MXPA97008182A - S $! azaborolinilo metallic complexs as olefi polymerization catalysts - Google Patents

Abstract

A catalyst having the general formula (I) in the L is described as a ligand having the formula (a). L'is L, Cp, Cp *, indenyl, fluorenyl, NR2, OR, or halogen, L can be bridged to L ', X is halogen, NR2, OR, or C1 to C12 alkyl, M is zirconium or hafnium, R is C 1 to C 12 alkyl or C 6 to C 12 aryl, R 1 is R, C 6 to C 12 alkaryl, C 6 to C 12 aralkyl, hydrogen, Si (R) 3, R 2 is R 1, halogen, COR, COOR, SOR, or SOOR, R3 is R2, OR, N (R) 2, SR, or a fused ring system, Cp is cyclopentadienyl, Cp + is pentamethylcyclopentadienyl, n is 0 to 3, and L8 is an optional Lewis base. Also disclosed is a method for making a poly-alpha-olefin which comprises polymerizing an alpha-olefin monomer using a catalyst such as that described above wherein M can be titanium, zirconium or hafn

Description

METABOLIC COMPOUNDS OF AZABOROLINYL AS OLEFIN POLYMERIZATION CATALYSTS DESCRIPTION Background and field of the invention This invention relates to catalysts useful in homo- and co-polymerization of ethylene and other olefinic hydrocarbons. In particular, it relates to catalysts containing a transition metal linked by p-bond to a ligand containing an azaborolino ring. Until recently, polyolefins have been made mainly with Ziegler catalyst systems. These catalysts generally consist of compounds containing transition metals and one or more organometallic compounds. For example, the polyethylene has been made using Ziegler catalysts such as titanium trichloride and diethylaluminum chloride, or a mixture of titanium tetrachloride, vanadium oxytrichloride and triethylaluminum. These catalysts are cheap but have low activity and therefore should be used in high concentrations. As a consequence, it is sometimes necessary to remove residues of the polymer catalyst, which increases production costs. Neutralizing agents and stabilizers must be added to the polymer to save the harmful effects of the residues of the catalyst. A failure in the removal of the catalyst residues leads to the polymers having a gray or yellow color and poor long-term stability and ultraviolet light. For example, waste containing residues can cause corrosion in the polymer processing equipment. In addition, Ziegler catalysts produce polymers that have a broad molecular weight distribution, which is undesirable for some applications such as injection molding. They are also not useful in the incorporation of α-olefin co-monomers. The poor incorporation of co-monomers makes it difficult to control the density of the polymer. Large amounts of excess co-monomer may be required to reach a certain density and many higher α-olefins, such as 1-octane, if at all may be incorporated at only very low levels. Although significant improvements have been made since the discovery of the Ziegler catalyst systems, these catalysts are now being replaced with the recently discovered metallocene catalyst systems. A metallocene catalyst generally consists of a transition metal compound which has one or more cyclopentadienyl ring ligands. These systems have low activities when used with organometallic compounds, such as aluminum alkyls, which are used with traditional Ziegler catalysts, but very high activities when used with aluminoxanes as co-catalysts. The activities are generally so high that the residues of the catalysts do not need to be removed from the polymer. In addition, they produce polymers with large molecular weights and narrow molecular weight distributions. They also incorporate either α-olefin co-monomers. However, at higher temperatures, metallocene catalysts tend to produce low molecular weight polymers. Thus, they are useful for ethylene polymerizations in the gas and semiliquid phases, which are carried out from about 80 ° C to about 95 ° C, but generally do not work well in polymerizations in ethylene solution, from about 150 ° C. up to approximately 250 ° C. The polymerization of ethylene in solution is desirable because it allows great flexibility to produce polymers in a very wide range of molecular weights and densities as well as the use of a large variety of co-monomers. One can produce polymers that are useful in a wide variety of applications. For example, high molecular weight (PE) high density polyethylene film useful as a protective film for food packaging and low density ethylene co-polymers with good tenacity and high impact resistance.

A new class of catalysts based on an azaborolin ring structure and containing a transition metal has been found. The catalysts of this invention have unusually high activities, which means that they can be used in very small amounts. They are also good at incorporating co-monomers into the polymer. They have had good activity at high temperatures and therefore are expected to be useful in polymerizations in ethylene solution. It has also been found that the hydrogen response of the polymerized monomers with the catalysts of this invention is better than with other catalysts. That is, when the catalysts of the present invention are used to polymerize monomers, small variations in the amount of hydrogen present have a large effect on the molecular weight of the resulting polymer.

