| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | December 29, 1998 |
| PATENT TITLE |
Synthesis and use of (perfluoroaryl) fluoro-aluminate anion |
| PATENT ABSTRACT | A trityl perfluorophenyl alumninate such as tris(2,2',2"-nonafluorobiphenyl) fluoroaluminate (PBA.sup.-) and its role as a cocatalyst in metallocene-mediated olefin polymerization is disclosed |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | August 18, 1997 |
| PATENT REFERENCES CITED |
Chen et al., Very Large Counteranion Modulation of Cationic Metallocene Polymerization Activity and Stereoregulation by a Sterically Congested (Perfluoroaryl) fluoroaluminate, J. Am. Chem. Soc., 1997, vol. 119, pp. 2582-2583. Jordan et al., J. Am. Chem. Soc., vol. 108, pp. 1718-1719 (1986). Marks, Tobin J., Surface-Bound Metal Hydrocarbyls. Organometallic Connections between Heterogeneous and Homogeneous Catalysts, Accounts of Chemical Research, vol. 25, No. 2, pp. 57-65, Feb., 1992. Yang et al., Cationic Zirconocene Olefin Polymerization Catalysts Based on the Organo-Lewis Acid Tris(pentafluorophenyl)borane. A Synthetic, Structural, Solution Dynamic, and Polymerization Catalytic Study, J. Am. Chem. Soc. 116, 10015-10031, 1994. Chen et al., Organo-Lewis Acids As Cocatalysts in Cationic Metallocene Polymerization Catalysts. Unusual Characteristics of Sterically Encumbered Tris(perfluorobiphenyl)borane, J. Am. Chem. Soc., 118, pp. 12451-12452, 1996. |
| PATENT GOVERNMENT INTERESTS | This invention was made with Government support under Contract No. DE-FG02-86ER13511 awarded by the Department of Energy. The Government has certain rights in this invention |
| PATENT PARENT CASE TEXT | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. A catalytic complex of the formula: (CpCp'MR).sup.+ AR'R"R'"F.sup.- where Cp and Cp' is each a group containing a cyclopentadienyl ligand M is Ti, Zr, Hf, Th, or U R is an alkyl or aryl group (C.ltoreq.20), or hydride A is Al, Ga, or In R', R", and R'" is each a fluorinated phenyl, fluorinated biphenyl or fluorinated polycyclic fused ring group. 2. The complex of claim 1, wherein said cyclopentadienyl ligand is selected from the group consisting of indenyl, .eta..sup.5 -C.sub.5 H.sub.5 ; .eta..sup.5 -1,2-Me.sub.2 C.sub.5 H.sub.3 ; .eta..sup.5 -1,3-(SiMe.sub.3).sub.2 C.sub.5 H.sub.3 ; .eta..sup.5 -C.sub.5 Me.sub.5 and Me.sub.2 Si(.eta..sup.5 -Me.sub.4 C.sub.5)(.sup.t BuN). 3. The complex of claim 1 wherein said polycyclic fused ring groups are naphthyl, anthracenyl, or fluorenyl. 4. A method of preparing a catalyst composition including the step of adding tris(2', 2", 2'"-nonafluorobiphenyl fluoroaluminate to a cationic metallocene. 5. The method of claim 4, wherein said cationic metallocene incorporates a cyclopentadienyl ligand. 6. The method of claim 4, wherein said cationic metallocene incorporates ligands selected from the group consisting of indenyl, .eta..sup.5 -C.sub.5 H.sub.5 ; .eta..sup.5 - 1,2-Me.sub.2 C.sub.5 H.sub.3 ; .eta..sup.5 -1,3-(SiMe.sub.3).sub.2 C.sub.5 H.sub.3 ; .eta..sup.5 -C.sub.5 Me.sub.5 and Me.sub.2 Si(.eta..sup.5 -Me.sub.4 C.sub.5)(.sup.t BuN). 7. A method of polymerizing an alpha olefin comprising the step of adding the catalyst (CpCp'MR).sup.+ AR'R"R'"F.sup.- to the alpha olefin where Cp and Cp' is each a group containing a cyclopentadienyl ligand M is Ti, Zr, Hf, Th, or U R is an alkyl, or aryl group (C.ltoreq.20), or hydride A is Al, Ga, or In R', R", and R'" is each a Fluorinated phenyl, fluorinated biphenyl or fluorinated polycyclic fused ring group. 8. The method of claim 7, wherein said alpha olefin is selected from the group consisting of ethylene, propylene and styrene. 9. The method of claim 7, wherein said cyclopentadienyl ligand is selected from the group consisting of indenyl, .eta..sup.5 -C.sub.5 H.sub.5 ; .eta..sup.5 -1,2-Me.sub.2 C.sub.5 H.sub.3 ; .eta..sup.5 -1,3-(SiMe.sub.3).sub.2 C.sub.5 H.sub.3 ; .eta..sup.5 -C.sub.5 Me.sub.5 and Me.sub.2 Si(.eta..sup.5 -Me.sub.4 C.sub.5)(.sup.t BuN). 10. The method of claim 7 wherein said reaction is carried out at ambient conditions. 11. The method of claim 7, wherein said reaction is initiated at temperatures from 25.degree. C. to 110.degree. C. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
