Phosphorus-nitrogen coordinated metallocene compound as well as preparation method and application thereof

Abstract

The invention provides a phosphorus-nitrogen coordinated metallocene compound and a preparation method and application thereof, the compound has a structure as shown in a formula I: in the formula I, M is selected from IVB group metals in the periodic table of elements; r1 is selected from hydrogen, halogen, C1-C10 direct or branched alkyl, and C1-C3 alkoxy; r2 is selected from hydrogen and C1-C6 straight chain or branched chain alkyl; y is selected from chlorine, C1-C3 alkyl substituted or unsubstituted by trimethylsilyl, and amino substituted by trimethylsilyl. The phosphorus-nitrogen coordinated metallocene compound provided by the invention has relatively high thermal stability, catalytic activity and comonomer insertion rate, and can realize high-temperature solution polymerization of ethylene and norbornene.

Description

Technical Field

[0001] This invention belongs to the field of metallocene catalyst technology, specifically relating to a phosphorus-nitrogen coordinated metallocene compound, its preparation method, and its application. Background Technology

[0002] Cyclic olefin copolymers (COCs) are amorphous polymers typically prepared by copolymerizing cyclic olefins with α-olefins. Compared to traditional polyolefins, polycarbonates, and polyoxymethylene (POM) plastics, cyclic olefin polymers exhibit exceptionally high transparency, low birefringence, rigidity, water vapor tightness, dimensional stability, heat resistance, scratch resistance, chemical resistance, and safety. Therefore, they are widely used in medical, packaging, optical, and electronic fields with stringent quality standards, such as in pre-filled syringes, pharmaceutical and food packaging films, and optical lenses.

[0003] The copolymerization of ethylene and norbornene is the most common method for producing cyclic olefin copolymers (COCs). Metallocene catalysts are widely used in this process due to their single active center and good copolymerization performance. However, for most catalysts, increasing the polymerization temperature within a certain range will decrease their polymerization activity. For example, the activity of most metallocene catalysts drops sharply above 100°C. For solution polymerization of cyclic olefin copolymers, the polymerization temperature needs to be above the polymer's melting point, meaning the catalyst must withstand at least 120°C. Therefore, achieving efficient high-temperature catalysis for the copolymerization of ethylene and norbornene is an important and practical research topic.

[0004] CN105175596A discloses a method for catalytic copolymerization of ethylene and norbornene. Under the action of a monoceramic titanium complex coordinated with a (thio)phenol-phosphoryl ligand and a co-catalyst, ethylene and norbornene can be copolymerized to obtain a cyclic olefin copolymer with a high and adjustable norbornene content. However, the copolymerization reaction temperature of this technology is only up to 25°C, making it unsuitable for high-temperature solution polymerization processes of cyclic olefin polymers.

[0005] CN117777208A discloses a nitrogen-containing heterocyclic borosilicate metal complex, its preparation method and application, and the copolymerization reaction of ethylene and norbornene. This method uses a nitrogen-containing heterocyclic borosilicate metal complex to catalyze the copolymerization of ethylene and norbornene to prepare cyclic olefin copolymers. However, in the copolymerization reaction of ethylene and norbornene disclosed in this technology, the molar ratio of catalyst to co-catalyst is 1:50-2000, and the amount of co-catalyst used is relatively large. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention aims to provide a phosphorus-nitrogen coordinated metallocene compound, its preparation method, and its applications.

[0007] To achieve the above objectives, the present invention provides a phosphorus-nitrogen coordinated metallocene compound having the structure shown in Formula I:

[0008]

[0009] In Formula I, M is selected from Group IVB metals in the periodic table;

[0010] R1 is selected from hydrogen, halogens, and C1-C. 10 R2 is selected from hydrogen, C1-C6 straight-chain or branched alkyl, or C1-C3 alkoxy; Y is selected from chlorine, C1-C3 alkyl substituted with or unsubstituted with trimethylsilyl, or amino group substituted with trimethylsilyl.

[0011] In the phosphorus-nitrogen coordinated metallocene compounds of the present invention, the ligands play two roles: on the one hand, based on the rigid structure of the ligands with large steric hindrance, they form strong metal-phosphorus and metal-nitrogen coordination bonds with the central metal M, which makes the metallocene compounds have good temperature resistance and thermal stability; on the other hand, the ligands of this structure can expose more of the central metal, thereby increasing the insertion rate of norbornene in the catalytic reaction.

[0012] In the above-mentioned phosphorus-nitrogen coordinated metallocene compounds, preferably, R1 and R2 are each independently selected from C1-C5 straight-chain or branched alkyl groups.

[0013] In the above-mentioned phosphorus-nitrogen coordinated metallocene compounds, preferably, R1 and R2 are each independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, isopentyl or tert-pentyl.

[0014] In the above-mentioned phosphorus-nitrogen coordinated metallocene compounds, preferably, R1 and R2 are each independently selected from methyl or isopropyl.

[0015] In the above-mentioned phosphorus-nitrogen coordination metallocene compounds, preferably, M is selected from titanium, zirconium, or hafnium, more preferably zirconium. M is selected from titanium ions (Ti). 4+ ), zirconium ions (Zr) 4+) or hafnium ions (Hf) 4+) More preferably, zirconium ions (Zr) 4+ ).

[0016] In the above-mentioned phosphorus-nitrogen coordinated metallocene compounds, preferably, Y is selected from trimethylsilylmethyl, di(trimethylsilyl)methylene, tri(trimethylsilyl)methoxymethyl or N,N-di(trimethylsilyl)amino.

