A method for synthesizing acetate-promoted amidinato cobalt complexes

Abstract

This invention discloses a method for synthesizing acetate-promoted amidine cobalt complexes. Specifically, when an N,N'-dialkyl-substituted amidine alkali metal salt reacts with a cobalt precursor, acetate is added as a promoter. The chelating effect of acetate regulates the reaction activity and selectivity, enabling the efficient preparation of amidine cobalt compounds. The reaction yield can reach up to 95%, with a product purity >98%. This invention features readily available raw materials, simple operation, mild reaction conditions, good selectivity for the target product, high synthesis efficiency, and convenient post-processing, making it promising for industrial applications.

Description

Technical Field

[0001] This invention relates to a method for synthesizing acetate-promoted amidocobalt complexes, specifically involving the addition of acetate as a promoter when N,N'-dialkyl-substituted amido alkali metal salts react with cobalt precursors, which can efficiently prepare amidocobalt compounds. Technical Background

[0002] Cobalt metal thin films have wide applications in fields such as magnetic information storage, computer chips, and catalysis. They are generally obtained through methods such as physical vapor deposition (PVD), chemical vapor deposition (CVD), or atomic layer deposition (ALD).

[0003] For the chemical synthesis of cobalt metal thin films, cobalt complexes are generally required to possess good volatility, thermal stability, and chemical reactivity suitable for producing pure thin films. Amidine-coated metal complexes can serve as precursor materials to form metal nanoparticles or metal thin films. However, these complexes are highly sensitive to water and oxygen, the synthesis techniques are demanding, and the yields are not high.

[0004] In 2003, Gordon et al. reported the synthesis of bis(N,N'-diisopropylacetamidine)cobalt, specifically by reacting N,N'-diisopropylcarbodiimide with methyllithium to prepare N,N'-diisopropylacetamidine lithium salt, which was then reacted with cobalt chloride to prepare bis(N,N'-diisopropylacetamidine)cobalt, with a yield of only 77% (Inorg. Chem. 2003, 42, 7951–7958). Subsequently, this group synthesized a series of amidocobalt complexes by reacting other amidolithium salts with cobalt chloride, with yields of 70-80% (Dalton Trans., 2008, 2592–2597). Overall, the synthesis efficiency of amidocobalt complexes is not high. Therefore, developing and exploring methods for preparing amidocobalt complexes to improve yield and purity is currently a key focus and challenge. Summary of the Invention

[0005] To address the problems of existing technologies, this invention provides a method for synthesizing acetate-promoted amidine cobalt complexes. The method involves reacting an amidine alkali metal salt with a cobalt precursor, using acetate as a promoter, and utilizing the chelating effect of acetate to regulate the activity and selectivity of the coordination reaction, thereby efficiently preparing amidine cobalt compounds.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A method for synthesizing an acetate-promoted amidocobalt complex involves reacting an N,N'-dialkyl-substituted amido alkali metal salt (A) with a cobalt precursor, adding acetate as a promoter, to prepare an amidocobalt compound (B).

[0008]

[0009] Wherein: R is methyl (Me), ethyl (Et), n-butyl (nBu), dimethylamino (Me2N) or diisopropylamino (iPr2N); R1 and R2 are independently selected from methyl (Me), ethyl (Et), n-propyl (nPr), isopropyl (iPr), tert-butyl (tBu) or cyclohexyl (Cy); M is lithium (Li) or potassium (K).

[0010] Based on the above technical solutions, the cobalt precursor can further be cobalt difluoride, cobalt dichloride, cobalt dibromide, cobalt diiodide, cobalt sulfate, cobalt nitrate, cobalt oxalate, cobalt tetrafluoroborate, or cobalt acetate.

[0011] Based on the above technical solutions, the accelerator acetate can be lithium acetate, sodium acetate, or potassium acetate.

