阅读说明：本技术 一种聚β-羟基脂肪酸酯的化学合成方法 (Chemical synthesis method of poly beta-hydroxy fatty acid ester ) 是由 刘野 杨金闯 吕小兵 于 2021-07-30 设计创作，主要内容包括：本发明提供了一种聚β-羟基脂肪酸酯的化学合成方法,用于合成具有高分子量聚羟基脂肪酸酯的双功能催化剂是通过苯基骨架将两个或三个金属中心连接起来的双或三核心、四齿席夫碱配合物。该催化剂可在较低浓度下催化一氧化碳与环氧烷烃反应高效率制备呈交替结构的聚羟基脂肪酸酯新材料。聚合物选择性>99％,区域结构选择性>99％,交替结构>99％,全同度P-m在0-100％之间,分子量在1.0-100kg/mol之间,分子量分布在1.01-2.00之间。(The invention provides a chemical synthesis method of poly beta-hydroxy fatty acid ester, and a bifunctional catalyst for synthesizing the poly beta-hydroxy fatty acid ester with high molecular weight is a double-core or triple-core and tetradentate Schiff base complex formed by connecting two or three metal centers through a phenyl skeleton. The catalyst can catalyze the reaction of carbon monoxide and alkylene oxide under lower concentration to prepare a new polyhydroxyalkanoate material with an alternate structure at high efficiency. Polymer selectivity>99% regioselectivity>99% of alternating structure>99% full concentricity of P m Between 0 and 100%, a molecular weight of between 1.0 and 100kg/mol and a molecular weight distribution of between 1.01 and 2.00.)

1. A chemical synthesis method of poly beta-hydroxy fatty acid ester is characterized in that the catalyst used in the chemical synthesis method is a bifunctional catalyst, which is a double-core or triple-core tetradentate Schiff base complex formed by connecting two or three metal centers through a phenyl framework;

the structure of the double-core or triple-core tetradentate Schiff base complex is as follows:

in the formula, M is Fe³⁺、Co³⁺、Ni³⁺、Cr³⁺、Mn³⁺、Al³⁺Or Ru³⁺；

R¹Is H, CH₃、CH₂CH₃、CH(CH₃)₂、C(CH₃)₃、OCH₃、OCH₂CH₃、F. Cl, Br, I or NO₂；

R²Is H, CH₃、CH₂CH₃、CH(CH₃)₂、C(CH₃)₃、OCH₃、OCH₂CH₃、F. Cl, Br, I or NO₂；

X is cobalt tetracarbonyl anion, F^-、Cl^-、Br^-、I^-、NO₃ ^-、CH₃COO^-、CCl₃COO^-、CF₃COO^-、ClO₄ ^-、BF₄ ^-、BPh₄ ^-、N₃ ^-P-methylbenzoate, p-toluenesulfonate, o-nitrophenol oxygen, p-nitrophenol oxygen, m-nitrophenol oxygen, 2, 4-dinitrophenol oxygen, 3, 5-dinitrophenol oxygen, 2,4, 6-trinitrophenol oxygen, 3, 5-dichlorophenol oxygen, 3, 5-difluorophenol oxygen, 3, 5-bis-trifluoromethylphenol oxygen or pentafluorophenol oxygen anions, wherein the following must be satisfied: for a dual-core tetradentate schiff base complex: the number of cobalt tetracarbonyl anions is 1 or 2, and the number of other anions is 1 or 0 correspondingly; for three-core tetradentate schiff base complexes: the number of cobalt tetracarbonyl anions is 1 or 2 or 3, and the corresponding number of other anions is 2 or 1 or 0;

the chemical synthesis method comprises the following specific steps:

controlling the molar ratio of the bifunctional catalyst to the alkylene oxide to be 1: 500-1: 50000, and adding any one of toluene, dichloromethane, trichloromethane, ethylene glycol dimethyl ether, benzene and chlorobenzene as a reaction solvent without a solvent; reacting for 1-48 hours under the conditions that the reaction temperature is 25-150 ℃ and the CO pressure is 1-15.0 MPa to obtain poly beta-hydroxy fatty acid ester with selectivity>99% regioselectivity>99% of alternating structure>99％，Full depth P_mBetween 0 and 100%, a molecular weight of between 1.0 and 100kg/mol and a molecular weight distribution of between 1.01 and 2.00.