[0017] According to a specific embodiment of the present invention, preferably, the structural formula of the phosphorus-nitrogen coordination metallocene compound is one of the following formulas:

[0018]

[0019] The present invention also provides a method for preparing the above-mentioned phosphorus-nitrogen coordination metallocene compound, comprising:

[0020] S1: The phosphorus-nitrogen compound shown in Formula II is reacted with alkyl lithium to obtain a phosphorus-nitrogen lithium salt compound;

[0021]

[0022] S2: The phosphorus-nitrogen lithium salt compound is reacted with a metallocene chloride of the general formula CpMCl3 to obtain a phosphorus-nitrogen coordinated metallocene dichloride compound; wherein, in the general formula CpMCl3, Cp is cyclopentadienyl;

[0023] S3: The phosphorus-nitrogen coordinated metallocene dichloride compound is reacted with compound ZY in a third reaction to obtain the phosphorus-nitrogen coordinated metallocene compound; wherein, in compound ZY, Z is selected from Li. + Na + or K + Li is preferred + or K + .

[0024] The reaction formula for the preparation method of the phosphorus-nitrogen coordinated metallocene compound of the present invention is as follows:

[0025]

[0026] In the method for preparing phosphorus-nitrogen coordination metallocene compounds provided by this invention, the compound represented by Formula II can be prepared using any existing method and its structure identified. The product of the second reaction does not need to be separated and can be directly subjected to the third reaction to prepare the phosphorus-nitrogen coordination metallocene compound in a one-pot process. Preferably, the product of the first reaction needs to be washed to remove unreacted alkyl lithium.

[0027] In the above-mentioned method for preparing phosphorus-nitrogen coordinated metallocene compounds, preferably, the metallocene chloride is selected from cyclopentadienyl titanium trichloride, cyclopentadienyl zirconium trichloride, or cyclopentadienyl hafnium trichloride.

[0028] In the above-mentioned method for preparing phosphorus-nitrogen coordinated metallocene compounds, preferably, the alkyl lithium reagent is selected from methyl lithium, n-butyl lithium, tert-butyl lithium or diisopropylamino lithium, more preferably n-butyl lithium.

[0029] In the above-mentioned method for preparing phosphorus-nitrogen coordinated metallocene compounds, preferably, the first reaction is carried out in a first solvent, which is an ether solvent; the second reaction is carried out in a second solvent, which is selected from toluene, xylene, benzene, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, cyclohexane or methylcyclohexane.

[0030] In the above-mentioned method for preparing phosphorus-nitrogen coordinated metallocene compounds, preferably, the first solvent is diethyl ether and / or tetrahydrofuran.

[0031] In the above-mentioned method for preparing phosphorus-nitrogen coordinated metallocene compounds, preferably, the third reaction is carried out in a third solvent, wherein the third solvent is one or a combination of two or more of diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, cyclohexane, methylcyclohexane, benzene, toluene, and xylene, more preferably toluene and / or diethyl ether.

[0032] In the above-mentioned method for preparing phosphorus-nitrogen coordinated metallocene compounds, preferably, the molar ratio of the compound shown in Formula II, alkyl lithium, metallocene chloride (CpMCl3) and compound ZY is 1:(0.5-2):(0.5-1.5):(1.5-3), more preferably 1:(0.5-1.5):(0.5-1):(1.5-2.5).

[0033] In the above-mentioned method for preparing phosphorus-nitrogen coordinated metallocene compounds, preferably, the conditions for the first reaction include: temperature -20℃ to 0℃, and reaction time of 3-6h; the conditions for the second reaction include: temperature 0-25℃, and reaction time of 1-3h; and the conditions for the third reaction include: temperature -5℃ to 25℃, and reaction time of 1-3h.

[0034] In the above-mentioned method for preparing phosphorus-nitrogen coordinated metallocene compounds, preferably, each reaction is carried out under an inert atmosphere.

[0035] In the preparation method of the phosphorus-nitrogen coordinated metallocene compound provided by the present invention, the phosphorus-nitrogen coordinated metallocene dichloride compound does not require purification and is directly reacted with compound ZY. After the reaction is completed, it can be post-processed according to conventional industry methods, such as recrystallization, column chromatography, etc. The post-processing method recommended by the present invention is to directly remove the solvent from the reaction solution after the reaction of the phosphorus-nitrogen coordinated metallocene dichloride compound with ZY, and then wash it with a solvent (selected from slightly soluble and very slightly soluble, such as n-hexane, n-heptane, n-pentane, etc.). The solid obtained is the phosphorus-nitrogen coordinated metallocene compound.

[0036] The present invention also provides the application of phosphorus-nitrogen coordinated metallocene compounds or phosphorus-nitrogen coordinated metallocene compounds obtained by the above preparation method in the catalytic copolymerization reaction of α-olefins and cycloolefins, and more preferably in the catalytic copolymerization of ethylene and norbornene to prepare cycloolefin copolymers.

[0037] This invention discloses a method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene, comprising:

[0038] In the presence of a main catalyst, a co-catalyst, and a copolymerization solvent, ethylene and norbornene are contacted and copolymerized to obtain an ethylene-norbornene copolymer.

[0039] The main catalyst is the above-mentioned phosphorus-nitrogen coordinated metallocene compound or the phosphorus-nitrogen coordinated metallocene compound obtained by the above preparation method; the co-catalyst is a mixed system composed of alkyl aluminum and organoboron compounds.

[0040] In the above method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene, preferably, the molar ratio of the main catalyst to norbornene is 1:500-25000, more preferably 1:1000-15000; the molar ratio of the main catalyst, organoboron compound, and alkylaluminum is 1:(1-3):(50-800).

[0041] In the above method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene, preferably, the alkylaluminum includes one or more combinations of trimethylaluminum, triethylaluminum, and triisobutylaluminum; the organoboron compound includes one or more combinations of Ph3CB(C6F5)4, B(C6F5)3, PhNMe2HB(C6F5)4, and Ph3CB[(CF3)2C6H3].

[0042] In the above method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene, preferably, the copolymerization solvent includes one or more of benzene, toluene, xylene, cyclohexane, and methylcyclohexane, more preferably one or more of toluene, xylene, or methylcyclohexane.

