Phosphine sulfonic acid type ligands, nickel phosphine sulfonic acid catalysts, and methods of making and using the same

Abstract

This invention relates to the field of polyolefin technology, specifically to a phosphonic sulfonic acid ligand for olefin polymerization, a nickel phosphonic sulfonate catalyst, its preparation method, and its application. The phosphonic sulfonic acid ligand structure is shown in Formula L, and the nickel phosphonic sulfonate catalyst is formed by a phosphonic sulfonic acid ligand and an organonitrile complex. The catalyst provided by this invention is a Drent-type catalyst composed of benzenesulfonic acid and 1,3,2-diazaphosphonic acid, which is resistant to polar comonomers and facilitates the preparation of high molecular weight polyolefins with biased polarity.

Description

Technical Field

[0001] This invention relates to the field of polyolefin technology, specifically to a phosphonic sulfonic acid ligand for olefin polymerization, a nickel phosphonic sulfonic acid catalyst, its preparation method, and its application. Background Technology

[0002] Due to their abundant raw materials, low price, ease of processing and molding, and corrosion resistance, polyolefins have become the world's largest-produced and most widely used polymer materials. For example, ultra-high molecular weight polyethylene (UHMWPE), which is well-known, possesses excellent chemical stability, electrical insulation, and processability, and has been widely used in new energy and new materials fields. However, most traditional polyolefins are non-polar polymers, and their hydrophilicity, colorability, and poor compatibility with polar polymers severely hinder their application in many fields. Therefore, effective functional modification of polyolefins can improve their surface polarity, increase their added value, and expand their application range.

[0003] To address the aforementioned issues, ethylene can be copolymerized with polar monomers (such as acrylic acid, vinyl acetate, acrylates, and carbon monoxide) to introduce polar groups into the traditional UHMWPE chain, thereby improving the material's properties. For example, by copolymerizing ethylene with carbon monoxide, carbonyl groups can be introduced into the polymer backbone, producing polyketide polymers with high strength, high rigidity, high heat resistance, gas barrier properties, solvent resistance, and fatigue resistance, which can then be used in the field of engineering plastics.

[0004] However, copolymerizing ethylene with polar monomers is not easy, and obtaining high-molecular-weight polar polyolefins is even more challenging. Traditional Ziggler-Natt catalysts and metallocene catalysts are highly sensitive to polar monomers; for example, oxygen atoms in carbon monoxide can easily poison the active sites of the catalyst, leading to its deactivation. To address this, researchers have employed carefully designed metallocene / restricted geometry catalysts to promote the copolymerization of ethylene and carbon monoxide. However, the synthesis of metallocene / restricted geometry catalysts is difficult, and industrial scale-up is even more challenging, hindering future industrial applications. Therefore, further research is needed to develop a novel catalyst for the preparation of high-molecular-weight polar polyolefins. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems by providing a phosphonic acid ligand for olefin polymerization, a nickel phosphonic acid sulfonate catalyst, its preparation method, and its application.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A first aspect of the present invention provides a phosphonic acid ligand having the general structure shown in Formula L:

[0008]

[0009] Wherein, R1-R4 can be the same or different groups, and are independently selected from H, C1-C6 alkyl, C1-C6 alkoxy, C6-C 12 Aryl or halogen.

[0010] The C1-C6 alkyl group includes straight-chain or branched alkyl groups, for example, including but not limited to methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl or hexyl, preferably methyl.

[0011] The C1-C6 alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, pentoxy, or hexoxy.

[0012] The C6-C 12 Aryl is a monovalent aromatic carbocyclic ring system having at least one aromatic ring or at least one of the rings being aromatic rings, such as phenyl or m-xylyl.

[0013] As a preferred technical solution, in R1-R4, R1 and R2 are selected from the same group, and R3 and R4 are selected from the same group.

[0014] More preferably, R3 and R4 are H, and R1 and R2 are selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, and C6 aryl.

[0015] In a preferred embodiment of the present invention, the phosphonic acid ligand is selected from any one of the compounds represented by formulas L1-L3:

[0016]

[0017]

[0018] .

[0019] The second aspect of the present invention provides a method for preparing the above-mentioned phosphonic acid ligand, which is prepared by a nucleophilic substitution reaction using benzenesulfonic acid of the general formula shown in Formula I and 1,3,2-diazaphosphonic acid derivative of the general formula shown in Formula II as raw materials. The specific reaction formula is as follows:

[0020] .