Description of the preferred modalities.

The catalysts of the present invention have the general formula where L is a ligand that has the formula L 'is L, Cp, Cp *, indenyl, fluorenyl, NR2, OR, or halogen, L can be bridged to L', X is halogen, NR2, OR, or Ci to Ci2 alkyl, M is titanium, zirconium, or hafnium, R is C 1 to C 2 alkyl or C 6 to C 12 aryl, Ri is R, C 6 to C 12 alkaryl, C 6 to C 2 aralkyl, hydrogen, or Si (R) 3, R 2 is R 1 halogen, COR, COOR, SOR, or SOOR, R3 is R2, OR, N (R) 2, SR, or a fused ring system, Cp is cyclopentadienyl and Cp * is pentamethylcyclopentadienyl. Ligand L 'is preferably Cp, Cp *, or L because those compounds are easy to make and have good activity. The group X is preferably halogen and more preferably chlorine because those compounds are more readily available. The group R is preferably Ci to C alkyl, the Rt group is preferably C3 to C12 alkyl or aryl, the R2 group is preferably t-butyl or trimethylsilyl, and the R3 group is preferably hydrogen or methyl because those compounds are easier to do Examples of molten ring structures that can be used for R3 include The metal M is preferably zirconium, because the zirconium catalysts provide a good combination of activity and stability. Optionally, L may be bridged to L '. Groups that can be used to bridge the two ligands include methylene, ethylene, 1-2-phenylene, dimethylsilyl, diphenylsilyl, diethylsilyl and methylphenylsilyl. Normally, only a simple bridge in a catalyst is used. It is believed that bridging the ligands changes the geometry around the catalytically active transition metal and improves the catalyst activity and other properties, such as the incorporation of monomers and thermal stability. In the general formula, LB is an optional Lewis base. Up to an equimolar amount (with M) of the base can be used. The use of a Lewis base is generally not preferred because it tends to decrease catalyst activity. However, it also tends to improve the stability of the catalyst, so that its inclusion may be desirable, depending on the process in which the catalyst is to be used.

The base may be resl solvent from the preparation of the compound containing the azaborolino or it may be added separately to enhance the properties of the catalyst. Examples of bases that can be used in the present invention include ethers such as diethyl ether, dibutyl ether, tetrahydrofuran, 1,2-dimethoxyethane, esters such as n-butyl phthalate, ethylbenzoate and ethyl p-aniseate, tertiary amines such as triethylamine, and phosphines such as triethylphosphine, tributylphosphine and triphenylphosphine. The catalysts of the present invention can be prepared from commercially available raw materials. Specific raw materials that can not be obtained commercially can be prepared by techniques well known in the literature as exemplified below. The azaborolino ligand precursor of the catalysts can be prepared from allylamine by reacting its dianion (generated by means of a strong base) with an alkyl boron dihalide as described in the literature (J. Schulze, G Schmid, J. Organomet. Chem., 193, 1980, p 83).

