A metallocene complex containing amidine group structure, its preparation method and application in catalyzing ethylene / alpha-olefin copolymerization

Abstract

The application provides a metallocene complex containing amidine group structure. The metallocene catalyst containing amidine group structure provided by the application has double chelated η2-type coordination side arms, can have stronger interaction with the central metal, can reduce the positive electricity of the metal, is more favorable to the stability of the metal center, and improves the temperature resistance of the catalyst. The catalyst can still catalyze ethylene and alpha-olefin copolymerization at 180 DEG C and has higher catalytic activity, alpha-olefin insertion rate and higher molecular weight, is suitable for the needs of large-scale industrial production, and has important industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of olefin polymerization technology, specifically relating to a metallocene complex containing an amidine group, its preparation method, and its application in catalytic ethylene / α-olefin copolymerization. Background Technology

[0002] Polyolefin elastomers (POEs) are a class of elastomer materials formed by the random copolymerization of ethylene with higher α-olefins (such as 1-butene, 1-hexene, and 1-octene). Due to their saturated main chain, they possess excellent low-temperature toughness, aging resistance, and corrosion resistance, and are widely used in modified toughening agents, foaming materials, packaging films, and other fields, making them a high-value-added polyolefin product. POE is mainly produced using a high-temperature solution polymerization process, requiring the polymerization temperature to be set above the melting point of the polyethylene chain segment. Therefore, the development of novel high-temperature stable catalysts is currently the core focus in this field. Ziegler-Natta (ZN) catalysts and metallocene catalysts are the most important catalyst systems for the industrial preparation of POE materials. ZN catalysts have multiple active centers, a wide distribution of polymer molecular weight and chemical composition, and limited comonomer insertion capability. Metallocene catalysts are currently the more mature catalysts used in industry. For example, EP416815A2 discloses a restricted geometry catalyst developed for catalyzing the polymerization of ethylene and copolymerization with α-olefins, exhibiting high catalytic activity, but with low temperature resistance. CN1408731A reports a metallocene catalyst containing a Schiff base structure. This catalyst exhibits poor temperature resistance, low catalytic activity, and produces polymers with low molecular weights and a wide molecular weight distribution. Therefore, in the research of catalysts for catalytic ethylene / α-olefin copolymerization, enhancing the high-temperature stability of the catalyst while maintaining sufficient catalytic activity, the comonomer insertion rate, and the molecular weight of the product are key factors in the rational design of novel catalyst structures. Summary of the Invention

[0003] In view of this, the technical problem to be solved by the present invention is to provide a metallocene complex containing an amidine group, a method for preparing the same, and its application in the catalytic copolymerization of ethylene / α-olefins. The metallocene complex provided by the present invention has high-temperature stability when used as a catalyst for the copolymerization of ethylene / α-olefins, while also having sufficient catalytic activity.

[0004] This invention provides a metallocene complex containing an amidine group, having the structure shown in formula (I):

[0005]

[0006] M is a metal of titanium, zirconium, or hafnium;

[0007] R1 and R2 may be the same or different, independent of each other or connected to form a ring, and are respectively substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C1-C30 cycloalkyl, substituted or unsubstituted C6-C30 aromatic group, or substituted or unsubstituted C6-C30 aromatic heterocyclic group.

[0008] R3 to R6 may be the same or different, and may be independent of each other or connected to form a ring, respectively H, substituted or unsubstituted C1 to C30 alkyl, substituted or unsubstituted C1 to C30 cycloalkyl, substituted or unsubstituted C6 to C30 aromatic group, and substituted or unsubstituted C6 to C30 aromatic heterocyclic group.

[0009] X is a halogen, a C2-C50 unsaturated hydrocarbon group, a C2-C50 unsaturated heterohydrocarbon group, a C1-C50 alkyl group, a C6-C50 aryl group, a C6-C50 heteroaryl group, a cyclopentadienyl group, a substituted cyclopentadienyl group, or a C4-C12 dienyl group.

[0010] Preferably, R1 to R2 are the same or different, independent of each other or connected to form a ring, and are respectively substituted C1 to C8 alkyl, substituted or unsubstituted C1 to C8 cycloalkyl, substituted or unsubstituted C6 to C10 aromatic group, or substituted or unsubstituted C6 to C10 aromatic heterocyclic group.

[0011] Preferably, R3 to R6 are the same or different, independent of each other or connected to form a ring, and are respectively H, substituted or unsubstituted C1 to C8 alkyl, substituted or unsubstituted C1 to C8 cycloalkyl, substituted or unsubstituted C6 to C10 aromatic group, or substituted or unsubstituted C6 to C10 aromatic heterocyclic group.