[0021] In the 1,3,2-diazaphosphonic derivatives with the general formula shown in Formula II, the definitions of R1-R4 are as described above.

[0022] In a preferred embodiment of the present invention, the 1,3,2-diazaphosphonium derivative may be selected from 2-chloro-1,3-diphenyl-1,3,2-diazaphosphonium, 2-chloro-1,3-bis(2,6-dimethylphenyl)-1,3,2-diazaphosphonium, or 2-chloro-1,3-dimethyl-1,3,2-diazaphosphonium.

[0023] As a preferred technical solution, the preparation method of the phosphonic acid ligand of the present invention specifically includes the following steps: under an inert atmosphere and at low temperature, a base reagent and benzenesulfonic acid are reacted in a solvent to generate a benzenesulfonic acid intermediate; the obtained benzenesulfonic acid intermediate is reacted with a 1,3,2-diazaphosphonic acid derivative in an organic solvent to generate a nucleophilic substitution reaction to generate a product; and the product is obtained by post-processing separation and purification to obtain the phosphonic acid ligand.

[0024] Preferably, the alkaline reagent is an organolithium reagent, including one of n-butyllithium, tert-butyllithium, methyllithium, or phenyllithium, with n-butyllithium being the most preferred. Preferably, the organolithium reagent is dissolved in a solvent (e.g., an inert alkane solvent, such as n-hexane) beforehand.

[0025] Preferably, the organic solvent used is a polar aprotic solvent capable of dissolving the reactants, and commonly used solvents in the art, such as tetrahydrofuran, can be used.

[0026] Preferably, the molar ratio of benzenesulfonic acid, 1,3,2-diazaphosphonic acid derivative and organolithium reagent is 1:1:1.2-2.5.

[0027] Preferably, solvent removal can be performed using conventional methods in the art, such as vacuum evaporation; product purification can be performed using conventional methods in the art, such as column chromatography.

[0028] As a typical preparation example, the preparation method of the phosphonic acid ligand of the present invention is as follows: under nitrogen protection, at 0°C, a hexane solution containing n-butyllithium is slowly added dropwise to a tetrahydrofuran solution containing benzenesulfonic acid, and the reaction is carried out for 1-3 h. Then, a tetrahydrofuran solution containing a 1,3,2-diazaphosphonic acid derivative (such as 2-chloro-1,3-diphenyl-1,3,2-diazaphosphonic acid) is added dropwise to the mixed solution using a constant pressure dropping funnel. The reaction is then slowly raised to room temperature for 2-18 h. After the reaction is completed, the solvent is removed under reduced pressure, and the product is obtained by separation and purification by column chromatography.

[0029] A third aspect of this invention provides a nickel phosphononsulfonate catalyst, which is a coordination compound formed by the phosphononsulfonic acid ligand described above and an organonitrile complex, and is a nickel phosphononsulfonate catalyst having the general structure shown in Formula C:

[0030] .

[0031] The definitions of R1-R4 are as described above.

[0032] In a preferred embodiment of the present invention, the nickel phosphonate catalyst is selected from any one of the following formulas C1 to C3:

[0033]

[0034]

[0035]

[0036] In this catalyst structure, the P atom and N atom are connected in the 1,3,2-diazaphosphonidine five-membered ring ligand. The lone pair electrons on the N atom and the substituents improve the electronic structure of the P atom. The substituents on the N atom further affect the steric hindrance of the active center, which has an impact on the subsequent insertion of polar monomers. The two work together to promote the copolymerization of phosphonic acid-type catalytic ethylene and polar monomers with Ni as the active center, and obtain polyolefins with high polar monomer insertion rate and high molecular weight.

[0037] The fourth aspect of this invention provides a method for preparing the above-mentioned catalyst, wherein the catalyst can be prepared by synthesizing coordination compounds: the phosphonic acid ligand and an organonitrile complex (such as allyl nickel chloride) are dissolved in an anhydrous aprotic organic solvent at a molar ratio of 1:1-4, and reacted in an anhydrous and oxygen-free environment, as shown in the following specific reaction formula:

[0038] .

