Silicon-bridged metallocene catalyst and use thereof

Abstract

A silicon-bridged metallocene catalyst and the use thereof. The catalyst comprises a cyclopentadiene ligand, a substituted fluorenyl ligand and a silicon-based bridge group for connecting the two ligands. Further disclosed is a method for producing an olefin polymer by using a catalytic system comprising such a metallocene compound, the catalytic system comprising at least one metallocene catalyst and at least one activator. The catalytic system has a high activity when being used for catalyzing propylene polymerization, and the resulting polymer has a high molecular weight and flexibly controllable syndiotacticity.

Description

A silicon-bridged metallocene catalyst and its application Technical Field

[0001] The invention belongs to the technical field of catalyst preparation and relates to a silicon-bridged metallocene catalyst and application thereof. Background Art

[0002] Syndiotactic polypropylene has the characteristics of high transparency, good impact resistance, good room temperature toughness, etc., and can be used in the fields of medical supplies, packaging materials and sanitary products. At present, many petrochemical companies have successfully developed a variety of syndiotactic polypropylene industrial production catalytic systems and processes (US 4892851, US 5155080, US 5225500, US 5428121, US 6713426, EP 0896022). Ewen et al. (Journal of the American Chemical Society 1988, 110 (18), 6255-6256) first synthesized a dimethyl-substituted carbon bridged fluorene-type catalyst for the preparation of syndiotactic polypropylene, but the molecular weight of the polypropylene obtained by this type of catalyst is usually low (M w =3×10 4 ~1.3×10 5 g·mol -1 )

[0003] In order to increase the molecular weight of syndiotactic polypropylene, diphenyl substituted carbon bridged fluorene type catalysts were used in propylene polymerization. Compared with dimethyl substituted carbon bridged catalysts, the molecular weight of polypropylene obtained by diphenyl substituted carbon bridged fluorene type catalysts was improved (M w =5.6×10 5 g·mol -1 ), but the catalytic activity was significantly reduced (6.82×10 4 vs 1.94×10 5 gPP·(g Cat.) -1 ·h -1 The literature (Journal of Organometallic Chemistry 1993, 459 (1), 117-123) also reported that the molecular weight of polypropylene obtained by Hf-coordinated fluorene-type catalyst is higher than that of the same type of Zr-coordinated catalyst (M w =7.77×10 5 ), but the activity was also significantly reduced (5.4×10 4 g·(g Cat.) -1 ·h -1However, Hf-coordinated metallocene compounds usually have a strong β-R migration tendency, which leads to an increase in the insertion error fragments of the obtained syndiotactic polypropylene and a decrease in the regularity of the polymer chain.

[0004] Silicon-bridged bis-indene metallocene catalysts have been successfully applied in polypropylene production, particularly isotactic polypropylene. Compared to carbon-bridged catalysts, silicon-bridged catalysts exhibit superior stereoselectivity and regioselectivity. More importantly, compared to the lower operating temperatures (0°C to 30°C) of many carbon-bridged catalysts, silicon-bridged catalysts exhibit excellent thermal stability, maintaining good activity and control over stereoregularity, regioregularity, and molecular weight at industrial production temperatures. Their application temperature can even reach 60°C to 120°C. Literature (Journal of Organometallic Chemistry 1996, 509(1), 63-71; Journal of Molecular Catalysis A: Chemical 1998, 128(1-3), 245-256; Organometallics, 2021, 40, 4055-4065) reported that silicon-bridged catalysts can produce higher molecular weight syndiotactic polypropylene, but there are still problems such as low activity and poor syndiotactic control (Macromolecular Symposia 1995, 89, 181-196; Chemical Reviews 2000, 100(4), 1253-1345). US6559089 discloses a silicon-bridged fluorene-type catalyst modified with multiple substituents on the cyclopentadiene ring, but it can only be used for the production of isotactic polypropylene and cannot achieve syndiotactic polypropylene.

[0005] In summary, there is still a need for new silicon-bridged metallocene compounds to achieve high molecular weight, high regularity syndiotactic polypropylene with high activity at high industrial temperatures.

[0006] Summary of the Invention

[0007] One of the purposes of the present invention is to provide a silicon-bridged metallocene catalyst, the general structure of which is shown in the following formula (I):

[0008] Wherein, M is a Group 4 transition metal element;

[0009] L is a monovalent anionic ligand;

[0010] X is C1~C 10 Unsubstituted or substituted alkyl, phenyl, containing 1 to 3 C1 to C 10 aryl groups which are unsubstituted or substituted alkyl groups;

[0011] R 1 and R8 independently selected from hydrogen, trifluoromethyl, phenyl, halogen, C5-C 10 Unsubstituted or substituted cycloalkyl, C1~C 10 Unsubstituted or substituted alkyl, C1~C 10 Unsubstituted or substituted alkoxy, containing 2 C1~C 10 Unsubstituted or substituted alkyl amino group, containing 3 C1~C 10 Unsubstituted or substituted alkyl silicon group, containing 1 to 3 C1 to C 10 unsubstituted or substituted alkyl aryl, unsubstituted or substituted heteroaryl;

[0012] R 2 、R 3 、R 6 and R 7 independently selected from hydrogen, trifluoromethyl, phenyl, naphthyl, anthracenyl, phenanthrenyl, halogen, C5-C 10 Unsubstituted or substituted cycloalkyl, C1~C 10 Unsubstituted or substituted alkyl, C1~C 10 Unsubstituted or substituted alkoxy, containing 2 C1~C 10 Unsubstituted or substituted alkyl amino group, containing 3 C1~C 10 Unsubstituted or substituted alkyl silicon group, containing 1 to 3 C1 to C 10 Aryl groups of unsubstituted or substituted alkyl groups, aryl groups containing 1 to 3 unsubstituted or substituted aryl groups, or unsubstituted or substituted heteroaryl groups;

[0013] R 4 and R 5 independently selected from hydrogen, trifluoromethyl, halogen, C1-C 10 Unsubstituted or substituted alkyl, C1~C 10 Unsubstituted or substituted alkoxy, containing 2 C1~C 10 Unsubstituted or substituted alkyl amino group, containing 3 C1~C 10 unsubstituted or substituted alkyl silicon groups.

[0014] Furthermore, M is zirconium or hafnium.

[0015] Furthermore, L is halogen, or C1~C 10 Unsubstituted or substituted alkyl. Preferably, L is halogen or C1-C6 unsubstituted or substituted alkyl.

[0016] Furthermore, X is a C1-C6 unsubstituted or substituted alkyl group, a phenyl group, or an aryl group containing 1 to 3 C1-C6 unsubstituted or substituted alkyl groups. More preferably, X is a methyl group or a phenyl group.

[0017] Furthermore, R 1 and R 8 are independently selected from hydrogen, trifluoromethyl, C1-C6 unsubstituted or substituted alkyl. More preferably, R 1 and R 8 Independently selected from hydrogen, trifluoromethyl, and C1-C6 unsubstituted or substituted alkyl.

