α-Diimine ligand compound, nickel complex and preparation method and application thereof

Abstract

This invention provides an α-diimine ligand compound, a nickel complex, its preparation method, and its application, belonging to the field of catalytic olefin polymerization technology. The α-diimine ligand compound has the structure shown in formula (I): #imgabs0# Formula (I). R1, R2, and R3 may be the same or different, and each is independently selected from hydrogen, substituted or unsubstituted C1-C5 alkyl groups, and substituted or unsubstituted C6-C12 aryl groups; wherein, when there is a substituent on the substituted or unsubstituted group, the substituent is selected from any one of C1-C5 alkyl groups and C6-C12 aryl groups.

Description

Technical Field

[0001] The invention relates to the technical field of catalytic olefin polymerization, and in particular to an alpha-diimine ligand compound, a nickel complex, and a preparation method and application thereof. Background Art

[0002] One of the biggest advantages of olefin polymerization catalysts is that their catalytic performance is controlled by the structure of the catalyst ligands. In the related art, the properties of the resulting polymer are controlled by adjusting the electronic effect and steric hindrance of the catalyst ligand structure.

[0003] Due to the unpredictability of catalyst performance, a new catalyst with excellent performance is often born out of repeated experiments and trial and error, accompanied by a large degree of contingency. In addition, in many cases, the carefully designed catalyst ligand structure will also lead to an increase in the synthesis steps and preparation costs. Summary of the invention

[0004] In view of this, the present invention provides an α-diimine ligand compound, a nickel complex, and a preparation method and application thereof.

[0005] According to an embodiment of one aspect of the present invention, there is provided an α-diimine ligand compound, wherein the α-diimine ligand compound has a structure shown in formula (I):

[0006] Formula (I).

[0007] R 1 , R 2 , R 3 are the same or different and are independently selected from any one of hydrogen, substituted or unsubstituted C1~C5 alkyl, and substituted or unsubstituted C6~C12 aryl; wherein, when there is a substituent on the substituted or unsubstituted group, the substituent is selected from any one of C1~C5 alkyl and C6~C12 aryl.

[0008] According to another embodiment of the present invention, an α-diimine nickel complex is provided, wherein the α-diimine nickel complex has a structure shown in formula (II):

[0009] Formula (II).

[0010] R 1 , R 2 , R 3 are the same or different and are independently selected from any one of hydrogen, substituted or unsubstituted C1-C5 alkyl, and substituted or unsubstituted C6-C12 aryl; R 4Any one selected from hydrogen, methylene acetate, thienyl, benzothienyl, substituted or unsubstituted C1~C5 alkyl, substituted or unsubstituted C6~C12 aryl; wherein, when there is a substituent on the substituted or unsubstituted group, the substituent is selected from any one of C1~C5 alkyl and C6~C12 aryl.

[0011] According to an embodiment of another aspect of the present invention, a method for preparing the above-mentioned α-diimine nickel complex is provided, comprising the following steps: reacting an α-diimine ligand compound having a structure shown in formula (I) with a divalent nickel salt to obtain a first α-diimine nickel complex; subjecting the above-mentioned first α-diimine nickel complex to an olefin metathesis reaction, connecting any group selected from the group consisting of methylene acetate, thienyl, benzothienyl, substituted or unsubstituted C1~C5 alkyl, substituted or unsubstituted C6~C12 aryl to the end of the olefin to form a second α-diimine nickel complex.

[0012] Formula (I).

[0013] R 1 , R 2 , R 3 are the same or different and are independently selected from any one of hydrogen, substituted or unsubstituted C1~C5 alkyl, and substituted or unsubstituted C6~C12 aryl; wherein, when there is a substituent on the substituted or unsubstituted group, the substituent is selected from any one of C1~C5 alkyl and C6~C12 aryl.

[0014] According to another embodiment of the present invention, there is provided the use of the above-mentioned α-diimine nickel complex in the screening of olefin polymerization catalysts, wherein R of the α-diimine nickel complex 4 Selected from hydrogen.

