CN108530491B

CN108530491B - Preparation method of difluoro-boron-based bridged cobalt diketodioxime complex

Info

Publication number: CN108530491B
Application number: CN201810536197.9A
Authority: CN
Inventors: 胡剑; 蒋隆恒
Original assignee: Nippon Industry Paint Shanghai Co ltd; Guangzhou Nippon Paint Co Ltd
Current assignee: Nippon Industry Paint Shanghai Co ltd; Guangzhou Nippon Paint Co Ltd
Priority date: 2018-05-30
Filing date: 2018-05-30
Publication date: 2020-10-20
Anticipated expiration: 2038-05-30
Also published as: CN108530491A

Abstract

The invention discloses a preparation method of a difluoro boron group bridged cobalt diketodioxime complex, and the molecular formula is

In the formula, R¹，R²，R³,R⁴Is hydrogen (H) or a substituent group, which may be the same or different, may be independent or belong to a cyclic substituent group, L¹And L²Is an axial ligand and is a solvent or water molecule with weaker coordination capacity; under the atmosphere of nitrogen or inert gas, mixing and stirring divalent cobalt salt, a diketo dioxime ligand and a reaction solvent; adding boron trifluoride ether complex, stirring for reaction at room temperature or under heating or ice water bath, and filtering the obtained reaction mixture to obtain a precipitate, namely a crude product; and mixing and stirring the crude product with a purification solvent or water with polarity not lower than that of isobutanol for 5-30 minutes or carrying out ultrasonic treatment for 1-10 minutes, filtering, and drying in vacuum or under reduced pressure to obtain the purified difluoro boron group bridged diketo dioxime cobalt complex. The invention simplifies the purification steps and improves the yield.

Description

Preparation method of difluoro-boron-based bridged cobalt diketodioxime complex

Technical Field

The invention belongs to the technical field of metal-organic matter complex materials, and particularly relates to a preparation method and application of a cobalt diketodioxime complex.

Background

A bis [ (difluoroboryl) diketodioxime subunit ] cobaltic acid complex (hereinafter referred to as difluoroboryl dioxime cobalt complex) having a molecular formula of

R¹，R²，R³,R⁴Is hydrogen (H) or a substituent group,may be the same or different, may be independent or belong to the group of cyclic substituents, L¹And L²Is an axial ligand, is a solvent or water molecule with weaker coordination capacity, and can be used as a catalyst for catalyzing chain transfer polymerization with high efficiency. Catalytic chain transfer polymerization can be used to synthesize macromonomers, which can be further copolymerized with other monomers to form graft copolymers. Graft copolymers are widely used in the field of resins and pigment dispersants.

The synthesis of cobalt complexes with glyoxime as ligand has been reported in the literature. Typically, a bis (diketonedioxime) cobaltate complex is formed by reacting a diketonedioxime ligand with a divalent cobalt salt. Such cobalt complexes are also very active catalysts for catalyzing chain transfer polymerization, but have poor resistance to hydrolysis and oxidation. The harsh anhydrous, oxygen-free operating and use environment limits its use as a catalyst for catalyzing chain transfer polymerization. Such cobalt complexes, when reacted with boron trifluoride ether complexes, can form difluoroboron-based bridged cobalt diketodioximates complexes (i.e., difluoroboron-based cobalt dioximates complexes). The difluoro boron group bridging can greatly improve the stability of the cobalt complex on hydrolysis and oxidation, and greatly improve the application range of the cobalt complex as a catalyst for catalyzing chain transfer polymerization.

The difluoroboron-based dioxime cobalt complex is generally synthesized by a one-pot synthesis method, and a boron trifluoride ether complex is directly added to a reaction mixture of the glyoxime cobalt complex to form a difluoroboron-based bridged cobalt complex. The stepwise synthesis method firstly synthesizes and separates the mediator of the complex of the cobalt diketodioxime, and then the mediator reacts with the complex of boron trifluoride ether. Both syntheses suffer from low yields and difficulties in isolation and purification. Reliable and stable purity is critical to the use of such catalysts to provide a stable rate of chain transfer catalysis and thus a macromer with a stable degree of polymerization. Since such catalysts have very high activity, the degree of polymerization of macromonomers by chain transfer catalytic polymerization becomes very unpredictable and extremely difficult to apply in the case where even a very small amount of impurities is incorporated, particularly in the case where the impurities themselves are relatively unstable but are also highly active catalysts.

It should be noted that the cobalt salt, the ligand, the intermediate and the final product have poor solubility in common organic solvents, the reaction is substantially heterogeneous, the intermediate and the final product of the whole reaction mostly exist in a precipitated form, and even after a long reaction time, the intermediate is difficult to completely convert, so that the product is impure due to the inclusion of the intermediate, and the purification is difficult due to the similarity of the structure.

The general purification method is to cool and recrystallize in organic solvents such as methanol, i.e. crude products are dissolved in the organic solvents, insoluble impurities are filtered, the solution is cooled and kept stand for a period of time, and the products are crystallized and separated out; however, because the solubility of the cobalt complex in common organic solvents is very low (less than-1%) and the chemical stability to impurities (acid, alkali, oxidant and the like) in the solvents is poor, a large amount of high-purity and high-toxicity solvents and low-temperature (minus 25 ℃) freezing treatment are needed, the purification steps are long, the time consumption is long, the conditions are harsh, the yield is very low, the synthesis is not practical, a large amount of solvent waste liquid is generated, the environment is not friendly, the cost is high, and the industrial production is not easy to realize. Furthermore, characterization of such complexes is difficult, with elemental analysis and uv-vis absorption spectroscopy being common. Most literature reports generally do not mention product purity or yield.

U.S. Pat. No. 5,5028677 to Dupont corporation reports bis [ (difluoroboryl) dimethylglyoxime]Cobaltic acid complex (i.e., in formula I, R)¹、R²、R³And R⁴Both methyl groups, hereinafter abbreviated as COBF) and a method of recrystallization. The mixture of cobalt acetate salt and dimethylglyoxime in diethyl ether was stirred at room temperature overnight after addition of boron trifluoride diethyl etherate, filtered to give the crude product, which was then purified by recrystallization from methanol at-25 ℃ overnight by cooling and standing. The final yield was approximately 0.57 grams, or 17%.

It can be seen that the synthesis and purification process described above uses a large amount of the volatile low boiling point solvent diethyl ether (150ml per 2 g of cobalt salt, or about 18.7L per mole of cobalt salt) as the reaction solvent and a large amount of methanol (250ml per 2 g of cobalt salt, or about 31L per mole of cobalt salt) for purification and recrystallization, with very low final yields. The requirements of large-scale industrial production are not suitable from the viewpoints of safety, environment and cost.

In view of the above, there is a need for a more efficient synthesis and purification method for preparing high purity cobalt difluoroboryl oxime complexes.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a preparation method of a difluoro-boron-based bridged cobalt diketodioxime complex for synthesizing a high-purity and high-yield chain transfer catalyst of the difluoro-boron-based cobalt dioxime complex. The invention solves the serious problems of low yield and purity, difficult purification and the like in the prior art, and other problems of using a large amount of organic solvents with low boiling points and high toxicity, being environment-friendly, consuming time, having high cost and the like.