[0018] Furthermore, R 2 、R 3 、R 6 and R 7 independently selected from hydrogen, phenyl, naphthyl, C1-C 10 Unsubstituted or substituted alkyl, containing 3 C1~C 10 Unsubstituted or substituted alkyl silicon group, containing 1 to 3 C1 to C 10 Unsubstituted or substituted alkyl aryl, containing 1 to 3 unsubstituted or substituted aryl groups. More preferably, R 2 、R 3 、R 6 and R 7 Independently selected from hydrogen, phenyl, C1-C6 unsubstituted or substituted alkyl, silicon group containing 3 C1-C6 unsubstituted or substituted alkyl groups, aryl group containing 1-3 C1-C6 unsubstituted or substituted alkyl groups.

[0019] Furthermore, R 4 and R 5 independently selected from hydrogen, C1-C 10 Unsubstituted or substituted alkyl. More preferably, R 4 and R 5 Independently selected from hydrogen, C1-C6 unsubstituted or substituted alkyl.

[0020] Further, preferred examples of compounds of formula (I) are:

[0021] Another object of the present invention is to provide a use of a silicon-bridged metallocene catalyst in preparing a catalytic system for olefin polymerization.

[0022] The third object of the present invention is to provide a catalytic system for olefin polymerization, comprising an activator, an inert carrier, and a silicon-bridged metallocene catalyst having a structure as shown in formula (I).

[0023] Furthermore, the activator is selected from one or more of aluminoxane, alkyl aluminum, and borate.

[0024] Furthermore, the alkylaluminum activator suitable for the present invention is selected from one or more of trimethylaluminum, triethylaluminum, triisopropylaluminum, tri-n-propylaluminum, triisobutylaluminum, tri-n-butylaluminum, triisopentylaluminum, tri-n-pentylaluminum, triisohexylaluminum, tri-n-hexylaluminum, triisoheptylaluminum, tri-n-heptylaluminum, triisooctylaluminum, tri-n-octylaluminum, triisononylaluminum, tri-n-nonylaluminum, triisodecylaluminum and tri-n-decylaluminum.

[0025] Furthermore, the borate activator suitable for the present invention is selected from one or more of dimethylanilinium tetrakis(pentafluorophenyl)borate, diethylanilinium tetrakis(pentafluorophenyl)borate, dibutylanilinium tetrakis(pentafluorophenyl)borate, trimethylammonium tetrakis(pentafluorophenyl)borate, diethylammonium tetrakis(pentafluorophenyl)borate and tributylammonium tetrakis(pentafluorophenyl)borate.

[0026] Furthermore, the aluminoxane activator suitable for the present invention is selected from one or more of methylaluminoxane, modified methylaluminoxane, triisobutyldialuminoxane, polyisobutylaluminoxane, tetraethyldialuminoxane, pentaisobutyltrialuminoxane, 1,3-dichloro-1,3-diethyldialuminoxane, and 1,3-dichloro-1,3-dimethyldialuminoxane.

[0027] Furthermore, the inert carrier is selected from one or more of a silicon-containing inorganic porous carrier, an aluminum-containing inorganic porous carrier, a magnesium-containing inorganic porous carrier, and a polymer organic porous carrier. Preferably, the specific surface area of ​​the carrier is not less than 20 m 2 / g.

[0028] Furthermore, the inert carrier suitable for the present invention is selected from one or more of silica, alumina, montmorillonite, magnesium chloride, molecular sieves, cyclodextrin, polyethylene, polystyrene, polyvinyl alcohol and mesoporous silica fiber; preferably selected from one or more of silica, alumina, montmorillonite, magnesium chloride and molecular sieves.

[0029] Another object of the present invention is to provide a method for preparing propylene polymer, comprising the steps of:

[0030] 1) adding the catalyst system as described above into the reactor;

[0031] 2) introducing propylene monomer into the reactor after the catalytic system to contact the catalytic system;

[0032] 3) Maintaining the polymerization conditions to obtain a propylene polymer.

[0033] The propylene polymerization reaction of the present invention is carried out in slurry or gas phase, and the obtained propylene polymer has a weight average molecular weight of 50,000 to 500,000 g / mol and a pentad syndiotacticity of 30% to 90%. DETAILED DESCRIPTION

[0034] The present invention is described in detail below with reference to specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0035] In the following examples, unless otherwise specified, raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0036] Example 1

[0037] Preparation of 1-methylfluorene

[0038] In a 100 mL three-necked flask, add 433 mg of Pd(PPh3)4 (0.38 mmol) and 3.98 g of Na2CO3 (37.5 mmol). The atmosphere was replaced with nitrogen three times, followed by 1.51 g of 2-bromophenylboronic acid (7.50 mmol) and 1.66 g of 2-methylbenzyl bromide (9.00 mmol). 40 mL of ethylene glycol dimethyl ether, 15 mL of water, and 3 mL of ethanol were added. The mixture was heated to 90°C and reacted for 12 h. The mixture was cooled to room temperature and extracted twice with 25 mL of dichloroethane. The organic phases were combined, washed twice with 10 mL of water, and dried over anhydrous MgSO4. Filtered and the solvent removed to obtain 1-bromo-2-(2-methylbenzyl)benzene.

[0039] In a 50 mL reaction flask, add 1.3 g of 1-bromo-2-(2-methylbenzyl)benzene (5 mmol), 22.5 mg of Pd(OAc)2 (0.1 mmol), 84.6 mg of 1,3-bis(2,6-diisopropylphenyl)imidazole chloride (0.2 mmol), and 0.69 g of K2CO3 (5 mmol). The atmosphere is purged with nitrogen three times, and 15 mL of N-methylpyrrolidone is added. Heat to 130°C and react for 12 h. Cool to room temperature, extract twice with 10 mL of n-hexane, and wash twice with 10 mL of water. Collect the organic phase, dry over anhydrous MgSO4, and filter. Remove the solvent to yield 2.7 g of 2-methylfluorene.

[0040] 1H NMR(500MHz,Chloroform-d)δ7.79(d,J=7.5Hz,1H),7.65(d,J=7.5Hz,1H),7.57(d,J=7.4Hz,1 H),7.38(t,J=7.4Hz,1H),7.34–7.28(m,2H),7.14(d,J=7.4Hz,1H),3.80(s,2H),2.44(s,3H).

[0041] Example 2

[0042] Preparation of dimethyl(cyclopentadienyl)(1-methyl-9-fluorenyl)silylzirconium dichloride (catalyst 1)

[0043] In a 100mL Schlenk flask (1), add 2-methylfluorene (1g, 5.05mmol). Purge the atmosphere with nitrogen three times, then add 12mL of toluene and 3.5mL of tetrahydrofuran. Slowly add n-BuLi (2.1mL, 5.3mmol) at -40°C, and react at 25°C for 3.5h. In another 100mL Schlenk flask (2), purge the atmosphere with nitrogen three times, add 27mL of toluene and dimethyldichlorosilane (3.9g, 30.3mmol). Add the solution from flask (1) at -25°C, and react at 25°C for 18h. Drain the reaction solvent, add 5mL of toluene, and drain the mixture. Add 10mL of toluene and 2.5mL of tetrahydrofuran. In another 25 mL Schlenk flask 3, replace the atmosphere with nitrogen three times, add 13.5 mL of tetrahydrofuran, add cyclopentadiene (0.38 g, 5.05 mmol), add 2.1 mL of n-BuLi (5.3 mmol) at -75°C, and react at 25°C for 2 h. Then, add the solution in reaction flask 3 to flask 2 at -45°C, and stir at 25°C for 3 h.

