Ruthenium ammonia complex, preparation method and application of ruthenium ammonia complex in photocatalytic ammoxidation

Abstract

The invention discloses a ruthenium ammonia complex, a preparation method and application of the ruthenium ammonia complex in photocatalytic ammoxidation, and belongs to the technical field of organic synthesis. According to the invention, p-cymene ruthenium dichloride dimer is taken as a precursor and is subjected to mixed reaction with a bipyridine ligand, and the obtained ruthenium ammonia complex or ruthenium diamine complex can be applied to ammoxidation as a photocatalyst. Compared with hydrazine prepared by electrocatalytic ammoxidation of a ruthenium complex, the complex prepared by the invention can be used for photocatalytic ammoxidation to obtain hydrazine, so that the blank that hydrazine is obtained by photocatalytic ammoxidation of the ruthenium complex is filled up, and a cleaner and more efficient method is provided for preparation and purification of hydrazine.

Description

A ruthenium-ammonia complex, its preparation method and its application in photocatalytic ammonia oxidation Technical Field

[0001] This invention belongs to the field of organic synthesis technology, specifically relating to a ruthenium-ammonia complex, its preparation method, and its application in photocatalytic ammonia oxidation. Background Technology

[0002] Ammonia (NH3), as a high-hydrogen (H) carrier, is widely used in the energy field. Electrocatalytic ammonia oxidation (AOR) using organometallic small molecules started relatively late, until 2019 when Smith III discovered the complex [Ru]. II [trpy)(bpy(NMe2)2)NH3]PF6 can catalyze the oxidation of ammonia to nitrogen (N2). To date, complexes of Ru, Ni, Mn, Fe, and Cu have also been found to possess electrocatalytic ammonia oxidation properties, with NO3 being a more commercially viable product in addition to N2. - NO2 - Hydrazine (N2H4) was also synthesized. Due to its strong reducing properties, hydrazine is widely used in industrial production, while its extremely high energy density is applied in aerospace and defense, giving it immense commercial value. However, the synthesis of hydrazine still relies on the Raschig process, which has been used for over 100 years, resulting in low yields and significant environmental pollution from chlorine-containing byproducts. This limits large-scale production and keeps hydrazine prices high.

[0003] Compared to electricity, solar energy has garnered widespread attention as a simple and readily available clean energy source. While photocatalytic water oxidation is becoming increasingly mature, research on photocatalytic ammonia oxidation remains incomplete. To further reduce energy consumption and improve the controllability and sustainability of the reaction, extending the ammonia oxidation reaction from electrocatalytic systems to photocatalytic systems has significant research value. Photocatalytic ammonia oxidation can utilize solar energy as a driving force to achieve the selective conversion of ammonia at ambient temperature and pressure. This not only holds promise for overcoming the limitations of electrode polarization and mass transfer in electrocatalysis but also allows for coupling with processes such as photocatalytic water splitting and photocatalytic nitrogen fixation to construct a more efficient and green "nitrogen-hydrogen" cycle system. Therefore, developing efficient and stable photocatalytic ammonia oxidation systems has become a cutting-edge direction in the fields of nitrogen chemistry and renewable energy conversion. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a complex, a preparation method and its application in photocatalytic ammonia oxidation, so as to solve the technical problem of poor catalytic performance of photocatalytic ammonia oxidation catalysts.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is to provide a coordination compound with the following general structural formula: , , or Where x is Cl, NH3, or N2H4; y is Cl - or PF6 - .

[0006] Based on the above technical solution, the present invention can be further improved as follows: Further, the coordination compound is coordination compound 1-7, and its structural formula is: , , , , , or .

