Mononuclear manganese complexes containing acetylacetone and beta-ketimine ligands and methods of making same

Abstract

This invention provides a mononuclear manganese complex containing acetylacetone and β-ketoimine ligands, and a method for its preparation. This invention synthesizes a novel mononuclear divalent manganese complex Mn. II (acac)2(Hki)2. This compound is readily soluble in a variety of organic solvents, exhibits good stability, and is not easily deliquescent, making it an ideal source of divalent manganese. This invention employs a solution method to synthesize the aforementioned mononuclear divalent manganese complex, utilizing inexpensive and readily available raw materials; the reaction conditions are mild and can be carried out at room temperature; only water is used as the solvent, making it environmentally friendly; the reaction product is singular, easily purified, and yields the target compound in high quantities. This invention also synthesizes a novel mononuclear trivalent manganese complex, Mn. III (acac)2(ki), which differs from manganese acetylacetonate (III) in that one acetylacetonate anion is replaced by a ⁻-ketoimine anion. Mn III (acac)2(ki) is soluble in a variety of organic solvents and is an ideal trivalent manganese source reagent for anhydrous organic reactions.

Description

Technical Field

[0001] This invention belongs to the field of mononuclear manganese complex preparation technology, specifically relating to mononuclear manganese complexes containing acetylacetone and β-ketoimine ligands and their preparation methods. Background Technology

[0002] Mononuclear divalent manganese complexes containing two acetylacetone anions are commonly used manganese-containing reagents due to their good solubility and the ease with which the acetylacetone ligands can be removed. They are widely used in the preparation of manganese-based catalysts, magnetic materials, and battery materials. However, since divalent manganese ions are generally six-coordinated, and each acetylacetone anion provides at most two oxygen atoms for coordination, mononuclear divalent manganese complexes containing two acetylacetone ligands usually also bind at least two water molecules. Furthermore, these complexes are highly deliquescent, resulting in the presence of even more water molecules (including coordinated and non-coordinated water molecules), making accurate quantification difficult and severely limiting their application in strictly anhydrous systems. In addition, it is worth noting that complexes containing other types of ligands (such as ClO4) are also problematic. - Cl - CH3CO2 - Mononuclear divalent manganese compounds also suffer from the problem of an uncertain number of water molecules, making it difficult to accurately quantify these compounds and use them in strictly anhydrous reactions. There is an urgent need to develop inexpensive, readily available, well-defined, and anhydrous divalent mononuclear manganese reagents.

[0003] There are relatively few mononuclear trivalent manganese ion compounds, mainly because mononuclear trivalent Mn ions have high oxidizing power, making them very unstable. Currently, the most common trivalent manganese ion reagent is the acetylacetone trivalent manganese complex (Mn... III (acac)3). Its preparation requires potassium permanganate as a manganese source and oxidant, but due to the strong oxidizing power of potassium permanganate, there are significant safety risks, and the preparation process generates acetic acid as a byproduct, making purification difficult. Currently, there is an urgent need to develop a cheap, readily available, well-defined mononuclear trivalent manganese reagent that is anhydrous. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a mononuclear divalent manganese complex Mn containing two acetylacetonate anions (acac) and two neutral β-ketoimine (4-amino-3-penten-2-one, abbreviated as "Hki") ligands. II (acac)2(Hki)2 and its preparation method. This complex is completely water-free, readily soluble in organic solvents such as acetonitrile and chloroform, and can be used in organic systems under strictly anhydrous conditions. Furthermore, this novel mononuclear divalent manganese complex Mn... II(acac)2(Hki)2, in solution, can be gently and efficiently oxidized by oxygen in air at room temperature and pressure, directly converting into a compound containing two acetylacetonates and one... The mononuclear trivalent manganese complex of -ketoimine (ki) is abbreviated as Mn. III (acac)2(ki). This oxidation process does not use highly oxidizing reagents such as potassium permanganate, which reduces the preparation cost and operational risks of mononuclear trivalent manganese complexes, and realizes the safe, economical, and environmentally friendly green synthesis of mononuclear trivalent manganese complexes.

[0005] The technical solution of the present invention is as follows: A mononuclear divalent manganese complex Mn having the following formula (I) II (acac)2(Hki)2, its molecular formula is C 20 H 32 N₂O₆Mn has a core Mn ion coordinated to two acetylacetonate anions and two neutral β-ketoimine molecules. .

