A nickel or palladium catalyst, its preparation method and application

Abstract

The present invention discloses a nickel or palladium catalyst, a preparation method thereof and an application thereof, belonging to the technical field of catalytic polymerization. The nickel or palladium catalyst has a structure shown in formula (I). By adjusting the axial steric hindrance, the present invention obtains a nickel or palladium catalyst with good high-temperature resistance and high activity. When used in olefin polymerization, polyolefins with a molecular weight of up to 1 million and a branching degree of 63-101 / 1000C can be obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic polymerization, and particularly relates to a nickel or palladium catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Polyolefins, i.e., polymers of olefins, are a type of polymer material with the largest output and the most applications. Among them, polyethylene and polypropylene are the most important. Due to the characteristics of rich raw materials, low price, easy processing and molding, and excellent comprehensive performance, they are the most widely used in real life, and their application in automobiles is also becoming increasingly important and shows a trend of gradual expansion.

[0003] Catalysts play an important role in olefin polymerization, which can improve the reaction rate, product selectivity, and product molecular weight. Common catalysts include metal catalysts, acid catalysts, organic catalysts, etc. In olefin polymerization reactions, metal catalysts are the most common. Metal catalysts can be divided into homogeneous catalysts and heterogeneous catalysts. Homogeneous catalysts refer to catalysts and reactants in the same state during the reaction, such as metal catalysts like palladium, nickel, platinum, chromium, etc. Metal catalysts cause olefin monomers to undergo addition reactions through the catalytic action of metal ions to form polymer chains. Commonly used palladium catalysts can promote the polymerization reaction rate but will reduce the molecular weight of the product, and chromium catalysts can increase the molecular weight of the product but will reduce the reaction rate.

[0004] Currently, α-diimine late transition metal nickel or palladium catalysts can use ethylene as the sole monomer to prepare polyolefins with a branched structure. However, there are still some problems that have not been solved, such as the catalyst is easily deactivated at high temperatures, especially showing extremely poor performance above 90 °C, low molecular weight, low activity, and at high temperatures, the molecular weight of the polymer is low and the degree of branching is generally not high, and it is difficult to obtain elastomers with a higher molecular weight. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a nickel or palladium catalyst, a preparation method thereof, and an application thereof. The nickel or palladium catalyst has good thermal stability and high activity, and when used in olefin polymerization, polyolefins with high molecular weight and high degree of branching can be obtained.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] The present invention provides a nickel or palladium catalyst having the structure shown in formula (Ⅰ):

[0008]

[0009] Among them, L is selected from a nickel atom or a palladium atom.

[0010] R1, R2, R3, and R4 are independently selected from substituted or unsubstituted straight-chain or branched C1-C20 An alkyl group, a substituted or unsubstituted 5- to 8-membered cycloalkyl group, a substituted or unsubstituted aryl group, One or more of the following.

[0011] R a 、R b Independently selected from one or more of a substituted or unsubstituted 5- to 8-membered cycloalkyl group and a substituted or unsubstituted aryl group.

[0012] R5 and R6 are independently selected from a substituted or unsubstituted straight-chain or branched C1-C 20 alkyl group.

[0013] Alternatively, R5, R6 and the adjacent carbon atoms are connected to form an acenaphthene ring.

[0014] R7 and R8 are independently selected from a halogen atom or a methyl group.

[0015] n is selected from 1 or 2.

[0016] Ring A is empty or selected from a substituted or unsubstituted cyclopentyl group or a cyclohexyl group.

[0017] In the structure shown in formula (I), the 5- to 8-membered cycloalkyl group includes, but is not limited to, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, etc.

[0018] The aryl group is selected from a phenyl group or a benzyl group.

[0019] The straight-chain or branched C1-C 20 substituents of the alkyl group are preferably one or more of a halogen, a nitro group, a cyano group, an amino group, and a hydroxyl group.

[0020] The substituents of the 5- to 8-membered cycloalkyl group and the aryl group are preferably one or more of a halogen, a nitro group, a cyano group, an amino group, a hydroxyl group, an acyl group, an amide group, a substituted or unsubstituted straight-chain or branched C1-C5 alkyl group, a substituted or unsubstituted straight-chain or branched C1-C5 alkoxy group, a substituted or unsubstituted C2-C5 alkenyl group, and a substituted or unsubstituted C2-C5 alkynyl group.

[0021] Among the above substituents, the straight-chain or branched C1-C5 alkyl group includes, but is not limited to, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a tert-butyl group, a sec-butyl group, a n-pentyl group, an isopentyl group, and a neopentyl group.

[0022] The straight-chain or branched C1-C5 alkoxy group includes, but is not limited to, a methoxy group, an ethoxy group, a n-propoxy group, an isopropoxy group, a n-butoxy group, an isobutoxy group, a tert-butoxy group, a sec-butoxy group, a n-pentyloxy group, an isopentyloxy group, and a neopentyloxy group, etc.

[0023] The substituents of the straight-chain or branched C1-C5 alkyl group and the straight-chain or branched C1-C5 alkoxy group are preferably one or more of halogen, nitro, cyano, amino, and hydroxyl.

[0024] The C2-C5 alkenyl group includes but is not limited to vinyl, propenyl, allyl, 1-butenyl, 2-butenyl, 2-methyl-1-propenyl, pentenyl, 3-methyl-1-butenyl, etc.

[0025] The C2-C5 alkynyl group includes but is not limited to ethynyl, propynyl, 1-butynyl, 2-butynyl, 2-methyl-1-propynyl, 3-methyl-1-butynyl, etc.

[0026] The substituents of the C2-C5 alkenyl group and the C2-C5 alkynyl group are preferably one or more of halogen, nitro, cyano, amino, and hydroxyl.

[0027] In the present invention, by changing the structure of the R1-R8 groups, the axial steric hindrance of the nickel or palladium catalyst or the electronic effect of the ligand is regulated, thereby improving the catalytic performance of the nickel or palladium catalyst.

[0028] Preferably in the present invention, R1, R2, R3, and R4 are independently selected from substituted or unsubstituted straight-chain or branched C1-C 10 alkyl groups, substituted or unsubstituted 5-6 membered cycloalkyl groups, substituted or unsubstituted phenyl groups, substituted or unsubstituted benzyl groups, and one or more of them.

[0029] R a and R b are independently selected from one or more of substituted or unsubstituted 5-6 membered cycloalkyl groups and substituted or unsubstituted phenyl groups.

[0030] R5 and R6 are independently selected from substituted or unsubstituted straight-chain or branched C1-C 10 alkyl groups.