[0039] Preferably, the catalyst is prepared by the following method: Under inert gas protection, the ligand L and the organonickel complex are dissolved in an anhydrous aprotic organic solvent (e.g., acetonitrile, toluene, dichloromethane) at a molar ratio of 1:1-4. Preferably, the molar ratio of ligand L to the organonickel complex is 1:1-1.5. The reaction is carried out in an anhydrous and oxygen-free environment at a reaction temperature of 0-60 °C for 8-36 h under the action of an alkaline reagent (e.g., Na₂CO₃). After the reaction is completed, the product is obtained by post-processing separation and purification.

[0040] Preferably, solvent removal can be performed using conventional methods in the art, such as vacuum evaporation; product purification can be performed using conventional methods in the art, such as diatomaceous earth filtration, ether recrystallization, etc.

[0041] A fifth aspect of the invention provides the use of the above-described catalyst in the preparation of polar polyolefins, for example, in the polymerization of ethylene with carbon monoxide to produce ethylene / CO copolymers.

[0042] Preferably, the catalyst uses ethylene and carbon monoxide as raw materials to carry out a polymerization reaction in a solvent to obtain a high / ultra-high molecular weight ethylene / CO copolymer with polar groups.

[0043] Furthermore, when preparing the ethylene / CO copolymer, the pressure is 0.1-10 MPa, preferably 0.5-6 MPa; more preferably 1-5.5 MPa; and the reaction temperature is controlled at 50-150℃, preferably 60-100℃.

[0044] Furthermore, the selected solvent is mainly an inert solvent, preferably a straight-chain alkane, benzene and its derivatives, such as benzene, toluene, xylene, chlorobenzene, hexane, pentane, etc.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] This invention provides a novel phosphonic sulfonic acid ligand and a nickel phosphonic sulfonic acid catalyst, which is a novel Drent-type catalyst composed of benzenesulfonic acid and 1,3,2-diazaphosphonic acid. The 1,3,2-diazaphosphonic acid serves as the backbone, containing two N atoms directly bonded to P atoms. The lone pairs of electrons on the N atoms and the attached substituents effectively improve the electronic state of the P atoms, ultimately affecting the oxyphilicity of the Ni active center and enhancing the catalyst's tolerance to polar comonomers. Under the combined effects of electronic effects and steric hindrance, the oxyphilicity of the Ni active center is reduced, and the insertion rate of polar groups is increased, which is beneficial for preparing high / ultra-high molecular weight polyolefins with biased polarity. Detailed Implementation

[0047] The following description is provided to disclose the present invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples and are not intended to limit the scope of the invention; other obvious variations will be apparent to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention. Unless otherwise specified, the instruments or reagents used in the embodiments of the present invention are conventional commercial instruments or reagents.

[0048] The main reagents used in the examples are from the following sources:

[0049] Benzenesulfonic acid CAS: 98-11-3

[0050] CAS number for n-butyllithium: 109-78-8

[0051] Tetrahydrofuran CAS: 109-99-9

[0052] n-Hexane CAS: 110-54-3

[0053] Toluene CAS: 108-88-3

[0054] Ethylene CAS: 74-85-1

[0055] Dichloromethane CAS: 75-09-2

[0056] Allyl nickel(II) chloride dimer CAS: 12145-00-5

[0057] 2-Chloro-1,3-diphenyl-1,3,2-diazaphosphonium CAS: 82017-87-6

[0058] 2-Chloro-1,3-bis(2,6-dimethylphenyl)-1,3,2-diazaphosphonium CAS: 674783-84-7

[0059] 2-Chloro-1,3-dimethyl-1,3,2-diazaphosphonium CAS: 6069-36-9

[0060] Dimethylsilane (tert-butylamino)tetramethylcyclopentadienyldimethyltitanium CAS: 135072-62-7

[0061] 2-(Diphenylphosphino)benzenesulfonic acid CAS: 111864-25-6

[0062] Unless otherwise specified, all solvents involved must be anhydrous.