2. The method of claim 1, wherein the alkylene oxide has the formula:

3. a chemical synthesis process according to claim 1 or 2, characterized in that the bifunctional catalyst is prepared by the following steps:

in the nitrogen atmosphere, diamine compounds and 3, 5-di-tert-butyl salicylaldehyde are put into methanol according to the molar ratio of 1:1 to obtain a mixed solution, and the mixed solution is heated and refluxed for 6 hours; wherein the concentration of the diamine compound in the mixed solution is not higher than 1.0 mol/L; after cooling, adding anhydrous tetrahydrofuran and 2, 4-dihydroxy isophthalaldehyde into the system, and stirring at room temperature overnight; wherein the molar ratio of the 2, 4-dihydroxy isophthalaldehyde to the diamine compound is 1:2, and the volume ratio of the anhydrous tetrahydrofuran to the methanol is 2: 3; concentrating the reaction solution under reduced pressure to remove the solvent, and purifying the crude product by silica gel column chromatography to obtain a target ligand;

under argon atmosphere, the target ligand and CrCl are added₂Dissolving the target ligand in anhydrous tetrahydrofuran according to a molar ratio of 1:2, wherein the concentration of the target ligand in the anhydrous tetrahydrofuran is not higher than 0.2mol/L, stirring at room temperature overnight, introducing oxygen, and continuing stirring for 12 hours; stopping the reaction, removing the solvent by rotation, dissolving the dichloromethane and saturating NH₄The organic layer was washed with an aqueous solution of Cl and saturated brine in this order, and dried over anhydrous Na₂SO₄Drying; filtering and removing the solvent by spinning; dissolving the target complex in anhydrous tetrahydrofuran, and adding NaCo (CO) according to the concentration of the target complex in the anhydrous tetrahydrofuran not higher than 0.2mol/L₄，NaCo(CO)₄With CrCl₂According to a molar ratio of 1: 1; stirring at room temperature overnight; the mixture is concentrated and then is subjected to concentration,adding n-hexane, wherein the volume ratio of the n-hexane to the anhydrous tetrahydrofuran is 1: 1; filtering after solid is separated out, and drying the red powder in vacuum to obtain the bifunctional catalyst.

4. The production method according to claim 3, the diamine compound is ethylenediamine, (R) -1, 2-propanediamine, (S) -1, 2-propanediamine, (rac) -1, 2-propanediamine, (R) -1, 2-butanediamine, (S) -1, 2-butanediamine, (rac) -1, 2-butanediamine, (R, R) -2, 3-butanediamine, (S, S) -2, 3-butanediamine, (rac) -2, 3-butanediamine, (R, R) -cyclohexanediamine, (S, S) -cyclohexanediamine, (rac) -cyclohexanediamine, o-phenylenediamine, (R, R) -diphenylethylenediamine, (S, S) -diphenylethylenediamine or (rac) -diphenylethylenediamine.

Technical Field

The invention relates to a chemical synthesis method of poly beta-hydroxy fatty acid ester macromolecules, which uses a catalytic system consisting of dual-functional bimetallic chromium and aluminum complexes to realize the polymerization reaction of alkylene oxide and carbon monoxide with various structures to obtain a series of new functional poly beta-hydroxy fatty acid ester materials, the performance of the new functional poly beta-hydroxy fatty acid ester materials is equivalent to that of bio-based poly beta-hydroxy fatty acid esters, but the new functional poly beta-hydroxy fatty acid ester materials can be produced on a large scale more easily.

Background

Biodegradable polymer materials are materials that can be directly biodegraded under certain conditions, and the development of biodegradable polymer materials is considered as an important way to solve environmental pollution, and has become one of the hot spots of research in the polymer field. At present, the yield is the most ecological plastic at home and abroad, and the plastic mainly comprises polylactic acid, polyhydroxyalkanoate and starch plastic. Polyhydroxyalkanoates (PHAs) are a class of high molecular polyesters, of which poly-beta-hydroxyalkanoate is the most widely studied; r is a variable pendant group, and is mostly n-alkyl with different carbon chain lengths. Among them, poly-3-hydroxybutyrate (P3HB) having a methyl group as a side chain is most common.