[0043] In the above method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene, preferably, the copolymerization reaction conditions include: a temperature of 60-180℃, more preferably 120-140℃; an ethylene pressure of 0.5-6 MPa, more preferably 0.3-2 MPa; and a reaction time of 1-15 min, more preferably 1-5 min.

[0044] The technical solution provided by this invention has the following beneficial effects:

[0045] The phosphorus-nitrogen coordinated metallocene compound provided by this invention has high thermal stability, catalytic activity and comonomer insertion rate, which can realize high-temperature solution polymerization of ethylene and norbornene. The norbornene insertion rate of the resulting cyclic olefin polymer is adjustable in the range of 48-72%, and it is particularly suitable for high-temperature solution catalytic copolymerization of ethylene and norbornene to produce cyclic olefin copolymers. Detailed Implementation

[0046] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0047] The phosphorus-nitrogen compound represented by Formula II used in the embodiments of this invention includes ligand A and ligand B, and its chemical structure is as follows:

[0048]

[0049] Ligand A was prepared according to the method disclosed in the literature (Liu, B.; Cui, D.; Ma, J.; Chen, X.; Jing, X. Synthesis and Reactivity of RaRe eaRth metal alkyl complexes stabilized by anilidophosphinimine and amino phosphine ligands. Chem.-EuR.J. 2007, 13, 834-845), and analyzed by HPLC-MS. 1 H NMR and 13 The structure was confirmed by C10 NMR; ligand B was prepared according to the method disclosed in the literature (Wei, C.; Han, B.; Q.; Zheng, D.; Zheng, Q.; Liu, S.; Li, Z. Aluminum Complexes Bea Ring Bidentate Amido-Phosphine Ligands for Ring-Opening Polymerization of εCapRolactone: SteRic Effect on CooRdination ChemistRy and Reactivity ORganometallics 2019, 38, 3816-3823), and analyzed by HPLC-MS, 1 H NMR and 13 The structure was confirmed by C NMR.

[0050] Example 1: Preparation of phosphorus-nitrogen coordinated metallocene compound 1

[0051] This embodiment provides a method for preparing phosphorus-nitrogen coordinated metallocene compounds, as detailed below:

[0052]

[0053] Under inert gas protection, ligand A (phosphorus nitrogen compound) (3.951 g, 10 mmol, Fw = 395.18) was dissolved in 50 mL of dry tetrahydrofuran, cooled to -10 °C, and a hexane solution containing 12 mmol of n-butyllithium was added dropwise, reacting for 3 h. After the solvent was removed, 20 mL of hexane was added to wash away unreacted n-butyllithium, yielding the phosphorus nitrogen lithium salt compound. 50 mL of toluene and cyclopentadienyl titanium trichloride (metallocene trichloride) (1.581 g, 10 mmol, Fw = 158.06) were added back to the phosphorus nitrogen lithium salt compound, and the reaction was carried out at room temperature for 2 h to obtain the reaction solution. Then, 10 mL of 1M... A tetrahydrofuran solution of KN(SiMe3)2 was slowly added dropwise to the above reaction solution at 0°C (approximately 30 min). The reaction was allowed to proceed for 3 h. The solvent was then removed by vacuum drying, and the mixture was washed with 20 mL of hexane to obtain a red solid, namely phosphorus-nitrogen coordinated metallocene compound 1 (7.03 g, yield 85%, Fw = 827.36). The characterization results are as follows:

[0054] Elemental analysis data for C44H66N3PSi4Ti: Calculated values: C, 63.81; H, 8.0; N, 5.07. Measured values: C, 63.78; H, 7.98; N, 5.12.

[0055] NMR data: 1 H NMR (400Hz, CDCl3, δ, ppm): 7.56-7.49 (m, 2H), 7.49-7.43 (m, 4H), 7.43-7.36 (m, 4H), 7.31 (t, 1H), 7.22 (t ,1H),7.09-7.01(m,2H),6.99(d,2H),6.84(t,1H),6.71(s,5H)4.15(s,2H),1.98(s,6H),-0.67(s,36H).

[0056] Example 2: Preparation of phosphorus-nitrogen coordinated metallocene compound 2

[0057]

[0058] This embodiment provides a method for preparing a phosphorus-nitrogen coordinated metallocene compound, which differs from Example 1 only in that the metallocene trichloride is cyclopentadienyl zirconium trichloride; the other conditions are the same as in Example 1.

[0059] In this embodiment, a red solid product was obtained, denoted as phosphorus-nitrogen coordinated metallocene compound 2, with a yield of 87% (7.56 g, Fw = 869.31).

[0060] Elemental analysis data for C44H66N3PSi4ZR: Calculated values: C, 60.64; H, 7.63; N, 4.82. Measured values: C, 60.70; H, 7.65; N, 4.85.

[0061] NMR data: 1 H NMR (400Hz, CDCl3, δ, ppm): 7.68-7.52(m,2H),7.49-7.45(m,4H),7.44-7.38(m,4H),7.35(t,1H),7.29(t ,1H),7.14-7.12(m,2H),6.94(d,2H),6.79(t,1H),6.70(s,5H),4.17(s,2H),1.96(s,6H),-0.49(s,36H).

[0062] Example 3: Preparation of phosphorus-nitrogen coordinated metallocene compound 3

[0063]

[0064] This embodiment provides a method for preparing a phosphorus-nitrogen coordinated metallocene compound, which differs from Example 1 only in that the metallocene trichloride used is cyclopentadienyl hafnium trichloride; the other conditions are the same as in Example 1.

[0065] In this example, a yellow solid product was obtained, designated as phosphorus-nitrogen coordinated metallocene compound 3, with a yield of 88% (8.44 g, Fw = 959.35).

[0066] Elemental analysis data for C44H66N3PSi4Hf: Calculated values: C, 55.12; H, 6.94; N, 4.38. Measured values: C, 55.14; H, 6.90; N, 4.36.