[0012] Preferably, in the X, each X is independently a halogen, a C1-C20 alkyl group, a C7-C20 aralkyl group, a C1-C6 alkyl-substituted aryl group, or a C1-C6 alkyl-substituted benzyl group.

[0013] The present invention also provides a method for olefin polymerization, wherein the catalyst used in the method comprises a main catalyst and a co-catalyst, and the main catalyst is the above-mentioned metallocene complex containing an amidine group structure.

[0014] Preferably, the co-catalyst is selected from one or more of alkylaluminum and borates.

[0015] Preferably, the alkylaluminum is selected from one or more aluminum oxanes or modified aluminum oxanes containing C1 to C8 alkyl groups;

[0016] The borate additive is selected from one or more of triphenylmethyltetra(pentafluorophenyl)borate, tetra(pentafluorophenyl)borate-methyl di-(octadecyl)ammonium salt, and N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate.

[0017] Preferably, the molar ratio of the alkylaluminum to the metallocene complex is 3 to 5000, more preferably 50 to 3000, based on the molar ratio of aluminum to metal M in the metallocene complex; and the molar ratio of the borate auxiliary to the metal complex catalyst is 0 to 40, more preferably 0 to 15, based on the molar ratio of element B to metal M in the metallocene complex.

[0018] Preferably, the olefin polymerization is a homopolymerization of ethylene and / or a copolymerization of ethylene and α-olefin;

[0019] The polymerization reaction temperature is 20–250℃; the polymerization pressure is 0.1–40 MPa.

[0020] The amount of the olefin polymerization catalyst composition used, based on the molar concentration of metal M in the metallocene complex in the reaction solvent, is 0.1–20 μmol / L.

[0021] Preferably, the method for copolymerizing ethylene with α-olefins includes the following steps:

[0022] In the presence of a catalyst, ethylene and α-olefins undergo a polymerization reaction to obtain polyolefins;

[0023] The α-olefin is selected from any one or more of propylene, 1-butene, 1-hexene, and 1-octene.

[0024] Compared with existing technologies, this invention provides a metallocene complex containing an amidine group. The metallocene catalyst containing an amidine group provided by this invention has a double-chelated η2-type coordination arm, which enables stronger interaction with the central metal, reduces the positive charge of the metal, is more conducive to the stability of the metal center, and improves the catalyst's temperature resistance. This catalyst can still catalyze the copolymerization of ethylene and α-olefins at 180℃ while maintaining high catalytic activity, α-olefin insertion rate, and high molecular weight, making it suitable for large-scale industrial production and possessing significant industrial application prospects. Detailed Implementation

[0025] This invention provides a metallocene complex containing an amidine group, having the structure shown in formula (I):

[0026]

[0027] M is a metal of titanium, zirconium, or hafnium;

[0028] R1 and R2 may be the same or different, independent of each other or connected to form a ring, and are respectively substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C1-C30 cycloalkyl, substituted or unsubstituted C6-C30 aromatic group, or substituted or unsubstituted C6-C30 aromatic heterocyclic group.

[0029] R3 to R6 may be the same or different, and may be independent of each other or connected to form a ring, respectively H, substituted or unsubstituted C1 to C30 alkyl, substituted or unsubstituted C1 to C30 cycloalkyl, substituted or unsubstituted C6 to C30 aromatic group, and substituted or unsubstituted C6 to C30 aromatic heterocyclic group.

[0030] X is a halogen, a C2-C50 unsaturated hydrocarbon group, a C2-C50 unsaturated heterohydrocarbon group, a C1-C50 alkyl group, a C6-C50 aryl group, a C6-C50 heteroaryl group, a cyclopentadienyl group, a substituted cyclopentadienyl group, or a C4-C12 dienyl group.

[0031] Preferably, R1 to R2 are the same or different, independent of each other or connected to form a ring, and are respectively substituted C1 to C8 alkyl, substituted or unsubstituted C1 to C8 cycloalkyl, substituted or unsubstituted C6 to C10 aromatic group, or substituted or unsubstituted C6 to C10 aromatic heterocyclic group.

[0032] Preferably, R3 to R6 are the same or different, independent of each other or connected to form a ring, and are respectively H, substituted or unsubstituted C1 to C8 alkyl, substituted or unsubstituted C1 to C8 cycloalkyl, substituted or unsubstituted C6 to C10 aromatic group, or substituted or unsubstituted C6 to C10 aromatic heterocyclic group.

[0033] Preferably, in the X, each X is independently a halogen, a C1-C20 alkyl group, a C7-C20 aralkyl group, a C1-C6 alkyl-substituted aryl group, or a C1-C6 alkyl-substituted benzyl group.