[0063] Example 1

[0064] The ligand L1 was prepared, and its structural formula is as follows:

[0065]

[0066] The synthetic route is as follows:

[0067]

[0068] The specific preparation method is as follows: Under nitrogen protection, at 0℃, 5 ml of n-hexane solution containing n-butyllithium (2 mmol, 128 mg) was slowly added dropwise to 10 ml of tetrahydrofuran solution containing benzenesulfonic acid (1 mmol, 158 mg). The reaction was allowed to proceed for 1 h. Then, 5 ml of tetrahydrofuran solution containing 2-chloro-1,3-diphenyl-1,3,2-diazaphosphadin (1 mmol, 276.7 mg) was added dropwise to the mixed solution using a constant pressure dropping funnel. The mixture was then slowly heated to room temperature and reacted for 4 h. After the reaction was completed, the solvent was removed under reduced pressure, and the product sample L1 was obtained by column chromatography with a yield of 47%. 1H (400 MHz, CDCl3) δ=8.46(s,1H -OH); δ=7.80-7.50(m,4H -Ar-H); δ=7.17-6.84(m,10H -Ar-H); δ=3.41(m,4H -CH2).

[0069] Example 2

[0070] The ligand L2 was prepared, and its structural formula is as follows:

[0071]

[0072] The synthetic route is as follows:

[0073]

[0074] The specific preparation method is as follows: Under nitrogen protection, at 0℃, 5 ml of n-hexane solution containing n-butyllithium (2 mmol, 128 mg) was slowly added dropwise to 10 ml of tetrahydrofuran solution containing benzenesulfonic acid (1 mmol, 158 mg). The reaction was allowed to proceed for 1 h. Then, 5 ml of tetrahydrofuran solution containing 2-chloro-1,3-bis(2,6-dimethylphenyl)-1,3,2-diazaphosphazene (1 mmol, 332.8 mg) was added dropwise to the mixed solution using a constant pressure dropping funnel. The mixture was then slowly heated to room temperature and reacted for 5 h. After the reaction was completed, the solvent was removed under reduced pressure, and the product sample L2 was obtained by column chromatography with a yield of 33%. 1H (400 MHz, CDCl3) δ=8.52(s,1H-OH); δ=7.80-7.64(m,4H-Ar-H); δ=6.97-6.82(m,6H-Ar-H); δ=3.26(s,4H-CH2); δ=2.13(s,6H-CH3).

[0075] Example 3

[0076] The ligand L3 was prepared, and its structural formula is as follows:

[0077]

[0078] The synthetic route is as follows:

[0079]

[0080] The specific preparation method is as follows: Under nitrogen protection, at 0℃, 5 ml of n-hexane solution containing n-butyllithium (2 mmol, 128 mg) was slowly added dropwise to 10 ml of tetrahydrofuran solution containing benzenesulfonic acid (1 mmol, 158 mg). The reaction was allowed to proceed for 1 h. Then, 5 ml of tetrahydrofuran solution containing 2-chloro-1,3-dimethyl-1,3,2-diazaphosphazene (1 mmol, 152.56 mg) was added dropwise to the mixed solution using a constant pressure dropping funnel. The mixture was then slowly heated to room temperature and reacted for 4 h. After the reaction was completed, the solvent was removed under reduced pressure, and the product sample L3 was obtained by column chromatography with a yield of 40%. 1H (400 MHz, CDCl3) δ=8.50(s,1H -OH); δ=7.80-7.53(s,4H -Ar-H); δ=2.66(s,4H -CH2); δ=2.46(s,6H -CH3).

[0081] Example 4

[0082] The structural formula of catalyst C1 is as follows:

[0083]

[0084] The synthetic route is as follows:

[0085]

[0086] The specific preparation method is as follows: Ligand L1 (0.384 g, 1.00 mmol) and Na2CO3 (0.42 g, 2.00 mmol) were dissolved in 10 mL of DCM in a glove box and reacted at room temperature for 2 h. Allyl nickel chloride (0.30 g, 1.10 mmol) was then added, and the reaction was continued at room temperature for 10 h. After filtration through diatomaceous earth, the resulting liquid was dried under vacuum. A mixed solution of dichloromethane and n-hexane was added, and the mixture was stirred for 10–15 min before filtration to obtain catalyst C1, with a yield of 76%.

[0087] Example 5

[0088] The structural formula of catalyst C2 is as follows:

[0089]

[0090] The synthetic route is as follows:

[0091]

[0092] The specific preparation method is as follows: Ligand L2 (0.432 g, 1.00 mmol) and Na2CO3 (0.42 g, 2.00 mmol) were dissolved in 10 mL of DCM in a glove box and reacted at room temperature for 2 h. Allyl nickel chloride (0.30 g, 1.10 mmol) was then added, and the reaction was continued at room temperature for 10 h. After filtration through diatomaceous earth, the resulting liquid was dried under vacuum. A mixed solution of dichloromethane and n-hexane was added, and the mixture was stirred for 10–15 min before filtration to obtain catalyst C2, with a yield of 80%.