[0007] This invention also discloses a method for preparing the above-mentioned complexes, comprising the following steps: a. using p-cymene ruthenium dichloride dimer as a precursor, dissolving it in an organic solvent with bipyridine ligand A at a molar ratio of 1:1-3, and then reacting at room temperature for 22-26 h to obtain ruthenium-amine complexes, i.e., complexes 1-4; bipyridine ligand A is 2,2'-bipyridine or a 2,2'-bipyridine derivative; or b. using p-cymene ruthenium dichloride dimer as a precursor, dissolving it in an organic solvent with bipyridine ligand B at a molar ratio of 1:1-3, and then reacting at room temperature for 3-7 days to obtain an intermediate; then dissolving the intermediate and a dehalogenating agent separately, and then adding the dehalogenating agent solution dropwise to the intermediate solution; reacting under vacuum for 22-26 h; filtering; and passing ammonia gas into the filtrate for 10-30 min to react with the central metal R. After coordination with u, and finally standing for 1-2 hours, a ruthenium-amine complex, i.e., complex 5, is obtained; the bipyridine ligand B is 2,2'-bipyridine; the mass ratio of the intermediate to the dehalogenating agent is 1:1-1.2; the dehalogenating agent is silver trifluoromethanesulfonate, amine trifluoromethanesulfonate, or sodium trifluoromethanesulfonate; or c. using p-cymene ruthenium dichloride dimer as a precursor, dissolved with bipyridine ligand B in an organic solvent at a molar ratio of 1:1-3, and then reacted at room temperature for 3-7 days to obtain an intermediate. Then the intermediate and the dehalogenating agent are dissolved separately, and the dehalogenating agent solution is added dropwise to the intermediate solution. The reaction is carried out under vacuum for 22-26 hours, filtered, and 100wt%-300wt% tetrahydrofuran solution containing N2H4 is added dropwise to the filtrate. Finally, it is allowed to stand for 1-2 hours to obtain a ruthenium-hydrazine complex, i.e., complex 6 or complex 7.

[0008] Based on the above technical solution, the present invention can be further improved as follows: The structural formula of the ruthenium dichloride dimer of cymene is: .

[0009] Furthermore, the bipyridine ligand A is 4,4'-dimethyl-2,2'-bipyridine, 5,5'-dimethyl-2,2'-bipyridine, or 6,6'-dimethyl-2,2'-bipyridine.

[0010] Furthermore, the molar ratio of ruthenium dichloride dimer to bipyridine ligand A / B is 1:2.

[0011] Furthermore, the organic solvent is dichloromethane, tetrahydrofuran, or toluene.

[0012] Furthermore, the ammonia ventilation rate is 1.5-2.5 L / h.

[0013] Furthermore, the concentration of the tetrahydrofuran solution containing N2H4 is 1-3 mol / L.

[0014] The present invention also discloses the application of the above-mentioned complex in photocatalytic ammonia oxidation.

[0015] The beneficial effects of this invention are as follows: Compared with the electrocatalytic ammonia oxidation of ruthenium complexes to prepare hydrazine, the complexes prepared by this invention can be photocatalytically oxidized to hydrazine, filling the gap in the photocatalytic ammonia oxidation of ruthenium complexes to hydrazine, and providing a cleaner and more efficient method for the preparation and purification of hydrazine. Attached Figure Description