By fully considering the defects of the prior art, after the reaction mechanism of the dioxime cobalt complex is systematically researched and verified, the invention greatly reduces the using amount of the reaction solvent, improves the safety performance of the reaction solvent, greatly simplifies the purification steps, omits a lengthy recrystallization process and can achieve the purity equivalent to or better than that of recrystallization only by simply washing with a small amount of solvent by optimizing and combining the polarity and the solubility of the reaction solvent and the solvent used in the purification process; furthermore, the side reaction which is possibly generated is verified, and the side reaction is reduced by adding the monoxime as a weak base neutralizing agent, so that the reaction yield is greatly improved to 80-95%; furthermore, reaction conditions including reaction temperature, time, reagent dosage and purification process are optimized, and reaction time and synthesis cost are greatly reduced.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a preparation method of a difluoro boron group bridged cobalt diketodioxime complex, wherein the molecular formula of the difluoro boron group bridged cobalt diketodioxime complex is

In the formula I, R¹，R²，R³,R⁴Is hydrogen (H) or a substituent group, which may be the same or different, may be independent or belong to a cyclic substituent group, L¹And L²Is an axial ligand and is a solvent or water molecule with weaker coordination capacity;

the method comprises the following steps:

under the atmosphere of nitrogen or inert gas, divalent cobalt salt, a diketo dioxime ligand and a high-polarity ether reaction solvent are mixed and stirred;

then adding a boron trifluoride ether complex, stirring for reaction at a corresponding reaction temperature, and filtering the obtained reaction mixture to obtain a precipitate, namely a crude product of the difluoroboron-bridged diketodioxime cobalt complex;

and (3) purification: and mixing and stirring the crude product of the boron difluoride-bridged cobalt diketonate complex with a purification solvent or water with the polarity not lower than that of isobutanol for 5-30 minutes or carrying out ultrasonic treatment for 1-10 minutes, filtering again, and drying in vacuum or under reduced pressure to obtain the purified boron difluoride-bridged cobalt diketonate complex.

Preferably, the monoxime is added prior to the addition of the boron trifluoride ether complex.

Preferably, the monooxime has the general formula R⁵R⁶C ═ NOH, where R⁵，R⁶Are hydrogen or aliphatic or aromatic substituents, which may be the same or different; or is a cyclic substituent group; the monoxime is at least one of acetone oxime, cyclohexanone oxime, methyl ethyl ketone oxime, acetophenone oxime, propionaldehyde oxime, acetaldoxime, 2-hexanone oxime and 3-methyl-2-pentanone oxime; more preferably methyl ethyl ketoxime.

Preferably, the molar ratio of the monoxime to the cobaltous divalent salt is 1-6: 1.

Preferably, the molar ratio of the monoxime to the cobaltous salt is 2-3: 1.

Preferably, the molar ratio of the boron trifluoride ether complex to the divalent cobalt salt is 4-12: 1, and more preferably 6-10: 1.

Preferably, the high-polarity ether reaction solvent is tetrahydrofuran, dioxane or chain or cyclic monoether or polyether with a polarity index (or polarity parameter) not lower than that of tetrahydrofuran. Preferably, the high-polarity ether reaction solvent is a polyether with polarity higher than tetrahydrofuran, and comprises: the polyethylene glycol diether or polypropylene glycol diether is preferably at least one of diethylene glycol dimethyl ether, diethylene glycol diethyl ether and dipropylene glycol dimethyl ether.

Preferably, the divalent cobalt salt comprises: at least one of organic acid cobalt salt, organic acid cobalt salt hydrate, inorganic acid cobalt salt or inorganic acid cobalt salt hydrate.

Preferably, the ethanedione dioxime ligand is dimethylglyoxime, i.e. R¹＝R²＝R³＝R⁴Is methyl.

Preferably, the diketoglyoxime ligand is benzil dioxime, i.e. R¹＝R²＝R³＝R⁴Is a phenyl group.

Preferably, the boron trifluoride ether complex is at least one of boron trifluoride diethyl etherate complex, boron trifluoride methyl ether complex, boron trifluoride butyl ether complex, and boron trifluoride tetrahydrofuran complex.

Preferably, the purification solvent used in the purification step is an organic solvent with polarity not lower than that of isopropanol or water, and comprises at least one of methanol, ethanol, isopropanol, water and acetone; more preferably, the purification solvent is methanol.

Preferably, the purification step is repeated at least once. More preferably, said step of purifying comprises purifying said purified difluoroboron based bridged cobalt diketodioxime complex again to obtain a second purified difluoroboron based bridged cobalt diketodioxime complex.

Preferably, the molar ratio of the divalent cobalt salt to the diketo dioxime ligand is 1: 1.9-3.0.

More preferably, the molar ratio of the divalent cobalt salt to the diketodioxime ligand is 1:1.9 to 2.1, and the molar ratio of the boron trifluoride ether complex to the divalent cobalt salt is 6 to 10: 1.

Preferably, the amount of the high-polarity ether reaction solvent is 2 to 10 liters, preferably 4 to 6 liters, per mole of the divalent cobalt salt.

Preferably, the amount of the purification solvent is 5-10 times of the mass of the difluoroboron-bridged cobalt diketodioxime complex to be purified. Wherein the difluoroboron based bridged cobalt diketonate complex to be purified is the crude difluoroboron based bridged cobalt diketonate complex in the purification step, and is the purified difluoroboron based bridged cobalt diketonate complex in a step in which the purification step is repeated at least once.

Preferably, the corresponding reaction temperature comprises the lower value of the boiling point of the solvent at normal pressure and the lower value of the boiling point of the solvent at 0-65 ℃ in an ice-water bath or at low temperature or room temperature or under a heating condition; wherein the ice-water bath or low temperature is 0-5 ℃; the room temperature or the heating temperature is 5-65 ℃, specifically, the heating temperature comprises heating until the specified temperature is 65 ℃ or above; the stirring reaction time is 1-9 hours.

Further, the present invention defines a parameter that embodies the relative purity of the difluoroboron based bridged cobalt dioximate complex product. Bis [ (difluoroboryl) dimethylglyoxime]The parameters for the relative purity of the cobaltic acid Complex (COBF) are defined as follows: in acetonitrile solution, COBF has 2 absorption peaks at 425nm and 322nm (A)_425nm,A_322nm) The ratio of the extinction coefficients is set as R, i.e. R is A_425nm/A_322nm(ii) a The purified COBF was additionally set to the standard ratio Ro. (e.g. Ro-3010/1943-1.549 with 3010 and 1943 being the extinction coefficients at 425nm and 322nm, respectively, of a purified COBF sample (as a standard) in acetonitrile in dm³mol^-1cm^-1). The parameter for the relative purity of the sample to be tested is defined as Δ R% ═ R-Ro)/Ro. It can be seen that the closer to 0 the Δ R%, the closer to the purity of the standard sample. When Δ R% is negative, the sample has a higher absorption coefficient at 322nm and a lower absorption coefficient at 425nm, and contains more impurities. Similarly, difluoroboron-based bridged cobalt dioximates synthesized from other diketodioxime ligands can also define relative purity parameters. For example, bis [ (difluoroboryl) -1, 2-diphenylethanedione dioxime subunit]Cobaltic acid (i.e., in formula I, R)¹、R²、R³And R⁴Both phenyl radicals, hereinafter referred to as COPhBF) have absorption peaks at 462nm and 325nm, and the R value is correspondingly defined as R ═ a_462nm/A_325nm. The relative purity parameter is compared with the ratio of two absorption peaks, so that experimental errors generated on the calculation of the extinction coefficient due to inaccurate solution concentration can be eliminated well.