[0044] The reaction solvent was drained, and 20 mL of toluene and 5 mL of ether were added. n-BuLi (4.1 mL, 10.4 mmol) was added at -40°C and allowed to react at 25°C for 20 h. ZrCl4 (1.23 g, 5.15 mmol) was added at -75°C, and the mixture was stirred in an ice bath at -20°C for 3 h, followed by 15 h at 25°C. The reaction solvent was drained, and 50 mL of toluene was added, heated to 75°C, and the mixture was filtered through Celite while hot and washed with 20 mL of toluene. The filtrate crystallized at -40°C and filtered to yield 0.3 g of an orange-yellow solid.

[0045] 1H NMR(500MHz,Chloroform-d)δ8.15(d,J=6.2Hz,1H),8.02(d,J=8.3Hz,1H),7.79 (d,J=8.7Hz,1H),7.61(t,J=7.2Hz,1H),7.52–7.47(m,1H),7.34–7.29(m,1H),7.15(d,J=9.1Hz,1H),6.72–6. 68(m,1H),6.51–6.47(m,1H),5.82(q,J=2.7Hz,1H),5.69(q,J=2.5Hz,1H),2.59(s,3H),1.21(d,J=7.0Hz,6H).

[0046] Example 3

[0047] Preparation of 2-methylfluorene

[0048] 4.9 g (20 mmol) of 2-bromofluorene was weighed into a 100 mL three-necked flask, and 0.22 g (1,3-bis(diphenylphosphino)propane) nickel dichloride (0.4 mmol) was added. The atmosphere was purged with nitrogen three times, and 20 mL of diethyl ether was added. 7.51 mL of methylmagnesium bromide (24 mmol) was added dropwise at 20-30°C. The reaction was then allowed to react at 25°C, monitored by gas chromatography. After completion of the reaction, the reaction solution was added to 100 mL of water and extracted twice with 15 mL of toluene solution. The solvent was removed to yield 3.6 g of 2-methylfluorene with a GC purity of 98.1%.

[0049] 1 H NMR(500MHz,Chloroform-d)δ7.78(d,J=7.6Hz,1H),7.71(d,J=7.7Hz,1H),7.56(d,J=7.4Hz,1 H),7.42–7.37(m,2H),7.31(t,J=7.4Hz,1H),7.22(d,J=6.9Hz,1H),3.89(s,2H),2.47(s,3H).

[0050] Example 4

[0051] Preparation of dimethyl(cyclopentadienyl)(2-methyl-9-fluorenyl)silylzirconium dichloride (catalyst 2)

[0052] In a 100mL Schlenk flask (1), add 2-methylfluorene (3g, 16.6mmol). The atmosphere was flushed with nitrogen three times. 35mL of toluene and 5mL of tetrahydrofuran were added. n-BuLi (7mL, 17.5mmol) was added at -40°C and the reaction was allowed to proceed for 3h at 25°C. In another 250mL Schlenk flask (2), the atmosphere was flushed with nitrogen three times. 40mL of toluene and dimethyldichlorosilane (12.9g, 100mmol) were added to the solution in flask (1) at -25°C and the reaction was allowed to proceed for 18h at 25°C. The reaction solvent was drained, 40mL of toluene was added, the atmosphere was drained again, and 40mL of toluene was added. In another 100mL Schlenk flask (3), the atmosphere was flushed with nitrogen three times. 35mL of toluene and 5mL of tetrahydrofuran were added. Cyclopentadiene (1.10g, 16.6mmol) was added. n-BuLi (7mL, 17.5mmol) was slowly added at -75°C and the reaction was allowed to proceed for 2h at 25°C. Then, the solution in reaction bottle 3 was added to bottle 2 at -45°C and stirred at 25°C for 6 h.

[0053] The reaction solvent was drained, and 30 mL of toluene and 7.5 mL of ether were added. n-BuLi (13.6 mL, 34 mmol) was added at -45°C and the reaction was allowed to proceed for 20 h at 25°C. ZrCl4 (3.43 g, 14.6 mmol) was added at -75°C and the reaction was allowed to proceed for 20 h at 25°C. The reaction solvent was drained, and 250 mL of toluene was added. The mixture was filtered through celite and the celite was washed with 50 mL of toluene. The filtrate was collected, the solvent removed, and n-hexane was added at -40°C, stirred for 30 min, and filtered to yield approximately 0.2 g of a red solid.

[0054] 1 H NMR(500MHz,Chloroform-d)δ8.07(d,J=8.3Hz,1H),8.01(d,J=8.4Hz,1H),7.85(t,J=6.5Hz,1H),7.78(d,J=7.7Hz,1H), 7.63(t,J=7.6Hz,1H),7.53(t,J=7.2Hz,1H),7.48(d,J=8.9Hz,2H),6.61(s,2H),5.75(s,2H),2.42(s,3H),1.15(s,6H).

[0055] Example 5

[0056] Preparation of dimethyl(cyclopentadienyl)(3-methyl-9-fluorenyl)silylzirconium dichloride (catalyst 3)

[0057] In a 100mL Schlenk flask (1), add 3-methylfluorene (1g, 5.05mmol). Purge the atmosphere with nitrogen three times, then add 12mL of toluene and 3.5mL of tetrahydrofuran. Slowly add n-BuLi (2.1mL, 5.3mmol) at -40°C, and react at 25°C for 3.5h. In another 100mL Schlenk flask (2), purge the atmosphere with nitrogen three times, add 27mL of toluene and dimethyldichlorosilane (3.9g, 30.3mmol). Add the solution from flask (1) at -25°C, and react at 25°C for 18h. Drain the reaction solvent, add 5mL of toluene, and drain the mixture. Add 10mL of toluene and 2.5mL of tetrahydrofuran. In another 25 mL Schlenk flask 3, replace the atmosphere with nitrogen three times, add 13.5 mL of tetrahydrofuran, add cyclopentadiene (0.38 g, 5.05 mmol), add 2.1 mL of n-BuLi (5.3 mmol) at -75°C, and react at 25°C for 2 h. Then, add the solution in reaction flask 3 to flask 2 at -45°C, and stir at 25°C for 3 h.

[0058] The reaction solvent was drained at 35°C, and 20 mL of toluene and 5 mL of ether were added. n-BuLi (4.1 mL, 10.4 mmol) was added at -45°C and allowed to react at 25°C for 20 h. ZrCl4 (1.23 g, 5.15 mmol) was added at -75°C, and the mixture was stirred in an ice bath at -20°C for 3 h, then transferred to 25°C and allowed to react for 15 h. The reaction solvent was drained, and 50 mL of toluene was added and heated to 75°C. The mixture was filtered through celite while hot, and the celite was washed with 20 mL of toluene. The filtrate was collected, crystallized at -40°C, and filtered to yield 0.6 g of an orange-yellow solid.

[0059] 1 H NMR(500MHz,Chloroform-d)δ8.07(d,J=8.3Hz,1H),8.01(d,J=8.4Hz,1H),7.85(t,J=6.5Hz,1H),7.78(d,J=7.7Hz,1H), 7.63(t,J=7.6Hz,1H),7.53(t,J=7.2Hz,1H),7.48(d,J=8.9Hz,2H),6.61(s,2H),5.75(s,2H),2.42(s,3H),1.15(s,6H).