BACKGROUND OF THE INVENTION This invention relates to the compositions of matter useful as a catalyst system, to a method for preparing these catalyst systems and to a method for polymerization utilizing the catalyst system. The use of soluble Ziegler-Natta type catalysts in the polymerization of olefins is well known in the prior art. In general, such systems include a Group IV-B metal compound and a metal or metalloid alkyl cocatalyst, such as aluminum alkyl cocatalyst. More broadly, it may be said to include a mixture of a Group I-III metal alkyl and a transition metal complex from Group IVB-VB metals, particularly titanium, zirconium, or hafnium with aluminum alkyl cocatalysts. First generation cocatalyst systems for homogeneous metallocene Ziegler-Natta olefin polymerization, alkylaluminum chlorides (AlR.sub.2 Cl), exhibit low ethylene polymerization activity levels and no propylene polymerization activity. Second generation cocatalyst systems, utilizing methyl aluminoxane (MAO), raise activities by several orders of magnitude. In practice however, a large stoichiometric excess of MAO over catalyst ranging from several hundred to ten thousand must be employed to have good activities and stereoselectivities. Moreover, it has not been possible to isolate characterizable metallocene active species using MAO. The third generation of cocatalyst, B(C.sub.6 F.sub.5).sub.3, proves to be far more efficient while utilizing a 1:1 catalyst-cocatalyst ratio. Although active catalyst species generated with B(C.sub.6 F.sub.5).sub.3 are isolable and characterizable, the anion MeB(C.sub.6 F.sub.5).sub.3.sup.- formed after Me.sup.- abstraction from metallocene dimethyl complexes is weakly coordinated to the electron-deficient metal center, thus resulting in a decrease of certain catalytic activities. The recently developed B(C.sub.6 F.sub.5).sub.4.sup.- type of non-coordinating anion exhibits some of the highest reported catalytic activities, but such catalysts have proven difficult to obtain in the pure state due to poor thermal stability and poor crystallizability, which is crucial for long-lived catalysts and for understanding the role of true catalytic species in the catalysis for the future catalyst design. Synthetically, it also takes two more steps to prepare such an anion than for the neutral organo-Lewis acid. SUMMARY OF THE INVENTION Accordingly, it is an object of the subject invention to prepare and utilize a new class of olefin polymerization catalytic system. A further object of the subject invention is a catalytic system which permits better control over molecular weight, molecular distribution, stereoselectivity, and comonomer incorporation. Another object of the subject invention is a Ziegler-Natta type catalytic system which reduces the use of excess cocatalyst and activates previously unresponsive metallocenes. These and other objects are attained by the subject invention whereby in one embodiment, a strong organo-Lewis acid, such as a (perfluoroaryl)aluminate anion and in particular tris(2,2',2" nonafluorobiphenyl)fluoroaluminate (PBA.sup.-) is utilized as a highly efficient cocatalyst for metallocene-mediated olefin polymerization. PBA.sup.- exhibits higher catalytic activities and can activate previously unresponsive metallocenes. The synthesis of the stable perfluoroaryl aluminum anion, tris(2,2',2"-nonafluorobiphenyl)fluoroaluminate (PBA.sup.