PHAs are thermoplastic polyesters that, depending on the type and structure of the pendant groups, can be hard, brittle, hard plastics or can be converted to soft elastomers. PHAs not only have the characteristics of chemically synthesized plastics, but also have the characteristics of biodegradability, biocompatibility, optical activity, surface modifiability and the like. As an outstanding representative of PHAs, thermoplastic P3HB is an isotactic polypropylene (A) having Young's modulus, impact strength, UV and oxygen barrier properties comparable to those of widely used polypropyleneⁱPP), has also been consideredⁱPP is an ideal substitute product in the field of packaging. Because the P3HB has simple chemical structure and high crystallinity up to 80 percent, the product is crisp and strong, and the elongation at break (3-5 percent) is obviously lower than that of the productⁱPP (400%). In particular, P3HB, when it is higher than the melting point (180 ℃), will undergo pyrolysis, increasing the difficulty and cost of processing and forming. Therefore, products of PHAs in the later period mostly apply the strategy of copolymerization, such as 3-hydroxybutyric acid/3-hydroxyvaleric acid copolyester (PHBV) and 3-hydroxybutyric acid/3-hydroxyhexanoic acid copolyester (PHBHHx) are developed by introducing a second monomer with long alkyl side chain, and the PHAs have better flexibility than P3 HB. Due to its excellent biodegradability and mechanical properties comparable to petroleum-based materials, PHAs have become the first choice for green packaging materials such as films, bags, boxes, paper, and the like.

In conclusion, in view of the wide application of PHAs in various fields such as biomedical science, tissue engineering and green packaging, PHAs, as a "green plastic" and an "environment-friendly plastic", have attracted much attention from the scientific and industrial circles of all countries in the world.

PHAs technical basis and preparation method: the research of PHAs began with the discovery of P3HB in B.megaterium by Lemoigne, Pasteur research, France 1926, and began in the 70 th 20 th century, when ICI, UK, produced PHAs by fermentation using microorganisms in natural soil. At present, China has the largest production line for preparing PHA by a biological fermentation method in the world, but the productivity is always in the kiloton level, the market price is higher (about 7 ten thousand/ton), the production line cannot be compared with the polyolefin material on the market, the production line is higher than the bio-based polymer such as polylactide, polycarbonate propylene ester and the like by 3-4 times, and the high price becomes the biggest obstacle for the application of polyhydroxyalkanoate. Compared with a biological method, the chemical method has the advantages of high efficiency, low cost, wide substrate applicability and the like, and further development of the industry can be promoted if the chemical method production of the polyhydroxyalkanoate can be realized.

The chemical method for preparing the polyhydroxyalkanoate at present has three main methods: asymmetric hydrogenation of diketene can produce optically active beta-butyrolactone. Beta-butyrolactone is subjected to ring opening polymerization under the action of a catalyst to prepare P3 HB. Spassky et al, as early as 1989, used a metal alkyl reagent/chiral diol to catalyze the ring-opening polymerization of racemic β -butyrolactone in an attempt to obtain P3HB having an identical structure, however, this reaction was low in activity and poor in resolution. Subsequently, the ring-opening polymerization of racemic β -butyrolactone was explored by various groups of topics both at home and abroad, typically BDI-Zn complexes developed by professor Coates, Chromium (III) Salophen complexes developed by professor Rieger, and rare earth metal complexes reported by professor Carpentier, Changchun-Yingmei researcher and professor Yaoyingin Suzhou university. Although the activity of preparing P3HB by ring-opening polymerization of lactone is high, the reaction is controllable, and a polymer with regularity can be prepared, the monomer used in the method is only limited to beta-butyrolactone, so that the price is high, and the method is not favorable for large-scale production. The acetaldehyde is subjected to aldol condensation and oxidation to obtain 3-hydroxybutyric acid, and the polycondensation reaction can obtain P3HB, so that the method has the defects of more side reactions in monomer preparation, high energy consumption in high-temperature polycondensation reaction, poor atom economy and cracking reaction of P3 HB. Recently, the european professor y-x.chen has enabled highly efficient preparation of stereosequential and property-controllable poly 3-hydroxybutyrate esters by catalyst-controlled diastereoselective polymerization of eight-membered cyclic lactide monomers.

Alkylene oxide is a bulk chemical which is cheap and easy to obtain, carbon monoxide is an important C1 resource, and the carbonylation polymerization of alkylene oxide to obtain polyhydroxyalkanoate is undoubtedly very competitive. As early as 1965, scientists reported this reaction, however, the reaction activity was low and the selectivity was poor. In 2002, Rieger et al scientist catalyzed the polymerization of propylene oxide and carbon monoxide with additives such as cobaltosic octacarbonyl and 3-hydroxypyridine as catalysts to obtain oligomers with molecular weights below 2kg/mol and with a large amount of lactone by-products. Teaching of Jia USA uses acyl cobalt complex coordinated by organic phosphine as catalyst, and explores copolymerization reaction of high activity ethylene oxide and carbon monoxide. In 2010, Coates teaches that poly-3-hydroxybutyrate is directly obtained by a two-step one-pot reaction of "carbonylation of alkylene oxide to lactone" and "ring-opening polymerization" of lactone, with addition of carbonylation and ring-opening polymerization catalysts, respectively, without separation of lactone intermediates.