[0060] Example 6

[0061] Preparation of 2,7-dimethylfluorene

[0062] 6.5 g (20 mmol) of 2,7-dibromofluorene was weighed into a 100 mL three-necked flask, and 0.22 g (1,3-bis(diphenylphosphino)propane)nickel dichloride (0.4 mmol) was added. The atmosphere was purged with nitrogen three times, and 20 mL of ether was added. 7.51 mL of methylmagnesium bromide (24 mmol) was added dropwise at 20-30°C. The reaction was then allowed to react at 25°C, monitored by gas chromatography. After completion of the reaction, the reaction solution was added to 100 mL of water and extracted twice with 15 mL of toluene solution. The solvent was removed to yield 3.88 g of 2,7-dimethylfluorene with a GC purity of 100%.

[0063] 1 H NMR (500MHz, Chloroform-d) δ7.65(d,J=7.6Hz,1H),7.35(s,1H),7.19(d,J=7.8Hz,1H),3.84(s,1H),2.45(s,3H).

[0064] Example 7

[0065] Preparation of dimethyl(cyclopentadienyl)(2,7-dimethyl-9-fluorenyl)silylzirconium dichloride (catalyst 4)

[0066] In a 100mL Schlenk flask (1), add 2,7-dimethylfluorene (2.8g, 14.4mmol). Purge the atmosphere with nitrogen three times, then add 35mL of toluene and 5mL of tetrahydrofuran. Add n-BuLi (6.05mL, 15.1mmol) at -40°C and react at 25°C for 3h. In another 250mL Schlenk flask (2), purge the atmosphere with nitrogen three times, add 40mL of toluene and dimethyldichlorosilane (11.20g, 86.5mmol). Add the solution from flask (1) at -25°C and react at 25°C for 18h. Drain the reaction solvent, add 40mL of toluene, drain again, and then add 40mL of toluene. Take another 100 mL Schlenk flask 3, replace the atmosphere with nitrogen three times, add 35 mL of toluene, 5 mL of tetrahydrofuran, and cyclopentadiene (1.002 g, 14.4 mmol). Add n-BuLi (6.05 mL, 15.1 mmol) at -75°C, and react at 25°C for 2 h. Then, add the solution in reaction flask 3 to flask 2 at -45°C and stir at 25°C for 3 h.

[0067] The reaction solvent was drained, and 30 mL of toluene and 7.5 mL of ether were added. n-BuLi (11.8 mL, 29.5 mmol) was added at -45°C and allowed to react at 25°C for 20 h. ZrCl4 (3.43 g, 14.6 mmol) was added at -75°C and allowed to react at 25°C for 3 h. The reaction solvent was drained, and 100 mL of toluene was added and heated to 45°C. The mixture was filtered through celite while hot, and the celite was washed twice with 20 mL of toluene. The filtrate was collected, crystallized at -20°C, and filtered to yield 0.35 g of an orange solid.

[0068] 1 H NMR(500MHz,Chloroform-d)δ7.95(d,J=8.5Hz,2H),7.45(d,J=8.6Hz,2H),7.18(d,J =7.1Hz,2H),6.62(t,J=2.4Hz,2H),5.73(t,J=2.4Hz,2H),2.41(s,6H),1.13(s,6H).

[0069] Example 8

[0070] Preparation of 3,6-dimethylfluorene

[0071] 6.5 g (20 mmol) of 3,6-dibromofluorene was weighed into a 100 mL three-necked flask, and 0.22 g (1,3-bis(diphenylphosphino)propane)nickel dichloride (0.4 mmol) was added. The atmosphere was purged with nitrogen three times, and 20 mL of ether was added. 7.51 mL of methylmagnesium bromide (24 mmol) was added dropwise at 20-30°C. The reaction was then allowed to react at 25°C, monitored by gas chromatography. After completion of the reaction, the reaction solution was added to 100 mL of water and extracted twice with 15 mL of toluene solution. The solvent was removed to yield 3.9 g of 3,6-dimethylfluorene with a GC purity of 99.8%.

[0072] 1 H NMR (500MHz, Chloroform-d) δ7.58 (s, 2H), 7.41 (d, J = 7.6Hz, 2H), 7.10 (d, J = 7.6Hz, 2H), 3.80 (s, 2H), 2.45 (s, 6H).

[0073] Example 9

[0074] Preparation of dimethyl(cyclopentadienyl)(3,6-dimethyl-9-fluorenyl)silylzirconium dichloride (catalyst 5)

[0075] In a 100mL Schlenk flask (1), add 3,6-dimethylfluorene (2.8g, 14.4mmol). Purge the atmosphere with nitrogen three times, then add 35mL of toluene and 5mL of tetrahydrofuran. Add n-BuLi (6.05mL, 15.1mmol) at -40°C and react at 25°C for 3h. In another 250mL Schlenk flask (2), purge the atmosphere with nitrogen three times, add 40mL of toluene and dimethyldichlorosilane (11.20g, 86.5mmol). Add the solution from flask (1) at -25°C and react at 25°C for 18h. Drain the reaction solvent, add 40mL of toluene, drain again, and then add 40mL of toluene. Take another 100 mL Schlenk flask 3, replace the atmosphere with nitrogen three times, add 35 mL of toluene, 5 mL of tetrahydrofuran, and cyclopentadiene (1.002 g, 14.4 mmol). Add n-BuLi (6.05 mL, 15.1 mmol) at -75°C, and react at 25°C for 2 h. Then, add the solution in reaction flask 3 to flask 2 at -45°C and stir at 25°C for 3 h.

[0076] The reaction solvent was drained, and 30 mL of toluene and 7.5 mL of ether were added. n-BuLi (11.8 mL, 29.5 mmol) was added at -45°C, and the reaction was continued at 25°C for 20 h. ZrCl4 (3.43 g, 14.6 mmol) was added at -75°C, and the reaction was continued at 25°C for 3 h. The reaction solvent was drained, and the product was washed with toluene (150 mL), filtered, and the filtrate was concentrated to 40 mL. 40 mL of n-hexane was added, filtered, and dried to obtain 0.6 g of a yellow solid.

[0077] 1 H NMR (500MHz, CDCl3) δ7.91 (s, 2H), 7.40 (d, J = 8.6Hz, 2H), 7.14 (dd, J = 8.7, 1.6H z,2H),6.59(t,J=2.4Hz,2H),5.71(t,J=2.4Hz,2H),2.61(s,6H),1.11(s,6H).

[0078] Example 10

[0079] Preparation of 2,7-bis(3,5-dimethylphenyl)fluorene

[0080] To a 100mL two-necked flask, add 2,7-dibromofluorene (3.24g, 10mmol), 3,5-dimethylphenylboronic acid (3.19g, 21.27mmol), tetrakis(triphenylphosphine)palladium (0.17g, 0.147mmol), and anhydrous sodium carbonate (3.20g, 30.19mmol) in sequence. The atmosphere was purged with nitrogen three times. 50mL of ethanol and 4mL of water were added, and the mixture was refluxed for 24h. After cooling, 250mL of water and 100mL of ethyl acetate were added, and the layers were separated. The organic phase was washed twice with water, dried over anhydrous sodium sulfate, and the solvent was removed to yield 3.18g of a solid powder (HPLC purity 98.85%).