[0067] NMR data: 1 H NMR (400Hz, CDCl3, δ, ppm): 7.64-7.51 (m, 2H), 7.44-7.39 (m, 4H), 7.36-7.29 (m, 4H), 7.24 (t, 1H), 7.18 (t ,1H),7.11-7.06(m,2H),6.96(d,2H),6.87(t,1H),6.75(s,5H),4.18(s,2H),1.96(s,6H),-0.66(s,36H).

[0068] Example 4: Preparation of phosphorus-nitrogen coordinated metallocene compound 4

[0069] This embodiment provides a method for preparing phosphorus-nitrogen coordinated metallocene compounds, as detailed below:

[0070]

[0071] Under inert gas protection, ligand A (phosphorus nitrogen compound) (7.413 g, 10 mmol, Fw = 741.35) was dissolved in 50 mL of dry tetrahydrofuran, and then 12 mmol of n-butyllithium was added and reacted at 0 °C for 2 h. After the solvent was removed, 20 mL of n-hexane was added to wash away the unreacted n-butyllithium, yielding a phosphorus nitrogen lithium salt compound. 50 mL of toluene and cyclopentadienyl titanium trichloride (1.581 g, 10 mmol, Fw = 158.06) were added back to the phosphorus nitrogen lithium salt compound, and the reaction was carried out at room temperature for 2 h to obtain a reaction solution. Then, 10 mL of a 1 M LiCH2SiMe3 tetrahydrofuran solution was added to the above reaction solution at 25 °C, and the reaction was carried out for 1 h. After the solvent was removed, 20 mL of hexane was added for washing to obtain a red solid, designated as phosphorus nitrogen coordinated metallocene compound 4 (9.25 g, yield 90%, Fw = 1027.46). Its characterization results are as follows:

[0072] Elemental analysis data for C67H74NPSi2Ti: Calculated values: C, 78.26; H, 7.25; N, 1.36. Measured values: C, 78.19; H, 7.32; N, 1.32.

[0073] NMR data: 1 H NMR (400Hz, CDCl3, δ, ppm): 7.45-7.37(m,2H),7.36-7.29(m,8H),7.20-7.00(m,14H),6.94-6.87(m,1H),6.85(d,4H),6.81-6.76(m,4 H),6.69(s,5H),6.30(s,2H),6.20-6.21(m,1H),6.09(s,2H),3.84(s,2H),2.62(hept,1H),1.15(s,4H),0.99(d,6H),-0.05(s,18H).

[0074] Example 5: Preparation of phosphorus-nitrogen coordinated metallocene compound 5

[0075]

[0076] This embodiment provides a method for preparing a phosphorus-nitrogen coordinated metallocene compound, which differs from Example 4 only in that the metallocene trichloride is cyclopentadienyl zirconium trichloride; the other conditions are the same as in Example 4.

[0077] In this embodiment, a red solid product was obtained, denoted as phosphorus-nitrogen coordinated metallocene compound 5, with a yield of 88% (9.41 g, Fw = 1069.41).

[0078] Elemental analysis data for C67H74NPSi2ZR: Calculated values: C, 75.09; H, 6.96; N, 1.31. Measured values: C, 75.12; H, 6.91; N, 1.35.

[0079] NMR data: 1 H NMR (400Hz, CDCl3, δ, ppm): 7.55-7.42(m,2H),7.40-7.29(m,8H),7.25-7.06(m,14H),6.99-6.87(m,1H),6.87(d,4H),6.83-6.78(m,4 H),6.70(s,5H),6.35(s,2H),6.26-6.22(m,1H),6.13(s,2H),3.88(s,2H),2.66(hept,1H),1.21(s,4H),0.97(d,6H),-0.07(s,18H).

[0080] Example 6: Preparation of phosphorus-nitrogen coordinated metallocene compound 6

[0081]

[0082] This embodiment provides a method for preparing a phosphorus-nitrogen coordinated metallocene compound, which differs from Example 4 only in that the metallocene trichloride used is cyclopentadienyl hafnium trichloride; the other conditions are the same as in Example 4.

[0083] In this example, a yellow solid product was obtained, designated as phosphorus-nitrogen coordinated metallocene compound 6, with a yield of 84% (9.74 g, Fw = 1159.46).

[0084] Elemental analysis data for C67H74NPSi2Hf: Calculated values: C, 69.44; H, 6.44; N, 1.21. Measured values: C, 69.48; H, 6.49; N, 1.23.

[0085] NMR data: 1 H NMR (400Hz, CDCl3, δ, ppm): 7.52-7.39 (m, 2H), 7.37-7.27 (m, 8H), 7.23-7.06 (m, 14H), 6.98-6.79 (m, 1H), 6.75 (d, 4H), 6.72-6.68 (m, 4 H),6.65(s,5H),6.37(s,2H),6.29-6.24(m,1H),6.15(s,2H),3.41(s,2H),2.61(hept,1H),1.19(s,4H),0.95(d,6H),-0.09(s,18H).

[0086] Example 7

[0087] This embodiment provides a method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene, wherein the aforementioned phosphorus-nitrogen coordinated metallocene compound 1 is used as the main catalyst, as detailed below:

[0088] After baking a 300 mL reactor at 150 °C under vacuum for 3-4 hours, nitrogen gas was introduced to maintain positive pressure, and the reaction temperature was set to 90 °C. Once the temperature stabilized, 150 mL of toluene, 400 mmol of norbornene, and 2.5 mmol of triisobutylaluminum were added to the reactor under vacuum. Ethylene gas was introduced and the pressure inside the reactor was maintained at 2 MPa. Then, a toluene solution containing 50 μmol of the main catalyst and 100 μmol of triphenylcarbon fluorophenyl borate was injected through ethylene at a pressure of 2.6 MPa to initiate the polymerization reaction. After reacting for 5 minutes, the pressure was released, the reactor was opened, and the polymer in the reactor was poured into an ethanol solution. The polymer was washed, filtered, and collected. It was then dried in a vacuum oven at 60 °C to constant weight to obtain the ethylene-norbornene copolymer.