Due to the adoption of the technical scheme, the invention has the following advantages and beneficial effects:

1. the invention adopts an experimental step different from the prior technical scheme to simplify the purification step and improve the product purity of the difluoro boron-based bridged dioxime cobalt complex. Firstly, a reaction solvent different from the prior art scheme is adopted. The new solvent is characterized by belonging to an ether solvent, having relatively high polarity and high boiling point, not generating irreversible complexation and decomposition reaction with boron trifluoride, and being capable of better dissolving intermediate products, thereby improving the safety and environmental friendliness of the generation, and particularly importantly improving the conversion speed and degree.

2. The present invention provides a simpler and more efficient purification process. Filtering the solid obtained by the reaction, washing the solid with a small amount of solvents such as alcohols, ketones, water and the like, filtering the solid, repeating the steps once, and drying the solid under vacuum or reduced pressure to obtain a high-purity product without complicated purification steps of recrystallization. The combination of the reaction solvent and the purification solvent provided by the invention can effectively reduce the content of impurities which are difficult to separate, and realizes that the high-purity difluoro boron-based dioxime cobalt complex is obtained through a simple washing step, and the relative purity parameter of the product is generally between-5% and 1%. Because a recrystallization process is not needed, the product loss is reduced, and the yield is improved, generally between 40 and 60 percent.

3. The invention also provides a method for effectively improving the yield of the difluoro boron dioxime cobalt complex, which greatly improves the extremely low yield in the prior technical scheme. The method comprises the following steps: in the reaction step provided above, an appropriate amount of a monoxime reagent is added to the reaction prior to the addition of the boron trifluoride ether complex. The molar ratio of the monoxime to the cobaltous divalent salt is generally 1 to 6:1, preferably 2 to 3: 1. In generalThe yield can be improved to 80-95%. Without limiting the invention, the mechanism of yield enhancement is as follows: in the mechanism of the difluoroboryl bridged cobalt complex reaction, 2 ligands release a total of 4 hydrogen cations, 2 of which combine with the anion of the cobalt salt to form the corresponding acid (e.g., acetic acid), and the remaining 2 hydrogen cations combine with tetrafluoroborate (formed from BF)₃F released during bridging reaction^-The ion reacts with boron trifluoride) to form tetrafluoroboric acid. The tetrafluoroboric acid is strong acid and has acid-base neutralization reaction with dioxime ligand to produce ionic ammonium tetrafluoroborate salt. The ionic ammonium tetrafluoroborate salt is poorly soluble in ether solvents and precipitates out, thereby consuming a portion of the dioxime ligand, resulting in a low final yield. After the addition of the monoxime ligand, the monoxime is used as a weak base to react with tetrafluoroboric acid, thus reducing the consumption of the dioxime ligand in the side reaction. Meanwhile, the monoxime is a monodentate ligand, and the coordination ability with cobalt is not as good as that of the bidentate ligand dioxime, so that the monoxime does not compete with the dioxime ligand for a cobalt center at a proper concentration.

4. The monoxime itself is a good solvent, and the use of an excessive amount results in the dissolution of the cobalt difluoroboryl dioxime complex, resulting in the loss of the product. The method optimizes the consumption of the monoxime, and can remarkably improve the yield of the difluoro boron based dioxime cobalt complex when the molar ratio of the monoxime to the divalent cobalt salt is 1-6: 1, preferably 2-3: 1. Commonly available monooximes include methyl ethyl ketone oxime, acetone oxime, cyclohexanone oxime, acetophenone oxime, propionaldehyde oxime, acetaldoxime, 2-hexanone oxime, 3-methyl-2-pentanone oxime, and the like. Methyl ethyl ketoxime, a common monooxime, is commonly used industrially, for example in the coating field, as an antiskinning agent, a blocking agent for isocyanates, and the like. It is noted that organic amine reagents, such as triethylamine, are generally not suitable for use herein because they can undergo degradation reactions with cobalt complexes.

5. The invention also provides an optimized synthesis reaction condition, the reaction temperature is increased to 40 ℃, and the reaction time is shortened to 1-2 hours. The invention provides for optimized reaction temperatures. An excessively high reaction temperature can shorten the reaction time, but accelerates the oxidation of the divalent cobalt complex. For example, oxidation with oxygen remaining in the reaction system produces by-products that are difficult to separate, resulting in a decrease in yield and purity. Too low a reaction temperature, such as in an ice water bath, requires longer reaction times to achieve high yields.

6. The invention further reduces the dosage of the boron trifluoride ether complex reagent, thereby improving the synthesis efficiency and reducing the production cost. The boron trifluoride ether complex reagent can reduce the dosage by 20-30%, and the yield and the purity are kept unchanged or are not obviously changed.

7. The invention further optimizes the dosage of the reaction solvent, generally only needs about 20 percent of the prior art, and the yield and the purity are kept unchanged or have no obvious change.

8. The method further optimizes the using amount of the purification solvent in the purification step, and generally only needs to wash with the solvent which is 5-10 times of the product quality, so that the high-purity product can be obtained. The purifying solvent is methanol, water, acetone or other common solvents with higher polarity than the ether solvents used in the synthesis reaction; the purification solvent can effectively dissolve impurities in the product, including ammonium salt generated by the reaction, an intermediate product without boron difluoride bridging or with only one boron difluoride bridging, and a small amount of possible reaction raw materials which are not completely converted; at the same time, the purification solvent will dissolve only a very small amount of the final product, without a significant reduction in yield.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts. Wherein:

FIG. 1 is a reaction mechanism diagram of a difluoroboryl bridged cobalt diketodioxime complex of the prior art;

FIG. 2 is a diagram of a side reaction mechanism in the synthesis of a difluoroboryl bridged cobalt diketodioxime complex in the prior art;

FIG. 3 is a UV-VIS absorption spectrum of COBF according to the present invention;

FIG. 4 shows COBF UV-visible absorption spectra of comparative examples 1 to 4 and 6 to 8 according to the present invention;

FIG. 5 shows a COBF UV-VIS absorption spectrum of comparative example 5 according to the present invention;

FIG. 6 shows the UV-VIS absorption spectra of COPHBF in comparative examples 9 to 10 according to the present invention;

FIG. 7 shows COBF UV-visible absorption spectra in examples 1 to 3 of the present invention; and

FIG. 8 shows the UV-VIS absorption spectra of COPHBF in examples 4 to 6 of the present invention.