[0015] According to another embodiment of the present invention, there is provided a use of the above-mentioned α-diimine nickel complex as a catalyst in olefin polymerization.

[0016] According to an embodiment of the present invention, an allyl group is introduced into the structure of the α-diimine ligand compound, and the allyl group can be efficiently converted into other substituents through olefin metathesis reaction, thereby obtaining a new catalyst.

[0017] According to an embodiment of the present invention, an α-diimine ligand compound is reacted with a divalent nickel salt to obtain a first α-diimine nickel complex, and then the first α-diimine nickel complex is efficiently converted into a second α-diimine nickel complex through an olefin metathesis reaction. The preparation method of the α-diimine nickel complex provided by the present invention is simple and efficient, and facilitates the synthesis and screening of olefin polymerization catalysts.

[0018] According to an embodiment of the present invention, an α-diimine nickel complex is used as a catalyst to catalyze the polymerization reaction of olefin monomers, has good catalytic activity, can obtain olefins of different molecular weights, dispersities and branching degrees, has simple synthesis steps and low preparation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The single crystal structure of the α-diimine nickel complex provided in Example 1 of the present invention is shown. DETAILED DESCRIPTION

[0020] Below, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of concepts of the present invention.

[0021] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The term "comprising" used herein indicates the existence of features, steps, operations, but does not exclude the existence or addition of one or more other features.

[0022] One of the biggest advantages of olefin polymerization catalysts is that their catalytic performance is controlled by the structure of the catalyst ligands. In the related art, the properties of the resulting polymer, such as molecular weight, branching degree, stereo configuration, and comonomer insertion ratio, are controlled by adjusting the electronic effect and steric hindrance of the catalyst ligand structure. Generally, once the structure of the catalyst is determined, its catalytic performance is also determined.

[0023] Due to the unpredictability of catalyst performance, a new catalyst with excellent performance is often born out of repeated experiments and trial and error, accompanied by a large degree of contingency. In addition, in many cases, the carefully designed catalyst ligand structure will also lead to an increase in the synthesis steps and preparation costs.

[0024] In response to the above problems, the present application provides an α-diimine ligand compound. By introducing an allyl group into the structure of the α-diimine ligand compound, the allyl group can be efficiently converted into other substituents through olefin metathesis reaction, thereby obtaining a new catalyst. The synthesis method is simple and the screening efficiency of the catalyst is improved.

[0025] Specifically, according to an embodiment of one aspect of the present invention, an α-diimine ligand compound is provided, and the α-diimine ligand compound has a structure shown in formula (I):

[0026] Formula (I).

[0027] R 1 , R 2 , R 3 are the same or different and are independently selected from any one of hydrogen, substituted or unsubstituted C1~C5 alkyl, and substituted or unsubstituted C6~C12 aryl; wherein, when there is a substituent on the substituted or unsubstituted group, the substituent is selected from any one of C1~C5 alkyl and C6~C12 aryl.

[0028] According to an embodiment of the present invention, the substituted or unsubstituted group may be any one of a substituted or unsubstituted C1-C5 alkyl group and a substituted or unsubstituted C6-C12 aryl group.

[0029] Specifically, when there is a substituent on the substituted or unsubstituted C1-C5 alkyl group, the substituent is selected from any one of a C1-C5 alkyl group and a C6-C12 aryl group. When there is a substituent on the substituted or unsubstituted C6-C12 aryl group, the substituent is selected from any one of a C1-C5 alkyl group and a C6-C12 aryl group.

[0030] According to an embodiment of the present invention, a ketimine compound having a structure represented by formula (A) and 2-allyl-aniline having a structure represented by formula (B) are dissolved in toluene, and an appropriate amount of p-toluenesulfonic acid is added as a catalyst, and refluxed at 130-150° C. for 0.5-2 days, preferably at 140° C. for 1 day. After the reaction is completed, the solvent is evaporated, and an α-diimine ligand compound having a structure represented by formula (I) is obtained by column chromatography.

[0031] Formula (A), Formula (B).