[0081] 1 H NMR(500MHz,Chloroform-d)δ7.84-7.01(m,12H),4.01(s,2H),2.41(s,12H).

[0082] Example 11

[0083] Preparation of dimethyl(cyclopentadienyl)(2,7-bis(3,5-dimethylphenyl)-9-fluorenyl)silylzirconium dichloride (catalyst 6)

[0084] In a 100mL Schlenk flask (1), add 2,7-bis(3,5-dimethylphenyl)fluorene (5.4g, 14.4mmol). The atmosphere was flushed with nitrogen three times, followed by the addition of 35mL of toluene and 5mL of tetrahydrofuran. At -40°C, n-BuLi (6.05mL, 15.1mmol) was added, and the reaction was allowed to proceed at 25°C for 18h. In another 250mL Schlenk flask (2), the atmosphere was flushed with nitrogen three times, followed by the addition of 40mL of toluene and dimethyldichlorosilane (11.20g, 86.5mmol). The reaction was then added to the solution in flask (1) at -25°C, and the reaction was allowed to proceed at 25°C for 24h. The reaction solvent was drained, and 40mL of toluene was added, which was then drained again. Another 40mL of toluene was added. Take another 100 mL Schlenk flask 3, replace the atmosphere with nitrogen three times, add 35 mL of toluene, 5 mL of tetrahydrofuran, and cyclopentadiene (1.002 g, 14.4 mmol). Add n-BuLi (6.05 mL, 15.1 mmol) at -75°C, and react at 25°C for 2 h. Then, add the solution in reaction flask 3 to flask 2 at -45°C and stir at 25°C for 3 h.

[0085] The reaction solvent was drained, and 30 mL of toluene and 7.5 mL of ether were added. n-BuLi (11.8 mL, 29.5 mmol) was added at -45°C, and the reaction was continued at 25°C for 20 h. ZrCl4 (3.43 g, 14.6 mmol) was added at -75°C, and the reaction was continued at 25°C for 3 h. The reaction solvent was drained, and the product was washed with toluene (150 mL), filtered, and the filtrate was concentrated to 40 mL. 40 mL of n-hexane was added, filtered, and dried to obtain 1.43 g of a yellow solid.

[0086] 1 H NMR (500MHz, CDCl3) δ7.92-7.05(m,12H),6.60(t,J=2.4Hz,2H),5.72(t,J=2.4Hz,2H),2.56(s,12H),1.11(s,6H).

[0087] Example 12

[0088] Preparation of 2,7-bis(3,5-di-tert-butylphenyl)fluorene

[0089] To a 100mL two-necked flask, add 2,7-dibromofluorene (3.24g, 10mmol), 3,5-di-tert-butylphenylboronic acid (5.00g, 21.35mmol), tetrakis(triphenylphosphine)palladium (0.13g, 0.11mmol), and anhydrous sodium carbonate (3.20g, 30.19mmol) in sequence. The atmosphere was purged with nitrogen three times. 50mL of ethanol and 4mL of water were added, and the mixture was refluxed for 24h. After cooling, 250mL of water and 100mL of ethyl acetate were added, and the layers were separated. The organic phase was washed twice with water, dried over anhydrous sodium sulfate, and the solvent was removed to yield 4.08g of a solid powder (HPLC purity 98.32%).

[0090] 1 H NMR(500MHz,Chloroform-d)δ7.89–7.43(m,12H),4.05(s,2H),1.41(s,36H).

[0091] Example 13

[0092] Preparation of dimethyl(cyclopentadienyl)(2,7-bis(3,5-di-tert-butylphenyl)-9-fluorenyl)silylzirconium dichloride (Catalyst 7)

[0093] In a 100mL Schlenk flask (1), add 2,7-bis(3,5-di-tert-butylphenyl)fluorene (7.8g, 14.4mmol). The atmosphere was flushed with nitrogen three times, followed by the addition of 35mL of toluene and 5mL of tetrahydrofuran. At -40°C, n-BuLi (6.05mL, 15.1mmol) was added, and the reaction was allowed to proceed at 25°C for 18h. In another 250mL Schlenk flask (2), the atmosphere was flushed with nitrogen three times, followed by the addition of 40mL of toluene and dimethyldichlorosilane (11.20g, 86.5mmol). The reaction was then added to the solution in flask (1) at -25°C, and the reaction was allowed to proceed at 25°C for 24h. The reaction solvent was drained, and 40mL of toluene was added, which was then drained again. Another 40mL of toluene was added. Take another 100 mL Schlenk flask 3, replace the atmosphere with nitrogen three times, add 35 mL of toluene, 5 mL of tetrahydrofuran, and cyclopentadiene (1.002 g, 14.4 mmol). Add n-BuLi (6.05 mL, 15.1 mmol) at -75°C, and react at 25°C for 2 h. Then, add the solution in reaction flask 3 to flask 2 at -45°C and stir at 25°C for 3 h.

[0094] The reaction solvent was drained, and 30 mL of toluene and 7.5 mL of ether were added. n-BuLi (11.8 mL, 29.5 mmol) was added at -45°C, and the reaction was continued at 25°C for 20 h. ZrCl4 (3.43 g, 14.6 mmol) was added at -75°C, and the reaction was continued at 25°C for 3 h. The reaction solvent was drained, and the product was washed with toluene (150 mL), filtered, and the filtrate was concentrated to 40 mL. 40 mL of n-hexane was added, filtered, and dried to obtain 1.6 g of a yellow solid.

[0095] 1 H NMR (500MHz, CDCl3) δ7.91-7.45(m,12H),6.60(t,J=2.4Hz,2H),5.72(t,J=2.4Hz,2H),2.55(s,36H),1.11(s,6H).

[0096] Example 14

[0097] 3,6-Bis(4-tert-butylphenyl)fluorene

[0098] To a 100mL two-necked flask, add 3,6-dibromofluorene (3.24g, 10mmol), 4-tert-butylphenylboronic acid (3.76g, 21.12mmol), tetrakis(triphenylphosphine)palladium (0.13g, 0.11mmol), and anhydrous sodium carbonate (3.18g, 30mmol) in sequence. The atmosphere was purged with nitrogen three times. 50mL of ethanol and 4mL of water were added, and the mixture was refluxed for 24h. After cooling, 250mL of water and 100mL of ethyl acetate were added, and the layers were separated. The organic phase was washed twice with water, dried over anhydrous sodium sulfate, and the solvent was removed to yield 2.36g of a solid powder (HPLC purity 98.24%).

[0099] 1 H NMR(500MHz,Chloroform-d)δ7.84-7.46(m,14H),4.02(s,2H),1.38(s,18H).