[0012] Based on the above technical solution, the amount of accelerator acetate is further 0-250 mol% of the cobalt precursor, for example 0 mol%, 5 mol%, 10 mol%, 40 mol%, 50 mol%, 80 mol%, 100 mol%, 150 mol%, 200 mol%, and 250 mol%.

[0013] Based on the above technical solution, the molar ratio of the N,N'-dialkyl-substituted amidine alkali metal salt to the cobalt precursor is 3:1-2:1.

[0014] Based on the above technical solution, further, when the cobalt precursor is cobalt acetate, no additional accelerator is used. The N,N'-dialkyl-substituted amido alkali metal salt reacts directly with cobalt acetate to obtain the amido cobalt complex (B); the molar ratio of the N,N'-dialkyl-substituted amido alkali metal salt to cobalt acetate is 3:1-2:1.

[0015] Based on the above technical solution, the reaction solvent is further selected from one or more of diethyl ether, tetrahydrofuran, 1,4-dioxane, 2-methyltetrahydrofuran, methyl tert-butyl ether, ethylene glycol dimethyl ether, and diethoxymethane.

[0016] Based on the above technical solution, the reaction temperature is further 0-70℃ and the reaction time is 1-48h.

[0017] Based on the above technical solution, the reaction atmosphere is further defined as nitrogen or argon.

[0018] Based on the above technical solution, the product is further separated by conventional separation and purification methods after the reaction to obtain a high-purity amidine cobalt compound product.

[0019] Based on the above technical solution, the method for synthesizing the N,N'-dialkyl-substituted amidine alkali metal salt (A) is as follows:

[0020] The reaction of N,N'-dialkyl-substituted amidine compounds with n-butyllithium or potassium hydride yields N,N'-dialkyl-substituted amidine alkali metal salts (A).

[0021] The synthetic route is shown in the following reaction equation:

[0022]

[0023] Preferably, the molar ratio of the N,N'-dialkyl-substituted amidine compound to n-butyllithium or potassium hydride is 1:1 to 1:1.2; the reaction atmosphere is an inert gas, such as nitrogen or argon.

[0024] When using n-butyllithium, the N,N'-dialkyl-substituted amidine alkali metal salt (A) is an N,N'-dialkyl-substituted amidine lithium salt; the reaction solvent is diethyl ether or tetrahydrofuran, the reaction temperature is -78℃ to room temperature, and the reaction time is 4-24 hours.

[0025] When potassium hydride is used, the N,N'-dialkyl-substituted amidine alkali metal salt (A) is an N,N'-dialkyl-substituted amidine potassium salt; the reaction solvent is tetrahydrofuran; the reaction temperature is room temperature to 50°C; and the reaction time is 18 to 48 hours.

[0026] This invention has the following advantages: Under acetate ion promotion, an N,N'-dialkyl-substituted amidine alkali metal salt reacts with a cobalt precursor to prepare amidine-cobalt compounds. The preparation method of this invention has advantages such as readily available raw materials, simple operation, mild reaction conditions, good selectivity for the target product, high synthesis efficiency, and convenient post-processing, and has promising industrial application prospects. Using this method, the synthesis yield of amidine-cobalt compounds can reach up to 95%, and the product purity is >98%. Detailed Implementation

[0027] This invention relates to the preparation of amidocobalt compounds by reacting N,N'-dialkyl-substituted amido alkali metal salts with cobalt precursors under acetate-promoted conditions. The invention is further described below with reference to specific embodiments, but the scope of protection of this invention is not limited thereto.