[0089] Example 8

[0090] This embodiment provides a method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene, wherein the aforementioned phosphorus-nitrogen coordinated metallocene compound 1 is used as the main catalyst, as detailed below:

[0091] After baking a 300 mL reactor at 150 °C under vacuum for 3-4 hours, nitrogen gas was introduced to maintain positive pressure, and the reaction temperature was set to 90 °C. Once the temperature stabilized, 150 mL of toluene, 400 mmol of norbornene, and 2.5 mmol of methylaluminoxane were added to the reactor under vacuum, and ethylene gas was introduced while maintaining the pressure inside the reactor at 4 MPa. Then, a solution containing 50 μmol of the main catalyst and 100 μmol of triphenylcarbon non-fluorinated phenyl borate toluene was injected through ethylene at a pressure of 4.6 MPa to initiate the polymerization reaction. After reacting for 5 minutes, the pressure was released, the reactor was opened, and the polymer in the reactor was poured into an ethanol solution. The polymer was washed, filtered, and collected, then dried in a 60 °C vacuum oven to constant weight to obtain the ethylene-norbornene copolymer.

[0092] Example 9

[0093] This embodiment provides a method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene, wherein the aforementioned phosphorus-nitrogen coordinated metallocene compound 2 is used as the main catalyst, as detailed below:

[0094] After baking a 300 mL reactor at 150 °C under vacuum for 3-4 hours, nitrogen gas was introduced to maintain positive pressure, and the reaction temperature was set to 80 °C. Once the temperature stabilized, 150 mL of methylcyclohexane, 400 mmol of norbornene, and 20 mmol of methylaluminoxane were added to the reactor under vacuum. Ethylene gas was introduced and the pressure inside the reactor was maintained at 2.5 MPa. Then, a solution containing 40 μmol of the main catalyst and 40 μmol of triphenylcarbon non-fluorinated phenylborate methylcyclohexane was injected through ethylene at a pressure of 3.1 MPa to start the polymerization reaction. After reacting for 10 minutes, the pressure was released, the reactor was opened, and the polymer in the reactor was poured into an ethanol solution. The polymer was washed, filtered, and collected. It was then dried in a 60 °C vacuum oven to constant weight to obtain the ethylene-norbornene copolymer.

[0095] Example 10

[0096] This embodiment provides a method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene, wherein the aforementioned phosphorus-nitrogen coordinated metallocene compound 2 is used as the main catalyst, as detailed below:

[0097] After baking a 300 mL reactor at 150 °C under vacuum for 3-4 hours, nitrogen gas was introduced to maintain positive pressure, and the reaction temperature was set to 120 °C. Once the temperature stabilized, 150 mL of methylcyclohexane, 400 mmol of norbornene, and 20 mmol of methylaluminoxane were added to the reactor under vacuum. Ethylene gas was introduced and the pressure inside the reactor was maintained at 2.5 MPa. Then, a solution containing 40 μmol of the main catalyst and 40 μmol of triphenylcarbon non-fluorinated phenyl borate methylcyclohexane was injected through ethylene at a pressure of 3.1 MPa to start the polymerization reaction. After reacting for 10 minutes, the pressure was released, the reactor was opened, and the polymer in the reactor was poured into an ethanol solution. The polymer was washed, filtered, and collected. It was then dried in a vacuum oven at 60 °C to constant weight to obtain the ethylene-norbornene copolymer.

[0098] Example 11

[0099] This embodiment provides a method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene, wherein the aforementioned phosphorus-nitrogen coordinated metallocene compound 2 is used as the main catalyst, as detailed below:

[0100] After baking a 300 mL reactor at 150 °C under vacuum for 3-4 hours, nitrogen gas was introduced to maintain positive pressure, and the reaction temperature was set to 160 °C. Once the temperature stabilized, 150 mL of methylcyclohexane, 400 mmol of norbornene, and 20 mmol of methylaluminoxane were added to the reactor under vacuum. Ethylene gas was introduced and the pressure inside the reactor was maintained at 2.5 MPa. Then, a solution containing 40 μmol of the main catalyst and 60 μmol of triphenylcarbon non-fluorinated phenyl borate methylcyclohexane was injected through ethylene at a pressure of 3.1 MPa to start the polymerization reaction. After reacting for 10 minutes, the pressure was released, the reactor was opened, and the polymer in the reactor was poured into an ethanol solution. The polymer was washed, filtered, and collected. It was then dried in a 60 °C vacuum oven to constant weight to obtain the ethylene-norbornene copolymer.

[0101] Example 12

[0102] This embodiment provides a method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene, wherein the aforementioned phosphorus-nitrogen coordinated metallocene compound 3 is used as the main catalyst, as detailed below:

[0103] After baking a 300 mL reactor at 150 °C under vacuum for 3-4 hours, nitrogen gas was introduced to maintain positive pressure, and the reaction temperature was set to 140 °C. Once the temperature stabilized, 150 mL of toluene, 400 mmol of norbornene, and 8 mmol of methylaluminoxane were added to the reactor under vacuum. Ethylene gas was introduced and the pressure inside the reactor was maintained at 1.5 MPa. Then, a solution containing 80 μmol of the main catalyst and 160 μmol of triphenylcarbon non-fluorophenyl borate toluene was injected through ethylene at a pressure of 2.1 MPa to start the polymerization reaction. After reacting for 5 minutes, the pressure was released, the reactor was opened, and the polymer in the reactor was poured into an ethanol solution. The polymer was washed, filtered, and collected. It was then dried in a 60 °C vacuum oven to constant weight to obtain the ethylene-norbornene copolymer.

