionality; substituted C.sub.1 -C.sub.20 hydrocarbyl radicals wherein the substituent contains an atom selected from the group 14 of the Periodic Table of Elements (where group 14 refers to IUPAC nomenclature); and halogen radicals, amido radicals, phosphido radicals, alkoxy radicals, alkyborido radicals, or a radical containing Lewis acidic or basic functionality; or a ring in which two adjacent R-groups are joined forming C.sub.1 -C.sub.20 ring to give a saturated or unsaturated polycyclic ligand. It should be further noted that the aforementioned Frey et al references teach cyclopentadienyl type ligands (including indenyl and fluorenyl) which may be substituted with phosphorus-containing substituents. By way of clarification, the phosphorus-containing substituents disclosed by Frey et al are not within a ring structure (i.e. Frey et al do not disclose phospholes but, rather, phosphido or phosphino substituted cyclopentadienyls). The inventive phospholes contain a metalloid bridge between the phosphole ring and the cyclopentadienyl structure. The term "metalloid" as used herein is meant to refer to the group which includes silicon (Si); germanium (Ge); Tin (Sn); nitrogen (N); phosphorus (P); boron (B); and aluminum (Al). The "metalloid" is a "bridging" atom which is bonded to a carbon atom in the phosphole ring and to the cyclopentadienyl group. The metalloid has additional valences which are filled with "spectator" ligands (i.e. ligands which must be on the metalloid but which are not important to the substance of this invention). Illustrative examples of spectator ligands include hydrogen, halides, and hydrocarbyl ligands containing from 1 to 15 carbon atoms. For convenience, it is preferred that each of the spectator ligands is either a --CH.sub.3 (methyl) fragment or phenyl fragment. The preferred metalloids are Si, Ge, and Sn with Si being especially preferred. Thus, the preferred phospholes are illustrated by the formula: ##STR7## wherein: R.sub.1, R.sub.2, and R.sub.3 are hydrogen or non-interfering substituents; Y is Si, Ge or Sn; Sl is a spectator ligand; L is a leaving group; and Cp* is a cyclopentadienyl-type structure as described above. As shown in the above formula, it is most preferred that the metalloid is bonded to a carbon atom adjacent to the phosphorus atom of the phosphole. The (optional) "non-interfering" substituents on the phosphole (i.e. R.sub.1, R.sub.2, and R.sub.3) generally encompass any substituent which doesn't interfere with further manipulation of the phosphole. An illustrative list of non-interfering substituents includes C.sub.1 -C.sub.20 hydrocarbyl radicals; substituted C.sub.1 -C.sub.20 hydrocarbyl radicals wherein one or more hydrogen atoms is replaced by a halogen radical, an amido radical, a phosphido radical, an alkoxy radical or a radical containing a Lewis acidic or basic functionality; substituted C.sub.1 -C.sub.20 hydrocarbyl radicals wherein the substituent contains an atom selected from the group 14 of the Periodic Table of Elements; and halogen radicals, amido radicals, phosphido radicals, alkoxy radicals, alkyborido radicals, or a radical containing Lewis acidic or basic functionality; or a ring in which two adjacent R-groups are joined forming C.sub.1 -C.sub.20 ring to give a saturated or unsaturated polycyclic ligand. The inventive phospholes are further characterized by having a "leaving group" bonded to the phosphorus atom in the ring. As used herein, the term "leaving group" is intended to convey its conventional meaning to organometallic chemists--i.e. a fragment or group which may be cleaved off in a manner which facilitates further manipulation of the subject molecule. Examples of suitable leaving groups bonded to the phosphorus atom include a single H atom (which may, for example, be cleaved off with an alkyl lithium reagent), trialkyl (or triaryl) tin, trialkyl (or triaryl) Si; group 1 or group 2 atoms, or aryl, with aryl (especially phenyl) being preferred. The inventive phospholes may be used to prepare organometallic complexes, such as Group 4 metal complexes having a dianonic ligand with a metalloid bridge, a phospholyl ligand group which is pi bonded to the metal and cyclopentadienyl-ligand group which is also pi bonded to the metal. PART II Process to Prepare the Phospholes The preferred process to prepare the novel phospholes is by reacting an organometallic cyclopentadienyl reagent and a "bifunctional phosphole". The organometallic cyclopentadienyl reagent is defined by the formula: Cp*M wherein Cp* is selected from unsubstituted cyclopentadienyl, substituted cyclopentadienyl, unsubstituted indenyl, substituted indenyl, unsubstituted fluorenyl, and substituted fluorenyl; and M is a group 1 or 2 metal (i.e. Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr or Ba) or Al or Tl. The "bifunctional phosphole" has (a) a leaving group bonded to the phosphorus atom and (b) a halogen or pseudohalogen containing group bonded to a carbon atom adjacent to the phosphorus atom. The preparation of such a bifunctional phosphole is described in the examples. The term "leaving group" is used in the manner previously discussed (with the preferred leaving group being aryl, especially phenyl). The term halogen is well known and the term pseudohalogen is also used conventionally--i.e. to identify (to a skilled organometallic chemist) a group which will behave similarly to a halogen in subsequent manipulations of the molecule. A common pseudohalogen is an --OR group (where the R is hydrogen or a hydrocarbyl fragment having from 1 to 20 carbon atoms). The preferred group of organometallic reagents are Li salts of substituted fluorenyls. The reaction preferably is undertaken in a solvent (or diluent) such as an ether, a C.sub.5-20 alkane, an aromatic or mixture thereof at a temperature of from -100.degree. C. to 150.degree. C. (most preferably from -78.degree. C. to 25.degree. C.). PART III Preparation of Group 4 Organometallic Complexes The preferred process to prepare the group 4 organometallic complexes is undertaken by reacting a group 4 metal (i.e. Ti, Hf or Zr) complex with a reagent derived from the novel phosphole complexes described in Part I above. The group 4 metal is preferably in the highest oxidation state (though Ti(III) is also suitable) and is most preferably a tetrahalide (especially ZrCl.sub.4). The preferred initial step is to lithiate the phosphole. In some instances it may be possible to obtain the desired group 4 organometallic complexes from a direct reaction between the lithiated phosphole and the metal halide. However, in other instances it may be necessary to prepare an intermediate reagent (for example, by reaction of the lithiated phosphole with trimethyl silicon chloride or trimethyl tin chloride, and then reacting this intermediate with the group 4 metal halide--as illustrated in the Examples). (Skilled organometallic chemists will recognize that the use of this intermediate involves extra time/expense but can improve the final yield of the group 4 organometallic complex.) The reaction preferably is done in a solvent (or diluent) such as an ether, alkane, or aromatic. Toluene is the most preferred solvent. The reaction temperature is preferably from -150.degree. C. to 250.degree. C. (most preferably from 20.degree. C. to 150.degree. C.). The resulting group 4 organometallic complexes are defined by the following formula ("formula 1"): ##STR8## wherein: R.sub.1, R.sub.2, and R.sub.3 are hydrogen or non-interfering substituents (as described in Part I above); ##STR9## is a metalloid bridge having at least one spectator ligand (as described in Part 1 above); Cp* is a cyclopentadienyl, indenyl or fluorenyl (each optionally substituted as described in Part 1 above); M4 is a group 4 metal (i.e. Ti, Zr or Hf); and X is a ligand or ligands bonded to the group 4 metal and n is 1 or 2 depending upon the oxidation state of M4. By way of further explanation: If the group 4 metal is in oxidation state +3 and X is a simple anionic ligand then there will be only one X (and similarly, there will be two X ligands if the metal is 4+). X is, in general, a simple anionic ligand. Any such simple anionic ligand which may be bonded to an analogous metallocene complex should be acceptable in the present complexes. An illustrative list of such anionic ligands includes hydrogen, amidos, halogens and hydrocarbyls having up to 10 carbon atoms (with chlorine being preferred, for simplicity). PART IV Polymerization The polymerization process of this invention is conducted in the presence of a catalyst which is an organometallic complex according to the aforedefined formula 1 and an "activator or cocatalyst". The terms "activator" or "cocatalyst" may be used interchangeably and refer to a catalyst component which combines with the organometallic complex to form a catalyst system that is active for olefin polymerization. Preferred cocatalysts are the well known alumoxane (also known as aluminoxane) and ionic activators. The term "alumoxane" refers to a well known article of commerce which is typically represented by the following formula: R.sub.2 'AlO(R'AlO).sub.m AlR.sub.2 ' where each R' is independently selected from alkyl, cycloalkyl, aryl or alkyl substituted aryl and has from 1-20 carbon atoms and where m is from 0 to about 50 (especially from 10 to 40). The preferred