[0028] The process for obtaining the amidine alkali metal salt in the following examples was as follows: Using an N,N'-dialkyl-substituted amidine compound (50 mmol) (its synthesis is referenced in J. Am. Chem. Soc. 1955, 77, 5872) as the starting material, under nitrogen protection, a 0.1 mol / L diethyl ether solution of the N,N'-dialkyl-substituted amidine compound was cooled to -78°C, and a hexane solution of n-butyllithium (2.5 M, 20 mL, 50 mmol) was added dropwise over half an hour. After the addition was complete, the temperature was slowly raised to room temperature over approximately 2 hours, and the reaction was continued at room temperature for 4 hours. After the reaction was complete, the solvent was removed by distillation, and n-hexane was added to the residual solid. The mixture was filtered under nitrogen protection, and the solid was washed three times with n-hexane to obtain the N,N'-dialkyl-substituted amidine lithium salt solid. In addition, under inert gas protection, potassium hydride (2.21 g, 55 mmol) was added to a 0.1 mol / L tetrahydrofuran solution of the N,N'-dialkyl-substituted amidine compound (after washing away mineral oil with n-hexane), and the reaction was carried out at room temperature for 24 hours. After the reaction was completed, unreacted potassium hydride was removed by filtration, the solvent was removed by distillation, n-hexane was added to the residual solid, and the mixture was filtered under nitrogen protection. The solid was washed three times with n-hexane to prepare the N,N'-dialkyl-substituted amidine potassium salt solid.

[0029] Example 1

[0030]

[0031] Under an argon atmosphere, cobalt dichloride (65 mg, 0.5 mmol), N,N'-diisopropylacetamidine potassium salt A1 (216 mg, 1.2 mmol), potassium acetate (2.5 mg, 0.025 mmol) and 5 mL tetrahydrofuran were added to a 25 mL L Schlenk flask. After the addition was complete, the mixture was stirred in an oil bath at 30 °C for 18 hours.

[0032] After the reaction was complete, all volatiles were removed under reduced pressure. 5 mL of n-hexane was added to the residual solid, and the resulting mixture was filtered through diatomaceous earth, washed with n-hexane (3 × 3 mL), and the filtrates were combined. Volatiles were removed under reduced pressure to obtain a crude solid product. The crude product was further purified by sublimation at 60 °C / vacuum (<1 mmHg) to obtain 155 mg of a green solid product, namely bis(N,N'-diisopropylethamidinyl)cobalt B1, with a yield of 90.6% and a purity of 98.5%.

[0033] The product di(N,N'-diisopropylethamidinyl)cobalt was characterized by proton nuclear magnetic resonance spectroscopy, matrix-assisted laser desorption / ionization time-of-flight mass spectrometry, and elemental analysis. 1HNMR (C6D6, 400MHz, 25℃) δ323.02(br,4H), 307.29(br,6H), -69.38(br,24H). MALDI-TOF MS(m / z)Calcd for[C 16 H 34 N4Co] + :341.2110; Found:341.2520. Anal.Calcd for C 16 H 34 N4Co: C, 56.29; H, 10.04; N, 16.41; Found: C, 55.36; H, 9.99; N, 15.74.

[0034] Example 2

[0035]

[0036] The reaction steps and operations were the same as in Example 1, except that the reaction atmosphere was nitrogen, the reaction raw materials were N,N'-di-tert-butylacetamidine lithium salt A2 (211 mg, 1.2 mmol) and cobalt difluoride (48.5 mg, 0.5 mmol) reacted in diethyl ether / tetrahydrofuran (v / v = 1:1), the promoter was sodium acetate (4.1 mg, 0.05 mmol), the reaction temperature was 25 °C, and the reaction time was 24 hours.

[0037] Reaction results: 183 mg of di(N,N'-di-tert-butylethamidinyl)cobalt B2 product was obtained, with a yield of 92.0% and a purity of 98.9%.

[0038] Example 3

[0039]

[0040] The reaction steps and operations were the same as in Example 1, except that N,N'-dicyclohexylacetamidine lithium salt A3 (228 mg, 1.0 mmol) and cobalt oxalate (73.5 mg, 0.5 mmol) were reacted in methyl tert-butyl ether, the promoter was lithium acetate (13.2 mg, 0.2 mmol), the reaction temperature was 50 °C, and the reaction time was 12 hours.