[0034] More preferably, the metallocene complex containing an amidine group is selected from complexes M1 to M6.

[0035]

[0036] The present invention also provides a method for preparing the above-mentioned metallocene complex containing an amidine group, comprising the following steps:

[0037] The specific chemical reaction process is as follows:

[0038]

[0039] Specifically, depending on the different substituents, there are two synthetic schemes for intermediate 1:

[0040] Scheme 1: Reference (Organic Process Research & Development (2015), 19(7), 831-840). 1,2-Dibromobenzene (1 eq) was dissolved in anhydrous tetrahydrofuran, cooled to -78℃, and nBu-Li (1~1.2 eq) was slowly added dropwise. The mixture was stirred at this temperature, and then an anhydrous tetrahydrofuran solution containing the substituted amine (1 eq) was added dropwise. After stirring for a period of time, the mixture was raised to room temperature. The reaction was monitored by TLC until it was complete. The solvent was then removed, the mixture was extracted with dichloromethane, washed with brine, dried over anhydrous sodium sulfate, filtered, concentrated, and separated by column chromatography to obtain intermediate 1.

[0041] Option 2: Under nitrogen protection, 1,2-dibromobenzene (1 eq), substituted amine (1 eq), Pd2(dba)3 (0.5–5 mol%), DPEPos (1–3 mol%), and sodium tert-butoxide (1.5–3 eq) were dissolved in anhydrous toluene. The mixture was heated to reflux for 24–72 h, cooled to room temperature, filtered with diatomaceous earth, washed with dichloromethane, and the organic phases were combined, washed with brine, dried with anhydrous sodium sulfate, filtered, and separated by column chromatography after rotary evaporation to obtain intermediate 1.

[0042] Intermediate 1, substituted cyclopentadienyl-dioxaborane (1–1.3 eq), Pd(PPh3)4 (0.02–0.1 eq) and K2CO3 (1.5–3 eq) were dissolved in a mixed solution of degassed 1,4-dioxane and degassed deionized water. The mixture was heated to reflux for 24–72 h. After the reaction was completed, the mixture was cooled to room temperature, separated by diatomaceous earth, washed with ethyl acetate, and the organic phases were combined, washed with brine, dried with anhydrous sodium sulfate, filtered, concentrated, and separated by column chromatography to obtain the ligands.

[0043] The ligand (1 eq) was dissolved in anhydrous toluene, and a toluene solution of MCl4 (1 eq) was added dropwise. The mixture was reacted overnight at room temperature. The toluene was dried under vacuum, anhydrous n-hexane was added, the mixture was filtered, and recrystallized in toluene / n-hexane to give the metallocene complex.

[0044] The present invention also provides a method for olefin polymerization, wherein the catalyst used in the method comprises a main catalyst and a co-catalyst, and the main catalyst is the above-mentioned metallocene complex containing an amidine group structure.

[0045] Preferably, the co-catalyst is selected from one or more of alkylaluminum and borates.

[0046] The alkylaluminum is selected from one or more aluminum oxanes or modified aluminum oxanes containing C1 to C8 alkyl groups, preferably from methylaluminoxanes or modified methylaluminoxanes.

[0047] The borate additive is selected from one or more of triphenylmethyltetra(pentafluorophenyl)borate, tetra(pentafluorophenyl)borate-methyl di-(octadecyl)ammonium salt, and N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate.

[0048] Preferably, the molar ratio of the alkylaluminum to the metallocene complex, based on the molar ratio of aluminum to metal M in the metallocene complex, is 3 to 5000, preferably 50 to 3000, and further, can be 50, 100, 500, 1000, 2000, 3000, or any value between 50 and 3000; the molar ratio of the borate auxiliary to the metal complex catalyst, based on the molar ratio of element B to metal M in the metallocene complex, is 0 to 40, preferably 0 to 15, and further, can be 0, 1, 3, 5, 7, 9, 10, 12, 15, or any value between 0 and 15.

[0049] The olefin polymerization is a homopolymerization of ethylene and / or a copolymerization of ethylene and α-olefins;

[0050] The amount of the olefin polymerization catalyst composition, based on the molar concentration of metal M in the metallocene complex in the reaction solvent, is 0.1 to 20 μmol / L, and can be any value between 0.1, 0.5, 1, 3, 5, 7, 9, 10, 11, 13, 15, 17, 19, 20, or 0.1 to 20 μmol / L.