Detailed Description

In order to more clearly illustrate the invention, the invention is further described below in connection with preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.

In the prior art, the synthesis of a difluoroboryl bridged cobalt diketodioxime complex involves several intermediate products, and the reaction mechanism is shown in fig. 1 (taking cobalt acetate tetrahydrate as an example):

first, 2 molecules of ligand H₂L (dimethylglyoxime) forms a first intermediate (co (hl)2) with 1 molecule of cobalt, while 2 positive hydrogen ions H + are generated, forming 2 molecules of acetic acid. In the first intermediate, 2 ligands are hydrogen bonded to form a macrocyclic ligand.

Secondly, the first intermediate Co (HL)2 is mixed with BF₃(boron trifluoride ether complex) to produce a second intermediate Co (HL) (L) (BF)₂) The second intermediate product is formed by a BF₂The group bridges two ligands, producing 1 hydrogen cation at the same time.

Finally, the second intermediate product is further followed by BF₃(boron trifluoride ether complex) to produce the final target product CoL₂(BF₂)₂(Difluoroboronyl-bridged cobalt diketodioxime complexes) the final target product has 2 BF₂Bridging of radicals with simultaneous generation ofThe other 1 hydrogen positive ion.

In the whole process, 2 ligands release 4 hydrogen cations in total, wherein 2 hydrogen cations are combined with the anion of the cobalt salt to generate corresponding acid (such as acetic acid), and the remaining 2 hydrogen cations are combined with tetrafluoroborate (prepared from BF)₃F released during bridging reaction^-The ion reacts with boron trifluoride) to form tetrafluoroboric acid.

In the aforementioned reaction mechanism of the difluoroboryl-bridged cobalt complex, tetrafluoroboric acid is a strong acid, and undergoes an acid-base neutralization reaction with a dioxime ligand to produce an ionic ammonium tetrafluoroborate salt, as shown in fig. 2. The ionic ammonium tetrafluoroborate salt is poorly soluble in ether solvents and precipitates out, thereby consuming a portion of the dioxime ligand, resulting in a low final yield.

In order to verify impurities in a difluoro boron group bridged cobalt dioxime complex product obtained by industrial synthesis, intermediate products without difluoro boron group bridging and intermediate products with only one difluoro boron group bridging are respectively synthesized by not adding or reducing boron trifluoride reagent.

The UV-visible absorption spectra of both demonstrate that the final product (the difluoroboron-based bridged cobalt dioximate complex) incorporates impurities mostly as both intermediates. The intermediate product has no obvious absorption peak in the wave band of 400-500 nm, and the extinction coefficient is very low; but has strong absorption in the band of 320-350 nm and high extinction coefficient. The purified final product has 2 difluoro boron groups which are bridged at the wave band of 400-500 nm and have strong absorption peaks, but the absorption is weaker at the wave band of 320-350 nm. The crude product without purification shows an absorption characteristic between the two: indicating a mixture thereof.

Thus, further, the present invention defines a parameter that embodies the relative purity of the COBF product of the difluoroboron-based bridged cobalt dioximate complex. Fig. 3 shows an ultraviolet-visible light absorption spectrum of COBF. In fig. 3, the solid line is the standard sample and the dashed line is the commercial sample (purchased from STREM); the values indicated are the extinction coefficients of the samples at the wavelength positions indicated by the arrows (322nm,425 nm). The relative purity parameter of the commercial Sample (STREM) was-52.4%; its absorption peak (extinction coefficient) at 425nm is only 70% of that of the standard sample.The parameters for the relative purity of COBF are defined as follows: in acetonitrile solution, COBF has 2 absorption peaks at 425nm and 322nm (A)_425nm,A_322nm) The ratio of the extinction coefficients is set as R, i.e. R is A_425nm/A_322nm(ii) a The purified COBF was additionally set to the standard ratio Ro. (e.g. Ro-3010/1943-1.549 with 3010 and 1943 being the extinction coefficients at 425nm and 322nm, respectively, of a purified COBF sample (standard) in acetonitrile in dm³mol^-1cm^-1). The parameter for the relative purity of the sample to be tested is defined as Δ R% ═ R-Ro)/Ro. It can be seen that the closer to 0 the Δ R%, the closer to the purity of the standard sample. When Δ R% is negative, the sample has a higher absorption coefficient at 322nm and a lower absorption coefficient at 425nm, and contains more impurities. Similarly, COPhBF may also define the corresponding relative purity parameters: the absorption peak values of the COPBF are 462nm and 325nm, and the R value is correspondingly defined as R ═ A_462nm/A_325nm. The relative purity parameter is compared with the ratio of two absorption peaks, so that experimental errors generated on the calculation of the extinction coefficient due to inaccurate solution concentration can be eliminated well.

Chemical reagents and materials used in the examples of the invention:

cobalt (II) acetate tetrahydrate: purchased from Alfa Aesar (Alfa Aesar).

Dimethylglyoxime: purchased from Sigma-Aldrich (Sigma Aldrich).

Biphenyl acyl dioxime: CAS number: 23873-81-6; 98 percent; purchased from TCI (ladder love company).

Boron trifluoride diethyl etherate: purchased from Sigma-Aldrich (Sigma Aldrich) and TCI (ladder love).

Diethyl ether: no water is contained; purchased from VWR.

Tetrahydrofuran: HPLC grade. TEDIA (world, Inc.) is offered.

1, 4-dioxane: anhydrous, purchased from Sigma-Aldrich (Sigma Aldrich).

Methanol: and AR grade.

Acetone: and AR grade.

Acetonitrile: HPLC/Sepctro grade, supplied by Fulltime (Oncui Seisakusho specialty solvents Co., Ltd.).

Water: deionized water.

For simplicity of calculation, the yield calculations in the examples of the present invention are based on the dihydrate of cobalt difluoroboryl dioxime: COBF dihydrate, molecular weight 420.78; CoPhBF dihydrate, molecular weight 669.06, i.e. water molecules coordinated to cobalt as axial ligands. In fact, since methanol was used as the purification solvent, the resulting product contained methanol as axial ligand, corresponding to a molecular weight of 449.08,697.12, respectively. All yields in the examples of the invention were calculated on the basis of the dihydrate, unless otherwise stated. In the embodiment of the invention, unless otherwise specified, the corresponding reaction temperature includes ice water bath or low temperature or room temperature or heating condition, which refers to the lower value of 0-65 ℃ and the boiling point of the solvent used under normal pressure; wherein the ice-water bath or low temperature is 0-5 ℃; the room temperature or heating is 5-65 ℃, specifically, the heating temperature comprises heating until the specified temperature is 65 ℃ or above, and the refluxing is to heat the reaction to the boiling temperature of the solvent under normal pressure.