[0006] According to an embodiment of the present invention, the mononuclear divalent manganese complex Mn II (acac)2(Hki)2 is a single crystal, which belongs to the monoclinic crystal system and has the space group [missing information]. C 2 / c The unit cell parameters are a = 18.0985(9) Å, b = 10.0016(4) Å, c = 13.9962(5) Å, α = 90 °, β = 107.111(5) °, γ = 90 °, Z = 4, and the volume is 2421.36(19) Å. 3 .

[0007] According to an embodiment of the present invention, the single crystal has the single crystal parameters shown in Table 1 below: Table 1 .

[0008] This invention also provides mononuclear divalent manganese complexes (Mn) as described above. II The preparation method of (acac)2(Hki)2 includes: Method 1. Reaction of divalent manganese salt, acetylacetone, and ammonia; Alternatively, method 2 involves reacting a divalent manganese salt with 4-amino-3-penten-2-one in water.

[0009] According to an embodiment of the present invention, the reaction temperatures of methods 1 and 2 may be the same or different, and are independently above 0°C, for example above 10°C, such as 15°C-30°C.

[0010] As described above, Method 1 uses divalent manganese salt, acetylacetone, and ammonia as raw materials to react under mild conditions to obtain a mononuclear divalent manganese complex (Mn). II (acac)2(Hki)2). This method has the advantages of inexpensive and readily available raw materials, mild reaction conditions, simple operation, high yield, and easy purification, making it suitable for large-scale preparation.

[0011] As described above, Method 2 involves the direct reaction of a divalent manganese salt with 4-amino-3-penten-2-one in water to obtain the product. This method has simpler synthetic steps and avoids the use of reagents with irritating odors, making it suitable for applications requiring more stringent experimental conditions or reagents.

[0012] According to an embodiment of the present invention, in method 1, the molar ratio of divalent manganese salt, acetylacetone, and ammonia (calculated as NH3) is 1: (2-10): (2-20), preferably 1: (2-5): (2-5).

[0013] According to an embodiment of the present invention, in method 1, the reaction time of acetylacetone with ammonia is 10 minutes to 48 hours, preferably 1 to 12 hours.

[0014] According to an embodiment of the present invention, in method 1, the divalent manganese salt is selected from manganese chloride tetrahydrate, manganese acetate tetrahydrate, manganese sulfate, manganese trifluoromethanesulfonate, manganese perchlorate hexahydrate, and manganese nitrate tetrahydrate, preferably manganese chloride tetrahydrate.

[0015] According to an embodiment of the present invention, in method 2, the molar ratio of divalent manganese salt and 4-amino-3-penten-2-one is 1:(2 to 20), preferably 1:(2 to 10), such as 1:(2 to 5).

[0016] According to an embodiment of the present invention, in method 2, the divalent manganese salt is selected from manganese chloride tetrahydrate, manganese acetate tetrahydrate, manganese sulfate, manganese trifluoromethanesulfonate, manganese perchlorate hexahydrate, and manganese nitrate tetrahydrate, preferably manganese chloride tetrahydrate.

[0017] This invention also provides the mononuclear divalent manganese complex Mn as described above. II (acac)2(Hki)2 in the preparation of the mononuclear trivalent manganese complex Mn shown in formula (II) III Uses of (acac)2(ki); .

[0018] The present invention also provides a mononuclear trivalent manganese complex Mn as shown in formula (II) above. III (acac)2(ki), its molecular formula is C 15 H 22NO5Mn has two acetylacetone anions and one β-ketoimine anion coordinated to its core Mn ion.

[0019] According to an embodiment of the present invention, the mononuclear trivalent manganese complex Mn III (acac)2(ki) is a single crystal, which belongs to the monoclinic crystal system and has the space group [missing information]. I 2 / a The unit cell parameters are a = 15.8811(2) Å, b = 12.89270(10) Å, c = 18.2250(2) Å, α = 90 °, β = 115.5020(10) °, γ = 90 °, Z = 8, and the volume is 3368.01(7) Å. 3 .

[0020] According to a specific embodiment of the present invention, the single crystal has the single crystal parameters shown in Table 2: Table 2. Mn III Single crystal parameters of (acac)2(ki) .