[0051] In some specific embodiments of the present invention, the method for copolymerizing ethylene with α-olefins includes the following steps:

[0052] In the presence of a catalyst, ethylene and α-olefins undergo a polymerization reaction to obtain polyolefins;

[0053] The polymerization reaction temperature is 20–250°C, and can be any value between 20, 50, 100, 150, 180, 200, 250°C, or 20–250°C, preferably 140–180°C; the polymerization pressure is 0.1–40 MPa, and can be any value between 0.1, 0.5, 1, 5, 10, 15, 20, 25, 30, 35, 40 MPa, or 0.1–40 MPa.

[0054] The α-olefin is selected from any one or more of propylene, 1-butene, 1-hexene, and 1-octene.

[0055] The metallocene complexes containing amidine groups described in this invention have the following advantages in catalytic homopolymerization of ethylene or copolymerization of ethylene with α-olefins:

[0056] 1. In amidine NCN, the π bond is delocalized through conjugation to form a conjugated η2-ligand with three centers and four electrons. The double-chelated η2-type coordination side arm can interact more strongly with the central metal and provides an extra lone pair of electrons, which can reduce the positive charge of the metal, which is more conducive to the stability of the metal center and improves the temperature resistance of the catalyst.

[0057] 2. Experimental results show that the metallocene catalyst with an amidine structure provided by this invention has good temperature resistance, and can still catalyze the copolymerization of ethylene and 1-octene at 180℃, with a copolymerization activity of up to 10. 8 g poly / mol metal h, the 1-octene molar insertion rate can reach 20 mol%. It is suitable for the needs of large-scale industrial production and has important industrial application prospects.

[0058] To further understand the present invention, the following description is provided in conjunction with embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0059] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0060] The polymerization activities of the polymers described in the following examples were calculated using the following formula: Polymer activity = Polymer mass / (Moles of metal in catalyst * Polymerization time). The weight-average molecular weight (Mw) of the polymers was obtained by GPC testing at 160°C using three tandem PLgel 10μm MIXED-B columns with 1,2,4-trichlorobenzene as the solvent. The method for calculating the comonomer insertion rate is referenced in (Macromolecules 1999, 32, 3817).

[0061] Example 1: Preparation of ligand L1

[0062] The metallocene catalyst ligand L1 containing an amidine group was prepared according to the following synthetic route:

[0063]

[0064] (1) Preparation of A1 according to reference (Organic Process Research & Development (2015), 19(7), 831-840). 1,2-Dibromobenzene (1eq) was dissolved in anhydrous tetrahydrofuran, cooled to -78℃, and nBu-Li (1eq) was slowly added dropwise. The mixture was stirred at this temperature, and then an anhydrous tetrahydrofuran solution containing A1 (1eq) was added dropwise. After stirring for a period of time, the mixture was raised to room temperature. The reaction was monitored by TLC until it was complete. The solvent was then removed, and the mixture was extracted with dichloromethane, washed with brine, dried over anhydrous sodium sulfate, filtered, concentrated, and separated by column chromatography to obtain the target product A2.

[0065] The NMR data for compound A2 are as follows:

[0066] 1 H NMR (CDCl3, 400MHz): δ7.82(d,2H),7.56-7.12(m,10H),6.87(d,2H),5.06(s,1H),4.52(m,1H),1.52(d,3H).

[0067] (2) Preparation of A3 (Reference: Organometallics 2006, 25, 2133-2134). Under nitrogen protection, compounds A2 (1 eq), A3 (1.1 eq), Pd(PPh3)4 (0.05 eq), and K2CO3 (1.5 eq) were dissolved in a mixture of degassed DME and degassed deionized water. The mixture was refluxed overnight. After the reaction was completed, the mixture was cooled to room temperature, extracted with ethyl acetate, washed with brine, dried over anhydrous sodium sulfate, filtered, concentrated, and separated by column chromatography to obtain the intermediate product. Then, under anhydrous and oxygen-free conditions, anhydrous CsCl3 (3 eq) was added to anhydrous tetrahydrofuran, and the mixture was cooled. LiMe (3 eq) was slowly added dropwise to -78℃. The mixture was stirred at this temperature for a period of time. The intermediate product (1 eq) obtained above was added. The mixture was stirred at -78℃ for a period of time and then brought to room temperature. Deionized water was added, and the mixture was extracted with ethyl acetate. The aqueous phase was extracted twice more with ethyl acetate. The organic phases were combined, and dilute hydrochloric acid solution (3M) was added and stirred for half an hour. Then, saturated NaHCO3 solution was added to adjust the pH to neutral. The organic phase was separated, dried over anhydrous sodium sulfate, filtered, concentrated, and the crude product was separated by column chromatography to obtain the target product L1.