-) is accomplished with the use sterically encumbered perfluorobiphenyl ligand. In one embodiment of the subject invention a strong organo-Lewis acid, such as a fluoraryl metal compound, is utilized to synthesize stoichiometrically precise, isolable/crystallographically characterizable, highly active "cation-like" metallocene polymerization catalysts. In the subject application, "Cp" represents a cyclopentadienyl radical which may be substituted or unsubstituted, and: (Cp)(Cp') or Cp-A-Cp' and Cp and Cp' are the same or different cyclopentadienyl ring substituted with zero to five substituent groups .beta. and each substituent group .beta. is, independently, a radical which can be hydrocarbyl, substituted-hydrocarbyl, halocarbyl, substituted-halocarbyl, hydrocarbyl-substituted organometalloid, halocarbyl-substituted organometalloid, or halogen radicals (the size of the radicals need not be limited to maintain catalytic activity; however, generally the radical will be a C.sub.1 to C.sub.20 radical) or Cp and Cp' are a cyclopentadienyl ring in which any two adjacent R groups are joined forming a C.sub.4 to C.sub.20 ring to give a saturated or unsaturated polycyclic cyclopentadienyl ligand such as indenyl, tetrahydroindenyl, fluorenyl, or octahydrofluorenyl and A is a bridging group which restricts rotation of the two Cp-groups. Each carbon atom in the cyclopentadienyl radical ("Cp") may be, independently, unsubstituted or substituted with the same or different radical group which is a hydrocarbyl, substituted-hydrocarbyl, halocarbyl, substituted-halocarbyl hydrocarbyl radicals in which adjacent substituents are joined to form a ring of 4 to 10 or more carbon atoms, hydrocarbyl- and halocarbyl-substituted organometalloid radicals and halogen radicals. More specifically, a fluoroaryl metal compound such as ER'R"R'"F.sup.- reacts with early transition metal or actinide alkyls to yield highly reactive cationic complexes: CpCp'MR.sub.2 +Ph.sub.3 C.sup.+ (ER'R"R'"F).sup.- .fwdarw.CpCp'MR.sup.+ (ER'R"R'"F).sup.- +Ph.sub.3 CR (1) where=cyclopentadienyl, cyclopentadienyl substituted or bridged CpCp' cyclopentadienyl ligands such as CpACp', indenyl Cp, allyl Cp, benzyl Cp; substituted indenyl Cp; substituted allyl Cp; substituted benzyl Cp; .eta..sup.5 -1,2-Me.sub.2 C.sub.5 H.sub.3 ;.eta..sup.5 -1,3-(SiMe.sub.3).sub.2 C.sub.5 H.sub.3 ;.eta..sup.5 -C.sub.5 Me.sub.5 ;(.sup.t BuN)Me.sub.2 Si(.eta..sup.5 -Me.sub.4 C.sub.5) M=early transition metal or actinide, e.g., Ti, Zr, Hf, Th, U R=PhCH.sub.2, alkyl or aryl group (C.ltoreq.20), hydride R', R", R'"=fluorinated phenyls, fluorinated biphenyl or fluorinated polycyclic fused ring groups E=Al, Ga, In As a specific example of the above, the reaction of PBA.sup.- with a variety of zirconocene dimethyl complexes proceeds rapidly and quantitatively to yield, after recrystallization from hydrocarbon solvents, in the catalytic complex set forth in Eq. 2. CpCp'MR.sub.2 +Ph.sub.3 C.sup.+ (ER'R"R'"F).sup.- .fwdarw.CpCp'MR.sup.+ (ER'R"R'"F).sup.- +Ph.sub.3 CR (2) Such catalytic complexes have been found to be active homogeneous catalysts for (.alpha.-olefin polymerization. The cocatalyst of the subject invention may be referred to as ER.sub.F 'R.sub.F "R.sub.F '"F.sup.- ; where R', R" and R'" represent at least one and maybe more fluorinated biphenyls or other fluorinated polycyclic groups, such as naphthyl. Two of the biphenyls may be substituted with a phenyl or other aryl group. Both the biphenyls and the phenyl groups should be highly fluorinated, preferably with only one or two hydrogens on a group, and most preferably, as in PBA.sup.- with no hydrogens and all fluorines. E represents Al, Ga or In. BRIEF DESCRIPTION OF THE DRAWINGS The cocatalyst system of the subject invention can be better understood with reference to the drawings wherein: FIG. 1 is a reaction pathway for the synthesis of PBA.sup.