[0032] According to an embodiment of the present invention, the term "alkyl" refers to a saturated aliphatic hydrocarbon group having a specified number of carbon atoms, either branched or straight. For example, C1 to C5, as defined in "C1 to C5 alkyl", includes groups having 1, 2, 3, 4 or 5 carbon atoms in a straight or branched structure. For example, "C1 to C5 alkyl" specifically includes methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, sec-pentyl, isopentyl, tert-pentyl, etc.

[0033] According to an embodiment of the present invention, the term "aryl" refers to any stable 6- to 10-membered monocyclic or bicyclic aromatic group, such as phenyl, naphthyl, and the like.

[0034] According to an embodiment of the present invention, when there are substituents on the C1-C5 alkyl group, the number of the substituents may be 1-5.

[0035] According to an embodiment of the present invention, when there are substituents on the C6-C12 aryl group, the number of the substituents may be 1-5.

[0036] According to an embodiment of the present invention, an allyl group is introduced into the structure of the α-diimine ligand compound, and the allyl group can be efficiently converted into other substituents through olefin metathesis reaction, thereby obtaining a new catalyst.

[0037] According to an embodiment of the present invention, R 1 , R 2 , R 3 Each is independently selected from any one of hydrogen, methyl, ethyl, isopropyl, tert-butyl, phenyl and benzhydryl.

[0038] According to an embodiment of the present invention, the α-diimine ligand compound has a structure shown in any one of Formula (I-1) to Formula (I-7):

[0039] , ,

[0040] , ,

[0041] , ,

[0042] .

[0043] According to another aspect of the present invention, there is provided an α-diimine nickel complex having a structure shown in formula (II):

[0044] Formula (II).

[0045] R 1 , R 2 , R 3 are the same or different and are independently selected from any one of hydrogen, substituted or unsubstituted C1-C5 alkyl, and substituted or unsubstituted C6-C12 aryl; R 4 Any one selected from hydrogen, methylene acetate, thienyl, benzothienyl, substituted or unsubstituted C1~C5 alkyl, substituted or unsubstituted C6~C12 aryl; wherein, when there is a substituent on the substituted or unsubstituted group, the substituent is selected from any one of C1~C5 alkyl and C6~C12 aryl.

[0046] According to an embodiment of the present invention, the wavy line " " indicates that the stereo configuration of the olefin is unknown, which can be either a cis olefin structure (or Z configuration) or a trans olefin structure (or E configuration).

[0047] According to an embodiment of the present invention, R 1 , R 2 , R 3 Each is independently selected from any one of hydrogen, methyl, ethyl, isopropyl, tert-butyl, phenyl and benzhydryl.

[0048] According to an embodiment of the present invention, R 4 Any one selected from the group consisting of hydrogen, methylene acetate, phenyl, thienyl and benzothienyl.

[0049] According to an embodiment of another aspect of the present invention, a method for preparing an α-diimine nickel complex is provided, comprising the following steps: reacting an α-diimine ligand compound having a structure represented by formula (I) with a divalent nickel salt to obtain a first α-diimine nickel complex; subjecting the first α-diimine nickel complex to an olefin metathesis reaction, connecting any group selected from the group consisting of methylene acetate, thienyl, benzothienyl, substituted or unsubstituted C1~C5 alkyl, and substituted or unsubstituted C6~C12 aryl to the end of the olefin to form a second α-diimine nickel complex.

[0050] Formula (I).

[0051] R 1 , R 2 , R 3 The definition of is the same as above and will not be repeated here.

[0052] According to an embodiment of the present invention, further, the α-diimine ligand compound having the structure shown in formula (I) and a divalent nickel salt can be dissolved in an organic solvent and reacted at room temperature for a period of time to obtain a first α-diimine nickel complex.

[0053] According to an embodiment of the present invention, the divalent nickel salt may be selected from ethylene glycol dimethyl ether nickel bromide.

[0054] According to an embodiment of the present invention, the organic solvent may be selected from one or more of dichloromethane, tetrahydrofuran, acetonitrile and 1,4-dioxane.