[0100] Example 15

[0101] Preparation of dimethyl(cyclopentadienyl)(3,6-di(4-tert-butylphenyl)-9-fluorenyl)silylzirconium dichloride (catalyst 8)

[0102] In a 100mL Schlenk flask (1), add 3,6-bis(4-tert-butylphenyl)fluorene (6.2g, 14.4mmol). Purge the atmosphere with nitrogen three times, then add 35mL of toluene and 5mL of tetrahydrofuran. Add n-BuLi (6.05mL, 15.1mmol) at -40°C and react at 25°C for 18h. In another 250mL Schlenk flask (2), purge the atmosphere with nitrogen three times, add 40mL of toluene and dimethyldichlorosilane (11.20g, 86.5mmol). Add the solution from flask (1) at -25°C and react at 25°C for 24h. Drain the reaction solvent, add 40mL of toluene, drain again, and then add 40mL of toluene. Take another 100 mL Schlenk flask 3, replace the atmosphere with nitrogen three times, add 35 mL of toluene, 5 mL of tetrahydrofuran, and cyclopentadiene (1.002 g, 14.4 mmol). Add n-BuLi (6.05 mL, 15.1 mmol) at -75°C, and react at 25°C for 2 h. Then, add the solution in reaction flask 3 to flask 2 at -45°C and stir at 25°C for 3 h.

[0103] The reaction solvent was drained, and 30 mL of toluene and 7.5 mL of ether were added. n-BuLi (11.8 mL, 29.5 mmol) was added at -45°C, and the reaction was continued at 25°C for 20 h. ZrCl4 (3.43 g, 14.6 mmol) was added at -75°C, and the reaction was continued at 25°C for 3 h. The reaction solvent was drained, and the product was washed with toluene (150 mL), filtered, and the filtrate was concentrated to 40 mL. 40 mL of n-hexane was added, filtered, and dried to obtain 1.83 g of a yellow solid.

[0104] 1 H NMR (500MHz, CDCl3) δ7.86-7.48(m,14H),6.61(t,J=2.4Hz,2H),5.73(t,J=2.4Hz,2H),2.53(s,18H),1.09(s,6H).

[0105] Example 16

[0106] Preparation of diphenyl(cyclopentadienyl)(2,7-bis(2-methylphenyl)-9-fluorenyl)silylzirconium dichloride (Catalyst 9)

[0107] In a 100mL Schlenk flask (1), add 2,7-bis(2-methylphenyl)fluorene (5.0g, 14.4mmol). The atmosphere was flushed with nitrogen three times, followed by the addition of 35mL of toluene and 5mL of tetrahydrofuran. At -40°C, n-BuLi (6.05mL, 15.1mmol) was added, and the reaction was continued at 25°C for 18h. In another 250mL Schlenk flask (2), the atmosphere was flushed with nitrogen three times, followed by the addition of 40mL of toluene and dimethyldichlorosilane (21.90g, 86.5mmol). The reaction was continued at -25°C for 24h. The reaction solvent was drained, and 40mL of toluene was added. The reaction was again drained, and 40mL of toluene was added. Take another 100 mL Schlenk flask 3, replace the atmosphere with nitrogen three times, add 35 mL of toluene, 5 mL of tetrahydrofuran, and cyclopentadiene (1.002 g, 14.4 mmol). Add n-BuLi (6.05 mL, 15.1 mmol) at -75°C, and react at 25°C for 2 h. Then, add the solution in reaction flask 3 to flask 2 at -45°C and stir at 25°C for 3 h.

[0108] The reaction solvent was drained, and 30 mL of toluene and 7.5 mL of ether were added. n-BuLi (11.8 mL, 29.5 mmol) was added at -45°C, and the reaction was continued at 25°C for 20 h. ZrCl4 (3.43 g, 14.6 mmol) was added at -75°C, and the reaction was continued at 25°C for 3 h. The reaction solvent was drained, and the product was washed with toluene (150 mL), filtered, and the filtrate was concentrated to 40 mL. 40 mL of n-hexane was added, filtered, and dried to obtain 2.48 g of a yellow solid.

[0109] 1 H NMR(500MHz,Chloroform-d)δ8.26-7.05(m,24H),6.43(s,2H),6.38(s,2H),5.79(s,2H),2.22(s,6H).

[0110] Example 17

[0111] Preparation of diphenyl(cyclopentadienyl)(2,7-bis(2,6-dimethylphenyl)-9-fluorenyl)silylzirconium dichloride (Catalyst 10)

[0112] In a 100mL Schlenk flask (1), add 2,7-bis(2,6-dimethylphenyl)fluorene (5.4g, 14.4mmol). The atmosphere was flushed with nitrogen three times, followed by the addition of 35mL of toluene and 5mL of tetrahydrofuran. At -40°C, n-BuLi (6.05mL, 15.1mmol) was added, and the reaction was continued at 25°C for 18h. In another 250mL Schlenk flask (2), the atmosphere was flushed with nitrogen three times, followed by the addition of 40mL of toluene and diphenyldichlorosilane (21.90g, 86.5mmol). The solution in flask (1) was added at -25°C, and the reaction was continued at 25°C for 24h. The reaction solvent was drained, and 40mL of toluene was added, which was then drained again. Another 40mL of toluene was added. Take another 100 mL Schlenk flask 3, replace the atmosphere with nitrogen three times, add 35 mL of toluene, 5 mL of tetrahydrofuran, and cyclopentadiene (1.002 g, 14.4 mmol). Add n-BuLi (6.05 mL, 15.1 mmol) at -75°C, and react at 25°C for 2 h. Then, add the solution in reaction flask 3 to flask 2 at -45°C and stir at 25°C for 3 h.

[0113] The reaction solvent was drained, and 30 mL of toluene and 7.5 mL of ether were added. n-BuLi (11.8 mL, 29.5 mmol) was added at -45°C, and the reaction was continued at 25°C for 20 h. ZrCl4 (3.43 g, 14.6 mmol) was added at -75°C, and the reaction was continued at 25°C for 3 h. The reaction solvent was drained, and the product was washed with toluene (150 mL), filtered, and the filtrate was concentrated to 40 mL. 40 mL of n-hexane was added, filtered, and dried to obtain 2.77 g of a yellow solid.

[0114] 1 H NMR (500MHz, Chloroform-d) δ8.29-6.97(m,22H),6.45(s,2H),6.37(s,2H),5.83–5.73(m,2H),2.07(s,6H),1.99(s,6H).

[0115] Example 18

[0116] Preparation of dimethyl(cyclopentadienyl)(1,8-dimethyl-9-fluorenyl)silyl hafnium dichloride (catalyst 11)

[0117] In a 100mL Schlenk flask (1), add 1,8-dimethylfluorene (2.8g, 14.4mmol). Purge the atmosphere with nitrogen three times, then add 35mL of toluene and 5mL of tetrahydrofuran. Add n-BuLi (6.05mL, 15.1mmol) at -40°C and react at 25°C for 3h. In another 250mL Schlenk flask (2), purge the atmosphere with nitrogen three times, add 40mL of toluene and dimethyldichlorosilane (11.20g, 86.5mmol). Add the solution from flask (1) at -25°C and react at 25°C for 18h. Drain the reaction solvent, add 40mL of toluene, drain again, and then add 40mL of toluene. Take another 100 mL Schlenk flask 3, replace the atmosphere with nitrogen three times, add 35 mL of toluene, 5 mL of tetrahydrofuran, and cyclopentadiene (1.002 g, 14.4 mmol). Add n-BuLi (6.05 mL, 15.1 mmol) at -75°C, and react at 25°C for 2 h. Then, add the solution in reaction flask 3 to flask 2 at -45°C and stir at 25°C for 3 h.

