Mechanical chemical synthesis method of N-heterocyclic carbene metal assembly

Abstract

The invention discloses a mechanochemical synthesis method of an N-heterocyclic carbene metal assembly, and relates to the technical field of chemical synthesis. The method comprises the following steps: mixing N-heterocyclic carbene precursor salt, silver oxide and alkali, adding grinding balls, and carrying out ball milling; and dissolving in a solvent, centrifuging, concentrating under reduced pressure, adding into a precipitant, centrifuging and drying in vacuum to obtain the N-heterocyclic carbene metal assembly. The method is used for synthesizing various types of metal supramolecular assemblies through one-pot ball milling under the condition of no solvent at the ambient temperature, and is carried out under the condition that the method is simpler and milder than other synthesis processes, and the yield is higher. Compared with harsh reaction conditions of a solution method, the solid ball milling method is simple and convenient to operate and rapid in reaction, and generation of by-products formed by AgI ions and a polar solvent is avoided. The problems that in the prior art, the reaction condition for preparing the N-heterocyclic carbene metal assembly is harsh, and by-products are likely to be generated are solved.

Description

Technical Field

[0001] The invention relates to the technical field of chemical synthesis, and in particular to a mechanochemical synthesis method of a nitrogen heterocyclic carbene metal assembly. Background Art

[0002] In the past decade, thanks to the proposal and development of a variety of synthetic strategies, especially the widespread application of classic solution preparation methods such as direct one-pot reaction strategy, stepwise synthesis strategy, and metal conversion, a large number of organometallic supramolecular assemblies based on nitrogen heterocyclic carbenes have been reported, which has promoted the significant growth and wide application of organometallic supramolecular assemblies in the fields of biochemistry, catalysis, and materials science. However, these reaction processes often require more stringent reaction conditions in solution, such as long reaction time, high reaction temperature, exclusion of oxygen and light, etc. In addition, the problem of additional solvent waste remains a continuous challenge for green synthesis. Usually in the long reaction process, the excess metal center is often easy to coordinate with the solvent (such as acetonitrile and DMF), thereby producing excess unwanted byproduct metal complexes, especially coin metals, such as tetra(acetonitrile)silver(I)tetrafluoroborate. Therefore, it is necessary to develop more convenient and efficient technologies to synthesize nitrogen heterocyclic carbene metal assemblies in large quantities. Summary of the invention

[0003] In order to solve the above technical problems, the purpose of the present invention is to provide a mechanochemical synthesis method of nitrogen heterocyclic carbene metal assemblies to solve the problems of harsh reaction conditions and easy generation of by-products in the prior art for preparing nitrogen heterocyclic carbene metal assemblies.

[0004] The technical solution of the present invention to solve the above technical problem is as follows: a mechanochemical synthesis method of a nitrogen heterocyclic carbene metal assembly is provided, comprising:

[0005] (1) mixing a nitrogen heterocyclic carbene precursor salt, silver oxide and a base, adding grinding balls, and ball milling to obtain a powder;

[0006] (2) dissolving the powder obtained in step (1) in a solvent, centrifuging, and concentrating under reduced pressure, adding the obtained clear solution to a precipitant, centrifuging, and vacuum drying to obtain a nitrogen heterocyclic carbene metal assembly.

[0007] On the basis of the above technical solution, the present invention can also be improved as follows:

[0008] Furthermore, in step (1), the molar ratio of the nitrogen heterocyclic carbene precursor salt, silver oxide and base is 0.026-0.403:0.069-0.605:0.207-2.419.

[0009] Furthermore, in step (1), the molar ratio of the nitrogen heterocyclic carbene precursor salt, silver oxide and base is 0.081:0.169:0.469.

[0010] Furthermore, in step (1), the molar ratio of the nitrogen heterocyclic carbene precursor salt, silver oxide and base is 0.189:0.189:1.132.

[0011] Furthermore, in step (1), the nitrogen heterocyclic carbene precursor salt is a hexafluorophosphate or a tetrafluoroborate of a nitrogen heterocyclic carbene precursor, and the nitrogen heterocyclic carbene precursor is an imidazole carbene, a triazole carbene, a benzimidazole carbene or an imidazole [1,5-α] pyridyl carbene.

[0012] Furthermore, in step (1), the base is potassium carbonate or cesium carbonate.

[0013] Furthermore, in step (1), the grinding balls are made of zirconium oxide.

[0014] Further, the diameters of the grinding balls are 5 mm, 8 mm and 10 mm.

[0015] The beneficial effect of adopting the above further technical solution is: using grinding balls of different sizes to make them have different filling degrees in the ball mill, so as to achieve an optimal grinding condition.

[0016] Furthermore, in step (1), the ball milling is performed at a rotation speed of 430-470 r / min for 80-100 min.

[0017] Furthermore, in step (1), the mixture is ball milled at a rotation speed of 450 r / min for 90 min.

[0018] Furthermore, in step (2), the solvent is N,N-dimethylformamide or acetonitrile.

[0019] Furthermore, in step (2), the volume ratio of the clear liquid to the precipitant is 0.5:8-12.

[0020] Furthermore, in step (2), the volume ratio of the clear liquid to the precipitant is 0.5:10.

[0021] Furthermore, in step (2), the precipitant is diethyl ether or isopropyl ether.

[0022] The present invention provides a nitrogen heterocyclic carbene metal assembly prepared by the mechanochemical synthesis method of the nitrogen heterocyclic carbene metal assembly.

