A metallocene complex and a method for its preparation
By optimizing the reaction conditions of indene with lithiating reagents and zirconium chloride, metallocene complexes suitable for industrial production were prepared, solving the problems of long reaction routes and high costs in existing methods, and achieving a simple and efficient synthesis and purification.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BAYECAO HEALTH IND RES INST (XIAMEN) CO LTD
- Filing Date
- 2026-03-31
- Publication Date
- 2026-07-31
AI Technical Summary
Existing methods for synthesizing metallocene catalysts suffer from problems such as excessively long reaction routes, high costs, harsh conditions, expensive starting materials, and complex purification methods, making them unsuitable for industrial production.
The synthetic route was simplified and the cost was reduced by reacting indene or its derivatives with a lithium reagent and 1,2-dibromoethane, followed by the formation of a metallocene complex with zirconium chloride. This was achieved by optimizing reaction conditions, such as controlling the dropping temperature and purification methods.
A simple and low-cost method for preparing metallocene complexes has been developed, which is suitable for industrial production, reduces energy consumption and equipment requirements, and simplifies the purification process.
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Figure CN122483115A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst preparation technology, specifically relating to a metallocene complex and its preparation method. Background Technology
[0002] Metallocene catalysts are defined as catalysts with a group IVB transition metal as the active center and at least one cyclopentadienyl (Cp) group or a cyclopentadiene derivative as the main catalyst. Forty years ago, Kaminsky et al. discovered the metallocene / methylaluminoxane (MAO) catalytic system for olefin polymerization in the Hamburg laboratory. This type of catalyst has only one metal active center (single-center catalyst), introducing a new transition metal complex system for the polymerization of olefins, dienes, and styrene.
[0003] Given that these single-active-site catalysts can control the microstructure of polymers, such as the distribution of comonomers, the stereoregularity of polymers, and regioselectivity, chemists and engineers have long been extremely interested in this type of metallocene catalyst. In 1980, Professors Kaminsky and Sinn, through a series of experimental studies, discovered that the presence of methylaluminoxane (MAO) in the dichlorodichlorocathocyanin / trimethylaluminum system could greatly increase the activity of the catalytic system. Using this homogeneous catalytic system, the polydispersity and microstructure of polymers could be tuned by simply changing the organic ligands surrounding the Group IV metal.
[0004] The single active site characteristic of metallocene catalysts allows for systematic analysis and research on the mechanism of catalytic olefin polymerization, deepening our understanding of the olefin polymerization process and laying a solid foundation for future research on catalytic polymerization.
[0005] Current metallocene synthesis methods have many drawbacks, such as excessively long reaction routes (CN 114195816 A, EP0834 514 A2, EP 0834515 A2) or excessively high total costs (J. AM. CHEM. SOC. 2004, 126, 15231-15244), which are not conducive to production scale-up, and the general method conditions are quite harsh (Practical synthesis of rac-ethylenebis(η 5 - indenyl)zirconium dichloride. Cheminform, 1996(2), 147-148.), the starting material price is too high (US005597935A), the purification method is costly and inconvenient (WO 2021 / 176213 Al), etc. Summary of the Invention
[0006] The purpose of this invention is to provide a metallocene complex and its preparation method, wherein the preparation method has the characteristics of simple reaction synthesis route and low cost, which is conducive to industrial production.
[0007] The technical solution of the present invention is as follows:
[0008] A method for preparing a metallocene complex includes the following steps:
[0009] (1) The indene or its derivative shown in formula (a) reacts with 1,2-dibromoethane in the presence of a lithifying agent to obtain 1,2-bis(3-indenyl)ethane or its derivative shown in formula (b), wherein the molar equivalent ratio of indene or its derivative, the lithifying agent and 1,2-dibromoethane is 1:(0.8~1.2):(0.4~0.6);
[0010] (2) 1,2-bis(3-indenyl)ethane or its derivatives react with a lithiation reagent, and then with zirconium chloride to form a metallocene complex as shown in formula (c), wherein the molar equivalent ratio of 1,2-bis(3-indenyl)ethane or its derivatives, the lithiation reagent and zirconium chloride is 1:(1.8~2.5):(0.8~1.5);
[0011] The structures of equations (a) to (c) are as follows:
[0012] Equation (a); Equation (b); Equation (c);
[0013] Among them, R1 and R2 are independently selected from H, C1~C1, respectively. 12 Substituted or unsubstituted alkyl or aryl groups.