[0068] The NMR data for ligand L1 are as follows:

[0069] 1 H NMR (CDCl3, 400MHz): δ7.82(d,2H),7.59(d,3H),7.32-7.45(m,5H),7.15(m,2H) ,6.82(m,2H),4.52(m,1H),2.92(s,2H),2.14(s,6H),1.79(s,3H),1.52(d,3H).

[0070] Example 2 Preparation of ligand L2

[0071] The metallocene catalyst ligand L2 containing an amidine group was prepared according to the following synthetic route:

[0072]

[0073] (1) Under nitrogen protection, 1,2-dibromobenzene (1 eq), 2-aminopyridine (1 eq), Pd2(dba)3 (0.5 mol%), DPEPos (1 mol%) and sodium tert-butoxide (1.5 eq) were dissolved in anhydrous toluene, heated to 110 °C and refluxed for 24 h, cooled to room temperature, filtered with diatomaceous earth, washed with dichloromethane, combined the organic phases, washed with brine, dried with anhydrous sodium sulfate, filtered, evaporated to dryness, and separated by column chromatography to obtain A4.

[0074] The NMR data for compound A4 are as follows:

[0075] 1 H NMR (CDCl3, 400MHz): δ8.05(d,1H),7.69(d,1H),7.56(d,1H),7.23(d,1H),7.05(d,2H),6.83(d,2H).

[0076] (2) Compound A4 (1 eq), 2-(1H-inden-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane (1.1 eq), Pd(PPh3)4 (0.05 eq) and K2CO3 (1.5 eq) were dissolved in a mixed solution of degassed 1,4-dioxane and degassed deionized water. The mixture was heated to reflux for 24 h. After the reaction was completed, the mixture was cooled to room temperature, separated by diatomaceous earth, washed with ethyl acetate, and the organic phases were combined, washed with brine, dried with anhydrous sodium sulfate, filtered, concentrated, and separated by column chromatography to obtain ligand L2.

[0077] The NMR data for ligand L2 are as follows:

[0078] 1 H NMR(CDCl3,400MHz): δ8.50(s,1H),8.09(d,1H),8.03(d,1H),7.54(d,2H),7 .51(d,2H),7.45(d,1H),7.37-7.33(d,2H),7.29-7.23(d,4H),3.99(d,2H).

[0079] Example 3 Preparation of ligand L3

[0080] The metallocene catalyst ligand L3 containing an amidine group was prepared according to the following synthetic route:

[0081]

[0082] (1) The synthesis steps of ligand L3 are similar to those of L2. The only difference is that the starting material 2-aminopyridine is replaced with 2-amino-2-thiazoline and 2-(1H-indene-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane is replaced with 2-(9H-fluorene-2-yl)-4,4,5,5-tetramethyl-[1,3,2]dioxaborane.

[0083] The NMR data for ligand L3 are as follows:

[0084] 1 H NMR (CDCl3, 400MHz): δ8.45(s,1H),8.19(d,1H),7.99(d,2H),7.74(d,2H),7.55(d, 1H),7.28(d,3H),6.94(d,1H),6.64(d,1H),4.12(s,2H),3.79(d,2H),3.25(d,2H).

[0085] Example 4: Preparation of ligand L4

[0086] The metallocene catalyst ligand L4 containing an amidine group was prepared according to the following synthetic route:

[0087]

[0088] (1) The synthesis steps of ligand L4 are similar to those of L2. The only difference is that the starting material 2-aminopyridine is replaced with 1-methyl-2-aminoimidazolium and 2-(1H-indene-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane is replaced with A7. A7 is prepared according to reference (KR2011120078 A).

[0089] The NMR data for ligand L4 are as follows:

[0090] 1 H NMR (CDCl3, 400MHz): δ8.85(s,1H),8.09(d,1H),7.79(d,1H),7.64-7.35(d,6H),7.25-7.08(m, 8H),6.88(d,1H),6.78(d,1H),3.95(d,2H),3.75(d,2H),3.55(d,2H),3.24(d,3H),3.15(d,3H).

[0091] Example 5 Preparation of complexes M1 and M2

[0092]

[0093] The synthesis steps are as follows:

[0094] Ligand L1 (1 eq) was dissolved in anhydrous toluene, and a toluene solution of Ti(NMe2)4 (1 eq) was added dropwise. The mixture was reacted overnight at room temperature. The toluene was dried under vacuum, and anhydrous n-hexane was added. The mixture was filtered, and recrystallized from toluene / n-hexane to give complex M1.

[0095] The NMR data of complex M1 are as follows

[0096] 1 H NMR(C6D6,400MHz): δ7.75(d,2H),7.56(d,3H),7.26-7.38(m,5H),7.10(m,2H),6.72( m,2H),6.25(d,1H),4.45(m,1H),2.76(s,12H),2.04(s,6H),1.69(s,3H),1.42(d,3H).