[0021] This invention provides the mononuclear trivalent manganese complex Mn as described above. III The preparation method of (acac)2(ki) includes: The above Mn II (acac)2(Hki)2 dissolves in an organic solvent and reacts in the presence of oxygen.

[0022] According to an embodiment of the present invention, the organic solvent is selected from at least one of methanol, ethanol, acetonitrile, dichloromethane, chloroform, and ethyl acetate, preferably dichloromethane.

[0023] According to an embodiment of the present invention, the conditions for the presence of oxygen include air.

[0024] According to an embodiment of the present invention, the temperature of the reaction is above 0°C, for example above 10°C, such as 15°C-30°C.

[0025] The technical solution of the present invention has the following beneficial effects: 1. This invention synthesizes a novel mononuclear divalent manganese complex Mn. II (acac)2(Hki)2. This compound is readily soluble in a variety of organic solvents, exhibits good stability, and is not easily deliquescent, making it an ideal source of divalent manganese.

[0026] 2. This invention uses a solution method to synthesize the mononuclear divalent manganese complex, which uses inexpensive and readily available raw materials; the reaction conditions are mild and can be carried out at room temperature; only water is used as a solvent, making it green and environmentally friendly; the reaction product is singular, easy to purify, and has a high yield of the target compound.

[0027] 3. This invention also synthesizes a novel mononuclear trivalent manganese complex Mn. III (acac)2(ki), which differs from manganese acetylacetonate(III) in that one acetylacetonate anion is replaced by a β-ketoimine anion. Mn III (acac)2(ki) is soluble in a variety of organic solvents and is an ideal trivalent manganese source reagent for anhydrous organic reactions.

[0028] 4. Synthesis of Mn III The (acac)2(ki) method is simple in steps and has mild reaction conditions. It can oxidize mononuclear divalent Mn complexes to mononuclear trivalent Mn complexes using oxygen in the air as an oxidant, which is economical and environmentally friendly. Attached Figure Description

[0029] Figure 1 For Mn II Crystal structure diagram of (acac)2(Hki)2.

[0030] Figure 2 For Mn II UV-Vis absorption spectrum of (acac)2(Hki)2 in 1,2-dichloroethane.

[0031] Figure 3 For Mn II Infrared spectrum of (acac)2(Hki)2 obtained by KBr pelleting.

[0032] Figure 4 For Mn III Crystal structure diagram of (acac)2(ki).

[0033] Figure 5 For Mn III UV-Vis absorption spectrum of (acac)2(ki) in 1,2-dichloroethane.

[0034] Figure 6 For Mn III (acac)2(ki) Infrared spectrum obtained by KBr pelleting. Detailed Implementation

[0035] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0036] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0037] Example 1: Novel mononuclear divalent manganese complex Mn II Synthesis method 1 of (acac)2(Hki)2: Acetylacetone (10 mmol) was added to a reaction tube, followed by 25 wt% ammonia (10 mmol, calculated as NH3). The mixture was stirred at room temperature until the liquid was completely dissolved, forming a yellow, transparent solution. The reaction was allowed to proceed for 12 hours at room temperature. Manganese chloride tetrahydrate (2 mmol) was weighed, dissolved in 1 mL of water, and added to the reaction tube. After mixing, a clear, pale yellow solution was formed and allowed to stand at 5 °C for crystallization. After 24 hours, yellow, transparent, flaky and elongated crystals precipitated from the solution. The crystallization solution was filtered, and the crystal sample was collected, washed with cold water, and then vacuum dried to obtain the target product Mn. II (acac)2(Hki)2, yield 80.8% (based on the number of moles of Mn).

[0038] Example 2: Novel mononuclear divalent manganese complex Mn II Synthesis method 2 of (acac)2(Hki)2: 4-Amino-3-penten-2-one (5 mmol) was added to the reaction tube, followed by 0.1 mL of water to dissolve it, forming a pale yellow solution. Manganese acetate tetrahydrate (1 mmol) was weighed and dissolved in 0.5 mL of water. This solution was added to the reaction tube, and the mixture was shaken to form a yellow transparent solution. The solution was then allowed to stand at 5°C for crystallization. After 48 hours, yellow transparent flaky and strip-shaped crystals precipitated from the solution. The crystallized solution was filtered, and the crystal sample was collected, washed with cold water, and then vacuum dried to obtain the target product Mn. II (acac)2(Hki)2, yield 56.2% (based on moles of Mn).