[0104] Example 13

[0105] This embodiment provides a method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene, wherein the aforementioned phosphorus-nitrogen coordinated metallocene compound 3 is used as the main catalyst, as detailed below:

[0106] After baking a 300 mL reactor at 150 °C under vacuum for 3-4 hours, nitrogen gas was introduced to maintain positive pressure, and the reaction temperature was set to 160 °C. Once the temperature stabilized, 150 mL of toluene, 400 mmol of norbornene, and 8 mmol of methylaluminoxane were added to the reactor under vacuum. Ethylene gas was introduced and the pressure inside the reactor was maintained at 1.5 MPa. Then, a solution containing 80 μmol of the main catalyst and 160 μmol of triphenylcarbon non-fluorophenyl borate toluene was injected through ethylene at a pressure of 2.1 MPa to initiate the polymerization reaction. After reacting for 5 minutes, the pressure was released, the reactor was opened, and the polymer in the reactor was poured into an ethanol solution. The polymer was washed, filtered, and collected. It was then dried in a 60 °C vacuum oven to constant weight to obtain the ethylene-norbornene copolymer.

[0107] Example 14

[0108] This embodiment provides a method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene, wherein the aforementioned phosphorus-nitrogen coordinated metallocene compound 4 is used as the main catalyst, as detailed below:

[0109] After baking a 300 mL reactor at 150 °C under vacuum for 3-4 hours, nitrogen gas was introduced to maintain positive pressure, and the reaction temperature was set to 120 °C. Once the temperature stabilized, 150 mL of toluene, 400 mmol of norbornene, and 8 mmol of methylaluminoxane were added to the reactor under vacuum. Ethylene gas was introduced and the pressure inside the reactor was maintained at 1.5 MPa. Then, a solution containing 40 μmol of the main catalyst and 100 μmol of triphenylcarbon non-fluorinated phenyl borate toluene was injected through ethylene at a pressure of 2.1 MPa to start the polymerization reaction. After reacting for 10 minutes, the pressure was released, the reactor was opened, and the polymer in the reactor was poured into an ethanol solution. The polymer was washed, filtered, and collected. It was then dried in a 60 °C vacuum oven to constant weight to obtain the ethylene-norbornene copolymer.

[0110] Example 15

[0111] This embodiment provides a method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene, wherein the aforementioned phosphorus-nitrogen coordinated metallocene compound 4 is used as the main catalyst, as detailed below:

[0112] After baking a 300 mL reactor at 150 °C under vacuum for 3-4 hours, nitrogen gas was introduced to maintain positive pressure, and the reaction temperature was set to 140 °C. Once the temperature stabilized, 150 mL of cyclohexane, 400 mmol of norbornene, and 8 mmol of methylaluminoxane were added to the reactor under vacuum. Ethylene gas was introduced and the pressure inside the reactor was maintained at 2 MPa. Then, a solution containing 16 μmol of the main catalyst and 40 μmol of triphenylcarbon fluorophenyl borate cyclohexane was injected through ethylene at a pressure of 2.6 MPa to start the polymerization reaction. After reacting for 10 minutes, the pressure was released, the reactor was opened, and the polymer in the reactor was poured into an ethanol solution. The polymer was washed, filtered, and collected. It was then dried in a 60 °C vacuum oven to constant weight to obtain the ethylene-norbornene copolymer.

[0113] Example 16

[0114] This embodiment provides a method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene, wherein the aforementioned phosphorus-nitrogen coordinated metallocene compound 5 is used as the main catalyst, as detailed below:

[0115] After baking a 300 mL reactor at 150 °C under vacuum for 3-4 hours, nitrogen gas was introduced to maintain positive pressure, and the reaction temperature was set to 140 °C. Once the temperature stabilized, 150 mL of xylene, 400 mmol of norbornene, and 28 mmol of methylaluminoxane were added to the reactor under vacuum. Ethylene gas was introduced and the pressure inside the reactor was maintained at 2 MPa. Then, a solution containing 40 μmol of the main catalyst and 80 μmol of triphenylcarbon non-fluorinated phenylborate xylene was introduced through ethylene gas at a pressure of 2.6 MPa to start the polymerization reaction. After reacting for 15 minutes, the pressure was released, the reactor was opened, and the polymer in the reactor was poured into an ethanol solution. The polymer was washed, filtered, and collected. It was then dried in a vacuum oven at 60 °C to constant weight to obtain the ethylene-norbornene copolymer.

[0116] Example 17

[0117] This embodiment provides a method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene, wherein the aforementioned phosphorus-nitrogen coordinated metallocene compound 5 is used as the main catalyst, as detailed below:

[0118] After baking a 300 mL reactor at 150 °C under vacuum for 3-4 hours, nitrogen gas was introduced to maintain positive pressure, and the reaction temperature was set to 160 °C. Once the temperature stabilized, 150 mL of toluene, 400 mmol of norbornene, and 28 mmol of methylaluminoxane were added to the reactor under vacuum. Ethylene gas was introduced and the pressure inside the reactor was maintained at 1.5 MPa. Then, a solution containing 27 μmol of the main catalyst and 41 μmol of triphenylcarbon non-fluorinated phenyl borate toluene was injected through ethylene at a pressure of 3.1 MPa to initiate the polymerization reaction. After reacting for 15 minutes, the pressure was released, the reactor was opened, and the polymer in the reactor was poured into an ethanol solution. The polymer was washed, filtered, and collected. It was then dried in a vacuum oven at 60 °C until constant weight to obtain the ethylene-norbornene copolymer.