[0055] For example, an α-diimine ligand compound having a structure shown in formula (I) and an equivalent amount of ethylene glycol dimethyl ether nickel bromide are dissolved in dichloromethane and reacted at room temperature for 12 hours to obtain a first α-diimine nickel complex.

[0056] According to an embodiment of the present invention, an α-diimine ligand compound reacts with a divalent nickel salt to obtain a first α-diimine nickel complex. The first α-diimine nickel complex can be directly used as a catalyst for olefin polymerization, or as a raw material to be converted into a second α-diimine nickel complex through an olefin metathesis reaction.

[0057] According to an embodiment of the present invention, further optionally, the first α-diimine nickel complex is subjected to olefin metathesis reaction, and any group selected from methylene acetate, phenyl, thienyl and benzothienyl is connected to the end of the olefin to form a second α-diimine nickel complex.

[0058] According to an embodiment of the present invention, the first α-diimine nickel complex and the second α-diimine nickel complex respectively have structures shown in formula (II):

[0059] Formula (II).

[0060] R 1 , R 2 , R 3 The definition of is the same as above and will not be repeated here; in the first α-diimine nickel complex, R 4 is selected from hydrogen; in the second α-diimine nickel complex, R 4 Any one selected from the group consisting of methylene acetate, thienyl, benzothienyl, substituted or unsubstituted C1-C5 alkyl, and substituted or unsubstituted C6-C12 aryl.

[0061] According to an embodiment of the present invention, further preferably, in the second α-diimine nickel complex, R 4 Any one selected from the group consisting of methylene acetate, phenyl, thienyl and benzothienyl.

[0062] According to an embodiment of the present invention, the allyl group in the first α-diimine nickel complex can be converted into other groups through olefin metathesis reaction to obtain the second α-diimine nickel complex, which has the advantages of simple preparation method and high efficiency.

[0063] According to an embodiment of the present invention, the olefin metathesis reaction comprises: dissolving an olefin reagent having a structure represented by formula (III) or formula (IV) and the first α-diimine nickel complex in a solvent, adding a metathesis catalyst, and reacting to obtain the second α-diimine nickel complex.

[0064] Formula (III); Formula (IV).

[0065] Among them, R 4Any one selected from the group consisting of methylene acetate, thienyl, benzothienyl, substituted or unsubstituted C1-C5 alkyl, substituted or unsubstituted C6-C12 aryl, preferably, R 4 Any one selected from the group consisting of methylene acetate, phenyl, thienyl and benzothienyl.

[0066] According to an embodiment of the present invention, the metathesis catalyst may be selected from Grubbs catalyst, specifically one or more of Grubbs first generation catalyst, Grubbs second generation catalyst, Grubbs third generation catalyst and Hoveyda-Grubbs second generation catalyst.

[0067] According to an embodiment of the present invention, the olefin metathesis reaction can be carried out under a protective atmosphere, which can be one or more of nitrogen, argon, and helium.

[0068] Specifically, in a nitrogen atmosphere, the first α-diimine nickel complex and an olefin reagent having a structure represented by formula (III) or formula (IV) are dissolved in a suitable solvent, a certain amount of metathesis catalyst is added, and the reaction is quenched with ethyl vinyl ether after a certain period of time, and the solvent is evaporated. The crude product is washed and recrystallized to obtain the second α-diimine nickel complex.

[0069] According to another embodiment of the present invention, there is provided an application of the above-mentioned α-diimine nickel complex in the screening of olefin polymerization catalysts, wherein R 4 Selected from hydrogen.

[0070] Specifically, the α-diimine nickel complex used in the screening of olefin polymerization catalysts is a first α-diimine nickel complex having a structure shown in formula (II-M):

[0071] Formula (II-M).

[0072] The first α-diimine nickel complex is prepared by the following method: an α-diimine ligand compound having a structure shown in formula (I) is reacted with a divalent nickel salt to obtain the first α-diimine nickel complex.

[0073] Formula (I).

[0074] R 1 , R 2 , R 3 The definition of is the same as above and will not be repeated here.