[0014] In some preferred embodiments, step (1) is carried out in an anhydrous and oxygen-free environment. Specifically, under an inert atmosphere, a lithium reagent is added dropwise to a solution of indene or its derivatives at a system temperature of -30 to 10°C. During the dropwise addition process, the system temperature is controlled to not exceed 10°C. Then, the reaction is carried out at -5 to 5°C for 0.5 to 16 hours. After the reaction is completed, the solution is transferred to a solution of 1,2-dibromoethane at a system temperature of -80 to -50°C. During the transfer process, the system temperature is controlled to not exceed -50°C. The reaction is then kept at this temperature for 2 to 6 hours. Finally, the reaction is carried out at room temperature for 2 to 12 hours to obtain 1,2-bis(3-indene)ethane or its derivatives.
[0015] In some preferred embodiments, step (1) further includes the following operation: after the reaction is completed, the system containing 1,2-bis(3-indene)ethane or its derivatives is quenched with a saturated ammonium chloride solution, and then subjected to liquid-liquid extraction, drying and concentration and ethanol recrystallization in sequence to obtain pure 1,2-bis(3-indene)ethane or its derivatives.
[0016] In some preferred embodiments, the concentration of the indene or its derivative solution is 0.05~2 mol / L, and the concentration of the 1,2-dibromoethane solution is 0.05~2 mol / L.
[0017] In some preferred embodiments, step (2) is carried out in an anhydrous and oxygen-free environment. Specifically, under an inert atmosphere, a lithium reagent is added dropwise to a solution of 1,2-bis(3-indenyl)ethane or its derivative at a system temperature of -30 to 10°C. The system becomes viscous, and then the reaction is carried out at 0 to 10°C for 0.5 to 12 hours. Then, the reaction is carried out at room temperature for 5 to 30 minutes. After the reaction is completed, the system is transferred to a solution of zirconium chloride at a system temperature of -30 to 10°C. During the transfer process, the system temperature is controlled to not exceed 20°C. Then, the reaction is carried out at room temperature for 8 to 16 hours to obtain a metallocene complex.
[0018] In some preferred embodiments, the method for preparing the zirconium chloride solution is as follows: under an inert atmosphere, a dry anhydrous organic solvent is cooled to -30~-20°C, and then the zirconium chloride is added to the organic solvent in batches, and the reaction is carried out at room temperature for 2~16 hours to obtain a zirconium chloride solution.
[0019] In some preferred embodiments, step (2) further includes the following operations: after the reaction is completed, the system containing the metallocene complex is concentrated to dryness, then dissolved in dichloromethane and filtered, the filtrate is allowed to stand until solid precipitates, filtered again and the filtrate is concentrated, and the solid precipitated in the filtrate is washed with n-hexane to obtain the product.
[0020] In some preferred embodiments, the concentration of the solution of 1,2-bis(3-indenyl)ethane or its derivatives is 0.05~2 mol / L, and the mass-to-volume ratio of solute to solvent in the zirconium chloride solution is 1 g: 5~30 mL.
[0021] In some preferred embodiments, the lithiation agent is n-butyllithium.
[0022] A metallocene complex was prepared by the above-described preparation method.
[0023] The present invention has at least the following beneficial effects:
[0024] (1) The present invention uses indene, which is inexpensive and commercially available, as a starting material, which has greater potential for scale-up production compared to some routes with complex starting materials or routes involving controlled drugs.
[0025] (2) In steps (1) and (2), the drop temperature of the lithium reagent is increased to -30~10℃ by optimizing the reaction conditions. Compared with the existing technology, the drop temperature at -78℃ is milder, which effectively reduces the energy consumption and cost of the reaction and significantly reduces the equipment requirements.