[0031] Alternatively, R5, R6, and the adjacent carbon atoms are connected to form an acenaphthene ring.

[0032] R7 and R8 are independently selected from one or more of a bromine atom, a chlorine atom, and a methyl group.

[0033] n is selected from 1 or 2.

[0034] Ring A is empty or is selected from substituted or unsubstituted cyclopentyl or cyclohexyl.

[0035] The straight-chain or branched C1-C 10The alkyl group includes but is not limited to methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, n-pentyl, isopentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, etc.

[0036] The 5- to 6-membered cycloalkyl group is preferably cyclopentyl or cyclohexyl.

[0037] The substituents of the straight-chain or branched C1-C 10 alkyl group are preferably one or more of halogen, nitro, cyano, amino, and hydroxyl.

[0038] The substituents of the 5- to 6-membered cycloalkyl group, phenyl group, and benzyl group are preferably one or more of halogen, nitro, cyano, amino, hydroxyl, acyl group, amide group, substituted or unsubstituted straight-chain or branched C1-C5 alkyl group, substituted or unsubstituted straight-chain or branched C1-C5 alkoxy group, substituted or unsubstituted C2-C5 alkenyl group, and substituted or unsubstituted C2-C5 alkynyl group.

[0039] Among them, the ranges of the substituted or unsubstituted straight-chain or branched C1-C5 alkyl group, substituted or unsubstituted straight-chain or branched C1-C5 alkoxy group, substituted or unsubstituted C2-C5 alkenyl group, and substituted or unsubstituted C2-C5 alkynyl group are the same as above and will not be repeated here.

[0040] Preferably in the present invention, the nickel or palladium catalyst has the structure shown in formula (Ⅰ-a) or formula (Ⅰ-b):

[0041]

[0042] Among them, R1, R2, R3, and R4 are independently selected from substituted or unsubstituted straight-chain or branched C1-C 10 alkyl group, substituted or unsubstituted 5- to 6-membered cycloalkyl group, substituted or unsubstituted phenyl group, substituted or unsubstituted benzyl group, and one or more of them.

[0043] R a 、R b are independently selected from substituted or unsubstituted 5- to 6-membered cycloalkyl group and substituted or unsubstituted phenyl group, and one or more of them.

[0044] R7 and R8 are independently selected from one or more of bromine atom, chlorine atom, and methyl group.

[0045] n is selected from 1 or 2.

[0046] The preferred ranges of the above-mentioned substituted or unsubstituted straight-chain or branched C1-C 10 alkyl group, substituted or unsubstituted 5- to 6-membered cycloalkyl group, substituted or unsubstituted phenyl group, and substituted or unsubstituted benzyl group are the same as above and will not be repeated here.

[0047] Preferably, the nickel or palladium catalyst has any of the following structures:

[0048]

[0049]

[0050]

[0051]

[0052] The present invention also provides a method for preparing the above-mentioned nickel or palladium catalyst, comprising the following steps:

[0053] Mixing and reacting the diimine ligand shown in formula (II) with a nickel- or palladium-containing compound to obtain a nickel or palladium catalyst;

[0054]

[0055] wherein, R1, R2, R3, and R4 are independently selected from substituted or unsubstituted straight-chain or branched C1-C 20 alkyl, substituted or unsubstituted 5- to 8-membered cycloalkyl, substituted or unsubstituted aryl, or one or more of them.

[0056] R a 、R b are independently selected from substituted or unsubstituted 5- to 8-membered cycloalkyl, substituted or unsubstituted aryl, or one or more of them.

[0057] R5 and R6 are independently selected from substituted or unsubstituted straight-chain or branched C1-C 20 alkyl.

[0058] Alternatively, R5, R6, and the adjacent carbon atoms are connected to form an acenaphthene ring.

[0059] n is selected from 1 or 2.

[0060] Ring A is empty or selected from substituted or unsubstituted cyclopentyl or cyclohexyl.

[0061] Preferably, the nickel- or palladium-containing compound is selected from nickel bromide dimethoxyethane (NiBr2(DME)) or methyl(cyclopentadienyl)palladium(II) chloride (PdMeCl(COD)).

[0062] Preferably, the molar ratio of the diimine ligand shown in formula (II) to nickel bromide dimethoxyethane (NiBr2(DME)) or methyl(1,5-cyclooctadiene)palladium(II) chloride (PdMeCl(COD)) is 1:(1-1.05).

[0063] Preferably, the temperature of the reaction is 20°C to 50°C.

[0064] Preferably, the solvent for the reaction is selected from dichloromethane or chloroform.

[0065] The preparation method of the above nickel or palladium catalyst can specifically be:

[0066]

[0067] Among them, the preparation method of the nickel-containing catalyst specifically includes:

[0068] After dissolving the above two diimine ligands and nickel bromide dimethoxyethane (NiBr2(DME)) in dichloromethane (or chloroform), carry out the reaction to obtain the above two nickel-containing catalysts.

[0069] The molar ratio of the above diimine ligand to NiBr2(DME) is preferably 1:(1 to 1.05).

[0070] The temperature of the reaction is preferably 20°C to 50°C.

[0071] After the reaction, it also includes post-treatments such as recrystallization, filtration, washing, and drying.

[0072] The present invention has no special limitation on the methods or solvents for the post-treatments such as recrystallization, filtration, washing, and drying, and they can be methods or solvents well-known to those skilled in the art.

[0073] Preferably, the solvent for recrystallization is selected from one or more of n-hexane, diethyl ether, dichloromethane, and chloroform.

[0074] Preferably, the solvent for washing is selected from n-hexane or diethyl ether.

[0075] Preferably, the drying is selected from vacuum drying.

[0076] The preparation method of the palladium-containing catalyst specifically includes:

[0077] Replace NiBr2(DME) in the preparation method of the above nickel-containing catalyst with PdMeCl(COD), and the others are the same, thereby preparing the palladium-containing catalyst.

[0078] In the present invention, the diimine ligand shown in formula (II) is prepared from an aromatic amine containing a flexible ring structure.

[0079] Preferably in the present invention, the diimine ligand shown in formula (II) is prepared by dehydration condensation reaction of the aromatic amines shown in formula (III) and formula (IV) with the diketone compound shown in formula (V);

[0080]

[0081] The ranges of R1, R2, R3, R4, R5, and R6 are the same as above and will not be repeated here. The above preparation method may specifically include:

[0082]

[0083] Mix and react the above diketone compound, aromatic amine shown in formula (IV), and acidic catalyst to obtain intermediate (a), and then continue to react intermediate (a) with formula (III-1) or formula (III-2) to obtain the above diimine ligand of formula (II-1) or formula (II-2).