[0075] According to the embodiments of the present invention, the first α-diimine nickel complex can be efficiently converted into the second α-diimine nickel complex through olefin metathesis reaction, which facilitates the synthesis and screening of olefin polymerization catalysts.

[0076] According to an embodiment of another aspect of the present invention, a method for screening olefin polymerization catalysts is provided, comprising the following steps: reacting a first α-diimine nickel complex having a structure represented by formula (II-M) with a monosubstituted olefin or a disubstituted olefin to obtain a plurality of third α-diimine nickel complexes; using the plurality of third α-diimine nickel complexes as catalysts to catalyze polymerization reactions of olefin monomers to obtain polyolefins; and screening an olefin polymerization catalyst from the plurality of third α-diimine nickel complexes based on the preparation cost of the polyolefin and the performance of the polyolefin.

[0077] According to an embodiment of the present invention, the third α-diimine nickel complex can be obtained by reacting the first α-diimine nickel complex with any monosubstituted olefin or disubstituted olefin, and the present invention does not limit the specific type of the monosubstituted olefin or disubstituted olefin.

[0078] According to another aspect of the present invention, there is provided a use of the above-mentioned α-diimine nickel complex as a catalyst in olefin polymerization.

[0079] According to an embodiment of the present invention, the olefin may be a straight-linked α-olefin, that is, a monoolefin with a double bond at the end of the molecular chain, and specifically may be ethylene, propylene, butene, and the like.

[0080] According to another embodiment of the present invention, taking ethylene as an example, an ethylene polymerization method is provided, comprising the following steps: dissolving a co-catalyst in an organic solvent, heating to a reaction temperature of 20 to 120°C, preferably 20 to 50°C, to obtain a mixed solution; adding the above-mentioned α-diimine nickel complex dissolved in an organic solvent to the mixed solution, introducing ethylene, and performing a polymerization reaction for 5 to 120 minutes at an ethylene pressure of 2 to 20 atm. Preferably, the polymerization reaction can be performed for 5 to 60 minutes at an ethylene pressure of 8 to 20 atm, more preferably at an ethylene pressure of 8 atm.

[0081] According to an embodiment of the present invention, the co-catalyst may include one or more of aluminoxane, alkylaluminum and alkylaluminum chloride, preferably diethylaluminum chloride.

[0082] According to an embodiment of the present invention, the reaction temperature may be 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C or 120°C, preferably 30°C.

[0083] According to an embodiment of the present invention, in the case of including both the main catalyst and the co-catalyst, the molar ratio of Al in the co-catalyst to Ni in the main catalyst is 50 to 3500: 1, preferably 100 to 500: 1. Specifically, the molar ratio of Al in the co-catalyst to Ni in the main catalyst is 50: 1, 100: 1, 200: 1, 300: 1, 500: 1, 1000: 1, 1500: 1, 2000: 1, 2500: 1, 3000: 1 or 3500: 1, preferably 200: 1.

[0084] According to an embodiment of the present invention, the organic solvent may include one or more of toluene, tetrahydrofuran, n-hexane, n-heptane and mixed alkanes, preferably toluene.

[0085] According to an embodiment of the present invention, an organic solvent can be added into a closed reactor, and air can be extracted and ethylene can be introduced while the temperature of the solvent in the reactor is raised to a reaction temperature of 20 to 120°C. Then, a co-catalyst is first injected into the reactor, and then an α-diimine nickel complex is added, and ethylene raw material is introduced, and a polymerization reaction is carried out for 5 to 60 minutes at a pressure of 8 to 20 atm.

[0086] According to an embodiment of the present invention, an α-diimine nickel complex is used as a catalyst to catalyze the polymerization reaction of olefin monomers, has good catalytic activity, can obtain olefins with different molecular weights, dispersities and branching degrees, has simple synthesis steps, and has low preparation cost.

[0087] The following lists a number of specific embodiments to illustrate the technical solution of the present invention in detail. It should be noted that the specific embodiments below are only used for illustration and are not used to limit the present invention.

[0088] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0089] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0090] The raw materials used in the following examples have no particular limitation on their purity, but analytically pure materials are preferably used in the present invention.