[0097] ICP and elemental analysis: Measured (calculated) C: 72.96 (73.37); H: 7.48 (7.97); Ti: 9.14 (8.60).

[0098] Under anhydrous and oxygen-free conditions, M1 (1 eq) was dissolved in anhydrous toluene, and then dichlorodimethylsilane (5 eq) was dissolved in anhydrous toluene. The solution was then added dropwise to the toluene solution of M1, and the mixture was stirred at room temperature for 24 h. The mixture was filtered, the filtrate was concentrated, anhydrous n-hexane was added to precipitate the filtrate, the insoluble matter was collected, washed with anhydrous n-hexane, and dried under vacuum to obtain complex M2.

[0099] The NMR data of complex M2 are as follows

[0100] 1 H NMR(C6D6,400MHz): δ7.75(d,2H),7.56(d,3H),7.26-7.38(m,5H),7.10(m,2H) ,6.72(m,2H),6.25(d,1H),4.45(m,1H),2.04(s,6H),1.69(s,3H),1.42(d,3H).

[0101] ICP and elemental analysis: Measured (calculated) C: 65.9 (66.8); H: 6.48 (5.98); Ti: 8.25 (8.87).

[0102] Example 6 Preparation of complexes M3 and M4

[0103]

[0104] Under anhydrous and oxygen-free conditions, ligand L2 (1 eq) was dissolved in anhydrous tetrahydrofuran, cooled to -78°C, and nBu-Li (1 eq) was added dropwise. The mixture was reacted at room temperature for a period of time, the solvent was dried, and the solution was dissolved in anhydrous toluene. This solution was then added dropwise to anhydrous toluene containing TiCl4 (1 eq), and the mixture was reacted overnight at room temperature. The mixture was filtered, the filtrate was dried, and washed with anhydrous n-hexane to obtain the crude product. The crude product was recrystallized in toluene / n-hexane to obtain the complex M3.

[0105] The NMR data of complex M3 are as follows:

[0106] 1 H NMR(C6D6,400MHz): δ,7.95(d,1H),7.86(d,1H),7.64(d,2H),7.53(d,2H),7.35(d,1H),7.25-7.30(d,2H),7.09-7.16(d,3H),6.59(d,2H).

[0107] ICP and elemental analysis: Measured (calculated) C: 61.2 (60.6); H: 3.92 (4.12); Ti: 12.23 (11.50).

[0108] Under anhydrous and oxygen-free conditions, M3 (1 eq) was dissolved in anhydrous toluene, cooled to -40°C, and MeMgBr (1 eq) was added dropwise. The mixture was then heated to room temperature and stirred for a period of time. After filtration, the filtrate was dried under vacuum, washed with anhydrous n-hexane, and the crude product was recrystallized in toluene / n-hexane to obtain complex M4.

[0109] The NMR data of complex M4 are as follows

[0110] 1 H NMR(C6D6,400MHz): δ,7.95(d,1H),7.86(d,1H),7.64(d,2H),7.53(d,2H),7 .35(d,1H),7.25-7.30(d,2H),7.09-7.16(d,3H),6.59(d,2H),0.57(s,6H).

[0111] ICP and elemental analysis: Measured (calculated) C: 72.92 (73.61); H: 5.96 (6.18); Ti: 12.14 (12.75).

[0112] Example 7 Preparation of complex M5

[0113]

[0114] The synthesis steps are as follows:

[0115] Under anhydrous and oxygen-free conditions, HfCl4 (1.1 eq) was dispersed in anhydrous toluene and cooled to -40°C. A solution of magnesium methyl bromide in diethyl ether (4.5 eq) was added dropwise, and the mixture was stirred for 30 minutes. Then, 10 mL of a toluene solution containing ligand L3 (1 eq) was added, and the reaction was allowed to proceed for 12 hours at room temperature. Insoluble matter was removed by filtration, and volatile components were removed from the filtrate under vacuum. The crude product was recrystallized from dichloromethane / n-hexane to obtain complex M5.

[0116] The NMR data of complex M5 are as follows:

[0117] 1 H NMR(C6D6,400MHz): δ8.25(s,1H),8.05(d,1H),7.82(d,2H),7.64(d,2H),7.42(d,1H),7. 18(d,3H),6.84(d,1H),6.54(d,1H),6.35(d,1H),3.69(d,2H),3.15(d,2H),-0.45(s,6H).

[0118] ICP and elemental analysis: Measured (calculated) C: 53.75 (53.14); H: 4.98 (4.64); Hf: 30.96 (31.59).