[0016] Figure 1 shows the crystal structure of coordination compound 1; Figure 2 shows the crystal structure of coordination compound 2; Figure 3 shows the crystal structure of coordination compound 3; Figure 4 shows the crystal structure of coordination compound 4; Figure 5 shows the crystal structure of coordination compound 5; where C1-C22 represent carbon atoms with ordinal numbers 1-22, N1-N3 represent nitrogen atoms with ordinal numbers 1-3, Cl1 represents chlorine atom with ordinal number 1, and Ru1 represents ruthenium atom with ordinal number 1; Figure 6 shows the crystal structure of coordination compound 1. 1 1H NMR spectrum; Figure 7 shows the 1H NMR spectrum of complex 2. 1 1H NMR spectrum; Figure 8 shows the complex 3. 1 1H NMR spectrum; Figure 9 shows the complex 4. 1 1H NMR spectrum; Figure 10 shows the complex 5. 1 1H NMR spectrum; Figure 11 shows the complex 6. 1 1H NMR spectrum; Figure 12 shows the complex 7. 1 IR spectra of complex 1; Figure 13: IR spectrum of complex 1; Figure 14: IR spectrum of complex 2; Figure 15: IR spectrum of complex 3; Figure 16: IR spectrum of complex 4; Figure 17: IR spectrum of complex 5; Figure 18: IR spectrum of complex 6; Figure 19: IR spectrum of complex 7; Figure 20: H2 gas phase standard curve; Figure 21: O2 gas phase standard curve; Figure 22: N2 gas phase standard curve; Figure 23: Gas chromatogram of gases in the system after photocatalytic ammonia oxidation experiment; Figure 24: Standard curve of hydrazine; Figure 25: UV absorption spectrum of hydrazine in the system after photocatalytic ammonia oxidation experiment; Figure 26: Standard curve of ammonium ions; Figure 27: Standard curve of nitrate ions; Figure 28: Standard curve of nitrite ions; Figure 29: Standard curve of hydroxylamine. Detailed Implementation

[0017] The specific embodiments of the present invention are described below to facilitate understanding of the invention by those skilled in the art. Unless otherwise specified, specific conditions are applied according to conventional conditions or the manufacturer's recommendations. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various modifications are obvious as long as they fall within the spirit and scope of the invention as defined and determined by the appended claims. All inventions utilizing the concept of this invention are protected.

[0018] The ruthenium dichloride dimer, photosensitizer-[Ru(bpy)3]Cl2, and electron acceptor-7,7,8,8-tetracyano-p-benzoquinone dimethyl ether used in the following examples were all purchased from Beijing Innocare Technology Co., Ltd.

[0019] Example 1: A method for preparing a ruthenium-amine complex, comprising the following steps: dissolving 80 mg of p-cymene ruthenium dichloride dimer and 2,2'-bipyridine in 10 mL of dichloromethane, and then reacting at room temperature for 24 h to obtain the ruthenium-amine complex, namely complex 1, with the following structural formula: .

[0020] Example 2 differs from Example 1 in that 2,2'-bipyridine is replaced with 4,4'-dimethyl-2,2'-bipyridine, while the other conditions remain the same as in Example 1, resulting in a ruthenium-amine complex, namely complex 2, with the following structural formula: .

[0021] Example 3 differs from Example 1 in that 2,2'-bipyridine is replaced with 5,5'-dimethyl-2,2'-bipyridine, while the other conditions remain the same as in Example 1, yielding a ruthenium-amine complex, namely complex 3, with the following structural formula: .

[0022] Example 4 differs from Example 1 in that 2,2'-bipyridine is replaced with 6,6'-dimethyl-2,2'-bipyridine, while the other conditions remain the same as in Example 1, yielding a ruthenium-amine complex, namely complex 4, with the following structural formula: .

[0023] Example 5: A method for preparing a ruthenium-amine complex, comprising the following steps: S1, dissolving p-cymene ruthenium dichloride dimer and 2,2'-bipyridine in dichloromethane at a molar ratio of 1:2, and then reacting at room temperature for 5 days to obtain an intermediate; S2, dissolving 120 mg of the intermediate and 50 mg of silver trifluoromethanesulfonate in 20 mL and 10 mL of acetonitrile, respectively, and then adding the silver trifluoromethanesulfonate solution dropwise to the intermediate solution over a period of 1.5 h, and then reacting under vacuum for 24 h. After the reaction is complete, the precipitate is filtered off, and ammonia gas is introduced into the filtrate for 20 min (at a rate of 2 L / h). Finally, the mixture is allowed to stand in the dark for 1 h to obtain the ruthenium-amine complex, namely complex 5, with the following structural formula: .