[0091] Unless otherwise specified, the concentrations in the following examples are molar concentrations.

[0092] The polymerization activities of the catalysts obtained in the following ethylene polymerization examples are calculated according to the following formula: polymerization activity = polymer yield / (catalyst dosage × polymerization time); the molecular weight and molecular weight distribution of the polymer are measured according to the conventional high temperature gel permeation chromatography method; the branching degree of the polymer is calculated according to the high temperature nuclear magnetic resonance hydrogen spectrum method.

[0093] Some of the synthesized compounds described below were confirmed by NMR.

[0094] Example 1

[0095] (1) This embodiment provides an α-diimine ligand compound having a structure shown in formula (I-1):

[0096] Formula (I-1).

[0097] The α-diimine ligand compound having the structure shown in formula (I-1) is prepared by the following method: under nitrogen protection, the ketimine compound having the structure shown in formula (A-1) (10 mmol) and the 2-allyl-aniline having the structure shown in formula (B) (10 mmol) are dissolved in 100 mL of toluene, 5% mmol of p-toluenesulfonic acid is added as a catalyst, and refluxed at 140° C. for 24 hours. After the reaction is completed, the solvent is evaporated, and the α-diimine ligand compound having the structure shown in formula (I-1) is obtained by column chromatography, and the yield is 89%.

[0098] Formula (A-1).

[0099] (2) This embodiment also provides an α-diimine nickel complex having a structure shown in formula (II-1):

[0100] Formula (II-1).

[0101] The α-diimine nickel complex having the structure shown in formula (II-1) is prepared by the following method: an α-diimine ligand compound having the structure shown in formula (I-1) (1 mmol) and an equivalent amount of ethylene glycol dimethyl ether nickel bromide are dissolved in 10 mL of dichloromethane, stirred at room temperature for 12 hours, an excess of n-hexane is added, and a solid powder is filtered out, and the α-diimine nickel complex (abbreviated as Ni0) shown in formula (II-1) is obtained by drying. Its single crystal structure is as shown Figure 1 shown.

[0102] The above reaction process is shown in Scheme 1:

[0103]

[0104] Route 1.

[0105] The α-diimine ligand compound having the structure shown in formula (I-1) obtained above was subjected to nuclear magnetic resonance detection. The detection results are as follows. After analysis, they are consistent with the compound structure information.

[0106]

[0107] Example 2

[0108] This embodiment provides an α-diimine nickel complex having a structure shown in formula (II-2):

[0109] Formula (II-2).

[0110] The α-diimine nickel complex having the structure shown in formula (II-2) is prepared by the following method: Under a nitrogen atmosphere, the α-diimine nickel complex (1 mmol) of the structure shown in formula (II-1) and trans-2-butene-1,4-diol diacetate (3 mmol) are dissolved in 30 mL of dichloromethane. At 40°C, the second generation catalyst (20 mmol%) of Hoveyda-Grubbs dissolved in 2 mL of dichloromethane is injected into the reaction system. After 4 hours, 5 mL of ethyl vinyl ether is added to the reaction system to quench the reaction. The solvent is then evaporated, the crude product is washed with n-hexane, and finally recrystallized with a dichloromethane / n-hexane mixed solvent to obtain the α-diimine nickel complex (referred to as Ni-OAc) having the structure shown in formula (II-2).

[0111] Example 3

[0112] This embodiment provides an α-diimine nickel complex having a structure shown in formula (II-3):

[0113] Formula (II-3).

[0114] The α-diimine nickel complex having the structure shown in formula (II-3) is prepared by the following method: Under a nitrogen atmosphere, the α-diimine nickel complex (1 mmol) having the structure shown in formula (II-1) and styrene (3 mmol) are dissolved in 30 mL of dichloromethane. At 40°C, the second generation catalyst (20 mmol%) of Hoveyda-Grubbs dissolved in 2 mL of dichloromethane is injected into the reaction system. After 4 hours, 5 mL of ethyl vinyl ether is added to the reaction system to quench the reaction. The solvent is then evaporated, the crude product is washed with n-hexane, and finally recrystallized with a dichloromethane / n-hexane mixed solvent to obtain an α-diimine nickel complex (referred to as Ni-Ph) having the structure shown in formula (II-3).