[0026] (3) In step (2), adding zirconium chloride to anhydrous tetrahydrofuran at low temperature can effectively avoid the problem of material overflow caused by the violent exothermic reaction when adding anhydrous tetrahydrofuran to zirconium chloride in the prior art.
[0027] (4) In this invention, the purification of intermediates and final products is carried out by crystallization, which is more convenient and cost-effective than the route involving column chromatography purification. Attached Figure Description
[0028] Figure 1 The NMR spectrum of 1,2-bis(3-indenyl)ethane prepared in Example 1;
[0029] Figure 2 The NMR spectrum of rac-vinylbisindenylzirconium dichloride prepared in Example 1 is shown. Detailed Implementation
[0030] The technical solution of the present invention will be further explained and described below through specific embodiments.
[0031] In the following embodiments, the water used can be one or more of distilled water, purified water, and drinking water; unless otherwise specified, the detection methods in the following embodiments are conventional detection methods; unless otherwise specified, the reagents in the following embodiments are all purchased from commercial channels.
[0032] The concentration mentioned in this invention refers to the removal of solvent from the reaction system. In the following examples, the specific method of concentration is rotary evaporation. This invention has no special requirements on the rotation speed and time of rotary evaporation, as long as the solvent can be removed. Unless otherwise specified, % in this invention refers to mass percentage.
[0033] Example 1
[0034] (1) Synthesis of 1,2-bis(3-indenyl)ethane
[0035]
[0036] A 500 mL three-necked flask was purged with nitrogen using a double-row tube. Anhydrous tetrahydrofuran (THF, 100 mL) and indene (20 mL, 1 eq) were then injected, and the system was cooled to -10 °C. A solution of n-butyllithium in n-hexane (68.6 mL, 1 eq, 2.5 M) was slowly added dropwise. The solution gradually changed from a clear, pale yellow to a transparent, orange-red color, with the internal temperature controlled to not exceed 10 °C. After the addition was complete, the system turned orange-red, and the reaction was carried out at -5 to 5 °C for 12 h.
[0037] In a separate 500 mL three-necked flask, purged with nitrogen using a double-row tube, a constant-pressure dropping funnel was placed on top, and anhydrous THF (50 mL) and 1,2-dibromoethane (7.38 mL, 0.5 eq) were added. The system was cooled to -60 °C. The indene system solution was transferred to the constant-pressure dropping funnel using a double needle, and the solution was added slowly, with the internal temperature controlled not to exceed -60 °C. The addition was completed in 1 hour, and the reaction was maintained at this temperature for 4 hours, then slowly raised to room temperature and reacted for 12 hours.
[0038] Post-processing: The system was quenched with saturated ammonium chloride and separated. The aqueous phase was extracted with ethyl acetate (EA), and the organic phases were combined, washed with saturated sodium chloride, and dried. The product was concentrated to obtain an orange-yellow solid. The crude product was refluxed with 25 mL of ethanol for 10 min. After being transferred to room temperature and allowed to cool naturally, crystals were precipitated. The crystals were filtered, and the filter cake was washed with a small amount of ethanol to obtain 17.1 g of a pale yellow solid, with a yield of 77%.
[0039] The NMR spectrum of 1,2-bis(3-indenyl)ethane is as follows: Figure 1 As shown, ¹H NMR (500 MHz, CDCl₃) δ 7.57 (d, J = 7.4 Hz, 1H), 7.50 (d, J = 7.5 Hz, 1H), 7.40 (dd, J = 10.9; 3.9 Hz, 1H), 7.33–7.27 (m, 1H), 6.38 (s, 1H), 3.44 (s, 2H), 3.04 (s, 2H).
[0040] (2) Synthesis of rac-vinylbisindenylzirconium dichloride
[0041]
[0042] Take a dry three-necked flask, place a solid powder feeder on it, purge with nitrogen using a double-row tube, add zirconium chloride (5.1 g, 1 eq), and purge with nitrogen again. Inject 25 mL of anhydrous THF into the flask and cool to -30°C. Slowly add zirconium chloride. After the addition is complete, transfer to room temperature and stir. The system will form a grayish-white suspension. Stir at room temperature for 12 h.