The above method for preparing polyhydroxyalkanoate has the problems of high price and limited varieties of lactone, but the direct carbonylation polymerization of alkylene oxide and carbon monoxide has low activity and poor polyester selectivity, and especially it is difficult to obtain high molecular weight polymer (M)_n<2kg/mol), most of which are low molecular weight oligomers.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a bifunctional catalyst for selectively catalyzing the reaction of alkylene oxide and carbon monoxide to prepare high molecular weight polyhydroxyalkanoate under the relatively mild reaction condition with low catalyst concentration.

The technical scheme of the invention is as follows:

a chemical synthesis method of poly beta-hydroxy fatty acid ester, the catalyst used in the chemical synthesis method is a bifunctional catalyst, which is a double or triple core tetradentate Schiff base complex formed by connecting two or three metal centers through a phenyl skeleton;

the structure of the double-core or triple-core tetradentate Schiff base complex is as follows:

in the formula, M is Fe³⁺、Co³⁺、Ni³⁺、Cr³⁺、Mn³⁺、Al³⁺Or Ru³⁺；

R¹Is H, CH₃、CH₂CH₃、CH(CH₃)₂、C(CH₃)₃、OCH₃、OCH₂CH₃、F. Cl, Br, I or NO₂；

R²Is H, CH₃、CH₂CH₃、CH(CH₃)₂、C(CH₃)₃、OCH₃、OCH₂CH₃、F. Cl, Br, I or NO₂；

X is cobalt tetracarbonyl anion, F^-、Cl^-、Br^-、I^-、NO₃ ^-、CH₃COO^-、CCl₃COO^-、CF₃COO^-、ClO₄ ^-、BF₄ ^-、BPh₄ ^-、N₃ ^-P-methylbenzoate, p-toluenesulfonate, o-nitrophenol oxygen, p-nitrophenol oxygen, m-nitrophenol oxygen, 2, 4-dinitrophenol oxygen, 3, 5-dinitrophenol oxygen, 2,4, 6-trinitrophenol oxygen, 3, 5-dichlorophenol oxygen, 3, 5-difluorophenol oxygen, 3, 5-bis-trifluoromethylphenol oxygen or pentafluorophenol oxygen anionWherein it must be satisfied: for a dual-core tetradentate schiff base complex: the number of cobalt tetracarbonyl anions is 1 or 2, and the number of other anions is 1 or 0 correspondingly; for three-core tetradentate schiff base complexes: the number of cobalt tetracarbonyl anions is 1 or 2 or 3, and the corresponding number of other anions is 2 or 1 or 0;

the chemical synthesis method comprises the following specific steps:

controlling the molar ratio of the bifunctional catalyst to the alkylene oxide to be 1: 500-1: 50000, and adding any one of toluene, dichloromethane, trichloromethane, ethylene glycol dimethyl ether, benzene and chlorobenzene as a reaction solvent without a solvent; reacting for 1-48 hours under the conditions that the reaction temperature is 25-150 ℃ and the CO pressure is 1-15.0 MPa to obtain poly beta-hydroxy fatty acid ester with selectivity>99% regioselectivity>99% of alternating structure>99% full concentricity of P_mBetween 0 and 100%, a molecular weight of between 1.0 and 100kg/mol and a molecular weight distribution of between 1.01 and 2.00.

For alkylene oxides of terminal structure, such as PO, BO, HO, OO, DO, DDO, BBO, PGE, BGE, IPGE, TBGE, BGE, NGE and AGE, chiral poly-beta-hydroxy fatty acid esters can be prepared if the above-mentioned alkylene oxides are used as substrates in the chiral R or S-configuration.