[0115] Example 4

[0116] This embodiment provides an α-diimine nickel complex having a structure shown in formula (II-4):

[0117] Formula (II-4).

[0118] The α-diimine nickel complex having the structure shown in formula (II-4) is prepared by the following method: (1 mmol) of the structure shown in formula (II-1) and 2-vinylthiophene (3 mmol) are dissolved in 30 mL of dichloromethane under a nitrogen atmosphere. At 40°C, the second generation catalyst (20 mmol%) of Hoveyda-Grubbs dissolved in 2 mL of dichloromethane is injected into the reaction system. After 4 hours, 5 mL of ethyl vinyl ether is added to the reaction system to quench the reaction. The solvent is then evaporated, the crude product is washed with n-hexane, and finally recrystallized with a dichloromethane / n-hexane mixed solvent to obtain an α-diimine nickel complex having the structure shown in formula (II-4) (referred to as Ni-S).

[0119] Example 5

[0120] This embodiment provides an α-diimine nickel complex having a structure shown in formula (II-5):

[0121] Formula (II-5).

[0122] The α-diimine nickel complex having the structure shown in formula (II-5) is prepared by the following method: Under a nitrogen atmosphere, (1 mmol) of the structure shown in formula (II-1) and 2-vinylbenzothiophene (3 mmol) are dissolved in 30 mL of dichloromethane. At 40°C, the second generation catalyst of Hoveyda-Grubbs (20 mmol%) dissolved in 2 mL of dichloromethane is injected into the reaction system. After 4 hours, 5 mL of ethyl vinyl ether is added to the reaction system to quench the reaction. The solvent is then evaporated, the crude product is washed with n-hexane, and finally recrystallized with a dichloromethane / n-hexane mixed solvent to obtain an α-diimine nickel complex having the structure shown in formula (II-5) (referred to as Ni-PhS).

[0123] Embodiment 6-15

[0124] The α-diimine nickel complex provided in the above Examples 1 to 5 was used to catalyze ethylene polymerization.

[0125] In a glove box under nitrogen atmosphere, add a stirrer to a 350 mL pressure bottle, add the required toluene and diethylaluminum chloride. Adjust the reaction temperature to the required value, adjust the ethylene pressure, and inject the dichloromethane solution containing the nickel complex. Close the valve, adjust the ethylene pressure to 8 atmospheres, and react for 30 minutes. Stop the reaction, add methanol solution to precipitate the solid, and add a little hydrochloric acid to remove the catalyst. The solid is then washed three times with pure methanol and dried.

[0126] Table 1 shows the specific experimental conditions, yield (Yield), catalytic activity (Act.), polymer molecular weight (Mn), polymer molecular weight distribution (PDI), degree of branching (B) and other polymerization result data of ethylene polymerization provided by the present invention.

[0127] Table 1

[0128]

[0129] Table 1 Examples a The polymerization conditions were: 18 mL toluene, 1 μmol nickel complex dissolved in 0.5 mL CH 2 Cl 2 In, Al / Ni=200, ethylene pressure=8 atm, time=30 minutes. Act. b Activity=10 6 g·mol -1 ·h -1 .PDI c The molecular weight (M) was determined by GPC in trichlorobenzene at 150°C. n ) and polydispersity index (PDI). d The degree of branching B ( / 1000C) was determined by high temperature hydrogen nuclear magnetic resonance spectroscopy.

[0130] Through the above polymerization data, it can be found that the catalytic performance of the catalysts Ni-OAc, Ni-Ph, Ni-S and Ni-PhS has changed significantly compared to the initial catalyst NiO. And with the different olefin reagents added in the reaction, the catalytic performance of the obtained new catalysts is also different. The above results prove that the catalyst synthesis strategy provided by the present invention has high efficiency and versatility, breaking through the complexity of traditional catalyst synthesis.