[0043] Take a dry three-necked flask, add 5.65 g (1 eq) of 1,2-bis(3-indenyl)ethane, purge with nitrogen in a double-row tube, and then dissolve in 25 mL of anhydrous THF. Cool to -5°C. Slowly add a hexane solution of n-butyllithium (17.51 mL, 2 eq, 2.5 M) to the flask. The system changes from pale yellow and transparent to pale yellow suspension, and stirring becomes difficult. Slowly heat to 5°C and stir for 4 h, then transfer to room temperature and react for 5 min. The system becomes a dark red solution.
[0044] The zirconium chloride system was cooled to -10°C. The 1,2-bis(3-indenyl)ethane solution was transferred via a double-needle transfer device to a constant-pressure dropping funnel containing the zirconium chloride system, and the solution was added slowly. The internal temperature was controlled to not exceed 20°C. After addition, the mixture was allowed to react at room temperature for 12 hours.
[0045] Post-processing: The system changed from a deep red to a yellow suspension. The solvent was concentrated to dryness, and the residue contained solvent entrained by n-hexane. The crude product was dissolved in dichloromethane, and filtered with diatomaceous earth. The filtrate was washed with dichloromethane until it became colorless (approximately 500 mL). The filtrate was concentrated to approximately 50 mL, and the supernatant was decanted. The remaining solid-liquid mixture was added with a small amount of dichloromethane and filtered again. The filter cake was washed with n-hexane to obtain 2.26 g of an orange-yellow solid, with a yield of 24.56%.
[0046] The NMR spectrum of rac-vinylbisindenylzirconium dichloride is as follows: Figure 2 Shown, ¹H NMR (500 MHz, CDCl3) δ7.72–7.66 (m, 2H), 7.51 (d, J = 8.6 Hz, 2H), 7.37–7.33 (m, 2H), 7.23 (dd, J =8.1, 7.2 Hz, 2H), 6.62 (d, J = 3.3 Hz, 2H), 6.24 (d, J = 3.4 Hz, 2H), 3.85–3.71 (m, 4H).
[0047] Comparative Example 1
[0048] (1) Synthesis of 1,2-bis(3-indenyl)ethane
[0049]
[0050] A 500 mL three-necked flask was purged with nitrogen using a double-row tube. Anhydrous THF (100 mL) and indene (20 mL, 1 eq) were then added, and the system was cooled to -10 °C. A solution of n-butyllithium in n-hexane (68.6 mL, 1 eq, 2.5 M) was slowly added dropwise. The solution gradually changed from a clear, pale yellow to a transparent, orange-red color, with the internal temperature controlled to not exceed 10 °C. After the addition was complete, the system turned orange-red. The reaction was maintained at this temperature for 3 hours, then slowly heated to room temperature and reacted for 12 hours. The system gradually turned dark red.
[0051] In a separate 500 mL three-necked flask, purge the double-row tube with nitrogen, set up a constant-pressure dropping funnel, and add anhydrous THF (50 mL) and 1,2-dibromoethane (7.38 mL, 0.5 eq). Cool the system to below -50 °C. Transfer the indene system solution to the constant-pressure dropping funnel using a double needle, add it slowly, and control the internal temperature to not exceed -50 °C. After the addition is completed in 1 hour, maintain the reaction temperature for 4 hours, then slowly raise it to room temperature and react for 12 hours.
[0052] Post-processing: The system was quenched with saturated ammonium chloride and separated. The aqueous phase was extracted with EA, the organic phases were combined, washed with saturated sodium chloride, and dried. The mixture was concentrated to obtain a viscous solid-liquid mixture. The crude product was completely dissolved by reflux with 25 mL of ethanol. The mixture was transferred to room temperature and allowed to cool naturally. 9 g of a yellow solid was obtained, with a yield of 40.6%.