[0084] The molar ratio of the diketone compound, aromatic amine, and acidic catalyst is preferably 1:1:0.001.

[0085] The acidic catalyst is preferably p-toluenesulfonic acid monohydrate, formic acid, or acetic acid.

[0086] The reaction temperature is preferably 25°C to 150°C.

[0087] The reaction solvent is preferably one or more of toluene, xylene, chlorobenzene, dichloromethane, chloroform, acetonitrile, methanol, and ethanol.

[0088] After the above reaction, post-treatments such as recrystallization and column chromatography are also included.

[0089] The recrystallization solvent is preferably methanol or ethanol.

[0090] In the present invention, the aromatic amine shown in formula (III) or formula (IV) is prepared by sequentially performing a coupling reaction and a reduction reaction on a haloaromatic amine and pinacol borate.

[0091] The reducing agent for the reduction reaction is preferably Pd / C.

[0092] Alternatively, when R1, R2, R3, and R4 are independently selected from and R a , R b are selected from bulky substituents such as phenyl or benzyl, the aromatic amine shown in formula (III) or formula (IV) is prepared by a substitution reaction of an aromatic amine and an alcohol compound.

[0093] The present invention also provides the use of the above nickel or palladium catalyst or the nickel or palladium catalyst prepared by the above preparation method in the catalytic homopolymerization of ethylene or the copolymerization of ethylene and methyl acrylate.

[0094] The present invention adjusts the polymerization reaction by adjusting the substituents to change the steric hindrance of the active center of the nickel or palladium catalyst.

[0095] The nickel or palladium catalyst described in the present invention has excellent performance in the homopolymerization of ethylene or the copolymerization of ethylene and methyl acrylate.

[0096] Preferably, the nickel catalyst can maintain a relatively high catalytic activity (10 6 gmol -1 h -1 ) at a high temperature (130 °C), and prepare polyolefins with high molecular weight and high degree of branching.

[0097] Preferably, the palladium catalyst can maintain a relatively high catalytic activity (10 4 g mol -1 h -1 ) at 70 °C, and prepare polyolefins with high molecular weight and high degree of branching.

[0098] Polyolefin elastomers have excellent properties such as high elasticity, aging resistance, and oil resistance, and are a new type of synthetic polyolefin material.

[0099] The present invention also provides a polyolefin elastomer, which is prepared by homopolymerizing ethylene catalyzed by the above-mentioned nickel or palladium catalyst or the nickel or palladium catalyst prepared by the above-mentioned preparation method.

[0100] Preferably, the molecular weight of the polyolefin elastomer of the present invention is ≤ 1 million.

[0101] In some specific embodiments of the present invention, the molecular weight of the polyolefin elastomer is preferably 90,000, 110,000, 130,000, 140,000, 190,000, 220,000, 240,000, 250,000, 270,000, 310,000, 320,000, 330,000, 370,000, 390,000, 430,000, 460,000, 470,000, 500,000, 560,000, 570,000, 520,000, 590,000, 660,000, 760,000, 830,000, 1,000,000. The highest molecular weight can reach 1 million.

[0102] Preferably, the degree of branching of the polyolefin elastomer is 63 - 101 / 1000C; more preferably, the degree of branching of the polyolefin elastomer is 90 - 101 / 1000C.

[0103] In some specific embodiments of the present invention, the degree of branching of the polyolefin elastomer is preferably 63 / 1000C, 69 / 1000C, 70 / 1000C, 72 / 1000C, 73 / 1000C, 76 / 1000C, 80 / 1000C, 83 / 1000C, 81 / 1000C, 84 / 1000C, 86 / 1000C, 87 / 1000C, 88 / 1000C, 90 / 1000C, 91 / 1000C, 94 / 1000C, 95 / 1000C, 92 / 1000C, 96 / 1000C, 99 / 1000C or 101 / 1000C. The highest degree of branching can reach 101 / 1000C.

[0104] Compared with the prior art, the nickel or palladium catalyst provided by the present invention has the structure shown in formula (I). By adjusting the axial steric hindrance, a nickel or palladium catalyst with good high-temperature resistance and high activity is obtained. When it is used for olefin polymerization, polyolefins with a molecular weight of up to 1 million and a degree of branching of 63-101 / 1000C can be obtained. Description of the Drawings

[0105] Figure 1 Single crystal diffraction pattern of the α-diimine nickel catalyst prepared in Example 9;

[0106] Figure 2 1H nuclear magnetic resonance spectrum of the α-diimine palladium catalyst prepared in Example 10;

[0107] Figure 3 1H nuclear magnetic resonance spectrum of the polymer prepared in Example 15 (Entry 1 in Table 1);

[0108] Figure 4 1H nuclear magnetic resonance spectrum of the polymer prepared in Example 17 (Entry 1 in Table 3);

[0109] Figure 5 1H nuclear magnetic resonance spectrum of the polymer prepared in Example 18 (Entry 6 in Table 4). Detailed Embodiments

[0110] To further illustrate the present invention, the nickel or palladium catalyst provided by the present invention, its preparation method and applications will be described in detail below in conjunction with examples.

[0111] Example 1

[0112] Preparation of flexible ring aromatic amine a

[0113]

[0114] 4,6-Dibromo-2,3-dihydro-1H-inden-5-amine (2 g, 6.87 mmol) and 2 equivalents of isopropenylpinacol borate (2.3 g, 13.74 mmol) were placed in a total of 200 mL of a mixed solvent of toluene, aqueous potassium carbonate solution, and ethanol (toluene / water / ethanol = 1:0.4:0.2, 5 equivalents of potassium carbonate). After bubbling nitrogen for 15 min, under a nitrogen atmosphere, a total of 10 mL of a mixed toluene solution of Sphos (2-dicyclohexylphosphino-2',6'-dimethoxy-1,1'-biphenyl) (0.226 g, 0.55 mmol) and Pd2dba3 (tris(dibenzylideneacetone)dipalladium) (0.126 g, 0.137 mmol) was added to the reaction system. The reaction mixture was stirred overnight at 85 °C. It was cooled to room temperature (20 - 25 °C), and the solvent was evaporated by rotary evaporation until all the organic phase was evaporated. Dichloromethane was added for extraction and liquid separation, and it was washed with water three times (3 x 50 ml). The organic phase was taken, and by column chromatography with PE:DCM = 6:4, the intermediate product was separated with a yield of 80%. The intermediate product was taken, dissolved in absolute ethanol, 5% palladium on carbon (1.5 g, 0.1 mmol) was added, and the reaction was carried out at 85 °C for 24 h under a nitrogen atmosphere. The palladium on carbon was filtered off, and the solvent was evaporated by rotary evaporation to obtain the final product, namely aromatic amine a containing a flexible ring structure, with a yield of over 80%.