[0131] Example 16

[0132] (1) This embodiment provides an α-diimine ligand compound having a structure shown in formula (I-6):

[0133] Formula (I-6).

[0134] The α-diimine ligand compound having the structure shown in formula (I-6) is prepared by the following method: under nitrogen protection, the ketimine compound having the structure shown in formula (A-2) (10 mmol) and the 2-allyl-aniline having the structure shown in formula (B) (10 mmol) are dissolved in 100 mL of toluene, 5% mmol of p-toluenesulfonic acid is added as a catalyst, and refluxed at 140 ° C for 24 hours. After the reaction is completed, the solvent is evaporated, and the α-diimine ligand compound having the structure shown in formula (I-6) is obtained by column chromatography, and the yield is 80%.

[0135] Formula (A-2).

[0136] (2) This embodiment also provides an α-diimine nickel complex having a structure shown in formula (II-6):

[0137] Formula (II-6).

[0138] The α-diimine nickel complex having the structure shown in formula (II-6) is prepared by the following method: the α-diimine ligand compound (1 mmol) shown in formula (I-6) and an equivalent amount of ethylene glycol dimethyl ether nickel bromide are dissolved in 10 mL of dichloromethane, stirred at room temperature for 12 hours, excess n-hexane is added, solid powder is filtered out, and the α-diimine nickel complex shown in (II-6) is obtained by drying.

[0139] The above reaction process is shown in Scheme 2:

[0140]

[0141] Route 2.

[0142] In line 2, Ph represents a benzene ring.

[0143] The α-diimine ligand compound having the structure shown in formula (I-6) obtained above was subjected to NMR detection, and the detection results are as follows: After analysis, it is consistent with the compound structure information.

[0144]

[0145] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An α-diimine nickel complex, characterized in that: The α-diimine nickel complex has a structure shown in formula (II): Formula (II); R1, R2, and R3 are the same or different, and are independently selected from any one of hydrogen, substituted or unsubstituted C1-C5 alkyl, and substituted or unsubstituted C6-C12 aryl; R4 is selected from thienyl or benzothienyl; When there is a substituent on the substituted or unsubstituted group, the substituent is selected from any one of a C1 to C5 alkyl group and a C6 to C12 aryl group.

2. The α-diimine nickel complex according to claim 1, characterized in that R1, R2, and R3 are each independently selected from any one of hydrogen, methyl, ethyl, isopropyl, tert-butyl, phenyl, and diphenylmethyl.

3. A method for preparing the α-diimine nickel complex according to claim 1 or 2, characterized in that: The following steps are involved: reacting an α-diimine ligand compound having a structure represented by formula (I) with a divalent nickel salt to obtain a first α-diimine nickel complex; The first α-diimine nickel complex is subjected to an olefin metathesis reaction to connect a thienyl group or a benzothienyl group to the end of the olefin to form a second α-diimine nickel complex; Formula (I); R1, R2, and R3 are the same or different, and are independently selected from any one of hydrogen, substituted or unsubstituted C1-C5 alkyl, and substituted or unsubstituted C6-C12 aryl; When there is a substituent on the substituted or unsubstituted group, the substituent is selected from any one of a C1 to C5 alkyl group and a C6 to C12 aryl group.

4. The preparation method according to claim 3, characterized in that: R1, R2, and R3 are each independently selected from any one of hydrogen, methyl, ethyl, isopropyl, tert-butyl, phenyl, and diphenylmethyl.

5. The preparation method according to claim 3, characterized in that: The α-diimine ligand compound has a structure shown in any one of formula (I-1) to formula (I-7): ， ， ， ， ， ， 。 6. The preparation method according to claim 3, characterized in that: The olefin metathesis reaction comprises: Dissolving an olefin reagent having a structure represented by formula (III) or formula (IV) and the first α-diimine nickel complex in a solvent, adding a metathesis catalyst, and reacting to obtain the second α-diimine nickel complex; Formula (III); Formula (IV); Wherein, R4 is selected from thienyl or benzothienyl.

7. Use of the α-diimine nickel complex according to claim 1 or 2 as a catalyst in olefin polymerization.

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