Examples of strong bases that may be employed include alkyl lithium compounds such as n-butyl lithium, methyl lithium, and hydrides such as sodium hydride and potassium hydride. 2 moles of base are used for each mole of allylamine. This reaction will be carried out at room temperature for several hours in a hydrocarbon solvent such as pentane or hexane. Tetramethylethylenediamine in a 1: 1 molar ratio with allylamine can be used to stabilize the lithium alkyl. The product can be isolated by vacuum and distilled for purification. In the next step, the product is reacted with a base such as a bound lithium reagent (for example lithium tetramethylpiperidide) to generate the azaborolinyl anion as described in the literature (G. Schmidt et al., Chem. Ber. ., 115, 1982, p.3830): In the final stage, the product from the second stage is cooled to approximately -60 ° C and MX4 or MCpX3 is added. The reagents are heated to room temperature and the reaction is completed when the reagents dissolve and LiX precipitates: Since the catalyst is usually used in conjunction with an organometallic co-catalyst, it is preferred to dissolve the catalyst in a solvent in which the catalyst is used. catalyst is also soluble. For example, if the co-catalyst is methylaluminoxane (MAO) then toluene, xylene, benzene or ethylbenzene can be used as solvents. Other suitable co-catalysts include aluminum alkyls having the formula AIR ' wherein 1 < x < 3 and R2 is hydrogen, halide or C 1 to C 20 alkyl or alkoxide, such as ethylaluminum dichloride and triethylaluminum. The preferred co-catalyst is MAO because it results in high activity and a polymer having a narrower molecular weight distribution. The molar ratio of the organometallic co-catalyst to the catalyst when used in a polymerization is generally in the range of 0.01: 1 to 100,000: 1, and preferably in the scale of 1: 1 to 10,000: 1. An alternate co-catalyst is an acid salt containing an uncoordinated inert anion (see U.S. Patent No. 5, 064, 802). The acid salt is generally a non-nucleophilic compound consisting of massive ligands bound to a boron or aluminum atom, such as lithium tetrakis (pentafluorophenyl) borate, lithium tetrakis (pentafluorophenyl) aluminate, anilinium tetrakis (pentafluorophenyl) borate, N, N-dimethylanilinium tetrakis (pentafluorophenyl) borate, trityl tetrakis (pentafluorophenyl) borate, and a mixture thereof. It is believed that the anion resulting from reacting these compounds with the catalyst is weakly coordinated with the metal that contains the cation. The molar ratio of acid salt to catalyst is on the scale from about 0.01: 1 to about 1000: 1, but is preferably from about 1: 1 to 10: 1. Although there is no limitation as to the method of preparing an active catalyst system from the catalyst and the acid salt, they are preferably mixed in an inert solvent at temperatures in the range of about -78 ° C to about 150 ° C. They can also be mixed in the presence of a monomer if desired. The acid salt can be used in combination with the organometallic co-catalyst described above. The catalyst and co-catalyst can be used on a base such as silica gel, alumina, silica, magnesia or titania, but it is preferred not to use the bases because they leave contaminants in the polymer. However, a base may be needed depending on the process that is being used. For example, a base is usually needed in gas phase polymerization processes and semiliquid phase polymerization processes in order to control the particle size of the polymer being produced and to avoid fouling in the reactor. The base can also increase the thermal stability of the catalyst. To use a base, both the catalyst and the cocatalyst are dissolved in the solvent and precipitated on the base material by, for example, evaporation of the solvent. As well the co-catalyst can be deposited on the base or it can be introduced into the reactor separately from the supported or base catalyst. Once the catalyst has been prepared, it should be used as soon as possible because it may lose some activity during storage. The storage of the catalyst should be at a low temperature, such as -100 ° to about 20 ° C. The catalyst is used conventionally in the polymerization of olefinic hydrocarbon monomers. While unsaturated monomers such as styrene can be polymerized using the catalysts of the present invention, these are particularly useful for the polymerization of α-olefins such as propylene, 1-butylene, 1-hexene, 1-octane, and especially ethylene. The catalyst is also useful in a conventional manner for the co-polymerization of mixtures of unsaturated monomers such as ethylene, propylene, 1-butane, 1-hexane, 1-octane, and the like; mixtures of ethylene and di-olefins such as 1,3-butadiene, 1,4-hexadiene, 1,5-hexadiene, and the like; and mixtures of ethylene and unsaturated co-monomers such as norbornene, ethylidene norbornene, vinyl norbornene, norbornadiene, and the like. The catalysts of the present invention can be used in a variety of different polymerization processes. They can be used in processes of liquid phase polymerization * (semiliquid, solution, suspension, bulk phase, or a combination of these), in a high pressure fluid phase, or in a gas phase polymerization process. You can use the processes in series or as simple individual processes. The pressure in the polymerization reaction areas may be in the range of about 15 psia to about 50,000 psia and the temperature may be on the scale from about -100 ° C to about 300 ° C. The following examples further describe this invention.