[0119] Example 18

[0120] This embodiment provides a method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene, wherein the aforementioned phosphorus-nitrogen coordinated metallocene compound 5 is used as the main catalyst, as detailed below:

[0121] After baking a 300 mL reactor at 150 °C under vacuum for 3-4 hours, nitrogen gas was introduced to maintain positive pressure, and the reaction temperature was set to 160 °C. Once the temperature stabilized, 150 mL of toluene, 400 mmol of norbornene, and 28 mmol of methylaluminoxane were added to the reactor under vacuum. Ethylene gas was introduced and the pressure inside the reactor was maintained at 3.0 MPa. Then, a solution containing 27 μmol of the main catalyst and 41 μmol of triphenylcarbon non-fluorophenyl borate toluene was injected through ethylene at a pressure of 3.6 MPa to initiate the polymerization reaction. After reacting for 15 minutes, the pressure was released, the reactor was opened, and the polymer in the reactor was poured into an ethanol solution. The polymer was washed, filtered, and collected. It was then dried in a vacuum oven at 60 °C until constant weight to obtain the ethylene-norbornene copolymer.

[0122] Example 19

[0123] This embodiment provides a method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene, using the aforementioned phosphorus-nitrogen coordinated metallocene compound 6 as the main catalyst, as detailed below:

[0124] After baking a 300 mL reactor at 150 °C under vacuum for 3-4 hours, nitrogen gas was introduced to maintain positive pressure, and the reaction temperature was set to 140 °C. Once the temperature stabilized, 150 mL of methylcyclohexane, 400 mmol of norbornene, and 12 mmol of methylaluminoxane were added to the reactor under vacuum. Ethylene gas was introduced and the pressure inside the reactor was maintained at 2.0 MPa. Then, a solution containing 40 μmol of the main catalyst and 40 μmol of triphenylcarbon non-fluorinated phenylborate methylcyclohexane was injected through ethylene at a pressure of 2.6 MPa to start the polymerization reaction. After reacting for 5 minutes, the pressure was released, the reactor was opened, and the polymer in the reactor was poured into an ethanol solution. The polymer was washed, filtered, and collected. It was then dried in a vacuum oven at 60 °C to constant weight to obtain the ethylene-norbornene copolymer.

[0125] Example 20

[0126] This embodiment provides a method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene, using the aforementioned phosphorus-nitrogen coordinated metallocene compound 6 as the main catalyst, as detailed below:

[0127] After baking a 300 mL reactor at 150 °C under vacuum for 3-4 hours, nitrogen gas was introduced to maintain positive pressure, and the reaction temperature was set to 140 °C. Once the temperature stabilized, 150 mL of methylcyclohexane, 400 mmol of norbornene, and 12 mmol of methylaluminoxane were added to the reactor under vacuum. Ethylene gas was introduced and the pressure inside the reactor was maintained at 2.0 MPa. Then, a solution containing 24 μmol of the main catalyst and 24 μmol of triphenylcarbon fluorophenyl borate methylcyclohexane was injected through ethylene gas at a pressure of 2.6 MPa to initiate the polymerization reaction. After reacting for 5 minutes, the pressure was released, the reactor was opened, and the polymer in the reactor was poured into an ethanol solution. The polymer was washed, filtered, and collected. It was then dried in a 60 °C vacuum oven to constant weight to obtain the ethylene-norbornene copolymer.

[0128] Comparative Example 1

[0129] This comparative example provides a method for preparing ethylene-norbornene copolymer, which differs from Example 15 only in that the main catalyst used in this comparative example is an aniline alkoxy titanium complex; the other conditions are the same as in Example 15.

[0130] The structure of the aniline alkoxy titanium complex used in this comparative example is as follows: It can be synthesized according to the method reported in the literature Vijayak Rishna, K.; Sunda RaRajan, G.; Polyme R. 2006, 47, 3363-71.

[0131] Comparative Example 2

[0132] This comparative example provides a method for preparing ethylene-norbornene copolymer, which differs from Example 7 only in that the main catalyst used in this comparative example is a metallocene compound stabilized by a ketimine ligand; the other conditions are the same as in Example 7.

[0133] The structure of the main catalyst in this comparative example is: It can be prepared according to the method reported in Zhang, S.; PieRs, WE; Gao, X.; PaRvez, MJAm. Chem. Soc. 2000, 122, 5499.

[0134] The polymerization results of Examples 7-20 and Comparative Examples 1-2 are shown in Table 1. The molecular weight and molecular weight distribution of the polymers were tested using a PL-GPC 220 high-temperature column chromatography system at 150°C. The mobile phase was 1,2,4-trichlorobenzene (TCB) with 0.05 wt% 2,6-di-tert-butyl-4-methylphenol (BHT) added as an antioxidant. The flow rate was set to 1.0 mL / min, and PL EasiCal PS-1 was used as a standard. The glass transition temperature (Tg) was measured using a differential scanning calorimeter (DSC) model PeRkin-ElmeR PyRis 1. The test procedure involved two heating cycles followed by one cooling cycle, with both heating and cooling rates at 20°C / min.

[0135] Table 1. Polymerization results of Examples 7-20 and Comparative Examples 1-2

[0136]

[0137] As shown in Table 1, the phosphorus-nitrogen coordinated metallocene compound provided by this invention has high thermal stability and can achieve high-temperature solution polymerization of ethylene and norbornene between 140-180℃, with a polymerization activity of up to 13.6 × 10⁻⁶. 7 The norbornene insertion rate of the obtained cyclic olefin polymer is adjustable in the range of 48-72% with g / (mol·cat), and has good application value.

[0138] In Comparative Example 1, the polymerization reaction did not occur under the above catalytic conditions, and the main catalyst (aniline alkoxy titanium complex) was deactivated at this temperature (140°C). In comparison, the phosphorus-nitrogen coordinated metallocene compound of the present invention exhibits good thermal stability and is suitable for high-temperature solution polymerization processes.

[0139] The ethylene-norbornene copolymer obtained in Comparative Example 2 had a lower weight-average molecular weight and a lower norbornene insertion rate. This demonstrates that the phosphorus-nitrogen coordinated metallocene compound of the present invention exhibits a higher norbornene insertion rate in the catalytic copolymerization of ethylene and norbornene, significantly superior to conventional metallocene compounds.