- ; FIGS. 2a, 2b and 2c each show the reaction pathway for a catalyst system according to the subject invention. DETAILED DESCRIPTION OF THE INVENTION Under a variety of reaction conditions and ratios of reagents, the reaction of 2-nonafluorobiphenyl lithium and AlCl.sub.3 all appear to lead to the formation of a compound with the formula Ar.sup.F.sub.3 F Al.sup.- Li.sup.+, resulting from fluoride abstraction by the strongly Lewis acidic trisperfluoro-biphenyl aluminum species generated in situ (FIG. 1). Ion exchange metathesis of this lithium salt with Ph.sub.3 CCl results in the formation of stable trityl perfluorobiphenyl aluminate (PBA.sup.-). The structure of PBA.sup.- has been characterized by X-ray diffraction and shows a non-associated trityl cation and aluminate anion. Isolation and Characterization of Cationic Group 4 Complexes Derived from PBA The reaction of PBA.sup.- with various metallocene dialkyls readily generates the corresponding cationic complexes (FIGS. 2a-2c). The PBA.sup.- anion is weakly coordinated to the metal center via F.sup.- bridges in these complexes. This coordination is evident from the large downfield shift (.gtoreq.30 ppm) of the Al--F F resonance in the .sup.19 F NMR as compared to that of free PBA. This coordination lowers the symmetry of the cation portion as well. Furthermore, the coordinated anion is chiral. The relatively stable chirality of the anion stems from the bulkiness of the molecule which suppresses the rotation of perfluoroaryl rings and renders the geometry fixed, resulting in nine (9) sets of characteristic resonances in the .sup.19 F NMR. The influence of the anion chirality on the cation portion can be observed spectroscopically. In the reaction product of FIG. 2a, there are two diastereotopic CH.sub.2 Ph protons with .sup.2 J value of 11.4 Hz and two magnetically nonequivalent Cp rings, which reflects the chiral environment of the coordinated anion. With diastereotopic ring substitution in the metallocene, the structure of the reaction product shown in FIG. 2b offers unique NMR probes for a better understanding of the molecular structure. Coordination of an achiral anion such as CH.sub.3 B(C.sub.6 F.sub.5).sub.3.sup.- to the metal center of the cation portion of FIG. 2b results in the observation of two diastereotopic Cp methyls and three types of Cp ring protons having different chemical shifts. However, in the reaction product of FIG. 2b with a coordinated chiral anion, all the Cp methyls (four types) and Cp ring protons (six types) have different chemical shifts, clearly indicating the chiral induction of the anion. Constrained geometry catalysts (FIG. 2c) activated by PBA exhibit two distinct silyl methyls and four different Cp methyls. The structure of the reaction product of FIG. 3c has been characterized by X-ray diffraction and reveals a chiral PBA.sup.- anion coordinated via an F-bridge with Zr--F and Al--F bond lengths of (2.123) and (6) .ANG., respectively. The Zr--CH.sub.3 of bond distance of 2.21(1) .ANG. is almost identical to that in (CGC)Zr(Me)›MeB(C.sub.6 F.sub.5).sub.3 ! (2.224 (5)) .ANG., reflecting the cationic character of the zirconium center. In cases where the bulkiness of cationic portion is increased, thereby pushing the anion away from the coordinative periphery, the product formed from the reaction appears neither stable nor isolable, e.g., ›(C.sub.5 Me.sub.5).sub.2 ZrMe.sub.2.sup.+ PBA.sup.- !. However, this distant contact cation-anion pair exhibits extremely high activity for olefin polymerization when generated in situ. Ph.sub.3 C.sup.+ PBA.sup.- has been synthesized in essentially quantitative yields as compared to the 30-50% yields experienced with B(C.sub.6 F.sub.5).sub.3, currently a very important Lewis acidic cocatalyst in the polyolefin industry. More particularly, reaction of PBA.sup.- with group 4 methyls proceeds cleanly to yield cationic complexes such as set forth below. ##STR1## CpCp'=Cp*=.eta..sup.5 -C.sub.5 Me.sub.5 =Cp"=.eta..sup.5 -1,2-Me.sub.2 C.sub.5 H.sub.3 M=Ti, Zr, Hf R=PhCH.sub.2, CH.sub.3, alkyl or aryl group with C.ltoreq.20; hydride CpCp'MR.sup.