Comparative examples 1 to 8: synthesis of COBF

Different reaction times and temperatures were used. The general procedure is as follows: cobalt (II) acetate tetrahydrate (2.0 g), dimethylglyoxime (1.90 g) and diethyl ether (150ml) were added to a 250-ml eggplant-shaped reaction flask under a nitrogen atmosphere at room temperature or in an ice-water bath, and after mixing and stirring for 15 to 30 minutes, boron trifluoride diethyl etherate (10ml) was slowly added dropwise over about 30 minutes. And then continuously stirring for 6-9 hours at room temperature or under the condition of heating reflux. And filtering and separating the obtained precipitate, washing with a small amount of water, methanol and diethyl ether respectively, and drying to obtain a crude difluoro boron group bridged dioxime cobalt complex. The crude boron difluoride-bridged cobalt dioximate complex is further recrystallized or suspended in a solvent, washed or sonicated, filtered and dried, and then analyzed for purity by uv-vis absorption spectroscopy. The results are shown in Table 1.

FIG. 4 shows COBF UV-VIS absorption spectra of comparative examples 1 to 4 and 6 to 8, wherein the black dotted line represents a standard sample (example 3, product after 2 purifications) with respect to the purity parameter. FIG. 5 shows a COBF UV-visible absorption spectrum of comparative example 5, and a broken line in FIG. 5 shows a crude product; the dotted line indicates the product after sonication with water; the solid line shows the product after final sonication with methanol.

Table 1: synthesis and purification of COBF in comparative examples 1 to 8

Ice bath: upon addition of the boron trifluoride reagent, the reaction vessel was placed in an ice-water bath. After completion, the ice-water bath was removed.

Comparative examples 9 to 10: synthesis of COPHBF

Different reaction times and temperatures were used. The general procedure is as follows: cobalt (II) acetate tetrahydrate (1.000 g), dibenzoyl dioxime (1.930 g) and diethyl ether (150ml) were added to a 250-ml eggplant-shaped reaction flask under nitrogen atmosphere at room temperature or in an ice-water bath, and after mixing and stirring for 15 to 30 minutes, boron trifluoride diethyl etherate (5ml) was slowly added dropwise over about 30 minutes. And then stirring is continued for 6-9 hours at room temperature. The obtained precipitate is filtered and separated, washed with a small amount of water, methanol and ether respectively and dried to obtain a crude product. Further washing or ultrasonic treating with recrystallization or suspension in solvent, filtering, drying, and analyzing purity by ultraviolet-visible light absorption spectroscopy. The results are shown in Table 2. FIG. 6 shows UV-VIS absorption spectra of crude COPHBF and the product of comparative examples 9-10 after attempted purification.

Table 2: synthesis of COPHBF in comparative examples 9 to 10

Examples 1 to 3: synthesis of COBF

The general procedure is as follows:

cobalt (II) acetate tetrahydrate (2.000 g), dimethylglyoxime (1.900 g) and tetrahydrofuran (abbreviated as THF in english) (40ml) were added to a 100-ml eggplant-shaped reaction flask under a nitrogen atmosphere at room temperature or under heating, and after mixing and stirring for 15 to 30 minutes, boron trifluoride etherate (10ml) was slowly added dropwise over about 15 to 30 minutes. Then stirring is continued for 6 to 9 hours at room temperature or under heating conditions (20 to 65 ℃). And (3) carrying out suction filtration and separation on the obtained dark brown precipitate by using filter paper or a sand core funnel, and then carrying out vacuum or reduced pressure drying to obtain a crude product of the difluoroboron-based bridged diketodioxime cobalt complex (hereinafter referred to as a crude product).

The purification steps are as follows: and mixing the crude product with methanol (6 times of the mass of the crude product), stirring for about 30 minutes or carrying out ultrasonic treatment for 1-10 minutes, then filtering again, and drying the obtained solid in vacuum or under reduced pressure to obtain a purified product, namely the purified difluoroboron-bridged cobalt diketodioxime complex (hereinafter also referred to as the purified product for short) once or 1 time. Repeating the purification step once to obtain a purified product twice, namely the secondary purified difluoroboron-based bridged cobalt diketodioxime complex (hereinafter, also referred to as a purified product twice or a purified product 2 times).

When the purification step is repeated, the amount of purification solvent used is 6 times the mass of the product to be purified. The product to be purified is the crude difluoroboryl-bridged cobalt diketonate complex in the first purification step, the product purified 1 time in the second purification step, and the product purified 2 times in the third purification step; in turn, the product is purified N-1 times in the nth repetition of the purification step. Purity was analyzed by uv-vis absorption spectroscopy. The results are shown in Table 3.

FIG. 7 shows the COBF UV-visible absorption spectra for examples 1-3, wherein the dotted line represents example 1, the dotted line represents example 2, the solid line represents example 3, and the dotted line represents the spectrum reported in the literature.

Examples 4 to 6: synthesis of COPHBF

Similarly, the general procedure is as follows:

cobalt (II) acetate tetrahydrate (1.000 g), dibenzoyl dioxime (1.930 g) and tetrahydrofuran (20ml) were added to a 100-ml eggplant-shaped reaction flask under nitrogen atmosphere at room temperature or under heating (20 to 65 ℃), and after mixing and stirring for 15 to 30 minutes, boron trifluoride diethyl etherate (5ml) was slowly added dropwise over about 15 to 30 minutes. Then stirring is continued for 6 to 9 hours at room temperature or under heating (20 to 65 ℃). And carrying out suction filtration and separation on the obtained dark brown precipitate by using filter paper or a sand core funnel, and then drying in vacuum or under reduced pressure to obtain a crude product.

The purification steps are as follows: mixing the crude product with a small amount of methanol (6 times of the mass of the crude product), stirring for about 30 minutes or carrying out ultrasonic treatment for 3-10 minutes, then filtering again, and drying the obtained solid in vacuum or under reduced pressure to obtain a product purified once or a product purified 1 time. Repeating the purification step once to obtain a product purified twice or 2 times).

When the purification step is repeated, the amount of purification solvent used is 6 times the mass of the product to be purified. The product to be purified is the crude product of the boron difluoride-bridged cobalt diketonate complex in the first purification step, is the product purified for 1 time in the second purification step, and is the product purified for 2 times in the third purification step; in turn, the product is purified N-1 times in the nth repetition of the purification step. In the following examples, the products to be purified are the same and will not be described in detail.

Purity was analyzed by uv-vis absorption spectroscopy. The results are shown in Table 3. FIG. 8 shows the UV-VIS absorption spectra of purified COPHBF in examples 4 to 6.

The products after 2 purifications of example 3 and example 6 are COBF and COPhBF, respectively, and the elemental analysis results of both are consistent with the theoretical values (see table 4).

Table 3: examples 1-3 Synthesis and purification of COBF

Examples 4-6 Synthesis and purification of COPHBF

^{^}For simplicity of calculation, the yield calculations in the examples of the present invention are based on the dihydrate of cobalt difluoroboryl dioxime: for example, COBF dihydrate, molecular weight 420.78; CoPhBF dihydrate, molecular weight 669.06, i.e. water molecules coordinated to cobalt as axial ligands. Since methanol was used as purification solvent, the resulting product contained methanol as axial ligand, corresponding to a molecular weight of 449.08,697.12, respectively. The yield calculations in the examples of the invention are based on the dihydrate, unless otherwise indicated.