A double-or three-core tetradentate Schiff base complex bifunctional catalyst is prepared by the following steps:

the synthesis method is characterized in that bidentate (L1) or tridentate ligand (L2) reacts with metal chloride salt and sodium cobalt tetracarbonyl at room temperature to prepare the catalyst. The ligand L1 is prepared by reacting salicylaldehyde (formula 1), salicylaldehyde with different substituents (formula 2) and diamine compounds (formula 3) in methanol. The ligand L2 is prepared by the reaction of salicylaldehyde (formula 4), salicylaldehyde with different substituents (formula 2) and diamine compounds (formula 3) in methanol, wherein the structures of the bidentate ligand L1, the tridentate ligand L2 and a synthesis precursor are as follows:

the method comprises the following specific steps:

in the nitrogen atmosphere, diamine compounds and 3, 5-di-tert-butyl salicylaldehyde are put into methanol according to the molar ratio of 1:1 to obtain a mixed solution, and the mixed solution is heated and refluxed for 6 hours; wherein the concentration of the diamine compound in the mixed solution is not higher than 1.0 mol/L; after cooling, adding anhydrous tetrahydrofuran and 2, 4-dihydroxy isophthalaldehyde into the system, and stirring at room temperature overnight; wherein the molar ratio of the 2, 4-dihydroxy isophthalaldehyde to the diamine compound is 1:2, and the volume ratio of the anhydrous tetrahydrofuran to the methanol is 2: 3; the reaction solution was concentrated under reduced pressure to remove the solvent, and the crude product was purified by silica gel column chromatography to give the target ligand L1;

under argon atmosphere, target ligands L1 and CrCl₂Dissolving the target ligand L1 in anhydrous tetrahydrofuran according to a molar ratio of 1:2, wherein the concentration of the target ligand L1 in the anhydrous tetrahydrofuran is not higher than 0.2mol/L, stirring at room temperature overnight, introducing oxygen, and continuing stirring for 12 hours; stopping the reaction, removing the solvent by rotation, dissolving the dichloromethane and saturating NH₄The organic layer was washed with an aqueous solution of Cl and saturated brine in this order, and dried over anhydrous Na₂SO₄Drying; filtering and removing the solvent by spinning; dissolving the target complex in anhydrous tetrahydrofuran, and adding NaCo (CO) according to the concentration of the target complex in the anhydrous tetrahydrofuran not higher than 0.2mol/L₄，NaCo(CO)₄With CrCl₂According to a molar ratio of 1: 1; stirring at room temperature overnight; concentrating, and adding n-hexane, wherein the volume ratio of n-hexane to anhydrous tetrahydrofuran is 1: 1; filtering after solid is separated out, and drying the red powder in vacuum to obtain the bifunctional catalyst.

The diamine compound is ethylenediamine, (R) -1, 2-propanediamine, (S) -1, 2-propanediamine, (rac) -1, 2-propanediamine, (R) -1, 2-butanediamine, (S) -1, 2-butanediamine, (rac) -1, 2-butanediamine, (R, R) -2, 3-butanediamine, (S, S) -2, 3-butanediamine, (rac) -2, 3-butanediamine, (R, R) -cyclohexanediamine, (S, S) -cyclohexanediamine, (rac) -cyclohexanediamine, o-phenylenediamine, (R, R) -diphenylethylenediamine, (S, S) -diphenylethylenediamine or (rac) -diphenylethylenediamine.

The invention has the beneficial effects that:

(1) the method takes a large amount of industrial products of alkylene oxide and carbon monoxide which are cheap and easy to obtain as raw materials, and is not suitable for lactone with high price; the alkylene oxide has various structures, and the reaction has compatibility with structures such as double bonds, halogen, benzene rings, ether and the like, so that the functional polyhydroxyalkanoate can be obtained.

(2) Under low catalyst concentration, still has higher catalytic activity;

(3) the reaction conditions are relatively mild, and the process is simple and convenient;

(4) the catalyst has high activity and the selectivity of the polymerization product is high;

(5) the alternating structure in the polyhydroxyalkanoate product is higher than 99%, the molecular weight distribution is controllable, and most polyhydroxyalkanoates with identical structures have crystallizability;

(6) the molecular weight of the polyhydroxyalkanoate can reach 38.2kg/mol, and the polyhydroxyalkanoate basically has the performance of preparing polymers by corresponding biological fermentation.

Drawings

FIG. 1 is a nuclear magnetic hydrogen spectrum of a copolymer of carbon monoxide and propylene oxide (P3 HB).

FIG. 2 is a nuclear magnetic carbon spectrum of a copolymer of carbon monoxide and chiral propylene oxide (P3 HB).

FIG. 3 is a nuclear magnetic hydrogen spectrum of carbon monoxide with phenyl glycidyl ether.

FIG. 4 is a nuclear magnetic carbon spectrum of carbon monoxide with phenyl glycidyl ether.

FIG. 5 is a nuclear magnetic hydrogen spectrum of a ligand with dual cores.