[0115] 1 H NMR (500 MHz, CDCl3, 298 K) δ 6.98 (s, 1H), 3.35 (s, 1H), 3.05 (s, 2H), 2.96 (t, J = 7.3 Hz, 2H), 2.83 (t, J = 7.4 Hz, 2H), 2.19–1.95 (m, 2H), 1.36 (d, J = 7.1 Hz, 5H), 1.27 (d, J = 6.7 Hz, 6H).

[0116] Example 2

[0117] Preparation of flexible ring aromatic amine b

[0118]

[0119] 4,6-Dibromo-2,3-dihydro-1H-inden-5-amine (2 g, 6.87 mmol) and 2 equivalents of phenylpinacol borate (2.80 g, 13.74 mmol) were placed in a total of 200 mL of a mixed solvent of toluene, aqueous potassium carbonate solution, and ethanol (toluene / water / ethanol = 3:1:1, 5 equivalents of potassium carbonate). After bubbling nitrogen for 15 min, while maintaining a nitrogen atmosphere, a total of 10 mL of a mixed toluene solution of tetrakis(triphenylphosphine)palladium(0) (0.159 g, 0.137 mmol) was added to the reaction system. The reaction mixture was stirred overnight at 85 °C. After cooling to room temperature (20 - 25 °C), the solvent was evaporated by rotary evaporation until the organic phase was completely evaporated. Dichloromethane was added for extraction and liquid separation, and it was washed three times with water (3 x 50 ml). The organic phase was taken, and the aromatic amine b with a flexible ring structure was obtained by column chromatography separation, with a yield of over 80%.

[0120] Example 3

[0121] Flexible-ring aromatic amine c

[0122]

[0123] 2,3-Dihydro-1H-inden-5-amine (2 g, 15.02 mmol) and 2 equivalents of diphenylmethanol (5.53 g, 30.04 mmol) were melted by heating in a 100 mL round-bottom flask at 120 °C. After adding a concentrated hydrochloric acid solution (37%) of anhydrous zinc chloride (1.02 g, 7.51 mmol), the mixture was heated to 160 °C and reacted for 1 h. Then it was cooled to room temperature, and dichloromethane and 1 M aqueous sodium hydroxide solution were added for extraction and liquid separation. The organic phase was washed three times with water (3 × 50 mL), washed once with 50 mL of brine, dried over anhydrous magnesium sulfate, filtered off the anhydrous magnesium sulfate, and the solvent was removed by rotary evaporation of the filtrate to obtain the aromatic amine c with a flexible ring structure, with a yield of over 80%.

[0124] 1 H NMR (500 MHz, Chloroform-d) δ 7.33–7.18 (m, 14H), 7.18–7.13 (m, 4H), 7.13–7.07 (m, 4H), 6.46 (s, 1H), 5.76 (s, 1H), 5.44 (s, 1H), 3.24 (s, 2H), 2.72 (t, J = 7.5 Hz, 2H), 2.62 (t, J = 7.4 Hz, 2H), 1.92 (p, J = 7.5 Hz, 2H).

[0125] Example 4

[0126] Preparation of diimine ligand d

[0127]

[0128] A solution of 4,6-diisopropyl-2,3-dihydro-1H-inden-5-amine (1.2 g, 5.52 mmol), butanedione (0.23 g, 2.67 mmol) and acetic acid (0.3 mg) in absolute ethanol (20 mL) was stirred under reflux for 72 hours. After returning to room temperature, a yellow solid precipitated. The yellow solid was separated by filtration, washed three times with ethanol and dried under vacuum to obtain a yellow solid product, diimine ligand d (0.9 g, 80.36% yield).

[0129] 1 H NMR (500 MHz, CDCl3, 298 K) δ 7.07 (s, 2H), 3.09–2.96 (m, 6H), 2.90 (t, J = 7.5 Hz, 4H), 2.72–2.57 (m, 2H), 2.07 (s, 10H), 1.26 (d, J = 7.1 Hz, 6H), 1.20 (t, J = 7.1 Hz, 12H), 1.13 (dd, J = 6.8, 4.2 Hz, 6H) ppm.

[0130] 13 C NMR (126 MHz, CDCl3, 298 K) δ 168.74, 145.31, 140.08, 139.93, 133.54, 130.55, 119.11, 33.09, 32.75, 29.81, 28.64, 25.73, 23.69, 22.94, 21.66, 20.60, 17.08 ppm.

[0131] Example 5

[0132] Preparation of diimine ligand e

[0133]

[0134] A solution of 4,6-dibenzyl-2,3-dihydro-1H-inden-5-amine (4.66 g, 10.00 mmol), butanedione (0.43 g, 5 mmol) and acetic acid (0.3 mg) in absolute ethanol (20 mL) was stirred under reflux for 72 hours. After returning to room temperature, a yellow solid precipitated. The yellow solid was separated by filtration, washed three times with ethanol and dried under vacuum to obtain a yellow solid product, diimine ligand e (4.05 g, 82.44% yield).

[0135] 11H NMR(500MHz,CDCl3,298K)δ 7.25–7.09(m,24H), 7.09–6.89(m,16H), 6.78(s,1H), 6.73(s,1H), 5.44(s,1H), 5.39(s,1H), 5.15(s,1H), 5.13(s,1H), 2.78–2.60(m,4H), 2.29(m,2H), 1.97–1.74(m,6H), 1.11(d, J = 9.5Hz,6H), 0.93–0.80(m,5H).

[0136] 13 13C NMR(126MHz,CDCl3)δ 170.20, 169.93, 146.52, 146.43, 144.02, 143.99, 143.70, 143.31, 143.03, 142.59, 142.58, 141.23, 140.96, 139.66, 139.63, 129.62, 129.55, 129.52, 129.33, 129.31, 129.29, 129.26, 129.16, 128.90, 128.27, 128.20, 128.18, 127.94, 127.91, 127.86, 127.73, 127.66, 126.65, 126.57, 126.14, 126.12, 126.08, 125.84, 125.76, 125.65, 125.57, 124.43, 124.40, 51.80, 51.67, 50.29, 50.22, 33.70, 33.68, 32.16, 25.60, 16.94, 16.68 ppm.