Purification process: suspending a product to be purified in methanol with the mass of 6 times of that of the product, and performing ultrasonic treatment for 10 minutes; then, the mixture is filtered by a sand core funnel or filter paper, rinsed by 1-time mass of methanol, and dried to constant weight under reduced pressure at room temperature.

Example 1 and 4 the purification process used 10 to 15 times the mass of methanol.

Table 4: COBF element analysis results in examples 3 and 6

Theoretical calculations in table 4 are based on 2 axial ligands being methanol, the reason for the slightly lower experimental hydrocarbon values is that part of the axial ligands are water.

Example 7

The procedure was similar to examples 1-3, as follows: cobalt (II) acetate tetrahydrate (20.00 g), dimethylglyoxime (19.00 g) and tetrahydrofuran (350ml) were charged in a 500-ml eggplant-shaped reaction flask under a nitrogen atmosphere at room temperature (25 ℃), and after mixing and stirring for 15 minutes, boron trifluoride etherate (100ml) was slowly added dropwise over about 15 minutes. The reaction flask was then placed in an oil bath at 61 ℃ and heated with stirring to 6.5 hours. And (4) carrying out suction filtration and separation on the obtained dark brown precipitate by using a sand core funnel, and then carrying out vacuum or reduced pressure drying to obtain a crude product.

The purification steps are the same as those described in examples 1-3: mixing the product to be purified with a small amount of methanol (6 times the weight of the product to be purified), stirring for about 30 minutes or carrying out ultrasonic treatment for 1-10 minutes, then filtering again, and drying the obtained solid in vacuum or under reduced pressure to obtain the product which is purified once. And repeating the purification step for one time to obtain a product purified for two times. Purity was analyzed by uv-vis absorption spectroscopy.

Example 8

Example 7 was repeated, but the oil bath temperature was 63 ℃.

Example 9

Example 8 was repeated, but the reaction time was 7 hours, i.e. heating with stirring to 7 hours.

The results obtained in examples 7 to 9 are shown in Table 5.

Table 5 preparation of COBF: amplification reaction

Examples 10 to 18

The general procedure is as follows:

cobalt (II) acetate tetrahydrate (2.000 g), dimethylglyoxime (1.900 g) and a reaction solvent (the type and the amount are shown in Table 6) are added into a 100-ml eggplant-shaped reaction flask under nitrogen atmosphere at room temperature, mixed and stirred for 15-30 minutes, and then boron trifluoride diethyl etherate (10ml) is slowly added dropwise over 15-30 minutes. Then, the mixture was stirred at room temperature or under heating (20 to 63 ℃ C.) for a period of time shown in Table 6. And carrying out suction filtration and separation on the obtained dark brown precipitate by using filter paper or a sand core funnel, and then drying in vacuum or under reduced pressure to obtain a crude product.

The purification steps are the same as those described in examples 1-3: mixing the product to be purified with a small amount of methanol (6 times the mass of the product to be purified), performing ultrasonic treatment for 1-10 minutes, then filtering again, and drying the obtained solid in vacuum or under reduced pressure to obtain the product which is purified once. And repeating the purification step for one time to obtain a product purified for two times. Purity was analyzed by uv-vis absorption spectroscopy.

TABLE 6 preparation of COBF in examples 10 to 18: optimization of reaction conditions

Boron trifluoride diethyl etherate (BF)₃·Et₂O) was used in an amount of 6 ml.

# was purified only once.

Examples 19 to 27: addition of monoxime to increase COBF yield

The steps are similar to those of examples 1-3, but a monoxime reagent is added before the boron trifluoride ether complex reagent is added. The general procedure is as follows: under nitrogen atmosphere, cobalt (II) acetate tetrahydrate (2.000 g), dimethylglyoxime (1.900 g) and tetrahydrofuran (40ml) are added into a 100-ml eggplant-shaped reaction bottle at room temperature, after mixing and stirring for 15-30 minutes, methyl ethyl ketoxime (0.70-2.80 g, shown in Table 7; the molar ratio to the cobalt salt is 1-4: 1, and the amount of methyl ethyl ketoxime is 0.70 g in an amount equal to the molar amount of 2.00 g of cobalt (II) acetate tetrahydrate is added, and then boron trifluoride ethyl ether complex (10.0ml) is slowly added dropwise over about 15-30 minutes. And then continuously stirring for 6-9 hours at room temperature under the condition of heating or ice-water bath (see table 7). And carrying out suction filtration and separation on the obtained dark brown precipitate by using filter paper or a sand core funnel, and then drying in vacuum or under reduced pressure to obtain a crude product.

The purification steps are the same as those described in examples 1-3: mixing the product to be purified with a small amount of methanol (6 times of the product to be purified), stirring for about 30 minutes or carrying out ultrasonic treatment for 1-10 minutes, then filtering again, and drying the obtained solid in vacuum or under reduced pressure to obtain the product which is purified once. And repeating the purification step for one time to obtain a product purified for two times. Purity was analyzed by uv-vis absorption spectroscopy. The results are shown in Table 7.

Table 7 examples 19 to 27: introduction of monoxime reagents in COBF Synthesis

EXAMPLE 23 the solvent used was 1, 4-dioxane, 40 ml.

Examples 26 and 27: carrying out 10 times of amplification reaction; the dosage of the reagent is 20.00 g of cobalt acetate tetrahydrate, 19.00 g of dimethylglyoxime, 350ml of tetrahydrofuran, 14.00 g of methyl ethyl ketoxime and 100.0ml of boron trifluoride diethyl etherate.

Examples 28 to 40: increasing the yield of COPHBF by addition of a monoxime

Similar to examples 4-6, but prior to the addition of boron trifluoride reagent, a monoxime reagent was added. The general procedure is as follows: under nitrogen atmosphere, adding 1.000 g of cobalt (II) acetate tetrahydrate, 1.930 g of dibenzoyl dioxime and a solvent (details are shown in Table 8) into a 100-ml eggplant-shaped reaction bottle at room temperature, mixing and stirring for 15-30 minutes, adding 0.70-1.4 g of methyl ethyl ketoxime (shown in Table 8; the molar ratio of the methyl ethyl ketoxime to cobalt salt is 2-4: 1, and the molar amount of the methyl ethyl ketoxime to 1.00 g of cobalt (II) acetate tetrahydrate is 0.35 g), and slowly dropwise adding boron trifluoride diethyl etherate (5.0ml) for 15-30 minutes. Then continuously stirring the mixture for 6 to 9 hours at room temperature or under a heating condition (20 to 63 ℃). And carrying out suction filtration and separation on the obtained dark brown precipitate by using filter paper or a sand core funnel, and then drying in vacuum or under reduced pressure to obtain a crude product.