[0119] Example 8 Preparation of complex M6

[0120]

[0121] ZrBn4(1 eq) was dissolved in anhydrous toluene, and a toluene solution containing ligand L4(1 eq) was added to the solution. The reaction was carried out at room temperature for 12 h. Volatile components in the filtrate were removed under vacuum, and the crude product was recrystallized from dichloromethane / n-hexane to obtain complex M6.

[0122] The NMR data of complex M6 are as follows

[0123] 1 H NMR(C6D6,400MHz): δ8.65(s,1H),7.75-8.12(m,7H),7.69(d,1H),7.54-7.25(d,10H),7.15-6.98(m,8H) ,6.75(d,1H),6.63(d,1H),6.35(d,1H),3.85(d,2H),3.72(d,2H),3.25(d,4H),3.14(d,3H),2.88(d,3H).

[0124] ICP and elemental analysis: Measured (calculated) C: 73.97 (74.46); H: 5.88 (6.12); Zr: 12.45 (12.03).

[0125] Example 9: Catalytic Homopolymerization of Ethylene

[0126] The homopolymerization of ethylene was carried out in a 500 mL stainless steel high-pressure reactor. The reactor, equipped with a mechanical stirrer, was heated to 140 °C and evacuated under vacuum for 2 hours. Ethylene gas was then introduced to a pressure of 1 bar. A toluene solution containing methylaluminoxane (MAO), the main catalyst, was then added to the reactor. The ethylene gas pressure was increased to 1.0 MPa, and the mixture was stirred for a certain period. After the polymerization reaction was complete, the ethylene gas was rapidly released, and the reactor was quickly cooled to 30 °C. The reactor was then opened, and the solid-liquid mixture was poured into a 1:1 (v / v) mixture of 3M hydrochloric acid and ethanol. After stirring for 30 minutes, the mixture was filtered and dried in a vacuum oven at 60 °C for 12 hours to obtain the polymer sample. The polymer analysis results are shown in Table 1.

[0127] Table 1. Results of ethylene homopolymerization catalyzed by complexes M1-M6 as the main catalysts. a

[0128]

[0129] a Polymerization conditions: The amount of main catalyst M1 to M6 is 0.2 μmol, the co-catalyst is MAO, Al / M = 1500, the polymerization temperature is 140℃, the polymerization pressure is 1.0 MPa, and the polymerization time is 10 min. b Molecular weight and molecular weight distribution (PDI) were determined by GPC.

[0130] Example 10: Catalytic copolymerization study of ethylene and 1-hexene

[0131] The copolymerization of ethylene and 1-hexene was carried out in a 500 mL stainless steel high-pressure reactor. The reactor, equipped with a mechanical stirrer, was heated to 140 °C and evacuated under vacuum for 1 h. The system was then heated to 160 °C, and ethylene gas was introduced to 1 bar. The main catalyst, a mixed isoalkane solution containing methylaluminoxane (MAO) and a certain concentration of 1-hexene (Isopar E) were then added to the polymerization reactor. The ethylene gas pressure was then increased to 2.0 MPa, and the mixture was stirred for a certain period. After the polymerization reaction was completed, the ethylene gas was rapidly released, and the reactor was quickly cooled to 30 °C. The reactor was then opened, and the solid-liquid mixture was poured into a 1:1 (v / v) mixture of 3M hydrochloric acid and ethanol. After stirring for 10 min, the mixture was filtered and dried in a vacuum oven at 60 °C for 12 h to obtain the polymer sample. The polymer analysis results are shown in Table 2.

[0132] Table 2. Results of the copolymerization of ethylene and 1-hexene catalyzed by complexes M1-M6 as the main catalysts. a

[0133]

[0134] a Polymerization conditions: The amount of main catalyst M1 to M6 is 0.2 μmol, the co-catalyst is MAO, Al / M = 1500, the polymerization temperature is 160℃, the concentration of 1-hexene is 1.0 mol / L, the polymerization pressure is 2.0 MPa, and the polymerization time is 10 min. b Molecular weight and molecular weight distribution (PDI) were determined by GPC. c The 1-hexene insertion rate was determined by 1H NMR and 1C NMR.

[0135] Example 11: Catalytic copolymerization of ethylene and 1-octene

[0136] The copolymerization of ethylene and 1-octene was carried out in a 500 mL stainless steel high-pressure reactor. The reactor, equipped with a mechanical stirrer, was heated to 140 °C and evacuated under vacuum for 1 h. The system was then heated to 180 °C, and ethylene gas was introduced to 1 bar. Then, 100 mL of a mixed isoalkane solution (Isopar E) containing the main catalyst, methylaluminoxane (MAO), and a certain concentration of 1-octene was added to the reactor. The ethylene gas pressure was then increased to 1.0 MPa, and the mixture was stirred for a certain period. After the polymerization reaction was completed, the ethylene gas was rapidly released, and the reactor was quickly cooled to 30 °C. The reactor was then opened, and the solid-liquid mixture was poured into a 1:1 (v / v) mixture of 3M hydrochloric acid and ethanol. After stirring for 10 min, the mixture was filtered and dried in a vacuum oven at 60 °C for 12 h to obtain the polymer sample. The polymer analysis results are shown in Table 3.