[0118] The reaction solvent was drained, and 30 mL of toluene and 7.5 mL of ether were added. n-BuLi (11.8 mL, 29.5 mmol) was added at -45°C and allowed to react at 25°C for 20 h. HfCl4 (4.67 g, 14.6 mmol) was added at -75°C and allowed to react at 25°C for 3 h. The reaction solvent was drained, and 100 mL of toluene was added and heated to 45°C. The mixture was filtered through celite while hot, and the celite was washed twice with 20 mL of toluene. The filtrate was collected, allowed to crystallize at -20°C, and filtered to yield 1.06 g of an orange solid.

[0119] 1 H NMR (500MHz, Chloroform-d) δ7.97-6.64 (m, 8H), 5.74 (t, J = 2.5Hz, 2H), 2.42 (s, 6H), 1.14 (s, 6H).

[0120] Example 19

[0121] Preparation of diphenyl(cyclopentadienyl)(2,7-bis(2,6-dimethylphenyl)-9-fluorenyl)silyl hafnium dichloride (catalyst 12)

[0122] In a 100mL Schlenk flask (1), add 2,7-bis(3,5-dimethylphenyl)fluorene (5.4g, 14.4mmol). The atmosphere was flushed with nitrogen three times, followed by the addition of 35mL of toluene and 5mL of tetrahydrofuran. At -40°C, n-BuLi (6.05mL, 15.1mmol) was added, and the reaction was continued at 25°C for 18h. In another 250mL Schlenk flask (2), the atmosphere was flushed with nitrogen three times, followed by the addition of 40mL of toluene and dimethyldichlorosilane (11.20g, 86.5mmol). The reaction was continued at -25°C for 24h. The reaction solvent was drained, and 40mL of toluene was added. The reaction was again drained, and 40mL of toluene was added. Take another 100 mL Schlenk flask 3, replace the atmosphere with nitrogen three times, add 35 mL of toluene, 5 mL of tetrahydrofuran, and cyclopentadiene (1.002 g, 14.4 mmol). Add n-BuLi (6.05 mL, 15.1 mmol) at -75°C, and react at 25°C for 2 h. Then, add the solution in reaction flask 3 to flask 2 at -45°C and stir at 25°C for 3 h.

[0123] The reaction solvent was drained, and 30 mL of toluene and 7.5 mL of ether were added. n-BuLi (11.8 mL, 29.5 mmol) was added at -45°C, and the reaction was continued at 25°C for 20 h. ZrCl4 (3.43 g, 14.6 mmol) was added at -75°C, and the reaction was continued at 25°C for 3 h. The reaction solvent was drained, and the product was washed with toluene (150 mL), filtered, and the filtrate was concentrated to 40 mL. 40 mL of n-hexane was added, filtered, and dried to obtain 1.43 g of a yellow solid.

[0124] 1 H NMR(500MHz,Chloroform-d)δ8.31-6.98(m,22H),6.54(s,2H),6.43(s,2H),5.85–5.75(m,2H),2.09(s,6H),1.88(s,6H).

[0125] Comparative Example 1

[0126] Preparation of dimethyl(cyclopentadienyl)(9-fluorenyl)silylzirconium dichloride (catalyst 13)

[0127] In a 100mL Schlenk flask (1), add fluorene (2.8g, 16.6mmol). The atmosphere was flushed with nitrogen three times. 35mL of toluene and 5mL of tetrahydrofuran were added. n-BuLi (7mL, 17.5mmol) was added at -40°C and the reaction was allowed to proceed for 3h at 25°C. In another 250mL Schlenk flask (2), the atmosphere was flushed with nitrogen three times. 40mL of toluene and dimethyldichlorosilane (12.9g, 100mmol) were added to the solution in flask (1) at -25°C and the reaction was allowed to proceed for 18h at 25°C. The reaction solvent was drained, 40mL of toluene was added, the atmosphere was drained again, and 40mL of toluene was added. In another 100mL Schlenk flask (3), the atmosphere was flushed with nitrogen three times. 35mL of toluene and 5mL of tetrahydrofuran were added. cyclopentadiene (1.10g, 16.6mmol) was added. n-BuLi (7mL, 17.5mmol) was added at -75°C and the reaction was allowed to proceed for 2h at 25°C. Then, the solution in reaction bottle 3 was added to bottle 2 at -45°C and stirred at 25°C for 3 h.

[0128] The reaction solvent was drained, and 30 mL of toluene and 7.5 mL of ether were added. n-BuLi (13.6 mL, 34 mmol) was slowly added at -45°C and allowed to react for 20 h at 25°C. ZrCl4 (3.96 g, 17.0 mmol) was added at -75°C and allowed to react for 20 h at 25°C. The reaction solvent was drained, and 100 mL of toluene was added at 55°C. The mixture was filtered through celite while hot, and the celite was washed twice with 20 mL of toluene. The filtrate was collected, crystallized at -40°C, and filtered to yield approximately 1.05 g of an orange-yellow solid.

[0129] 1 H NMR(500MHz,Chloroform-d)δ8.12(d,J=8.3Hz,2H),7.67–7.59(m,2H),7.54(d,J=8.6 Hz,2H),7.33–7.25(m,3H),6.61(t,J=2.4Hz,2H),5.75(t,J=2.4Hz,2H),1.14(s,6H).

[0130] Comparative Example 2

[0131] Preparation of dimethyl(cyclopentadienyl)(2,7-di-tert-butyl-9-fluorenyl)silylzirconium dichloride (catalyst 14)

[0132] In a 100mL Schlenk flask (1), add 2,7-di-tert-butylfluorene (3g, 10.8mmol). The atmosphere was flushed with nitrogen three times, followed by 22mL of toluene and 3mL of tetrahydrofuran. At -40°C, n-BuLi (4.5mL, 11.34mmol) was added and the reaction was continued at 25°C for 3h. In another 250mL Schlenk flask (2), the atmosphere was flushed with nitrogen three times, 30mL of toluene was added, followed by dimethyldichlorosilane (8.8g, 64.8mmol). The solution in flask (1) was added at -25°C, and the reaction was continued at 25°C for 18h. The reaction solvent was drained, and 40mL of toluene was added. The reaction was then drained again, followed by 40mL of toluene. Take another 100 mL Schlenk flask 3, replace the atmosphere with nitrogen three times, add 22 mL of toluene, 3 mL of tetrahydrofuran, and cyclopentadiene (0.75 g, 10.8 mmol). Add n-BuLi (4.5 mL, 11.34 mmol) at -75°C, and react at 25°C for 2 h. Then, add the solution in reaction flask 3 to flask 2 at -45°C and stir at 25°C for 3 h.

[0133] The reaction solvent was drained, and 30 mL of toluene and 7.5 mL of ether were added. n-BuLi (11.8 mL, 29.5 mmol) was added at -45°C, and the reaction was continued at 25°C for 20 h. ZrCl4 (2.51 g, 10.8 mmol) was added at -75°C, and the reaction was continued at 25°C for 3 h. The reaction solvent was drained, and the product was washed with toluene (150 mL), filtered, and the filtrate was concentrated to 40 mL. Hexane was added, filtered, and dried to obtain 1.01 g of a yellow solid.