[0137] Example 6

[0138] Preparation of Diimine Ligand f

[0139]

[0140] A solution of 4,6-dibenzyl-2,3-dihydro-1H-inden-5-amine (4.66 g, 10.00 mmol), butanedione (0.86 g, 10 mmol) and acetic acid (0.3 mg) in absolute ethanol (20 mL) was stirred under reflux for 72 hours. After returning to room temperature, a yellow solid precipitated. The yellow solid was separated by filtration and then refluxed with a solution of 4,6-diisopropyl-2,3-dihydro-1H-inden-5-amine (2.17 g, 10.00 mmol) and acetic acid (0.3 mg) in absolute ethanol (20 mL) for 72 hours. After returning to room temperature, a yellow solid precipitated. The yellow solid was separated by filtration, washed three times with ethanol and dried under vacuum to obtain a yellow solid product, diimine ligand f (5.74 g, 78.37% yield).

[0141] Example 7

[0142] Preparation of diimine ligand g

[0143]

[0144] A solution of 4,6-dibenzyl-2,3-dihydro-1H-inden-5-amine (4.66 g, 10.00 mmol), butanedione (0.86 g, 10 mmol) and acetic acid (0.3 mg) in absolute ethanol (20 mL) was stirred under reflux for 72 hours. After returning to room temperature, a yellow solid precipitated. The yellow solid was separated by filtration and then refluxed with a solution of 2,6-diisopropylaniline (1.77 g, 10.00 mmol) and acetic acid (0.3 mg) in absolute ethanol (20 mL) for 72 hours. After returning to room temperature, a yellow solid precipitated. The yellow solid was separated by filtration, washed three times with ethanol and dried under vacuum to obtain a yellow solid product, diimine ligand g (5.23 g, 75.48% yield).

[0145] Example 8

[0146] Preparation of diimine ligand h

[0147]

[0148] A solution of 4,6-diisopropyl-2,3-dihydro-1H-inden-5-amine (2.17 g, 10.00 mmol), acenaphthenequinone (0.86 g, 10 mmol) and acetic acid (0.3 mg) in acetonitrile (30 mL) was stirred under reflux for 24 hours. After returning to room temperature, a yellow solid precipitated. The yellow solid was separated by filtration. It was then stirred under reflux for 72 hours with a solution of 4,6-diisopropyl-2,3-dihydro-1H-inden-5-amine (2.17 g, 10.00 mmol) and p-toluenesulfonic acid (0.3 mg) in anhydrous toluene (30 mL). After returning to room temperature, a yellow solid precipitated. The yellow solid was separated by filtration, washed three times with ethanol and dried under vacuum to obtain the yellow solid product, diimine ligand h (4.06 g, 70.06% yield).

[0149] 1 H NMR (500 MHz, Chloroform-d) δ 7.84 (d, J = 8.3 Hz, 2H), 7.35 (t, J = 7.7 Hz, 2H), 7.15 (s, 2H), 6.53 (dd, J = 7.2, 2.7 Hz, 2H), 3.33–3.18 (m, 2H), 3.05 (t, J = 7.3 Hz, 4H), 2.97 (q, J = 7.6 Hz, 5H), 2.27–1.99 (m, 3H), 1.25–1.10 (m, 12H), 1.08–0.99 (m, 6H), 0.92 (dd, J = 6.9, 2.8 Hz, 6H).

[0150] 13 C NMR (126 MHz, CDCl3) δ 161.55, 146.54, 146.52, 140.78, 140.64, 140.28, 133.70, 133.66, 131.15, 130.79, 130.75, 129.88, 128.63, 127.86, 123.75, 119.59, 77.41, 77.16, 76.91, 33.20, 32.71, 29.83, 28.54, 25.87, 23.80, 23.78, 23.63, 23.57, 22.07, 22.02, 21.06, 21.01, 1.17 ppm.

[0151] Example 9

[0152] Preparation of Diimine Nickel Catalyst

[0153]

[0154] A mixture of diimine ligand d (0.2 g, 0.41 mmol) and (DME)NiBr2 (130 mg, 0.42 mmol) was stirred in 20 mL of dichloromethane at 25 °C for 72 h. After completion of the reaction, the mixture was filtered and the solvent was evaporated under reduced pressure to obtain an orange solid, which was a diimine nickel catalyst (0.26 g, 89.66% yield).

[0155] Example 10

[0156] Preparation of Diimine Palladium Catalyst

[0157]

[0158] A mixture of diimine ligand d (0.3 g, 0.62 mmol) and (COD)PdMeCl (164 mg, 0.62 mmol) (COD = 1,5-cyclooctadiene) was stirred in 20 mL of dichloromethane at 25 °C for 72 h. After completion of the reaction, the solvent was evaporated under reduced pressure to obtain a red-brown solid, which was then filtered and recrystallized from dichloromethane / hexane to obtain a pure compound, a red-brown solid, diimine palladium catalyst (0.35 g, 88.16% yield).

[0159] 1 1H NMR (500 MHz, CDCl3, 298 K) δ 7.14 (s, 1H), 7.10 (s, 1H), 3.25–3.14 (m, 2H), 3.10–2.76 (m, 11H), 2.17–2.06 (m, 2H), 2.02 (d, J = 4.8 Hz, 6H), 1.48–1.39 (m, 6H), 1.36 (dd, J = 7.0, 2.8 Hz, 3H), 1.32 (dd, J = 6.8, 4.0 Hz, 3H), 1.28–1.23 (m, 6H), 1.17–1.13 (m, 6H), 0.55 (s, 3H) ppm.

[0160] 13 13C NMR (126 MHz, CDCl3, 298 K) δ 173.89, 169.28, 144.50, 143.56, 140.48, 140.41, 140.38, 139.80, 136.60, 135.87, 133.32, 132.68, 33.20, 32.35, 29.67, 28.94, 28.54, 25.80, 25.60, 24.08, 23.65, 23.40, 21.38, 21.25, 21.17, 21.09, 20.85, 19.82, 2.99 ppm.

[0161] Example 11

[0162] The diimine ligand h prepared in Example 8 was used to prepare the corresponding catalyst containing an acenaphthene ring structure.

[0163]

[0164] A mixture of diimine ligand h (30 mg, 0.052 mmol) and (DME)NiBr2 (16 mg, 0.052 mmol) was stirred in 10 mL of dichloromethane at 25 °C for 72 hours. After the reaction was completed, it was filtered, and the solvent was evaporated under reduced pressure to obtain a brick-red solid, which was the diimine nickel catalyst. (35 mg, 84.77% yield).