[0093] Example 6

[0094] The structural formula of catalyst C3 is as follows:

[0095]

[0096] The synthetic route is as follows:

[0097]

[0098] The specific preparation method is as follows: Ligand L3 (0.258 g, 1.00 mmol) and Na2CO3 (0.42 g, 2.00 mmol) were dissolved in 10 mL of DCM in a glove box and reacted at room temperature for 2 h. Allyl nickel chloride (0.30 g, 1.10 mmol) was then added, and the reaction was continued at room temperature for 10 h. After filtration through diatomaceous earth, the resulting liquid was dried under vacuum. A mixed solution of dichloromethane and n-hexane was added, and the mixture was stirred for 10–15 min before filtration to obtain catalyst C3, with a yield of 85%.

[0099] Example 7

[0100] The obtained catalyst C1 was used to polymerize ethylene with carbon monoxide to produce an ethylene / CO copolymer. The synthesis steps were as follows: Under argon protection, nickel phosphonate catalyst (catalyst C1, 10 μmol) and 20 mL of toluene were added sequentially to a 75 mL autoclave equipped with a magnetic stirrer, and the autoclave was tightened. At room temperature, the autoclave was connected to the polymerization pipeline, and a C2H4 / CO mixture (molar ratio 9:1) with a total pressure of 5 MPa was introduced, and the mixture was stirred for 2 min until the gas in the autoclave was completely saturated. The pipeline was disconnected, and the autoclave was slowly placed in an 80 °C oil bath with magnetic stirring to carry out the polymerization reaction. After the reaction was completed for 3 h, the autoclave was cooled, the remaining gas in the autoclave was slowly released, anhydrous methanol was added to quench the reaction, the mixture was filtered, the solid polymer product was collected, and the product was dried under vacuum at 55 °C overnight. The yield was calculated by weighing.

[0101] Example 8

[0102] Compared to Example 7, catalyst C1 was replaced with catalyst C2, and all other steps were the same.

[0103] Example 9

[0104] Compared to Example 7, catalyst C1 was replaced with catalyst C3, and all other steps were the same.

[0105] Comparative Example 1

[0106] Compared to Example 7, catalyst D was used, which is a commercially available metallocene catalyst (dimethylsilane (tert-butylamino)tetramethylcyclopentadienyldimethyltitanium), and the co-catalyst was methylaluminoxane MAO (the molar ratio of metallocene catalyst to co-catalyst was 1:75). The rest was the same as in Example 7. As a result, only a small amount of high molecular weight polyethylene was generated, and no ethylene / CO copolymer was effectively generated.

[0107] Comparative Example 2

[0108] Compared to Example 7, catalyst C1 was replaced with catalyst Cat-Ref, and all other steps were the same.

[0109] The catalyst Cat-Ref is synthesized based on the phosphonic acid ligand structure. Its structure is (2-(diphenylphosphono)benzenesulfonic acid)nickel(II)-allyl complex, which has a similar [P,O] coordination mode to the catalyst in the example. However, it uses a benzene ring to improve the electronic structure of the active metal center. Compared with the 1,3,2-diazaphosphonic acid structure of the present invention, the electron density of the active center is reduced, which hinders its copolymerization performance with polar monomers.

[0110]

[0111] The specific synthesis method is as follows: In a glove box, 2-(diphenylphosphino)benzenesulfonic acid (0.35 g, 1.00 mmol) and Na₂CO₃ (0.42 g, 2.00 mmol) were added to 10 mL of dichloromethane and reacted at room temperature for 2 h. Then, allyl nickel chloride (0.30 g, 1.10 mmol) was added and reacted at room temperature for 10 h. After filtration through diatomaceous earth and vacuum drying, a mixed solution of dichloromethane and n-hexane was added, stirred, and filtered to obtain the catalyst Cat-Ref in approximately 75% yield.

[0112] [Performance Evaluation Test]

[0113] 1. Catalyst activity test: Calculated based on polymer yield, expressed as g copolymer / (mol catalyst × h).