[0137] Table 3. Results of the copolymerization of ethylene and 1-octene catalyzed by complexes M1-M6 as the main catalysts. a

[0138]

[0139]

[0140] a Polymerization conditions: The amount of main catalyst M1 to M6 is 0.2 μmol, the co-catalyst is MAO, Al / M = 2000, the polymerization temperature is 180℃, the concentration of 1-octene is 1.0 mol / L, the polymerization pressure is 1.0 MPa, and the polymerization time is 10 min. b Molecular weight and molecular weight distribution (PDI) were determined by GPC. c The 1-octene insertion rate was determined by 1H NMR and 1C NMR.

[0141] As can be seen from the above embodiments, the present invention provides a class of metallocene complexes containing amidine groups that can efficiently catalyze the homopolymerization of ethylene and the copolymerization of ethylene / α-olefins. Furthermore, these complexes exhibit high temperature resistance, achieving a yield as high as 10 in the copolymerization reactions of ethylene at 140°C, 1-hexene at 160°C, and 1-octene at 180°C. 8 The activity is g / mol h, and the α-olefin insertion rate and polymer molecular weight are high and adjustable.

[0142] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A metallocene complex containing an amidine group, characterized in that, It has the structure shown in equation (I): Formula (I) M is a metal of titanium, zirconium, or hafnium; R1 and R2 may be the same or different, and are independent of each other, and are respectively unsubstituted C6~C10 aromatic groups; Alternatively, R1 and R2 may be the same or different, connected to each other to form a ring, with or without substituted C6~C10 aromatic heterocyclic groups; R3 to R6 may be the same or different, and are independent of each other, being H and unsubstituted C1 to C8 alkyl groups, respectively; Alternatively, R3 to R6 may be the same or different, and they may be linked together to form a ring, which consists of unsubstituted aromatic groups of C6 to C30. X is a halogen, methyl, dimethylamino, or benzyl.

2. The metallocene complex according to claim 1, characterized in that, The metallocene complex is selected from at least one of the complexes having an M1 to M6 structure: 、 、 、 、 、 。 3. A method for olefin polymerization, characterized in that, The catalyst used in the method includes a main catalyst and a co-catalyst, wherein the main catalyst is a metallocene complex containing an amidine group structure as described in claim 1 or 2.

4. The method according to claim 3, characterized in that, The co-catalyst is selected from one or more of alkylaluminum and borates.

5. The method according to claim 4, characterized in that, The alkylaluminum is selected from one or more aluminum oxanes or modified aluminum oxanes containing C1 to C8 alkyl groups; The borate is selected from one or more of triphenylmethyltetra(pentafluorophenyl)borate, tetra(pentafluorophenyl)borate-methyl di-(octadecyl)ammonium salt, and N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate.

6. The method according to claim 4, characterized in that, The molar ratio of the alkylaluminum to the metallocene complex is 3 to 5000, based on the molar ratio of element B to metal M in the metallocene complex; the molar ratio of the borate to the metal complex catalyst is 0 to 40, based on the molar ratio of element B to metal M in the metallocene complex.

7. The method according to claim 4, characterized in that, The molar ratio of the alkylaluminum to the metallocene complex is 50 to 3000, based on the molar ratio of metallic aluminum to metal M in the metallocene complex. The molar ratio of the borate to the metal complex catalyst is 0 to 15, based on the molar ratio of element B to metal M in the metallocene complex.

8. The method according to claim 3, characterized in that, The olefin polymerization is a homopolymerization of ethylene and / or a copolymerization of ethylene and α-olefins; The polymerization reaction temperature is 20~250℃; the polymerization pressure is 0.1~40MPa; The amount of the olefin polymerization catalyst composition used, based on the molar concentration of metal M in the metallocene complex in the reaction solvent, is 0.1~20 μmol / L.

9. The method according to claim 8, characterized in that, The method for copolymerizing ethylene with α-olefins includes the following steps: In the presence of a catalyst, ethylene and α-olefins undergo a polymerization reaction to obtain polyolefins; The α-olefin is selected from any one or more of propylene, 1-butene, 1-hexene, and 1-octene.

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