[0024] Example 6: A method for preparing a ruthenium hydride complex, comprising the following steps: S1, dissolving p-cymene ruthenium dichloride dimer and 2,2'-bipyridine in tetrahydrofuran at a molar ratio of 1:1, and then reacting at room temperature for 3 days to obtain an intermediate; S2, dissolving 120 mg of the intermediate and 50 mg of trifluoromethanesulfonate in 20 mL and 10 mL of acetonitrile, respectively, and then adding the trifluoromethanesulfonate solution dropwise to the intermediate solution over a period of 1.5 h, and then reacting under vacuum for 22 h. After the reaction is complete, the precipitate is filtered off, and 200 wt% tetrahydrofuran solution containing N2H4 (concentration 2 mol / L) is added dropwise to the filtrate. Finally, the mixture is allowed to stand in the dark for 1 h to obtain the ruthenium hydride complex, namely complex 6, with the following structural formula: .

[0025] Example 7 differs from Example 6 in that the light-protected standing time in S2 is replaced with 2 hours instead of 1 hour. All other conditions remain the same as in Example 6, yielding a ruthenium hydrazine complex, namely complex 7, with the following structural formula: .

[0026] The crystal structures of complexes 1-5 prepared in Examples 1-5 are shown in Figures 1-5, and the crystal data are shown in Tables 1-6. The crystal structures of complexes 1-7 prepared in Examples 1-7 are also shown in Figures 1-5. 1 The H NMR spectra are shown in Figures 6-12, and the IR spectra are shown in Figures 13-19.

[0027] Table 1. Crystal data of complexes 1-5 prepared in Examples 1-5

[0028] a GooF = [Σw(|F o | |F c |) 2 / (N obs Nparam )] ½ . b R1=Σ||F o | |F c || / Σ|F o | c wR2[(Σw|F o | |F c |) 2 / Σw 2 |F o | 2 1 / 2. Table 2 Bond lengths and bond angles of complex 1

[0029] Table 3 Bond lengths and bond angles of coordination compound 2

[0030] Table 4 Bond lengths and bond angles of coordination compound 3

[0031] Table 5 Bond lengths and bond angles of coordination compound 4

[0032] Table 6 Bond lengths and bond angles of coordination compound 5

[0033] The following experiments were conducted using the ruthenium ammonia complexes (complexes 1-5) prepared in Examples 1-5 as catalyst samples.

[0034] Example 1: Photocatalytic ammonia oxidation experiment. 29.7 mg of photosensitizer-[Ru(bpy)3]Cl2 and 98.2 mg of electron acceptor-7,7,8,8-tetracyano-p-benzoquinone dimethane were weighed and dissolved in 40 mL of acetonitrile solution. Ammonia gas was continuously introduced into the closed reactor (3 h), and then the catalyst sample was added. The gas phase standard curves of H2, O2 and N2 in the standard gas are shown in Figures 20-22. Then, the reaction was carried out under 450 nm blue light irradiation for 2 h, and the light irradiation was stopped. After standing for 1 h, 100 μL of headspace gas was taken for gas chromatography detection, and the gas chromatography analysis results of H2, O2 and N2 were obtained (Figure 23).

[0035] As shown in Figure 23, after 2 hours of photocatalysis, the signal peak height of N2 in the system was significantly enhanced compared to that of O2. Quantitative calculations were performed using the N2 gas-phase standard curve equation (Figure 22) to obtain the N2 turnover number (TON) for different catalyst samples, and the results are shown in Table 7.

[0036] Table 7. Turnover rates of nitrogen and hydrazine for different catalyst samples

[0037] As shown in Table 7, due to electronic effects, complexes 2-5, with electron-donating -CH3 groups, exhibit higher nitrogen production from photocatalytic ammonia oxidation than complex 1. Simultaneously, due to steric hindrance, complex 2, which exposes more coordination space at the central ruthenium metal, has the highest nitrogen production compared to complexes 3-5 with other -CH3 modification positions. Complexes 5 and 6, with direct ammonia or hydrazine coordination, also show significantly higher nitrogen production than complex 1, with chlorine coordination, indicating that more hydrazine is converted to nitrogen, leading to a decrease in hydrazine turnover.