[0053] (2) Synthesis of rac-vinylbisindenylzirconium dichloride
[0054]
[0055] Take a dry three-necked flask, place a solid powder feeder on it, purge with nitrogen using a double-row tube, add zirconium chloride (5 g, 1 eq), and purge with nitrogen again. Pour 100 mL of anhydrous THF into the flask and cool to below -20°C. Slowly add zirconium chloride; after addition, transfer to room temperature and stir. The system appears as a grayish-white suspension. After 1 hour of reaction, the system becomes clear. After stirring at room temperature for 12 hours, the solution turns black.
[0056] Take a dry three-necked flask, add 5.53 g (1 eq) of 1,2-diindenylethane, purge with nitrogen using a double-row tube, and then inject 100 mL of anhydrous THF. Add 17.2 mL (2 eq, 2.5 M) of a hexane solution of n-butyllithium to a constant-pressure dropping funnel. Lower the internal temperature to -20 °C. Slowly add n-butyllithium dropwise into the flask; the system changes from a pale yellow transparent liquid to a pale yellow suspension. Stir the reaction for 2 h, during which the temperature is slowly increased to T. 内 =10℃.
[0057] The 1,2-bisindenylethane system was cooled to -20°C. The zirconium chloride solution was transferred using a double needle to a constant-pressure dropping funnel containing the 1,2-bisindenylethane system, and added slowly, controlling the internal temperature to not exceed -10°C. After the addition was complete, the system changed from a pale yellow suspension to a red solution. The mixture was then slowly raised to room temperature and reacted for 12 hours.
[0058] The red solution was transferred to a single-necked flask and concentrated to dryness. Hexane was added to entrain the solvent, yielding a yellow viscous substance. The solvent was then removed using an oil pump. The crude product was dissolved in dichloromethane, and stirring revealed an insoluble solid. Diatomaceous earth was added, and the mixture was filtered. The filter cake was washed with dichloromethane until colorless, and the filtrates were combined. The mixture was dispensed into 50 mL centrifuge tubes and allowed to stand for 2 hours. Centrifugation was performed (5000 rpm, 5 min). The supernatant was filtered and concentrated to dryness, resulting in a solid precipitation. Approximately 50 mL of toluene was added to the solid, and the mixture was stirred. The mixture was filtered, and the filter cake was washed with hexane to yield 1.4 g of a pale yellow, fine, sandy solid. The yield was 15.54%.
[0059] Comparative Example 2
[0060] (1) Synthesis of 1,2-bis(3-indenyl)ethane
[0061]
[0062] Take a 500mL three-necked flask, purge with nitrogen using a double-row tube, add n-hexane and sodium hydride (3.77g, 60wt% mineral oil dispersion, 1.1eq), stir, and after precipitation, decan the supernatant. Purge with nitrogen again. Add indene (10mL, 1eq) in anhydrous THF (150mL) solution to a constant-pressure dropping funnel, adding slowly. After addition, the system turns green. Slowly raise the temperature to 40℃ and react for 3.5h, the color of the system deepens. After reacting for 12h, stop heating and stirring, and a solid precipitates. Take another dry three-necked flask, purge with nitrogen using a double-row tube, and add 1,2-dibromoethane (3.7mL, 0.5eq) in anhydrous THF (50mL) solution. Transfer the supernatant of the indene system to a constant-pressure dropping funnel using a double-needle, and slowly add it to the anhydrous THF solution of 1,2-dibromoethane. The system gradually turns red. After addition, react at room temperature for 12h. After sampling and quenching, the sample was spotted onto a TLC plate. Hexane was developed, but no product was observed to form.
[0063] Comparative Example 3
[0064] (1) Synthesis of 1,2-bis(3-indenyl)ethane
[0065]
[0066] Take a 500 mL three-necked flask, purge with nitrogen using a double-row tube, and then inject indene (10 mL, 1 eq) and 150 mL of anhydrous THF. Cool the system to -60 °C. Slowly add n-butyllithium (35.7 mL, 1 eq, 2.5 M in Hexane), controlling the internal temperature to not exceed -58 °C. After the addition is complete, maintain the reaction temperature for 15 min, and the system will form an orange-yellow suspension. Transfer to room temperature and react for 1 h, and the system will turn red-orange.