Example 1 Preparation of bis (l-tert-butyl-2-methyl-? 5-l, 2-azaborolinyl) zirconium dichloride and l-tert-butyl-2-methyl-? 5-l, 2-azaborolinyl) tr ' zirconium chloride 2-Methyl-l-tert-butyl-1,2-azaborolinyl lithium was prepared by adding a solution of 0.438 g (3.2 millimole) of 2-methyl-1-tert-butyl-3-l, 2 (prepared in accordance with literature method: J Schultze and G Schmid, J. Organomet, Chem., 1980, 193, 83-91) in 6 mL of dry THF to a cold solution (-78 ° C) of lithium 2, 2, 6, 6-tetramethylpiperidide (3.2 millimole) which has been prepared by reacting equimolar amounts of 2, 2, 6, 6-tetramethylpiperididine and n-butyllithium / hexanes in 10 mL of THF. The hot bath was allowed to warm to 10 ° C for more than 1.5 hours after which they were removed the solvents by means of vacuum. The oily and yellowish residue was treated with 35 mL of toluene to give a yellow mud. This was cooled to -60 ° C and zirconium chloride (IV) was added (0.37 g, 1.6 mmol with good stirring) The bath was warmed to room temperature and the mixture was stirred overnight The solvent was evaporated by medium The residue was treated with 30 mL of toluene, eliminating the lithium chloride, the toluene filtrate was concentrated and a yellow sticky residue was extracted with hexane (2 x 15 mL) and filtered The evaporation of the hexane filtrate gave 0.14 g of a yellow solid.The H NMR spectrum of the material showed that this was a 273 mixture of the two desired compounds.

Example 2 Preparation of (? 5-cyclopentadienyl) (l-tert-butyl-2-methyl-? 5-1,2-azaborolinyl) zirconium dichloride. Method A - * 2-Methyl-l-tert-butyl-l, 2-azaborolinyl-lithium prepared from 0.49 g (3.5 millimol) of 2-methyl-l-tert-butyl-3-l, 2-azaborolino in 20 was prepared. mL of THF as described above. It was added dropwise by means of a syringe to a cold (-35 ° C) stirred solution of cyclopentadienylzirconium trichloride (0.93 g, 3.52 millimole) in 50 mL of THF. The bath was allowed to warm up to temperature atmosphere and the mixture stirred throughout the night. The solvents were evaporated in vacuo and the residue was extracted with 35 mL of toluene and filtered. The precipitate was washed with 10 mL of toluene and the combined filtrate was evaporated. The resulting chewy residue was stirred with 25 ml of dry hexane which yielded a beige solid and a pale yellow cream. The mixture was filtered and the solid was dried to give a product of 0.77 g of product as a light brown amorphous powder. The XH NMR spectrum of the material indicated that the indicated material was contaminated with some impurities.

Method B 2-Methyl-tert-butyl-l, 2-azaborolinyl lithium was prepared by adding a solution of 0.438 g (3.2 millimole) of 2-methyl-1-tert-butyl-3-l, 2-azaborolinyl (prepared in accordance with literature procedure: J. Schultze and G. Schmidt, J.

Organomet. Chem., 1980, 193, 83-91) in 10 ml of dry toluene until cooled to (-78 ° C) lithium solution 2,2,6,6-tetramethylpiperidide (3.2 millimole, prepared by reacting equimolar amounts of 2, 2,6,6-tetramethylpiperidine and n-butyllithium / hexanes in 15 mL) the solvents were evaporated in vacuo to one third of the initial volume, the solution was cooled to -78 ° C and 35 mL of dry toluene was added. The clear, yellow solution was well stirred at the same time that trichloride was added.

Cyclopentadienyl zirconium (0.84 g, 3.2 mmol) was added by means of a transfer tube. The bath was warmed to room temperature and stirred overnight. The reaction mixture was filtered and the filtrate was evaporated to dryness. To the solid residue was added 20 L of toluene and the mixture was filtered to remove a dark insoluble material from the yellow filtrate. The filtrate was concentrated to 0.34 g of a yellow amorphous powder whose XH NMR spectrum indicated that this was the product.

Examples 3 to 11 Polymerization of ethylene with azborolinyl zirconium catalysts The ethylene was polymerized using the catalysts prepared in accordance with method 2A. The polymerizations were carried out in a stirred 1.7 liter autoclave and at a temperature of 80 to 110 ° C. Oxygen-free dry toluene (840 mL) was charged to a dry, clean, oxygen-free reactor. For the polymerizations, MAO from Ethyl Corporation (10% by weight in toluene) was used. The desired amounts of MAO to give the known ratio shown in the table below was added by means of a syringe at 30 ° C. The reactor was heated to the desired temperature and sufficient ethylene was added to bring the reactor pressure up to 150 psig The reactor was allowed to equilibrate at the desired temperature and pressure. A catalyst solution was prepared by dissolving 0.100 grams of product in 100 ml of toluene. The co-catalyst was injected into the reactor first and the catalyst was injected separately. The amount of this solution necessary to provide the amount of catalyst shown in the table was used to initiate a polymerization. Ethylene flowed into the reactor as needed in order to maintain constant pressure at 150 psig as the polymer was produced. After one hour, (less, if the activity was very high) the ethylene flow was stopped and the reactor was rapidly cooled to room temperature. The reactor was opened and the toluene polymer was filtered. The product was dried overnight in a vacuum oven and weighed. Table 1 provides the reaction conditions and table 2 gives the results of the polymerizations.