[0038] In Experiment 2, to detect nitrogen-containing substances in the reaction solution after catalysis, the contents of hydrazine, ammonium, nitrate, nitrite and hydroxylamine in the catalytic solution were quantitatively detected by ultraviolet-visible method.

[0039] (1) Preparation of colorimetric reagent for hydrazine (N2H4) detection: Take 5 mL of hydrochloric acid and dilute to 100 mL with deionized water to obtain colorimetric reagent A with a concentration of 0.6 M; weigh 1.82 g of 4-dimethylaminobenzaldehyde and dilute to 100 mL with ethanol to obtain colorimetric reagent B with a concentration of 18.2 g / L.

[0040] Calibration Procedure: When preparing the N2H4 standard solution, transfer 0, 25, 50, 75, and 100 μL of 50 mg / L N2H4 solution to different test tubes. Add 0.5 mL of colorimetric reagent A and 1.5 mL of colorimetric reagent B to each tube, and then bring the volume to 10 mL. Shake the solution thoroughly and incubate at room temperature in the dark for 20 min. Quantitative analysis of N2H4 was performed using UV-Vis spectrophotometry. The absorbance of N2H4 solutions at different concentrations was monitored at its maximum absorption wavelength of 455 nm, yielding a standard curve for N2H4 (Figure 24), which was used for subsequent quantitative calculations.

[0041] Quantitative method for N2H4 in solution after photocatalytic ammonia oxidation experiment: Take 500 μL of reaction solution, add 0.5 mL of colorimetric reagent A and 1.5 mL of colorimetric reagent B, and then dilute to 10 mL with deionized water. Develop the solution in the dark for 20 min before detection. Quantitative detection of residual hydrazine (N2H4) in the reaction system is performed using ultraviolet-visible spectrophotometry.

[0042] As shown in Figure 25, the photocatalytic oxidation of hydrazine by complex 1 yielded significantly higher hydrazine than that of complexes 2-5, indicating that the steric hindrance of the complexes affects the hydrazine yield. When the intermediate ammonia-coordinated ruthenium ammonia complex 2 was directly added, its hydrazine turnover was twice that of the chlorine-coordinated complex 1, indicating that ammonia coordination can improve the hydrazine yield.

[0043] (2) Ammonium ions (NH4) + ) Preparation of colorimetric reagents: The concentration of NH3 is determined by the indophenol blue method. Prepare colorimetric reagent A (containing 1M sodium hydroxide, 5wt% salicylic acid and 5wt% sodium citrate), colorimetric reagent B (containing 0.05 M sodium hypochlorite solution) and colorimetric reagent C (1wt% sodium nitroprusside trihydrate).

[0044] Calibration Procedure: When preparing the nitrate standard solution, transfer 0, 250, 500, 750, and 1000 μL of 100 mg / L ammonium chloride solution to different test tubes. Add 2 mL of colorimetric reagent A, 1 mL of colorimetric reagent B, and 0.2 mL of colorimetric reagent C to each tube, then bring the volume to 10 mL. Shake the solution thoroughly and incubate at room temperature in the dark for 1 hour. Use UV-Vis spectrophotometry to analyze the NH4+. + Quantitative analysis was performed. Different concentrations of NH4 were monitored at its maximum absorption wavelength of 655 nm. + The absorbance of the solution yields NH4. + The standard working curve (Figure 26) is used for subsequent quantitative calculations.

[0045] NH4 in solution after photocatalytic ammonia oxidation experiment + Quantitative method: Take 100 μL of reaction solution, add 2 mL of colorimetric reagent A, 1 mL of indicator B and 0.2 mL of indicator C, and then dilute to 10 mL with deionized water. After developing the solution in the dark for 1 hour, perform the detection.