[0041] Reaction results: 233 mg of di(N,N'-dicyclohexylacetamidine)cobalt B3 product was obtained, with a yield of 92.8% and a purity of 98.5%.

[0042] Example 4

[0043]

[0044] The reaction steps and operations were the same as in Example 1, except that the reaction atmosphere was nitrogen, N,N'-dimethylacetamidine potassium salt A4 (124 mg, 1.0 mmol) reacted with cobalt tetrafluoroborate (73 mg, 0.5 mmol), the accelerator was sodium acetate (41.0 mg, 0.5 mmol), the reaction temperature was 65 °C, and the reaction time was 8 hours.

[0045] Reaction results: 106 mg of bis(N,N'-dimethylacetamidine)cobalt B4 product was obtained, with a yield of 92.2% and a purity of 99.0%.

[0046] Example 5

[0047]

[0048] The reaction steps and operations were the same as in Example 1, except that N-tert-butyl-N'-ethyl ethamidinium lithium salt A5 (193 mg, 1.3 mmol) and cobalt sulfate (77.5 mg, 0.5 mmol) were reacted in 2-methyltetrahydrofuran, the promoter was potassium acetate (24.5 mg, 0.25 mmol), the reaction temperature was 50 °C, and the reaction time was 48 hours.

[0049] Reaction results: 154 mg of bis(N-tert-N'-ethylethamidinyl)cobalt B5 product was obtained, with a yield of 90.1% and a purity of 98.3%.

[0050] Example 6

[0051]

[0052] The reaction steps and operations were the same as in Example 1, except that N,N'-diisopropylpropanediamine lithium salt A6 (243 mg, 1.5 mmol) and cobalt nitrate (91.5 mg, 0.5 mmol) were reacted in diethoxymethane, the promoter was lithium acetate (26.4 mg, 0.4 mmol), the reaction temperature was 60 °C, and the reaction time was 8 hours.

[0053] Reaction results: 171 mg of bis(N,N'-diisopropylpropanediyl)cobalt B6 product was obtained, with a yield of 92.4% and a purity of 98.6%.

[0054] Example 7

[0055]

[0056] The reaction steps and operations were the same as in Example 1, except that N,N'-diisopropylpentanediamine potassium salt A7 (245 mg, 1.1 mmol) and cobalt dibromide (109 mg, 0.5 mmol) were reacted in ethylene glycol dimethyl ether, potassium acetate (73.6 mg, 0.75 mmol) was used as the promoter, the reaction temperature was 25 °C, and the reaction time was 16 hours.

[0057] Reaction results: 201 mg of bis(N,N'-diisopropylpentamidine)cobalt B7 product was obtained, with a yield of 94.4% and a purity of 98.9%.

[0058] Example 8

[0059]

[0060] The reaction steps and operations were the same as in Example 1, except that N',N”-di-tert-butyl-N,N-dimethylformamidinium lithium salt A8 (246 mg, 1.2 mmol) and cobalt diiodide (156 mg, 0.5 mmol) were reacted in tetrahydrofuran, sodium acetate (82.0 mg, 1.0 mmol) was used as the promoter, the reaction temperature was 10 °C, and the reaction time was 18 hours.

[0061] Reaction results: 211 mg of bis(N',N”-di-tert-butyl-N,N-dimethylformamidinyl)cobalt B8 product was obtained, with a yield of 92.5% and a purity of 98.8%.

[0062] Example 9

[0063]

[0064] The reaction steps and operations were the same as in Example 1, except that N,N'-di-tert-butylacetamidine potassium salt A9 (292 mg, 1.4 mmol) and cobalt tetrafluoroborate (170 mg, 0.5 mmol) were reacted in 2-methyltetrahydrofuran / diethoxymethane (v / v = 2:1), the promoter was potassium acetate (122.7 mg, 1.25 mmol), the reaction temperature was 70 °C, and the reaction time was 1 hour.