[0067] Take a separate 1L three-necked flask, purge it with nitrogen using a double-row tube, and then add 3.7 mL of 1,2-dibromoethane (0.5 eq) and 35 mL of anhydrous THF. Cool the flask to -60°C. Transfer the indene solution to a constant-pressure dropping funnel containing the 1,2-dibromoethane solution using a double-needle transfer apparatus, adding the solution slowly while maintaining a constant internal temperature. After the addition is complete, maintain the reaction temperature for 2 hours. Then slowly raise the temperature to room temperature and react for 12 hours.
[0068] Post-processing: The system was quenched with approximately 50 mL of saturated ammonium chloride solution, separated, and the aqueous phase was extracted with 50 mL of dichloromethane. The combined organic phases were dried over anhydrous sodium sulfate, concentrated, and drained to dryness using an oil pump to obtain the crude product. The crude product was dissolved in acetone / ethanol (15 mL / 20 mL) and crystallized at -20 °C. The crystals were filtered, and the filter cake was washed with ethanol to give 5.26 g of product. Yield: 47.4%.
[0069] (2) Synthesis of rac-vinylbisindenylzirconium dichloride
[0070]
[0071] Take a dry three-necked flask, place a solid powder feeder on it, purge with nitrogen using a double-row tube, add zirconium chloride (3.78 g, 1 eq), and purge with nitrogen again. Inject 100 mL of anhydrous THF into the flask and cool to below -20°C. Slowly add zirconium chloride; after addition, transfer to room temperature and stir. The system initially appears as a grayish-white suspension. After 1 hour of reaction, the system becomes clear. After stirring at room temperature for 12 hours, the solution turns black.
[0072] Take a dry three-necked flask, add 4.18 g (1 eq) of 1,2-bis(3-indenyl)ethane, purge with nitrogen in a double-row tube, and then inject 100 mL of anhydrous THF. Add 13 mL (2 eq, 2.5 M) of a hexane solution of n-butyllithium to a constant-pressure dropping funnel, controlling the internal temperature to not exceed -20 °C. Slowly add n-butyllithium dropwise into the flask; the system changes from pale yellow and transparent to pale yellow suspension. Stir the reaction for 1 h, slowly raising the temperature to 10 °C during this period. Then transfer to room temperature and stir for 0.5 h; the system becomes a wine-red solution.
[0073] Take another dry three-necked flask, purge it with nitrogen using a double-row tube, and add 50 mL of anhydrous THF. Transfer the zirconium chloride solution and the 1,2-bisindenylethane anion solution separately into two constant-pressure dropping funnels using a double needle. Add them simultaneously at room temperature. After the addition is complete, react for 12 hours; the system will be an orange-yellow solution.
[0074] Post-processing: The solvent was removed by rotary evaporation, with n-pentane entrainment, yielding a pale yellow viscous substance. Approximately 250 mL of dichloromethane was added and stirred for 3.5 h. The mixture was filtered through a diatomaceous earth filter, and the filter cake was washed with dichloromethane until the filtrate was colorless. The filtrates were combined, and no solid precipitate was observed. After concentration to dryness, a crude product consisting of both solid and liquid was obtained.
[0075] The crude product was added to 16 mL of dichloromethane and stirred for 50 min. The mixture was then filtered, and the filter cake was washed with a small amount of dichloromethane and then with n-pentane to obtain 1.05 g of a light yellow powdery solid. The yield was 15.42%.
[0076] The above description is merely a preferred embodiment of the present invention, and therefore should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the patent and the contents of the specification should still fall within the scope of the present invention.