[0039] The novel mononuclear divalent manganese complex Mn prepared as described in Examples 1 and 2 above II (acac)2(Hki)2 has the structure shown in formula (I) and the molecular formula is C. 20 H 32The complex N₂O₆Mn has a central divalent Mn ion and ligands consisting of two acetylacetonate anions and two neutral β-ketoimine molecules. The theoretical elemental analysis (%) of this complex is: C, 53.21; H, 7.15; N, 6.21; experimental values ​​(%) are: C, 53.19; H, 7.15; N, 6.21.

[0040]

[0041] Mn II The crystal structure of (acac)2(Hki)2 is as follows: Figure 1 As shown, hydrogen atoms are not displayed for clarity. Mn II The single crystal parameters of (acac)2(Hki)2 are shown in Table 1.

[0042] Mn II Single crystals of (acac)2(Hki)2 belong to the monoclinic crystal system, space group 1. C 2 / c The unit cell parameters are a = 18.0985(9) Å, b = 10.0016(4) Å, c = 13.9962(5) Å, α = 90°, β = 107.111(5)°, γ = 90°, Z = 4, and the volume is 2421.36(19) Å. 3 .

[0043] Table 1. Mn II Single crystal parameters of (acac)2(Hki)2

[0044] Mn II The UV-Vis absorption spectrum of (acac)2(Hki)2 in 1,2-dichloroethane is shown below. Figure 2 As shown.

[0045] Mn II The infrared spectrum of (acac)2(Hki)2 obtained by KBr pellet compression is shown below. Figure 3 As shown.

[0046] Solubility test results show that: Mn II The (acac)2(Hki)2 compound is readily soluble in methanol, dichloromethane, and acetonitrile, soluble in ethyl acetate, and sparingly soluble in n-hexane or water.

[0047] Mn II Hygroscopic experiment of (acac)2(Hki)2: Mn IIThe (acac)2(Hki)2 sample was placed in a closed environment at 25°C and 75% relative humidity for 24 hours and the weight gain was 0.192%, with almost no hygroscopicity.

[0048] Example 3: Novel mononuclear trivalent manganese complex Mn III Synthesis of (acac)2(ki): Weigh out the Mn prepared in the above examples II (acac)₂(Hki)₂ solid (4 mmol) was dissolved in 20 mL of dichloromethane. After centrifugation, the supernatant was collected and diffuse-dried to obtain a brownish-black lumpy solid. The solid was washed with n-hexane (20 mL each time, 3 washes), then dissolved in ethyl acetate (16 mL) and recrystallized. This wash-recrystallization operation was repeated until black lumpy crystals were finally obtained. After washing with n-hexane and vacuum drying, the target product Mn was obtained. III (acac)2(ki).

[0049] The novel mononuclear trivalent manganese complex Mn III (acac)2(ki) has the structure shown in formula (II) and the molecular formula is C. 15 H 22 NO5Mn has a trivalent Mn ion at its center and two acetylacetone anions and one β-ketoimine anion as ligands. The theoretical elemental analysis (%) of this complex is: C, 51.29; H, 6.31; N, 3.99; experimental values ​​(%) are: C, 51.32; H, 6.33; N, 4.04.

[0050]

[0051] Mn III The crystal structure of (acac)2(ki) is as follows: Figure 4 As shown, hydrogen atoms are not displayed for clarity. Mn III The single crystal parameters of (acac)2(ki) are shown in Table 2.

[0052] Mn III Single crystals of (acac)2(ki) belong to the monoclinic crystal system, space group 1. I 2 / a The unit cell parameters are a = 15.8811(2) Å, b = 12.89270(10) Å, c = 18.2250(2) Å, α = 90 °, β = 115.5020(10) °, γ = 90 °, Z = 8, and the volume is 3368.01(7) Å. 3 .

[0053] Table 2. MnIII Single crystal parameters of (acac)2(ki)

[0054] Mn III The UV-Vis absorption spectrum of (acac)2(ki) in 1,2-dichloroethane is shown below. Figure 5 As shown.