The purification steps are the same as those described in examples 4-6: mixing the product to be purified with a small amount of methanol (6 times of the product to be purified), stirring for about 30 minutes or carrying out ultrasonic treatment for 1-10 minutes, then filtering again, and drying the obtained solid in vacuum or under reduced pressure to obtain the product which is purified once. And repeating the purification step for one time to obtain a product purified for two times. Purity was analyzed by uv-vis absorption spectroscopy. The results are shown in Table 8.

TABLE 8 examples 28 to 40: introduction of monoxime reagent in synthesis of COPHBF

# example 28 used 3.0ml of boron trifluoride diethyl etherate.

In EXAMPLE 34, methyl ethyl ketoxime was not added.

Examples 39 and 40: carrying out 9 times of amplification reaction; the dosage of the reagent is as follows: 9.00 g of cobalt acetate tetrahydrate, 17.36 g of dibenzoyl dioxime, 180ml of 1, 4-dioxane, 6.30 g of methyl ethyl ketoxime and 45.0ml of boron trifluoride diethyl etherate.

Crude product was not completely dried.

Examples 41 to 49: further optimization of reaction conditions

The general procedure is as follows:

cobalt (II) acetate tetrahydrate (4.000 g), dimethylglyoxime (3.800 g) and tetrahydrofuran (40ml) were added to a 100-ml eggplant-shaped reaction flask under a nitrogen atmosphere at room temperature, followed by mixing and stirring for 15 to 30 minutes, adding methylethylketoxime (2.8 g), and slowly dropwise adding boron trifluoride diethyl etherate (BF) complex₃·Et₂O, the dosage is shown in the table 9), and the addition is finished in about 15-30 minutes. Stirring was then continued in an oil bath at 40 ℃ for the time indicated in Table 9. And carrying out suction filtration and separation on the obtained dark brown precipitate by using filter paper or a sand core funnel, and then drying in vacuum or under reduced pressure to obtain a crude product.

The purification steps are as follows: for details, see table 9, the product to be purified is mixed with a purification solvent (6 times the mass of the product to be purified), stirred for about 30 minutes or sonicated for 10 minutes, then filtered again, and the resulting solid is dried under vacuum or reduced pressure to obtain a once purified product. And repeating the purification step for one time to obtain a product purified for two times. Purity was analyzed by uv-vis absorption spectroscopy. The results are shown in Table 9.

TABLE 9 further optimization of reaction conditions for examples 41-49

In # examples 45 and 46, the crude product of the same reaction was divided into two portions and then subjected to different purification treatments.

In examples 47, 48 and 49, the crude product of the same reaction was divided into three portions and then subjected to different purification treatments.

The invention adopts an experimental step different from the prior technical scheme to simplify the purification step and improve the product purity of the difluoro boron-based bridged dioxime cobalt complex. Firstly, a reaction solvent different from the prior art scheme is adopted. The new solvent is characterized by belonging to an ether solvent, having relatively high polarity and high boiling point, not generating irreversible complexation and decomposition reaction with boron trifluoride, and being capable of better dissolving intermediate products, thereby improving the safety and environmental friendliness of the generation, and particularly importantly improving the conversion speed and degree.

The present invention provides a simpler and more efficient purification process. Filtering the solid obtained by the reaction, washing the solid with a small amount of solvents such as alcohols, ketones, water and the like, filtering the solid, repeating the steps once, and drying the solid under vacuum or reduced pressure to obtain a high-purity product without complicated purification steps of recrystallization. The combination of the reaction solvent and the purification solvent provided by the invention can effectively reduce the content of impurities which are difficult to separate, and realizes that the high-purity difluoro boron-based dioxime cobalt complex is obtained through a simple washing step, and the relative purity parameter of the product is generally between-5% and 1%. Because a recrystallization process is not needed, the product loss is reduced, and the yield is improved, generally between 40 and 60 percent.

The invention also provides a method for effectively improving the yield of the difluoro boron dioxime cobalt complex, which greatly improves the extremely low yield in the prior technical scheme. The method comprises the following steps: in the reaction step provided above, an appropriate amount of a monoxime reagent is added to the reaction prior to the addition of the boron trifluoride ether complex. The molar ratio of the monoxime to the cobaltous divalent salt is generally 1 to 6:1, preferably 2 to 3: 1. Generally, the yield can be improved to 80-95%. Without limiting the invention, the mechanism of yield enhancement is as follows: in the mechanism of the reaction of the difluoroboron-based bridged cobalt complex, 2 ligands release 4 hydrogen cations in total, 2 of which are combined with the anion of the cobalt salt to generate the corresponding acid (such as acetic acid), and the remaining 2 hydrogen cations are combined with tetrafluoroborate (the fluorine ion F released in the boron trifluoride bridging reaction)^-Reacted with boron trifluoride) to form tetrafluoroboric acid. The tetrafluoroboric acid is strong acid and has acid-base neutralization reaction with dioxime ligand to produce ionic ammonium tetrafluoroborate salt. Ionic ammonium tetrafluoroborate salts in ethersThe solubility in the solvent-like is poor and thus precipitates out, thereby consuming a part of the dioxime ligand, resulting in a low final yield. After the addition of the monoxime ligand, the monoxime is used as a weak base to react with tetrafluoroboric acid, thus reducing the consumption of the dioxime ligand in the side reaction. Meanwhile, the monoxime is a monodentate ligand, and the coordination ability with cobalt is not as good as that of the bidentate ligand dioxime, so that the monoxime does not compete with the dioxime ligand for a cobalt center at a proper concentration. The monoxime itself is a good solvent, and the use of an excessive amount results in the dissolution of the cobalt difluoroboryl dioxime complex, resulting in the loss of the product. The method optimizes the consumption of the monoxime, and can remarkably improve the yield of the difluoro boron based dioxime cobalt complex when the molar ratio of the monoxime to the divalent cobalt salt is 1-6: 1, preferably 2-3: 1. Commonly available monooximes include methyl ethyl ketone oxime, acetone oxime, cyclohexanone oxime, acetophenone oxime, propionaldehyde oxime, acetaldoxime, 2-hexanone oxime, 3-methyl-2-pentanone oxime, and the like.

The invention also provides an optimized synthesis reaction condition, the reaction temperature is increased to 40 ℃, and the reaction time is shortened to 1-2 hours. The invention provides for optimized reaction temperatures. An excessively high reaction temperature, although the reaction time can be shortened, accelerates the oxidation of the divalent cobalt complex, for example, by oxidizing with oxygen remaining in the reaction system to produce a by-product which is difficult to separate, resulting in a decrease in yield and purity. Too low a reaction temperature, such as in an ice water bath, requires longer reaction times to achieve high yields.

The invention further reduces the dosage of the boron trifluoride ether complex reagent, thereby improving the synthesis efficiency and reducing the production cost. The boron trifluoride ether complex reagent can reduce the dosage by 20-30%, and the yield and the purity are kept unchanged or are not obviously changed.

The invention further optimizes the dosage of the reaction solvent, generally only needs about 20 percent of the prior art, and the yield and the purity are kept unchanged or have no obvious change.