[0065] Reaction results: 183 mg of di(N,N'-di-tert-butylethamidinyl)cobalt B2 product was obtained, with a yield of 92.0% and a purity of 98.6%.

[0066] Example 10

[0067]

[0068] The reaction steps and operations are the same as in Example 4, except that N,N'-dicyclohexylacetamidine potassium salt A 10(287 mg, 1.1 mmol) was reacted with cobalt dichloride (65 mg, 0.5 mmol) in diethoxymethane, with sodium acetate (82.0 mg, 1.0 mmol) as the accelerator. The reaction temperature was 40 °C and the reaction time was 24 hours.

[0069] Reaction results: 235 mg of di(N,N'-dicyclohexylacetamidine)cobalt B3 product was obtained, with a yield of 93.6% and a purity of 98.8%.

[0070] Example 11

[0071]

[0072] The reaction steps and operations are the same as in Example 1, except that N'-tert-butyl-N”-ethyl-N,N-diisopropylformamidinium potassium salt A is used. 11 (372 mg, 1.4 mmol) was reacted with cobalt acetate (88.5 mg, 0.5 mmol) in diethyl ether for 10 hours without an accelerator.

[0073] Reaction result: Di(N'-tert-butyl-N”-ethyl-N,N-diisopropylformamidinyl)cobalt B was obtained. 11 The product yield was 94.5% (242 mg), and the purity was 99.1%.

[0074] Example 12

[0075]

[0076] The reaction steps and operations were the same as in Example 1, except that N',N”-di-tert-butyl-N,N-dimethylformamidinium lithium salt A8 (246 mg, 1.2 mmol) and cobalt acetate (88.5 mg, 0.5 mmol) were reacted in diethyl ether / tetrahydrofuran (v / v = 2:1) without the addition of a accelerator, at a reaction temperature of 10 °C, and for a reaction time of 16 h.

[0077] Reaction results: 217 mg of bis(N',N”-di-tert-butyl-N,N-dimethylformamidinyl)cobalt B8 product was obtained, with a yield of 95.2% and a purity of 99.0%.

[0078] Example 13

[0079]

[0080] The reaction steps and operations were the same as in Example 1, except that N,N'-diisopropylpentanediamine potassium salt A7 (236 mg, 1.0 mmol) and cobalt acetate (88.5 mg, 0.5 mmol) were reacted in ethylene glycol dimethyl ether without an accelerator, at a reaction temperature of 70 °C, and for a reaction time of 5 hours.

[0081] Reaction results: 202 mg of di(N,N'-diisopropylpentamidine)cobalt B7 product was obtained, with a yield of 91.8% and a purity of 98.7%.

[0082] Example 14

[0083]

[0084] Under an argon atmosphere, cobalt dibromide (875 mg, 4 mmol) and N,N'-dicyclohexylpropanediamine potassium salt A were added to a 100 mL Schlenk flask. 12 (2.416 g, 8.8 mmol), potassium acetate (196 mg, 2.0 mmol) and 50 mL tetrahydrofuran were stirred at 25 °C for 20 hours.

[0085] After the reaction was complete, all volatiles were removed under reduced pressure. 20 mL of n-hexane was added to the residual solid, and the resulting mixture was filtered through diatomaceous earth, washed with n-hexane (3 × 10 mL), and the filtrates were combined. Volatiles were removed under reduced pressure to obtain a crude solid product. The crude product was further purified by sublimation at 60 °C / vacuum (<1 mmHg) to give 2.013 g of a green solid product, namely bis(N,N'-dicyclohexylpropanediyl)cobalt B. 12 The product yield was 95.0%, and the product purity was 99.3%.

[0086] Example 15

[0087]

[0088] The reaction steps and operations are the same as in Example 14, except that N',N”-di-tert-butyl-N,N-diisopropylformamidinium lithium salt A 13 (2.196 g, 8.4 mmol) reacted with cobalt tetrafluoroborate (929 mg, 4 mmol) in ethylene glycol dimethyl ether, with lithium acetate (264 mg, 4 mmol) as the accelerator, at a reaction temperature of 40 °C for 12 hours.