[0055] Mn III The infrared spectrum of (acac)2(ki) obtained by KBr pellet compression is shown below. Figure 6 As shown.

[0056] Solubility test results show that: Mn III (acac)2(ki) compounds are readily soluble in methanol, dichloromethane, acetonitrile, and ethyl acetate, but sparingly soluble in n-hexane or water.

[0057] The exemplary embodiments of the present invention have been described above. However, the scope of protection of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. The mononuclear divalent manganese complex Mn shown in formula (I) II (acac)2(Hki)2, its molecular formula is C 20 H 32 N₂O₆Mn has a core Mn ion coordinated with two acetylacetone anions and two neutral β-ketoimine molecules. 。 2. The mononuclear divalent manganese complex Mn according to claim 1 II (acac)2(Hki)2, where, The mononuclear divalent manganese complex Mn II (acac)2(Hki)2 is a single crystal, which belongs to the monoclinic crystal system and has the space group [missing information]. C 2 / c The unit cell parameters are a = 18.0985(9) Å, b = 10.0016(4) Å, c = 13.9962(5) Å, α = 90 °, β = 107.111(5) °, γ = 90 °, Z = 4, and the volume is 2421.36(19) Å. 3 .

3. The mononuclear divalent manganese complex Mn according to claim 2 II (acac)2(Hki)2, where, The single crystal has the following single crystal parameters: 。 4. The mononuclear divalent manganese complex (Mn) according to any one of claims 1-3 II The preparation method of (acac)2(Hki)2), wherein, include: Method 1. Reaction of divalent manganese salt, acetylacetone, and ammonia; Alternatively, method 2 involves reacting a divalent manganese salt with 4-amino-3-penten-2-one in water.

5. The preparation method according to claim 4, wherein, Methods 1 and 2 may have the same or different reaction temperatures, which are independently above 0°C; Preferably, in method 1, the molar ratio of divalent manganese salt, acetylacetone, and ammonia (calculated as NH3) is 1:(2-10):(2-20). Preferably, in method 1, the divalent manganese salt is selected from manganese chloride tetrahydrate, manganese acetate tetrahydrate, manganese sulfate, manganese trifluoromethanesulfonate, manganese perchlorate hexahydrate, and manganese nitrate tetrahydrate; Preferably, in method 2, the molar ratio of divalent manganese salt to 4-amino-3-penten-2-one is 1: (2 to 20). Preferably, in method 2, the divalent manganese salt is selected from manganese chloride tetrahydrate, manganese acetate tetrahydrate, manganese sulfate, manganese trifluoromethanesulfonate, manganese perchlorate hexahydrate, and manganese nitrate tetrahydrate.

6. The mononuclear divalent manganese complex Mn according to any one of claims 1-4 II (acac)2(Hki)2 is used in the preparation of the mononuclear trivalent manganese complex Mn as shown in formula (II). III Uses of (acac)2(ki); 。 7. The mononuclear trivalent manganese complex Mn shown in formula (II) III (acac)2(ki), its molecular formula is C 15 H 22 NO5Mn has two acetylacetonate anions and one β-ketoimine anion coordinated to the core Mn ion. 。 8. The mononuclear trivalent manganese complex Mn according to claim 7 III (acac)2(ki), where, The mononuclear trivalent manganese complex Mn III (acac)2(ki) is a single crystal, which belongs to the monoclinic crystal system and has the space group [missing information]. I 2 / a The unit cell parameters are a = 15.8811(2) Å, b = 12.89270(10) Å, c = 18.2250(2) Å, α = 90 °, β = 115.5020(10) °, γ = 90 °, Z = 8, and the volume is 3368.01(7) Å. 3 .

9. The mononuclear trivalent manganese complex Mn according to claim 8 III (acac)2(ki), where, The single crystal has the following single crystal parameters: 。 10. The mononuclear trivalent manganese complex Mn as described in claim 9 III The preparation method of (acac)2(ki), wherein, include: The Mn described in any one of claims 1-3 II (acac)2(Hki)2 dissolves in an organic solvent and reacts in the presence of oxygen; Preferably, the organic solvent is selected from at least one of methanol, ethanol, acetonitrile, dichloromethane, chloroform, and ethyl acetate; Preferably, the conditions for the presence of oxygen include air; Preferably, the reaction temperature is above 0°C.

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