Claims
1. A method for preparing a metallocene complex, characterized in that, Includes the following steps: (1) The indene or its derivative shown in formula (a) reacts with 1,2-dibromoethane in the presence of a lithifying agent to obtain 1,2-bis(3-indene)ethane or its derivative shown in formula (b), wherein the molar equivalent ratio of the indene or its derivative, the lithifying agent and the 1,2-dibromoethane is 1:(0.8~1.2):(0.4~0.6); (2) The 1,2-bis(3-indenyl)ethane or its derivative reacts with a lithiation reagent and then with zirconium chloride to form a metallocene complex as shown in formula (c), wherein the molar equivalent ratio of the 1,2-bis(3-indenyl)ethane or its derivative, the lithiation reagent and the zirconium chloride is 1:(1.8~2.5):(0.8~1.5); The structures of equations (a) to (c) are as follows: Equation (a); Equation (b); Equation (c); Among them, R1 and R2 are independently selected from H, C1~C1, respectively. 12 Substituted or unsubstituted alkyl or aryl groups.
2. The preparation method according to claim 1, characterized in that, Step (1) is carried out in an anhydrous and oxygen-free environment. The specific operation is as follows: under an inert atmosphere, the lithium reagent is added dropwise to the solution of indene or its derivative at a system temperature of -30~10℃. During the dropwise addition process, the system temperature is controlled not to exceed 10℃. Then, the reaction is carried out at -5~5℃ for 0.5~16h. After the reaction is completed, the solution is transferred to the solution of 1,2-dibromoethane at a system temperature of -80~-50℃. During the transfer process, the system temperature is controlled not to exceed -50℃. Then, the reaction is kept at the temperature for 2~6h. Finally, the reaction is carried out at room temperature for 2~12h to obtain the 1,2-bis(3-indene)ethane or its derivative.
3. The preparation method according to claim 2, characterized in that, Step (1) further includes the following operation: after the reaction is completed, the system containing the 1,2-bis(3-indenyl)ethane or its derivative is quenched with a saturated ammonium chloride solution, and then subjected to liquid-liquid extraction, drying and concentration and ethanol recrystallization in sequence to obtain the pure product of the 1,2-bis(3-indenyl)ethane or its derivative.
4. The preparation method according to claim 2, characterized in that, The concentration of the indene or its derivative solution is 0.05~2 mol / L, and the concentration of the 1,2-dibromoethane solution is 0.05~2 mol / L.
5. The preparation method according to claim 1, characterized in that, Step (2) is carried out in an anhydrous and oxygen-free environment. The specific operation is as follows: under an inert atmosphere, a lithium reagent is added dropwise to a solution of 1,2-bis(3-indenyl)ethane or its derivative at a system temperature of -30~10℃. The system becomes viscous. Then, the reaction is carried out at 0~10℃ for 0.5~12h, followed by a reaction at room temperature for 5~30min. After the reaction is completed, the system is transferred to a solution of zirconium chloride at a system temperature of -30~10℃. During the transfer process, the system temperature is controlled not to exceed 20℃. Then, the reaction is carried out at room temperature for 8~16h to obtain the metallocene complex.
6. The preparation method according to claim 5, characterized in that, The method for preparing the zirconium chloride solution is as follows: under an inert atmosphere, the dry anhydrous organic solvent is cooled to -30~-20℃, and then the zirconium chloride is added to the organic solvent in batches. The reaction is carried out at room temperature for 2~16 hours to obtain the zirconium chloride solution.
7. The preparation method according to claim 5, characterized in that, Step (2) also includes the following operations: after the reaction is completed, the system containing the metallocene complex is concentrated to dryness, then dissolved in dichloromethane and filtered. The filtrate is allowed to stand until a solid precipitates, then filtered again and the filtrate is concentrated. The solid precipitated in the filtrate is washed with n-hexane to obtain the product.
8. The preparation method according to claim 5, characterized in that, The concentration of the solution of 1,2-bis(3-indenyl)ethane or its derivative is 0.05~2 mol / L, and the mass-volume ratio of solute to solvent in the solution of zirconium chloride is 1 g: 5~30 mL.
9. The preparation method according to claim 1, characterized in that, The lithiation reagent is n-butyllithium.
10. A metallocene complex, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 9.