[0046] (3) Nitrate (NO3) - To prepare the colorimetric reagent: Take 4.165 mL of hydrochloric acid and dilute it to 50 mL with deionized water to obtain colorimetric reagent A; weigh 0.432 g of aminosulfonic acid, dissolve it in hydrochloric acid, and then dilute it to 50 mL with deionized water to obtain colorimetric reagent B.

[0047] Calibration Procedure: When preparing the nitrate standard solution, transfer 0, 250, 500, 750, and 1000 μL of 100 mg / L potassium nitrate solution to different test tubes. Add 100 μL of colorimetric reagent A and 10 μL of colorimetric reagent B to each tube, then bring the volume to 10 mL. Shake the solution thoroughly and incubate at room temperature in the dark for 5 min. Use UV-Vis spectrophotometry to determine the color of NO3-. - Quantitative analysis was performed. Different concentrations of NO3 were monitored at its maximum absorption wavelength of 220 nm. - The absorbance of the solution yields NO3. - The standard working curve (Figure 27) is used for subsequent quantitative calculations.

[0048] NO3 in solution after photocatalytic ammonia oxidation experiment - Quantitative method: Take 100 μL of reaction solution and add 100 μL of precipitate. L colorimetric reagent A and 10 After adding reagent B, dilute the solution to 10 mL with deionized water, and then perform color development in the dark for 5 minutes before detection.

[0049] (4) Nitrite (NO2) - Preparation of colorimetric reagent: Weigh 2g of p-aminobenzenesulfonamide, add 25mL of water to dissolve it, then add 5mL of phosphoric acid and 0.1g of 1-naphthylamine, and dilute to 50mL with deionized water to obtain the colorimetric reagent.

[0050] Calibration Procedure: When preparing the nitrite standard solution, transfer 0, 500, 1000, 1500, and 2000 μL of 20 mg / L potassium nitrite solution to different test tubes, add 100 μL of colorimetric reagent to each tube, shake the solution thoroughly, and incubate at room temperature in the dark for 10 min. Use UV-Vis spectrophotometry to measure NO2. - Quantitative analysis was performed. Different concentrations of NO2 were monitored at its maximum absorption wavelength of 540 nm. - The absorbance of the solution yields NO2. - The standard working curve (Figure 28) is used for subsequent quantitative calculations.

[0051] NO2 in solution after photocatalytic ammonia oxidation experiment - Quantitative method: Take 100 μL of reaction solution, add 100 μL of colorimetric reagent, and then dilute to 10 mL with deionized water. After developing the solution in the dark for 10 min, perform the detection.

[0052] (5) Preparation of colorimetric reagent for hydroxylamine (NH2OH) detection: Prepare 1M sodium acetate and 1M acetic acid, and then mix them in a 1:1 volume ratio to obtain colorimetric reagent A; weigh 0.1931g of ferric ammonium sulfate and dilute to 100mL with deionized water to obtain colorimetric reagent B; weigh 0.1982g of non-phosphoroline and dilute to 100mL with ethanol to obtain colorimetric reagent C.

[0053] Calibration Procedure: When preparing the hydroxylamine standard solution, transfer 0, 25, 50, 75, and 100 μL of 5 mmol / L hydroxylamine sulfate solution to different test tubes. Add 400 μL of colorimetric reagents A, B, and C to each tube, then bring the volume to 10 mL. Shake the solution thoroughly and incubate at room temperature in the dark for 15 min. Quantitative analysis of NH2OH was performed using UV-Vis spectrophotometry. The absorbance of NH2OH solutions at different concentrations was monitored at its maximum absorption wavelength of 510 nm, obtaining the standard working curve for NH2OH (Figure 29), which was used for subsequent quantitative calculations.

[0054] Quantitative method for NH2OH in solution after photocatalytic ammonia oxidation experiment: Take 100 μL of reaction solution, add 400 μL of colorimetric reagents A, B, and C respectively, and then dilute to 10 mL with deionized water. After developing the solution in the dark for 15 min, the solution is detected.