[0134] 1 H NMR(500MHz,Chloroform-d)δ7.99(d,J=7.9Hz,2H),7.71(dd,J=8.8,1.7Hz,2H),7. 43(s,2H),6.60(t,J=2.4Hz,2H),5.66(t,J=2.4Hz,2H),1.35(s,18H),1.15(s,6H).

[0135] Examples 20-38

[0136] Catalysts 1 to 12 catalyze propylene polymerization

[0137] In a 1L reactor, add 150mL of n-hexane, add MAO (30% by mass in toluene solution), add catalyst toluene solution (concentration 0.5g / L), stir for 5min, and introduce 1.0MPa propylene. After 1h, add ethanol (50mL) to terminate the reaction. The polymer is washed with ethanol, filtered, and vacuum dried to obtain polypropylene. Calculate the polymerization activity and 13 The polypropylene syndiotacticity (rrrr) was calculated by C NMR characterization. The weight average molecular weight M of polypropylene was measured by GPC.w The polymerization data are listed in Table 1.

[0138] Table 1

[0139] Comparative Examples 3-7 Catalysts 13 to 14 Catalyzed Propylene Polymerization

[0140] In a 1L reactor, add 150mL of n-hexane, add MAO (30% by mass in toluene solution), add catalyst toluene solution (concentration 1.0g / L), stir for 5min, and introduce 1.0MPa propylene. After 1h, add ethanol (50mL) to terminate the reaction. The polymer is washed with ethanol, filtered, and vacuum dried to obtain polypropylene. Calculate the polymerization activity and 13 The polypropylene syndiotacticity (rrrr) was calculated by C NMR characterization. The weight average molecular weight M of polypropylene was measured by GPC. w The polymerization data are listed in Table 2.

[0141] Table 2

[0142] As can be seen from Tables 1 and 2, the weight-average molecular weight of the polypropylene produced by Catalyst 13 is relatively low. The presence of the 1-methyl group in Catalyst 1 not only increases the weight-average molecular weight of the resulting polypropylene, but also improves polymerization activity. The presence of 2-methyl, 3-methyl, 2,7-dimethyl, and 3,5-dimethyl groups also increases the weight-average molecular weight of the resulting polypropylene. Although the weight-average molecular weight of the polypropylene produced by Catalyst 14 is relatively high, its syndiotacticity is significantly reduced. The presence of 1-methyl, 2-methyl, 3-methyl, 2,7-dimethyl, and 3,5-dimethyl groups in Catalysts 1-5, on the other hand, produces polypropylene with high syndiotacticity, even exceeding that of the polypropylene produced by Catalyst 13. Similarly, the presence of the 2,7-diaryl group in Catalysts 6, 7, and 8 also significantly increases the weight-average molecular weight of the polypropylene produced by Catalysts 13 and 14. Furthermore, the polypropylene produced by Catalysts 6, 7, and 8 also exhibits high syndiotacticity. When the bridging group is a diphenylsilyl bridge or the metal atom is hafnium, the weight-average molecular weight and polymerization activity of the polypropylene produced by Catalysts 9-12 are both improved.

[0143] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A silicon-bridged metallocene catalyst, characterized in that: Its general structural formula is shown in the following formula (I): Wherein, M is a transition metal element of Group 4; L is a monovalent anionic ligand; X is C1~C 10 Unsubstituted or substituted alkyl, phenyl, containing 1 to 3 C1 to C 10 Aryl groups of unsubstituted or substituted alkyl groups; R 1 and R 8 independently selected from hydrogen, trifluoromethyl, phenyl, halogen, C5-C 10 Unsubstituted or substituted cycloalkyl, C1~C 10 Unsubstituted or substituted alkyl, C1~C 10 Unsubstituted or substituted alkoxy, containing 2 C1~C 10 Unsubstituted or substituted alkyl amino group, containing 3 C1~C 10 Unsubstituted or substituted alkyl silicon group, containing 1 to 3 C1 to C 10 unsubstituted or substituted alkyl aryl, unsubstituted or substituted heteroaryl; R 2 , R 3 , R 6 and R 7 independently selected from hydrogen, trifluoromethyl, phenyl, naphthyl, anthracenyl, phenanthryl, halogen, C5-C 10 Unsubstituted or substituted cycloalkyl, C1~C 10 Unsubstituted or substituted alkyl, C1~C 10 Unsubstituted or substituted alkoxy, containing 2 C1~C 10 Unsubstituted or substituted alkyl amino group, containing 3 C1~C 10 Unsubstituted or substituted alkyl silicon group, containing 1 to 3 C1 to C 10 Aryl of unsubstituted or substituted alkyl, containing 1 to 3 unsubstituted or substituted aryl, unsubstituted or substituted heteroaryl; R 4 and R 5 independently selected from hydrogen, trifluoromethyl, halogen, C1-C 10 Unsubstituted or substituted alkyl, C1~C 10 Unsubstituted or substituted alkoxy, containing 2 C1~C 10 Unsubstituted or substituted alkyl amino group, containing 3 C1~C 10 Unsubstituted or substituted alkyl silicon groups.

2. A silicon-bridged metallocene catalyst according to claim 1, characterized in that: M is zirconium or hafnium.

3. A silicon-bridged metallocene catalyst according to claim 1, characterized in that: L is halogen, or C1~C 10 Unsubstituted or substituted alkyl.

4. The silicon-bridged metallocene catalyst according to claim 1, characterized in that: X is a C1-C6 unsubstituted or substituted alkyl group, a phenyl group, or an aryl group containing 1 to 3 C1-C6 unsubstituted or substituted alkyl groups.

5. The silicon-bridged metallocene catalyst according to claim 1, characterized in that: R 1 and R 8 Independently selected from hydrogen, trifluoromethyl, C1-C6 unsubstituted or substituted alkyl; R 2 , R 3 , R 6 and R 7 independently selected from hydrogen, phenyl, naphthyl, C1-C 10 Unsubstituted or substituted alkyl, containing 3 C1~C 10 Unsubstituted or substituted alkyl silicon group, containing 1 to 3 C1 to C 10 Aryl of unsubstituted or substituted alkyl, containing 1 to 3 unsubstituted or substituted aryl groups; R 4 and R 5 independently selected from hydrogen, C1-C 10 Unsubstituted or substituted alkyl.

6. Use of the silicon-bridged metallocene catalyst according to any one of claims 1 to 5 in preparing a catalytic system for olefin polymerization.

7. A catalytic system for olefin polymerization, comprising an activator, an inert carrier, and the silicon-bridged metallocene catalyst according to any one of claims 1 to 5.

8. The catalytic system for olefin polymerization according to claim 7, characterized in that: The activator is selected from one or more of aluminoxane, alkyl aluminum, and borate.

9. The catalytic system for olefin polymerization according to claim 7, characterized in that: The inert carrier is selected from one or more of a silicon-containing inorganic porous carrier, an aluminum-containing inorganic porous carrier, a magnesium-containing inorganic porous carrier and a polymer organic porous carrier.

10. A method for preparing a propylene polymer, characterized in that: The following steps are involved: 1) adding the catalyst system as claimed in claim 7 into a reactor; 2) introducing propylene monomer into the reactor after the catalyst system to contact with the catalyst system; 3) Maintaining the polymerization conditions to obtain a propylene polymer.

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