[0165] Example 12

[0166] Ethylene homopolymerization reaction catalyzed by the nickel catalyst prepared in Example 9

[0167] First, a 350 mL glass pressure reactor connected to a high-pressure gas pipeline was vacuum dried at 90 °C for at least 1 hour. Then the reactor was adjusted to 30 °C, and 98 mL of toluene and 500 equivalents of cocatalyst (Et2AlCl) were added to the reactor under an inert atmosphere. Then the nickel catalyst (2 μmol) was dissolved in 2 mL of dichloromethane or chloroform and injected into the polymerization system through a syringe. Under rapid stirring (more than 750 revolutions), ethylene was introduced and maintained at 8 atmospheres. After 15 minutes, the pressure reactor was emptied, and a large amount of acidic methanol (or ethanol) (hydrochloric acid alcohol solution with more than 5%) solution was added to quench the polymerization reaction. The polymer was filtered and dried in a vacuum oven to constant weight. The molecular weight of the polymer was 43.27×10 4 , and the activity was 8.96×10 6 g / mol Ni ·h, the degree of branching was 87, M w / M n was 1.83, and the yield was 4.48 g. (Table 1, entry 1)

[0168] Example 13

[0169] Ethylene homopolymerization reaction catalyzed by the palladium catalyst prepared in Example 10

[0170] First, a 350 mL glass pressure reactor connected to a high-pressure gas pipeline was vacuum-dried at 90 °C for at least 1 hour. Then the reactor was adjusted to 30 °C, and 98 mL of toluene and 7.5 μmol of NaBArF were added to the reactor under an inert atmosphere. Then, the palladium catalyst (5 μmol) was dissolved in 2 mL of dichloromethane or chloroform and injected into the polymerization system through a syringe. While stirring rapidly (above 750 revolutions), ethylene was introduced and maintained at 8 atmospheres. After 30 minutes, the pressure reactor was emptied, a large amount of methanol (or ethanol) solution was added to quench the polymerization reaction, the polymer was filtered, and dried to a constant weight in a vacuum oven. The polymer molecular weight was 27.1×10 4 , and the activity was 9.2×10 4 g / mol Ni ·h, the degree of branching was 83, and M w / M n was 9.53.

[0171] (Table 3, Entry 1)

[0172] Example 14

[0173] Copolymerization of ethylene and methyl acrylate catalyzed by the palladium catalyst prepared in Example 10:

[0174] First, a 150 mL glass pressure reactor connected to a high-pressure gas pipeline was vacuum-dried at 90 °C for at least 1 hour. Then the reactor was adjusted to 70 °C, and 28 mL of toluene, 15 μmol of NaBArF, 50 μmol of BHT (2,6-di-tert-butyl-4-methylphenol), and 30 mmol of MA were added to the reactor under an inert atmosphere. Then, 10 μmol of the palladium catalyst was dissolved in 2 mL of dichloromethane or chloroform and injected into the polymerization system through a syringe. While stirring rapidly (above 400 revolutions), ethylene was introduced and maintained at the specified pressure. After 3 hours, the pressure reactor was emptied, a large amount of ethanol solution was added to quench the polymerization reaction, the polymer was filtered, and dried to a constant weight in a vacuum oven. The polymer molecular weight was 13.67×10 4 , and the activity was 3.67×10 6 g / mol Pd ·h, the degree of branching was 84, the insertion rate of the polar monomer was 1.2 mol%, and Mw / Mn was 2.71. (Table 4, Entry 3)

[0175] Example 15

[0176] The effects of different nickel catalysts on the homopolymerization of ethylene were investigated from the changes in n, as well as the substituents R1, R2, R3, R4, R5, and R6.

[0177] Reaction conditions: nickel catalyst (2 μmol), Et2AlCl (1 mmol), toluene / dichloromethane (98 mL / 2 mL) or toluene / chloroform (98 mL / 2 mL), ethylene pressure (8 atmospheres), polymerization time (15 minutes), polymerization temperature (30 °C). All data are at least based on the results of two parallel experiments (unless otherwise stated).

[0178] Activity: in units of 10 6 g mol -1 h -1 . M w 、M w / M n : are the weight-average molecular weight and the polydispersity index of the polymer, respectively, measured by GPC in 1,2,4-trichlorobenzene at 150 °C relative to a polystyrene standard.

[0179] Degree of branching = number of carbon branches per 1000 carbons, determined by 1H NMR.

[0180] Polymerization process: First, a 350 mL glass pressure reactor connected to a high-pressure gas pipeline was vacuum dried at 90 °C for at least 1 hour. Then the reactor was adjusted to 30 °C, and 98 mL of toluene and 1 mmol of Et2AlCl were added to the reactor under an inert atmosphere. Then 2 μmol of nickel catalyst was dissolved in 2 mL of dichloromethane or chloroform and injected into the polymerization system through a syringe. Under rapid stirring (above 750 revolutions), ethylene was introduced and maintained at 8 atm. After 15 minutes, the pressure reactor was evacuated, and a large amount of acidic methanol or acidic ethanol (hydrochloric acid-alcohol solution with more than 5%) was added to quench the polymerization reaction. The polymer was filtered and dried to a constant weight in a vacuum oven.

[0181] In Table 1 below, the catalytic reaction was tested with R7 and R8 of the catalyst both being bromine atoms and the A ring being cyclopentyl as an example.

[0182] Table 1 Influence of different nickel catalysts on ethylene polymerization

[0183]

[0184]

[0185] Table 1 shows that when the catalyst substituents n, R5, and R6 are kept constant and the substituents R1, R2, R3, and R4 are changed, under the same polymerization conditions (the same time, temperature, pressure, and cocatalyst concentration), the greater the steric hindrance of R1, R2, R3, and R4 (cyclohexyl > cyclopentyl > isopropyl), the lower the polymerization activity, the higher the polymer molecular weight, and the lower the branching; when R1, R2, R3, R4, and R5, R6 are kept constant and n is changed, as n changes from 1 to 2, the polymer molecular weight increases, the activity decreases, and the branching also decreases; when n, R1, R2, R3, and R4 are kept constant, From to the polymerization activity increases, the molecular weight decreases, and the branching also decreases (from 83 to 80).

[0186] Example 16

[0187] The effects of different reaction conditions on the homopolymerization of ethylene catalyzed by nickel catalysts were investigated, and the results are shown in Table 2.