[0089] Reaction result: Di(N',N”-di-tert-butyl-N,N-diisopropylformamidinium)cobalt B was obtained. 13 Product weight: 2.162g, yield: 95.2%, purity: 99.2%.

[0090] Example 16

[0091]

[0092] The reaction steps and operations were the same as in Example 14, except that the reaction atmosphere was nitrogen, N-tert-butyl-N'-ethyl ethamidinium potassium salt A5 (2.164 g, 12 mmol) and cobalt oxalate (588 g, 4 mmol) were reacted in diethoxymethane, the accelerator was sodium acetate (656 mg, 8 mmol), the reaction temperature was 50 °C, and the reaction time was 12 hours.

[0093] Reaction results: 1.294 g of di(N-tert-butyl-N'-ethylethamidinyl)cobalt B5 product was obtained, with a yield of 94.7% and a purity of 99.0%.

[0094] Example 17

[0095]

[0096] The reaction steps and operations are the same as in Example 14, except that N,N'-diisopropylacetamidine lithium salt A 14 (1.660 g, 11.2 mmol) reacted with cobalt acetate (708 mg, 4 mmol) in methyl tert-butyl ether without an accelerator at a temperature of 25 °C for 18 hours.

[0097] Reaction results: 1.291 g of di(N,N'-diisopropylethamidinyl)cobalt B1 product was obtained, with a yield of 94.6% and a purity of 99.4%.

Claims

1. A method for synthesizing an acetate-promoted amidine cobalt complex, characterized in that: Using acetate as a promoter, an N,N'-dialkyl-substituted amidine alkali metal salt (A) was reacted with a cobalt precursor to prepare an amidine cobalt complex (B). The synthetic route is shown in the following reaction equation: Wherein: R is methyl, ethyl, n-butyl, dimethylamino or diisopropylamino; R1 and R2 are independently selected from methyl, ethyl, n-propyl, isopropyl, tert-butyl or cyclohexyl; M is lithium or potassium.

2. The synthesis method according to claim 1, characterized in that: The cobalt precursors are cobalt difluoride, cobalt dichloride, cobalt dibromide, cobalt diiodide, cobalt sulfate, cobalt nitrate, cobalt oxalate, cobalt tetrafluoroborate, or cobalt acetate.

3. The synthesis method according to claim 1, characterized in that: The accelerator acetate is lithium acetate, sodium acetate or potassium acetate.

4. The synthesis method according to claim 1, characterized in that: The amount of accelerator acetate is 0-250 mol% of the cobalt precursor.

5. The synthesis method according to claim 1, characterized in that: The molar ratio of the N,N'-dialkyl-substituted amido alkali metal salt (A) to the cobalt precursor is 3:1 to 2:

1.

6. The synthesis method according to claim 2, characterized in that: When the cobalt precursor is cobalt acetate, the N,N'-dialkyl-substituted amido alkali metal salt (A) reacts directly with cobalt acetate to obtain the amido cobalt complex (B). The molar ratio of the N,N'-dialkyl-substituted amido alkali metal salt (A) to cobalt acetate is 3:1-2:

1.

7. The synthesis method according to claim 1, characterized in that: The reaction solvent is one or more of the following: diethyl ether, tetrahydrofuran, 1,4-dioxane, 2-methyltetrahydrofuran, methyl tert-butyl ether, ethylene glycol dimethyl ether, and diethoxymethane.

8. The synthesis method according to claim 1, characterized in that: The reaction temperature is 0-70℃.

9. The synthesis method according to claim 1, characterized in that: The reaction time is 1-48 hours.

10. The synthesis method according to claim 1, characterized in that: The reaction atmosphere is nitrogen or argon.

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