TABLE 1 TABLE u > The above table shows that polymers having a wide range of molecular weights can be made using the catalysts of this invention because the catalysts are more sensitive to hydrogen The melt index of the polymer was measured in accordance with ASTM D-1238, Condition E and Condition F. MI2 is the Melt Index measured with a weight of 21.6 kg (condition F. MFR is the ratio of MI20 to MI2. of the polymer was measured in accordance with ASTM D-1505. The molecular weight distribution of the polymer was measured using a Waters 150C gel permeation chromatograph at 135 ° C with 1, 2,4-trichlorobenzene as the solvent. (Mw) as the ratio Mw to Mn (average number of molecular weight) were used to determine (distinguish or characterize) the molecular weight distribution.

Examples 12 and 13 The solution polymerizations were carried out in a 2.0 liter stainless steel autoclave with stirring at 150 ° C. One liter of dry and oxygen-free Isopar® G (from Exxon Chemical Company) was charged to the clean, dry and oxygen-free reactor. The reactor was allowed to stabilize at 150 ° C. It was pressurized with enough ethylene to obtain an ethylene partial pressure of 150 psig. No hydrogen or co-monomer was added. A catalyst solution described in Example 2 was mixed with a solution containing 10% methylaminoxane (MAO) in toluene (from Albermale Corporation and was used without further purification). This mixture was stirred for 15 minutes. 10.0 ml of this mixture were injected into the reactor to start the polymerization the amount of catalyst and MAO in the 10 ml is shown in table 3 together with the experimental conditions. In order to maintain constant pressure, ethylene was fed to the reactor. At the end of 15 minutes, the ethylene flow was stopped and the reaction mixture transferred to a vessel containing a solution of an antioxidant in Isopar® G. The solution was cooled to room temperature overnight. The polymer of the solvent was filtered by vacuum filtration. It was dried overnight in a vacuum oven and weighed. The weight of the polymer was 12.1 grams. The MI2 polymer was 118 dg / min. Additional properties of the polymer are shown in table 2.

Examples 14 to 18 The semi-liquid polymerizations were carried out in an identical manner to that described in examples 3 to 11. The catalyst described in example 1 was used in those polymerizations. The polymerization conditions are shown in Table 3. The properties of the polymers that were produced are shown in Table 4.

TABLE 3 TABLE 4 The above table shows that the catalyst has good activity and can produce polymer with very high density and crystallinity. The low MFR values indicate that the copolymer has a narrow molecular weight distribution.

Claims (23)