[0188] Reaction conditions: nickel catalyst (2 μmol, n = 1, ), Et2AlCl (1 mmol), toluene / dichloromethane (98 mL / 2 mL) or toluene / chloroform (98 mL / 2 mL), ethylene pressure (8 atmospheres), polymerization time (15 minutes), and all data are at least based on the results of two parallel experiments (unless otherwise stated). Activity: in units of 10 6 g mol -1 h -1 . M w , M w / M n : are the weight-average molecular weight and the polymer dispersity index, respectively, measured by GPC in 1,2,4-trichlorobenzene at 150 °C relative to a polystyrene standard. Degree of branching = number of carbon branches per 1000 carbons, determined by 1H NMR.

[0189] Polymerization reaction process: First, a 350 mL glass pressure reactor connected to a high-pressure gas pipeline was vacuum-dried at 90 °C for at least 1 hour. Then, the reactor was adjusted to the specified reaction temperature, and 98 mL of toluene and 1 mmol of Et2AlCl were added to the reactor under an inert atmosphere. Then, 2 μmol of the nickel catalyst was dissolved in 2 mL of dichloromethane (or chloroform) and injected into the polymerization system through a syringe. Under rapid stirring (above 750 revolutions), ethylene was introduced and maintained at the specified pressure. After the specified time, the pressure reactor was evacuated, and a large amount of acidic methanol or acidic ethanol (hydrochloric acid-alcohol solution with more than 5%) was added to quench the polymerization reaction. The polymer was filtered and dried to a constant weight in a vacuum oven.

[0190] In Table 2 below, taking the case where both R7 and R8 of the catalyst are bromine atoms, n is 1, and the A ring is a cyclopentyl group as an example, the catalytic reaction was tested.

[0191] Table 2 Influence of Different Reaction Conditions on the Homopolymerization of Ethylene Catalyzed by α-Diimine Nickel Catalyst

[0192]

[0193] Table 2 shows that when the catalyst is kept unchanged and the polymerization temperature is changed, regardless of whether R1, R2, R3, and R4 are cyclohexyl or isopropyl groups, the catalyst activity is the highest at 50 °C, and the catalyst activity decreases with increasing temperature. The higher the temperature, the lower the molecular weight and the higher the degree of branching.

[0194] Example 17

[0195] The influence of different reaction conditions on the polymerization of ethylene catalyzed by a palladium catalyst was investigated, and the investigation results are shown in Table 3.

[0196] Reaction conditions: Palladium catalyst (5 μmol, n = 1, ), NaBArF (7.5 μmol), toluene / dichloromethane (98 mL / 2 mL) or toluene / chloroform (98 mL / 2 mL), ethylene pressure (8 atmospheres), polymerization time (30 minutes), and all data are at least based on the results of two parallel experiments (unless otherwise stated). Activity: In units of 10 4 g mol -1 h -1 . M w 、M w / M n : They are the weight-average molecular weight and the polydispersity index of the polymer, respectively, and are measured by GPC in 1,2,4-trichlorobenzene at 150 °C relative to a polystyrene standard. Degree of branching = number of carbon branches per 1000 carbons, determined by 1H NMR.

[0197] Polymerization reaction process: First, a 350 mL glass pressure reactor connected to a high-pressure gas pipeline was vacuum-dried at 90 °C for at least 1 hour. Then, the reactor was adjusted to the specified temperature, and 98 mL of toluene and 7.5 μmol of NaBArF were added to the reactor under an inert atmosphere. Then, 5 μmol of the palladium catalyst was dissolved in 2 mL of dichloromethane (or chloroform) and injected into the polymerization system through a syringe. Under rapid stirring (more than 750 revolutions), ethylene was introduced and maintained at the specified pressure. After the specified time, the pressure reactor was evacuated, a large amount of methanol or ethanol was added to quench the polymerization reaction, the polymer was filtered, and dried to a constant weight in a vacuum oven.

[0198] In Table 3 below, taking the case where R5 and R6 of the catalyst are methyl, R7 and R8 are methyl and chlorine atoms, n is 1, and the A ring is cyclopentyl as an example, the catalytic reaction was tested.

[0199] Table 3 Influence of Different Reaction Conditions on the Homopolymerization of Ethylene Catalyzed by α-Diimine Palladium Catalyst

[0200]

[0201]

[0202] Table 3 shows that when the catalyst R5 and R6 are kept unchanged and are When the substituents R1, R2, R3, and R4 are all isopropyl groups, the activity is the highest at 50 °C. When the substituents R1, R2, R3, and R4 are all cyclopentyl groups, the activity is the highest at 70 °C. When the catalyst remains unchanged and the temperature increases, the molecular weight decreases. When R1 and R2 are isopropyl groups, the degree of branching remains unchanged. When R1 and R2 are cyclopentyl groups, the degree of branching increases slightly.

[0203] Example 18

[0204] The catalytic performance of the α-diimine palladium catalyst in the copolymerization of ethylene and methyl acrylate (MA) was investigated, and the investigation results are shown in Table 4.

[0205] Reaction conditions: palladium catalyst (10 μmol, n = 1, ), NaBArF (15 μmol), toluene / dichloromethane (28 mL + 2 mL), ethylene pressure (8 atmospheres), concentration of polar monomer MA (1 mol / L), polymerization time (180 minutes). All data are at least the results based on two parallel experiments (unless otherwise stated). Activity: in units of 10 4 g mol- 1 h -1 . M w 、M w / M n : are the weight-average molecular weight and the polydispersity index of the polymer, respectively, measured by GPC in 1,2,4-trichlorobenzene at 150 °C relative to a polystyrene standard. Degree of branching = number of carbon branches per 1000 carbons, determined by 1H NMR.

[0206] Table 4 Polymerization process: First, a 150 mL glass pressure reactor connected to a high-pressure gas pipeline was vacuum dried at 90 °C for at least 1 hour. Then, the reactor was adjusted to the specified temperature, and 28 mL of toluene, 15 μmol of NaBArF, 50 μmol of BHT, and 30 mmol of MA were added to the reactor under an inert atmosphere. Then, 10 μmol of a palladium catalyst was dissolved in 2 mL of dichloromethane or chloroform and injected into the polymerization system through a syringe. Under rapid stirring (above 400 revolutions), ethylene was introduced and maintained at the specified pressure. After the specified time, the pressure reactor was emptied, a large amount of ethanol solution was added to quench the polymerization reaction, the polymer was filtered, and dried to a constant weight in a vacuum oven.

[0207] In Table 4 below, taking the case where R5 and R6 of the catalyst are methyl, R7 and R8 are methyl and chlorine atoms, n is 1, and the A ring is cyclopentyl as an example, the catalytic reaction was tested.