[0055] For ammonium ions (NH4) in the reaction system + ), nitrate (NO3) - ), nitrite (NO2) - Quantitative analysis was performed on ammonium ions, nitrate ions, nitrite ions, and hydroxylamine (NH2OH). No significant absorbance response was detected at the characteristic absorption wavelengths of each target analyte, and no ammonium ions, nitrate ions, or hydroxylamine ions were detected in the reaction system.

Claims

1. A complex, characterized in that, The general structural formula of the complex is: 、 、 or Where x is Cl, NH3, or N2H4; y is Cl - or PF6 - .

2. The complex according to claim 1, characterized in that, The complexes are complexes 1-7, and their structural formulas are as follows: 、 、 、 、 、 or 。 3. The method for preparing the complex according to claim 1 or 2, characterized in that, Includes the following steps: a. Using p-cymene ruthenium dichloride dimer as a precursor, it is dissolved in an organic solvent with bipyridine ligand A at a molar ratio of 1:1-3, and then reacted at room temperature for 22-26 h to obtain ruthenium-amine complexes, i.e., complexes 1-4; wherein the bipyridine ligand A is 2,2'-bipyridine or a 2,2'-bipyridine derivative; or b. Using p-cymene ruthenium dichloride dimer as a precursor, it is dissolved in an organic solvent with bipyridine ligand B at a molar ratio of 1:1-3, and then reacted at room temperature for 3-7 days to obtain an intermediate. The intermediate and a dehalogenating agent are then dissolved separately, and the dehalogenating agent solution is added dropwise to the intermediate solution. The reaction is carried out under vacuum for 22-26 h, filtered, and ammonia gas is introduced into the filtrate for 10-30 min. Finally, the mixture is allowed to stand for 1-2 h to obtain the ruthenium-amine complex. The intermediate is complex 5; the bipyridine ligand B is 2,2'-bipyridine; the mass ratio of the intermediate to the dehalogenating agent is 1:1-1.2; the dehalogenating agent is silver trifluoromethanesulfonate, amine trifluoromethanesulfonate, or sodium trifluoromethanesulfonate; or c. using p-cymene ruthenium dichloride dimer as a precursor, dissolving it in an organic solvent with bipyridine ligand B at a molar ratio of 1:1-3, then reacting at room temperature for 3-7 days to obtain an intermediate, then dissolving the intermediate and the dehalogenating agent separately, then adding the dehalogenating agent solution dropwise to the intermediate solution, reacting under vacuum for 22-26 hours, filtering, adding 100wt%-300wt% tetrahydrofuran solution containing N2H4 dropwise to the filtrate, and finally letting it stand for 1-2 hours to obtain the ruthenium hydrazine complex, i.e., complex 6 or complex 7.

4. The method for preparing the complex according to claim 3, characterized in that, The structural formula of the ruthenium dichloride dimer of p-cymene is: 。 5. The method for preparing the complex according to claim 3, characterized in that, The bipyridine ligand A is 4,4'-dimethyl-2,2'-bipyridine, 5,5'-dimethyl-2,2'-bipyridine, or 6,6'-dimethyl-2,2'-bipyridine.

6. The method for preparing the complex according to claim 3, characterized in that, The molar ratio of the p-cymene ruthenium dichloride dimer to bipyridine ligand A / B is 1:

2.

7. The method for preparing the complex according to claim 3, characterized in that, The organic solvent is dichloromethane, tetrahydrofuran, or toluene.

8. The method for preparing the complex according to claim 3, characterized in that, The ammonia gas flow rate is 1.5-2.5 L / h.

9. The method for preparing the complex according to claim 3, characterized in that, The concentration of the tetrahydrofuran solution containing N2H4 is 1-3 mol / L.

10. The application of the complex according to claim 1 or 2 in photocatalytic ammonia oxidation.

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