[0140] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A phosphorus-nitrogen coordinated metallocene compound having the structure shown in Formula I: In Equation I, where, M is selected from Group IVB metals in the periodic table; R1 is selected from hydrogen, halogens, and C1-C. 10 R2 is selected from hydrogen, C1-C6 straight-chain or branched alkyl, or C1-C3 alkoxy; Y is selected from chlorine, C1-C3 alkyl substituted with or unsubstituted with trimethylsilyl, or amino group substituted with trimethylsilyl.

2. The phosphorus-nitrogen coordination metallocene compound according to claim 1, wherein, R1 and R2 are each independently selected from C1-C5 straight-chain or branched alkyl groups.

3. The phosphorus-nitrogen coordination metallocene compound according to claim 2, wherein, R1 and R2 are each independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, isopentyl, or tert-pentyl.

4. The phosphorus-nitrogen coordination metallocene compound according to claim 3, wherein, R1 and R2 are each independently selected from methyl or isopropyl.

5. The phosphorus-nitrogen coordination metallocene compound according to claim 1, wherein, M is selected from titanium, zirconium, or hafnium.

6. The phosphorus-nitrogen coordination metallocene compound according to claim 1, wherein, Y is selected from trimethylsilylmethyl, di(trimethylsilyl)methylene, tri(trimethylsilyl)methoxymethyl or N,N-di(trimethylsilyl)amino.

7. The phosphorus-nitrogen coordination metallocene compound according to claim 1, wherein, The structural formula of the phosphorus-nitrogen coordinated metallocene compound is one of the following:

8. A method for preparing the phosphorus-nitrogen coordination metallocene compound according to any one of claims 1-7, comprising: S1: The phosphorus-nitrogen compound shown in Formula II is reacted with alkyl lithium to obtain a phosphorus-nitrogen lithium salt compound; S2: The phosphorus-nitrogen lithium salt compound is reacted with a metallocene chloride of the general formula CpMCl3 to obtain a phosphorus-nitrogen coordinated metallocene dichloride compound; wherein, in the general formula CpMCl3, Cp is cyclopentadienyl; S3: The phosphorus-nitrogen coordinated metallocene dichloride compound is reacted with compound ZY in a third reaction to obtain the phosphorus-nitrogen coordinated metallocene compound; wherein, in compound ZY, Z is selected from Li. + Na + or K + .

9. The method for preparing the phosphorus-nitrogen coordinated metallocene compound according to claim 8, wherein, The metallocene chloride is selected from cyclopentadienyl titanium trichloride, cyclopentadienyl zirconium trichloride, or cyclopentadienyl hafnium trichloride.

10. The method for preparing the phosphorus-nitrogen coordinated metallocene compound according to claim 8, wherein, The alkyl lithium is selected from methyl lithium, n-butyl lithium, tert-butyl lithium, or diisopropylamino lithium.

11. The method for preparing the phosphorus-nitrogen coordinated metallocene compound according to claim 8, wherein, The first reaction is carried out in a first solvent, which is an ether solvent; the second reaction is carried out in a second solvent, which is selected from toluene, xylene, benzene, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, cyclohexane or methylcyclohexane.

12. The method for preparing the phosphorus-nitrogen coordinated metallocene compound according to claim 8, wherein, The third reaction is carried out in a third solvent, which is one or a combination of two or more of the following: diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, cyclohexane, methylcyclohexane, benzene, toluene, and xylene.

13. The method for preparing the phosphorus-nitrogen coordinated metallocene compound according to claim 8, wherein, The molar ratio of the compound shown in Formula II, alkyllithium, metallocene chloride and compound ZY is 1:(0.5-2):(0.5-1.5):(1.5-3).

14. The method for preparing the phosphorus-nitrogen coordinated metallocene compound according to claim 8, wherein, The conditions for the first reaction are: temperature -20℃ to 0℃, reaction time 3-6h; the conditions for the second reaction are: temperature 0-25℃, reaction time 1-3h; the conditions for the third reaction are: temperature -5℃ to 25℃, reaction time 1-3h.

15. The method for preparing the phosphorus-nitrogen coordinated metallocene compound according to claim 8, wherein, All reactions were carried out under an inert atmosphere.

16. The application of the phosphorus-nitrogen coordinated metallocene compound according to any one of claims 1-7 or the phosphorus-nitrogen coordinated metallocene compound obtained by the preparation method according to any one of claims 8-15 in the catalytic copolymerization reaction of α-olefins and cycloolefins.

17. A method for preparing cyclic olefin copolymers by copolymerizing ethylene with norbornene, comprising: In the presence of a main catalyst, a co-catalyst, and a copolymerization solvent, ethylene and norbornene are contacted and copolymerized to obtain an ethylene-norbornene copolymer. The main catalyst is the phosphorus-nitrogen coordinated metallocene compound according to any one of claims 1-7 or the phosphorus-nitrogen coordinated metallocene compound obtained by the preparation method according to any one of claims 8-15; the co-catalyst is a mixed system composed of alkylaluminum and organoboron compounds.

18. The method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene according to claim 17, wherein, The molar ratio of the main catalyst to norbornene is 1:500-25000; the molar ratio of the main catalyst, organoboron compound, and alkylaluminum is 1:(1-3):(50-800).

19. The method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene according to claim 17, wherein, The alkylaluminum includes one or more of trimethylaluminum, triethylaluminum, and triisobutylaluminum; the organoboron compound includes one or more of Ph3CB(C6F5)4, B(C6F5)3, PhNMe2HB(C6F5)4, and Ph3CB[(CF3)2C6H3].

20. The method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene according to claim 17, wherein, The copolymer solvent includes one or more of benzene, toluene, xylene, cyclohexane, and methylcyclohexane.

21. The method for preparing cyclic olefin copolymers by copolymerizing ethylene and norbornene according to claim 17, wherein, The conditions for the copolymerization reaction include: a temperature of 60-180℃, an ethylene pressure of 0.5-6 MPa, and a reaction time of 1-15 min.

Images