[0208] Table 4 Effects of different reaction conditions on the copolymerization of ethylene and methyl acrylate (MA) catalyzed by α-diimine palladium catalyst

[0209]

[0210] Table 4 shows that when the catalyst R5 and R6 are kept unchanged, the insertion rate of the polar monomer increases with the increase of temperature. When R1, R2, R3, and R4 of the catalyst are isopropyl, the molecular weight of the obtained polymer increases with the increase of temperature, and the activity is the highest at 50 °C. When R1, R2, R3, and R4 of the catalyst are cyclopentyl, the molecular weight of the copolymer is the highest at 50 °C, and the activity is the highest at 70 °C (4.33×10 4 g mol- 1 h -1 ).

[0211] In summary, the present invention provides a novel α-diimine palladium or nickel catalyst. On the basis of ensuring the thermal stability of the catalyst (up to 130 °C), ethylene homopolymers or ethylene-methyl acrylate copolymers with ultra-high molecular weight (M w up to 1 million) and a certain degree of branching (63 - 101 / 1000C) characteristics can be obtained by catalyzing ethylene polymerization.

[0212] The description of the above embodiments is only used to help understand the method and its core idea of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A nickel or palladium catalyst, characterized in that, It has the structure shown in formula (Ⅰ): wherein, L is selected from a nickel atom or a palladium atom; R1, R2, R3, and R4 are independently selected from one or more of substituted or unsubstituted straight-chain or branched C1-C 20 alkyl, substituted or unsubstituted 5- to 8-membered cycloalkyl, substituted or unsubstituted aryl, and the like; R a 、R b independently selected from one or more of substituted or unsubstituted 5- to 8-membered cycloalkyl groups, substituted or unsubstituted aryl groups; R5 and R6 are independently selected from substituted or unsubstituted straight-chain or branched C1-C 20 alkyl groups; alternatively, R5, R6 and the adjacent carbon atoms are connected to form an acenaphthene ring; R7 and R8 are independently selected from a halogen atom or a methyl group; n is selected from 1 or 2; Ring A is empty or is selected from a substituted or unsubstituted cyclopentyl group or a cyclohexyl group.

2. The nickel or palladium catalyst according to claim 1, characterized in that, The R1, R2, R3, and R4 are independently selected from substituted or unsubstituted straight-chain or branched C1-C 10 alkyl, substituted or unsubstituted 5- to 6-membered cycloalkyl, substituted or unsubstituted phenyl, substituted or unsubstituted benzyl, one or more of; R a 、R b independently selected from one or more of substituted or unsubstituted 5- to 6-membered cycloalkyl, substituted or unsubstituted phenyl; R5 and R6 are independently selected from substituted or unsubstituted straight-chain or branched C1-C 10 alkyl groups; alternatively, R5, R6 and the adjacent carbon atoms are connected to form an acenaphthene ring; R7 and R8 are independently selected from one or more of a bromine atom, a chlorine atom, and a methyl group; n is selected from 1 or 2; Ring A is empty or is selected from a substituted or unsubstituted cyclopentyl group or a cyclohexyl group.

3. The nickel or palladium catalyst according to claim 1, wherein The nickel or palladium catalyst has the structure shown in formula (Ⅰ-a) or formula (Ⅰ-b): Among them, R1, R2, R3, and R4 are independently selected from substituted or unsubstituted straight-chain or branched C1-C 10 alkyl, substituted or unsubstituted 5- to 6-membered cycloalkyl, substituted or unsubstituted phenyl, substituted or unsubstituted benzyl, one or more of; R a 、R b independently selected from one or more of substituted or unsubstituted 5- to 6-membered cycloalkyl, substituted or unsubstituted phenyl; R7 and R8 are independently selected from one or more of a bromine atom, a chlorine atom, and a methyl group; n is selected from 1 or 2.

4. The nickel or palladium catalyst according to claim 1, wherein The nickel or palladium catalyst has any of the following structures:

5. The method for preparing the nickel or palladium catalyst according to any one of claims 1 to 4, characterized in that, Comprising the following steps: Mixing and reacting the diimine ligand shown in formula (Ⅱ) with a nickel- or palladium-containing compound to obtain a nickel or palladium catalyst; Among them, R1, R2, R3, and R4 are independently selected from substituted or unsubstituted straight-chain or branched C1-C 20 alkyl, substituted or unsubstituted 5- to 8-membered cycloalkyl, substituted or unsubstituted aryl, one or more of; R a 、R b independently selected from one or more of substituted or unsubstituted 5- to 8-membered cycloalkyl groups and substituted or unsubstituted aryl groups; R5 and R6 are independently selected from substituted or unsubstituted straight-chain or branched C1-C 20 alkyl groups; alternatively, R5, R6 and the adjacent carbon atoms are connected to form an acenaphthene ring; n is selected from 1 or 2; Ring A is empty or is selected from a substituted or unsubstituted cyclopentyl group or a cyclohexyl group.

6. The method for preparing a nickel or palladium catalyst according to claim 5, wherein The nickel- or palladium-containing compound is selected from nickel bromide dimethoxyethane or chloro(1,5-cyclooctadiene)methylpalladium(II); The molar ratio of the diimine ligand shown in formula (Ⅱ) to nickel bromide dimethoxyethane or chloro(1,5-cyclooctadiene)methylpalladium(II) is 1:(1 to 1.05); The temperature of the reaction is 20°C to 50°C; The solvent for the reaction is selected from dichloromethane or chloroform.

7. The method for preparing a nickel or palladium catalyst according to claim 5, characterized in that, The diimine ligand shown in formula (Ⅱ) is prepared by subjecting the aromatic amines shown in formula (III) and formula (III-1) and the diketone compound shown in formula (IV) to a dehydration condensation reaction; 8. Use of the nickel or palladium catalyst according to any one of claims 1 to 4 or the nickel or palladium catalyst prepared by the preparation method according to any one of claims 5 to 7 in the catalytic homopolymerization of ethylene or the copolymerization of ethylene and methyl acrylate.

9. A polyolefin elastomer, characterized in that, Prepared by catalytic homopolymerization of ethylene using the nickel or palladium catalyst according to any one of claims 1 to 4 or the nickel or palladium catalyst prepared by the preparation method according to any one of claims 5 to 7.

10. The polyolefin elastomer according to claim 9, characterized in that, The molecular weight of the polyolefin elastomer ≤ 1 million; The degree of branching of the polyolefin elastomer is 63 to 101 / 1000C.

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