1. A catalyst that has the general formula in which L is a ligand that has the formula
2. L 'is cyclopentadienyl, pentamethylcyclopentadienyl, indenyl, fluorenyl, NR2, OR, or halogen, L' may be bridged to L; X is halogen, NR2, OR, or C1 to C2 alkyl, M is titanium, zirconium or hafnium, R is Ct to C12 alkyl or C6 to Ci2 aryl, Ri is R, Si (R) 3 or R4 , R is C6 to C2 alkaryl, C6 to C2 aralkyl, or hydrogen, R2 is R, R4, halogen, COR, COOR, SOR or SOOR, R3 is R2, Si (R) 3, OR, N ( R) 2, SR, or a fused ring system, n is 0 to 3, and LB is an optional Lewis base. 2. A catalyst according to claim 1, characterized in that L 'is cyclopentadienyl or pentamethylcyclopentadienyl, X is chlorine, M is zirconium, R is Ci to C4 alkyl, Ri is C3 to C2 alkyl or aryl, R2 is t-butyl and R3 is hydrogen or methyl.
3. 3. A catalyst according to claim 1, characterized in that it is bis (l-tert-butyl-2-methyl-? 5-l, 2-azaborolinyl) zirconium dichloride.
4. 4. A catalyst according to claim 1, characterized in that it is (l-tert-butyl-2-methyl-? 5-l, 2-azaborolinyl) zirconium trichloride.
5. 5. A method for making a poly-α-olefin characterized in that it comprises polymerizing an α-olefin monomer using a catalyst having the general formula in which L is a ligand that has the formula L 'is cyclopentadienyl, pentamethylcyclopentadienyl, indenyl, fluorenyl, NR2, OR, or halogen, L' may be bridged to L; X is halogen, NR2, OR, or Ci to C12 alkyl, M is titanium, zirconium or hafnium, R is Ci to C12 alkyl or C6 to C2 aryl, Ri is R, Si (R) 3 or R4 , R is C6 to C2 alkaryl, C6 to C2 aralkyl, or hydrogen, R2 is R, R4, halogen, COR, COOR, SOR or SOOR, R3 is R2, Si (R) 3OR, N (R) 2, SR, or a fused ring system, n is 0 to 3, and LB is an optional Lewis base.
6. 6. A method according to claim 5, characterized in that L 'is cyclopentadienyl or pentamethylcyclopentadienyl.
7. 7. A method according to claim 5, characterized in that X is halogen.
8. 8. A method according to claim 7, characterized in that X is chlorine.
9. 9. A method according to claim 5, characterized in that M is zirconium.
10. 10. A method in accordance with the claim 5, characterized in that R is alkyl of d to C4.
11. 11. A method according to claim 5, characterized in that Rx is C3 to C12 alkyl or aryl.
12. 12. A method according to claim 5, characterized in that R2 is t-butyl.
13. 13. A method according to claim 5, characterized in that R3 is hydrogen or methyl. A method according to claim 5, characterized in that the catalyst is used with from about 0.1 to about 100,000 moles of an organometallic co-catalyst per mole of such a catalyst. 15. A method according to claim 14, characterized in that the organometallic co-catalyst is methylaluminoxane. 16. A method in accordance with the claim 5, characterized in that the catalyst is used with about 0.01 to about 1000 moles of an acid salt containing an inert non-co-ordinating anion per mole of such a catalyst. 17. A method according to claim 16, characterized in that the acid salt is selected from the group consisting of lithium tetrakis (pentafluorophenyl) borate, lithium tetrakis (pentafluorophenyl) aluminate, anilinium tetrakis (pentafluorophenyl) borate, tetrakis (pentafluorophenyl) ) N, N-dimethylanilinium borate, trityl tetrakis (pentafluorophenyl) borate and mixtures thereof. 18. A method for making a poly-α-olefin characterized in that it comprises polymerizing an α-olefin monomer using a catalyst having the general formula in which L is a ligand that has the formula L 'is cyclopentadienyl or pentamethylcyclopentadienyl, L' may be bridged to L; X chloro, M is zirconium, R is Ci to C4 alkyl, Rt is C3 to C12 alkyl or aryl, R2 is t-butyl, R3 is hydrogen or methyl, n is 0 to 3, and LB is an optional Lewis base. 19. A method according to claim 18, characterized in that the catalyst is bis (l-tert-butyl-2-methyl-? 5-l, 2-azaborolinyl) zirconium dichloride. 20. A method according to claim 18, characterized in that the catalyst is (l-tert-butyl-2-methyl-? 5-l, 2-azaborolinyl) zirconium trichloride. 21. A catalyst according to claim 1, characterized in that M is zirconium. 22. A catalyst that has the general formula in which L is a ligand that has the formula L 'is cyclopentadienyl, pentamethylcyclopentadienyl, indenyl, fluorenyl, NR2, OR, or halogen, L' may be bridged to L; X is NR 2, OR, or C 1 to C 2 alkyl, M is titanium, zirconium or hafnium, R is C 1 to C 2 alkyl or C 6 to C 2 aryl, R 1 is R, C 6 to C 2 alkaryl, aralkyl from C6 to C12, hydrogen or Si (R) 3, R2 is Ri, halogen, COR, COOR, SOR or SOOR, R3 is R2, OR, SR, or a cast ring system, n is 0 to 3, and LB is an optional Lewis base. 23. A catalyst that has the general formula in which L is a ligand that has the formula L 'is cyclopentadienyl, pentamethylcyclopentadienyl, indenyl, fluorenyl, NR2, OR, or halogen, L' may be bridged to L; X is NR2, OR, or Ci to CX2 alkyl, M is titanium, zirconium or hafnium, R is Cx to C12 alkyl or C6 to C2 aryl, Ri is R, C6 to C2 alkaryl, aralkyl from C6 to C12, hydrogen or Si (R) 3, R2 is Ri, halogen, COR, COOR, SOR or SOOR, R3 is R2, OR, SR, or a fused ring system, n is 0 to 3, and LB it's an optional Lewis base.