FIG. 6 is an infrared spectrum of a dual-core tetradentate chromium complex.

Detailed Description

Specific examples of the present invention (tables 1 and 2) are described in detail below with reference to the technical schemes. Wherein table 1 relates to different metal complexes catalyzing the copolymerization of carbon monoxide and propylene oxide; table 2 relates to trivalent metal complexes catalyzing the copolymerization of carbon monoxide with different alkylene oxides.

In a 100mL stainless steel autoclave, the following were added in the following order at ambient temperature: a quantity of a metal catalyst (any of the claims describe)Which metal complex), 5mL of alkylene oxide, a certain amount of solvent (volume if necessary)<20mL) was added with carbon monoxide at the indicated pressure and rapidly raised to the set temperature. The autoclave was maintained at the appropriate temperature and pressure and after a regular reaction time, the stirring was stopped and unreacted carbon monoxide was slowly released at 0 ℃. Washing the polymerized product with chloroform/methanol precipitate for three times, drying under vacuum to constant weight, and measuring the molecular weight and distribution of the polymer by using gel permeation chromatography; it was determined using Varian INOVA-400MHz¹HNMR, calculating the parameters of the conversion rate of the alkylene oxide, the selectivity of the polymerization product, the regioselectivity and the like. Measurement of it with 500MHz NMR¹³CNMR, calculating the degree of identity of the polyester polymer.

TABLE 1 Metal complexes catalysis of alternating copolymerization of carbon monoxide and propylene oxide

Note 1: all catalytic reactions were bulk polymerizations with overall conversions greater than 99%.

Note 2: the polyester product obtained by applying the bimetallic, trimetallic aluminum and chromium catalytic system and the chemical structure selectivity¹HNMR determined that polyether and bis are present in the polymerization processCarbonylation and isomerization products.

Note 3: all catalysts are achiral or racemic, except where specifically noted.

TABLE 2 copolymerization of carbon monoxide with various alkylene oxides catalyzed by metal complexes

Note 1: all catalytic reactions were bulk polymerizations with overall conversions greater than 99%.

Note 2: polyester products and chemical structure selectivity obtained by applying such a trimetallic chromium catalytic system¹HNMR determined that some alkylene oxide had by-product formation during the polymerization.

A double-or three-core tetradentate Schiff base complex bifunctional catalyst is prepared by the following steps:

the compound is prepared by reacting salicylaldehyde or trialdehyde, salicylaldehyde with different substituents and diamine compounds in methanol, and is prepared by metallation reaction and axial group replacement, and a typical bimetallic chromium complex is synthesized as an example:

o-phenylenediamine (5g,0.046mol) and 3, 5-di-tert-butylsalicylaldehyde (10.76g,0.046mol) were dissolved in 150mL of an anhydrous methanol solution under a nitrogen atmosphere, and the mixed solution was heated under reflux for 6 hours. After cooling, 100mL of anhydrous tetrahydrofuran, 2, 4-dihydroxy-m-phenylenediamine (3.82g,0.023mol) was added to the system, and the mixture was stirred at room temperature overnight. The reaction solution was concentrated under reduced pressure to remove the solvent, and the crude product was purified by silica gel column chromatography (petroleum ether/ethyl acetate ═ 10:1v/v) to obtain 6.85g of the objective ligand.

Ligand (0.97g, 1) was added under an argon atmosphere.25mmol) and CrCl₂(0.31g,2.50mmol) was dissolved in 10mL of anhydrous tetrahydrofuran. After stirring overnight at room temperature, stirring was continued for 12h with oxygen. The reaction was stopped, the solvent was removed by rotation, dichloromethane (50mL) was dissolved, saturated NH₄The organic layer was washed with an aqueous solution of Cl (3X 50mL) and saturated brine (3X 50mL), and dried over anhydrous Na₂SO₄And (5) drying. Filtered, the solvent removed and dissolved in 10mL of anhydrous tetrahydrofuran, NaCo (CO) added₄(0.24g,1.25mmol) and stirred at room temperature overnight. Filtering NaCl, concentrating to 4mL, adding 20mL of n-hexane, filtering after solid is separated out, and vacuum drying red powder to obtain 1.4g of the required product. Paramagnetic Cr (III) complex, which cannot be obtained¹H NMR spectrum. HRMS (m/z): Calcd.for [ C₅₀H₅₄Cr₂N₄O₄]²⁺→[M-2Co(CO)₄]²⁺439.1477 and found 439.1469, with correct structure.