+ PBA.sup.- may be any cyclopentadienyl, substituted cyclopentadienyl or bridged cyclopentadienyl complex paired with PBA.sup.-, such as Cp.sub.2 ZrCH.sub.2 Ph.sup.+ PBA.sup.- ; Cp.sub.2 ZrH.sub.3.sup.+ PBA.sup.- ; Cp.sub.2 "ZrCH.sub.3.sup.+ PBA.sup.- ; (1,3-(Si, Me.sub.3).sub.2 C.sub.5 H.sub.3).sub.2 ZrCH.sub.3.sup.+ PBA.sup.- ; Cp'.sub.2 ZrCH.sub.3.sup.+ PBA.sup.- ; (CGC)ZrCH.sub.3.sup.+ PBA.sup.- ; (CGC)TiCH.sub.3.sup.+ PBA.sup.- ; and rac-Me.sub.2 Si(Ind).sub.2 ZrCH.sub.3.sup.+ PBA.sup.31 (CGC=.sup.t BuN Me.sub.2 Si(.eta..sup.5 -Me.sub.4 C.sub.5); (Ind=.eta..sup.5 -C.sub.9 H.sub.6), 2-methyl (Ind) ZrCH.sub.3.sup.+ PBA.sup.31 ; (CpZrCp'Zr).sub.2 ZrCH.sub.3.sup.30 PBA.sup.31. For polymerization of olefin monomers, catalytic activities of the cations generated from PBA.sup.- can be greater than those of monomeric cations generated from B(C.sub.6 F.sub.5).sub.3 in cases of bulky L and L' ligands presumably because PBA.sup.- functions as a non-coordinating anion as compared to the weakly coordinating anion MeB(C.sub.6 F.sub.5).sub.3. Polymerization reactions show very high activities for .alpha.-olefin polymerization, and identify PBA.sup.- to be a truly non-coordinating anion. When polymerizing .alpha.-olefins larger than ethylene and particularly propylene and styrene, high isotacticity can be observed. Experimental Materials and Methods. All manipulations of air-sensitive materials were performed with rigorous exclusion of oxygen and moisture in flamed Schlenk-type glassware on a dual-manifold Schlenk line or interfaced to a high-vacuum line (10.sup.-6 Torr), or in a nitrogen-filled vacuum atmospheres glovebox with a high capacity recirculator (1-2 ppm O.sub.2). Argon (Matheson, prepurified) and ethylene (Matheson, polymerization grade) were purified by passage through a supported MnO oxygen-removal column and an activated Davison 4A molecular sieve column. Ether solvents were purified by distillation from Na/K alloy/benzophenone ketyl. Hydrocarbon solvents (toluene, pentane) were distilled under nitrogen from Na/K alloy. All solvents for vacuum line manipulations were stored in vacuo over Na/K alloy in Teflon-valved bulbs. Deuterated solvents were obtained from Cambridge Isotope Laboratories (all.gtoreq.99 atom %D) and were freeze-pump-thaw degassed and dried over Na/K alloy and stored in resealable flasks. Non-halogenated solvents were dried over Na/K alloy and halogenated solvents were distilled over P.sub.2 O.sub.5 and stored over activated Davison 4 .ANG. molecular sieves. BrC.sub.6 F.sub.5 (Aldrich) was vacuum distilled over P.sub.2 O.sub.5. AlCl.sub.3, Ph.sub.3 CCl and BuLi (1.6M in hexanes) were purchased from Aldrich. The zirconocene and titanocene complexes Cp.sub.2 ZrMe.sub.2 ; Cp.sub.2 Zr(CH.sub.2 Ph).sub.2 ; (1,2-Me.sub.2 C.sub.5 H.sub.3).sub.2 ZrMe.sub.2 ; ›1,3-(SiMe.sub.3).sub.2 C.sub.5 H.sub.3 !.sub.2 ZrMe.sub.2 (C.sub.5 Me.sub.5).sub.2 ZrMe.sub.2, Me.sub.2 Si(Me.sub.4 C.sub.5)(.sup.t BuN) ZrMe.sub.2 and Me.sub.2 Si(Me.sub.4 C.sub.5).sup.t BuNTiMe.sub.2 were prepared according to known procedures. Physical and Analytical Measurements. NMR spectra were recorded on either Varian VXR 300 (FT 300 MHz, .sup.1 H; 75 MHz, .sup.13 C) or Varian Germini-300 (FT 300 MHz, .sup.1 H; 75 MHz, .sup.13 C; 282 MHz, .sup.19 F) instruments. Chemical shifts for .sup.1 H and .sup.13 C spectra were referenced using internal solvent resonances and are reported relative to tetramethylsilane. .sup.19 F NMR spectra were referenced to external CFCl.sub.3. NMR experiments on air-sensitive samples were conducted in Teflon valve-sealed sample tubes (J. Young). Melting temperatures of polymers were measured by DSC (DSC 2920, TA Instruments, Inc.) from the second scan with a heating rate of 20.degree. C./min. |
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