alumoxane is methylalumoxane or "MAO" (where each of the R' is methyl). Alumoxanes are typically used in substantial molar excess compared to the amount of metal in the catalyst. Aluminum:transition metal molar ratios of from 10:1 to 10,000:1 are preferred, especially from 50:1 to 500:1. As used herein, the term "ionic activator" is meant to refer to the well known cocatalyst systems described in the aforementioned Hlatky and Turner U.S. patent references, and the carbonium, sulfonium and oxonium analogues of such ionic activators which are disclosed by Ewen in U.S. Pat. No. 5,387,568. In general, these ionic activators form an anion which only weakly coordinates to a cationic form of the catalyst. Such "ionic cocatalysts" may or may not contain an active proton (e.g. trimethyl ammonium, tributylammonium; N,N-dimethyl anilinium, carbonium, oxonium or sulfonium). They do contain a labile substantially non-coordinating anion (such as tetraphenyl borate or tetrakis(pentafluorophenyl) borate). The preferred of these ionic activators are tris(pentafluorophenyl) borane (which can generate the borate upon reaction with the organometallic catalyst complex), [triphenyl methyl][tetrakis(pentafluorophenyl) borate] and [N,N-dimethyl anilinium][tetrakis(pentafluorophenyl) borate]. In commercial practice, the triphenyl methyl (or "carbonium") salts may be preferred. These ionic activators are typically used in approximately equimolar amounts (based on the transition metal in the catalyst) but lower levels may also be successful and higher levels also generally work (though sub-optimally with respect to the cost-effective use of the expensive activator). In addition to the catalyst and cocatalyst, the use of a "poison scavenger" may also be desirable. As may be inferred from the name "poison scavenger", these additives may be used in small amounts to scavenge impurities in the polymerization environment. Aluminum alkyls, for example triisobutyl aluminum, are suitable poison scavengers. (Note: some caution must be exercised when using poison scavengers as they may also react with, and deactivate, the catalyst.) Polymerizations according to this invention may be undertaken in any of the well known olefin polymerization processes including those known as "gas phase", "slurry", "high pressure" and "solution". The use of a supported catalyst is preferred for gas phase and slurry processes whereas a non-supported catalyst is preferred for the other two. When utilizing a supported catalyst, it may be preferable to initially support the cocatalyst, then the catalyst (as will be illustrated in the Examples). The polymerization process according to this invention uses at least one olefin monomer (such as ethylene, propylene, butene, hexene) and may include other monomers which are copolymerizable therewith (such as other alpha olefins, preferably butene, hexene or octene, and under certain conditions, dienes such as hexadiene isomers, vinyl aromatic monomers such as styrene or cyclic olefin monomers such as norbornene). It is especially preferred that the polymerization process utilize a major portion of ethylene monomer and a minor portion of an alpha olefin comonomer selected from butene, hexene and octene so as to produce a linear low density polyethylene ("LLDPE") product. Our experimental data illustrate that organometallic complexes prepared from phospholes according to this invention are excellent polymerization processes. The organometallic complexes having a bridged fluorenyl phospholyl ligand according to this invention display particularly desirable behavior in high temperature ethylene polymerization in that the resulting polyethylene has high molecular weight. The most preferred polymerization process of this invention encompasses the use of the novel catalysts (together with a cocatalyst) in a medium pressure solution process. As used herein, the term "medium pressure solution process" refers to a polymerization carried out in a solvent for the polymer at an operating temperature from 100 to 320.degree. C. (especially from 120 to 220.degree. C.) and a total pressure of from 3 to 35 mega Pascals. Hydrogen may be used in this process to control (reduce) molecular weight. Optimal catalyst and cocatalyst concentrations are affected by such variables as temperature and monomer concentration but may be quickly optimized by non-inventive tests. Further details concerning the medium pressure polymerization process (and the alternative gas phase, slurry and high pressure processes) are well known to those skilled in the art (and widely described in the open and patent literature). |
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