[0114] 2. Determination of weight-average molecular weight of copolymer samples: The weight-average molecular weight was determined by gel permeation chromatography in accordance with GB / T 27843-2011 "Determination of low molecular weight components of polymers in chemicals - Gel permeation chromatography (GPC)".

[0115] 3. Determination of CO monomer content in copolymer samples: The CO content was calculated using the 1H NMR spectrum of the copolymer products. See Table 1 for detailed results.

[0116] Table 1 Performance Evaluation Test Results

[0117]

[0118] Note: Comparative Example 1 produced only a very small amount of product, and no relevant tests were performed.

[0119] As shown in Table 1, the nickel phosphonate catalyst of this invention (Examples 7-9) exhibits excellent catalytic performance in the copolymerization of ethylene and carbon monoxide, effectively solving the problem of deactivation of existing catalysts due to poisoning by polar monomers, and obtaining a polar polymer with a moderate CO insertion rate and a high molecular weight. In Comparative Example 1, the metallocene catalyst was almost completely deactivated in the presence of CO and could not form a copolymer, indicating that it is highly sensitive to polar monomers and difficult to use in the ethylene / CO copolymerization reaction. Compared with the examples of this invention, although Comparative Example 2 can catalyze the copolymerization reaction, its catalytic activity, molecular weight, and CO insertion rate are significantly lower, indicating that the catalytic efficiency and copolymerization performance are significantly reduced when the electronic regulation of the 1,3,2-diazaphosphonic acid skeleton is lacking. This invention successfully obtains a polar polyolefin material with high activity, high molecular weight, and a moderate CO insertion rate by synergistically regulating the electronic effect and steric hindrance of the ligands through the 1,3,2-diazaphosphonic acid skeleton.

[0120] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A phosphonic acid ligand having the general structure shown in Formula L: in, R1-R4 are independently selected from H, C1-C6 alkyl, C1-C6 alkoxy, C6-C 12 Aryl or halogen.

2. The phosphonic acid ligand according to claim 1, characterized in that, In R1-R4, R1 and R2 are selected from the same group, and R3 and R4 are selected from the same group.

3. The phosphonic acid ligand according to claim 1, characterized in that, R3 and R4 are H, and R1 and R2 are both selected from one of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, and C6 aryl.

4. The phosphonic acid ligand according to claim 1, characterized in that, The phosphonic acid ligand is selected from any one of the compounds shown in formulas L1 to L3: 。 5. The method for preparing the phosphonic acid ligand according to any one of claims 1-4, characterized in that, The product was prepared by reaction using benzenesulfonic acid of formula I and 1,3,2-diazaphosphonic acid derivative of formula II as raw materials. The specific reaction formula is as follows: 。 6. The method for preparing the phosphonic acid ligand according to claim 5, characterized in that, The 1,3,2-diazaphosphonium derivative is selected from 2-chloro-1,3-diphenyl-1,3,2-diazaphosphonium, 2-chloro-1,3-bis(2,6-dimethylphenyl)-1,3,2-diazaphosphonium, and 2-chloro-1,3-dimethyl-1,3,2-diazaphosphonium.

7. The method for preparing the phosphonic acid ligand according to claim 5, characterized in that, The process includes the following steps: under an inert atmosphere and at low temperature, a base reagent is reacted with benzenesulfonic acid in a solvent to generate a benzenesulfonic acid intermediate. The obtained benzenesulfonic acid intermediate is then reacted with a 1,3,2-diazaphosphonic acid derivative in an organic solvent to generate a nucleophilic substitution reaction, and the product is obtained by post-processing, separation, and purification to obtain the phosphonic acid ligand. The alkaline reagent is an organolithium reagent; The organic solvent is a polar aprotic solvent capable of dissolving the reactants; The molar ratio of benzenesulfonic acid, 1,3,2-diazaphosphonic acid derivative, and base reagent is 1:1:1.2-2.

5.

8. A nickel phosphononsulfonate catalyst, characterized in that, It is a coordination compound formed by the phosphonic acid ligand as described in any one of claims 1-4 and an organonitrile complex.

9. The nickel phosphonate catalyst according to claim 8, characterized in that, Nickel phosphononsulfonate catalysts having the general structure shown in Formula C: 。 10. The use of the nickel phosphonate catalyst according to claim 8 or 9 in the preparation of polar polyolefins.

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