The method further optimizes the amount of the purification solvent in the purification step, and generally only needs to wash with the solvent which is 5-10 times of the mass of the product to be purified, so that the product with high purity can be obtained. The purifying solvent is methanol, water, acetone or other common solvents with higher polarity than the ether solvents used in the synthesis reaction; the purification solvent can effectively dissolve impurities in the product, including ammonium salt generated by the reaction, an intermediate product without boron difluoride bridging or with only one boron difluoride bridging, and a small amount of possible reaction raw materials which are not completely converted; meanwhile, the amount of the purification solvent is small, only a small amount of the final target product is dissolved, and the yield is not remarkably reduced.

It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications may be included within the scope of the present invention.

Claims

1. A preparation method of a difluoro boron group bridged cobalt diketodioxime complex, wherein the molecular formula of the difluoro boron group bridged cobalt diketodioxime complex is

In the formula I, R¹，R²，R³,R⁴Hydrogen (H) or a substituent group, which may be the same or different, may be independent or both cyclic substituent groups; l is¹And L²Is an axial ligand and is a solvent or water molecule with weaker coordination capacity;

the method is characterized by comprising the following steps:

and (3) purification: mixing and stirring the crude product of the boron difluoride-bridged cobalt diketonate complex with a purification solvent or water with the polarity not lower than that of isobutanol for 5-30 minutes or carrying out ultrasonic treatment for 1-10 minutes, then filtering again, and drying in vacuum or under reduced pressure to obtain the purified boron difluoride-bridged cobalt diketonate complex;

the high-polarity ether reaction solvent is at least one of tetrahydrofuran, dioxane or chain or annular monoether or polyether with polarity not lower than that of tetrahydrofuran;

the corresponding reaction temperature is the lower value of the boiling point of the solvent under the normal pressure and the temperature of 0-65 ℃ in an ice water bath or at low temperature or room temperature or under a heating condition.

2. The method of preparing a difluoroboron-based bridged cobalt diketodioxime complex according to claim 1, characterized in that a monooxime is added before the addition of the boron trifluoride ether complex.

3. A method of preparing a difluoroboryl-bridged cobalt diketodioxime complex according to claim 2, characterized in that the monoxime has the general formula R⁵R⁶C ═ NOH, where R⁵，R⁶Are hydrogen or aliphatic or aromatic substituents, which may be the same or different, or are cyclic substituents.

4. A method of producing a difluoroboron-based bridged cobalt glyoxime complex according to claim 3, wherein the monooxime is at least one of acetone oxime, cyclohexanone oxime, methyl ethyl ketone oxime, acetophenone oxime, propionaldehyde oxime, acetaldoxime, 2-hexanone oxime, 3-methyl-2-pentanone oxime.

5. A process for the preparation of a difluoroboryl-bridged cobalt diketodioxime complex according to claim 4, wherein the monooxime is methyl ethyl ketoxime.

6. The method of preparing a difluoroboryl-bridged cobalt diketodioxime complex according to claim 2, wherein the molar ratio of the monooxime to the divalent cobalt salt is 1 to 6: 1.

7. The method for preparing a difluoroboron-bridged cobalt diketodioxime complex according to any one of claims 1 to 6, wherein the high-polarity ether-based reaction solvent is a polyether having a polarity higher than that of tetrahydrofuran.

8. The method of preparing a difluoroboron-bridged cobalt diketodioxime complex according to any one of claim 7, wherein the polyether having a polarity higher than tetrahydrofuran comprises: polyethylene glycol diethers or polypropylene glycol diethers.

9. A method of preparing a difluoroboron-bridged cobalt diketodioxime complex according to any one of claim 8, characterized in that the polyether having a polarity higher than tetrahydrofuran is at least one of diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether.

10. The method of any of claims 1 to 6, wherein the divalent cobalt salt comprises: at least one of organic acid cobalt salt, organic acid cobalt salt hydrate, inorganic acid cobalt salt or inorganic acid cobalt salt hydrate.

11. The method of any of claims 1 to 6, wherein the diboron dioxime ligand is dimethylglyoxime, R is dimethylglyoxime¹＝R²＝R³＝R⁴Methyl group; or the diketoglyoxime ligand is benzil dioxime, i.e. R¹＝R²＝R³＝R⁴Is a phenyl group.

12. The method for producing a difluoroboron-bridged diketodioxime cobalt complex according to any one of claims 1 to 6, wherein the boron trifluoride ether complex is at least one of a boron trifluoride diethyl etherate complex, a boron trifluoride methyl ether complex, a boron trifluoride butyl ether complex, and a boron trifluoride tetrahydrofuran complex.

13. The method for preparing a difluoroboron-bridged cobalt diketodioxime complex according to any one of claims 1 to 6, wherein the molar ratio of the boron trifluoride ether complex to the divalent cobalt salt is 4 to 12: 1.

14. The method for producing a difluoroboron-bridged cobalt diketodioxime complex according to any one of claims 1 to 6, wherein the purification solvent used in the purification step is an organic solvent having a polarity of not less than isopropyl alcohol or water.

15. The method of claim 14, wherein the purification solvent comprises at least one of methanol, ethanol, isopropanol, water, and acetone.

16. The method of preparing a difluoroboryl-bridged cobalt diketodioxime complex according to claim 15, wherein the purification solvent is methanol.

17. The method for producing a difluoroboron-bridged cobalt diketodioxime complex according to any one of claims 1 to 6, characterized in that the purification step is repeated at least once; wherein said purifying step is repeated at least once comprising re-purifying said purified difluoroboron based bridged cobalt diketonate complex to obtain a second purified difluoroboron based bridged cobalt diketonate complex.

18. The method for producing a difluoroboron-bridged cobalt diketodioxime complex according to any one of claims 1 to 6, wherein the molar ratio of the divalent cobalt salt to the ligand of the diketodioxime is 1:1.9 to 3.0.

19. The method of preparing a difluoroboron-bridged cobalt diketodioxime complex according to any one of claim 18, wherein the molar ratio of the divalent cobalt salt to the ligand of the diketodioxime is 1:1.9 to 2.1, and the molar ratio of the boron trifluoride ether complex to the divalent cobalt salt is 6 to 10: 1.

20. The method of producing a difluoroboron-bridged cobalt diketodioxime complex according to any one of claims 1 to 6, wherein the amount of the highly polar ether-based reaction solvent is 2 to 10 liters per mole of the divalent cobalt salt.

21. The method of any one of claims 1 to 6, wherein the amount of the purification solvent is 5 to 10 times the amount of the crude difluoroboron-bridged cobalt diketodioxime complex.

22. The method of preparing a difluoroboron-bridged cobalt diketodioxime complex according to claim 17, wherein the amount of the purification solvent is 5 to 10 times the amount of the purified difluoroboron-bridged cobalt diketodioxime complex.

23. The method for producing a difluoroboron-bridged cobalt diketodioxime complex according to any one of claims 1 to 6, wherein the stirring reaction time is 1 to 9 hours.