[0023] The present invention has the following beneficial effects:

[0024] 1. Mechanochemistry, as an environmentally friendly and sustainable chemical synthesis technology, has been widely used in the fields of organic synthesis, organometallic catalysis, enzyme catalysis, covalent organic frameworks, metal-organic frameworks and advanced energy materials. Ball milling has emerged as a more environmentally friendly, cleaner and more effective strategy than traditional solution chemistry. It allows reactions to be carried out under milder and more economical conditions, such as sharply increased reaction rates, ambient temperature and less or no solvent, rather than drastic solution conditions, which is very beneficial for the construction of unstable organometallic compounds. More importantly, ball milling synthesis can not only effectively monitor the reaction process in real time, but also prepare unstable solid intermediates. At the same time, it is also a superior and rapid technology for screening and optimizing reaction conditions and exploring new reactions.

[0025] 2. The present invention provides a simplified general protocol for the one-pot ball-milling synthesis of various types of metal supramolecular assemblies at ambient temperature without solvent, and these processes are all carried out in less than 1.5 h and under simpler and milder conditions than other synthetic processes with higher yields.

[0026] 3. Compared with the harsh reaction conditions of the solution method, the solid-state ball milling method is not only simple to operate and fast in reaction, but also avoids the Ag I By-products formed by ions and polar solvents are produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the reaction equation of Example 1;

[0028] Figure 2 is the H NMR spectrum of the product of Example 1;

[0029] Figure 3 is the reaction equation of Example 2;

[0030] Figure 4 is the H NMR spectrum of the product of Example 2;

[0031] Figure 5 is the reaction equation of Example 3;

[0032] Figure 6 is the H NMR spectrum of the product of Example 3;

[0033] Figure 7 is the reaction equation of Example 4;

[0034] Figure 8 is the H NMR spectrum of the product of Example 4;

[0035] Fig. 9 is the reaction equation of Example 5;

[0036] Fig.10is the H NMR spectrum of the product of Example 5;

[0037] Fig.11 is the reaction equation of Example 6;

[0038] Fig.12 is the H NMR spectrum of the product of Example 6;

[0039] Fig.13 is the reaction equation of Example 7;

[0040] Fig.14 is the H NMR spectrum of the product of Example 7;

[0041] Fig.15 is the reaction equation of Example 8;

[0042] Fig.16 This is the H NMR spectrum of the product of Example 8.

[0043] Fig.17 The nitrogen heterocyclic carbene metal assembly 1 of the present invention;

[0044] Fig.18 The nitrogen heterocyclic carbene metal assembly 2 of the present invention;

[0045] Fig.19 The nitrogen heterocyclic carbene metal assembly 3 of the present invention;

[0046] Fig. 20 The nitrogen heterocyclic carbene metal assembly 4 of the present invention;

[0047] Fig.21 The nitrogen heterocyclic carbene metal assembly 5 of the present invention;

[0048] Fig. 22 The nitrogen heterocyclic carbene metal assembly 6 of the present invention;

[0049] Fig.23 The nitrogen heterocyclic carbene metal assembly 7 of the present invention; DETAILED DESCRIPTION

[0050] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples are only used to explain the present invention and are not used to limit the scope of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0051] The structural formulas of the nitrogen heterocyclic carbene precursor salts are

[0052]

[0053] or mixture.

[0054] Embodiment 1:

[0055] A mechanochemical synthesis method of a nitrogen heterocyclic carbene metal assembly comprises the following steps:

[0056] (1) In a 50 mL zirconium oxide ball mill, a nitrogen heterocyclic carbene precursor salt (bidentate imidazolium salt ligand L1), silver oxide and alkali (potassium carbonate) were added and mixed, and 36 zirconium oxide grinding balls with a diameter of 5 mm, 4 with a diameter of 8 mm and 4 with a diameter of 10 mm were added. The ball mill was sealed and placed on a planetary ball mill and ball milled at a speed of 450 r / min for 90 min. After the reaction was completed, a black powder was obtained; wherein the molar amounts of the nitrogen heterocyclic carbene precursor salt, silver oxide and alkali were 0.081 mmol, 0.169 mmol and 0.469 mmol, respectively;

[0057] (2) The black powder obtained in step (1) was dissolved in 6 mL of solvent (acetonitrile), centrifuged, and the clear liquid was concentrated under reduced pressure to 0.5 mL. The obtained clear liquid was added to 10 mL of precipitant (ether), and a large amount of white precipitate was immediately precipitated. The precipitate was collected by centrifugation and vacuum dried to obtain 36.6 mg of light gray solid powder, that is, the nitrogen heterocyclic carbene metal assembly was obtained. (Yield 99%)

[0058] Reaction equation see Figure 1 ;

[0059] The product H NMR spectrum is shown in Figure 2 , 1 H NMR (400MHz, DMSO-d6): δ = 7.68 (s, 4H), 7.58 (s, 4H), 4.07 (m, 8H), 3.49ppm (s, 12H). ESI-TOF MS: m / z=769.0529(calcd for 1 + :769.0486).

[0060] Embodiment 2:

[0061] A mechanochemical synthesis method of a nitrogen heterocyclic carbene metal assembly comprises the following steps:

[0062] (1) In a 50 mL zirconium oxide ball mill, a nitrogen heterocyclic carbene precursor salt (bidentate imidazolium salt ligand L2), silver oxide and alkali (potassium carbonate) were added and mixed, and 36 zirconium oxide grinding balls with a diameter of 5 mm, 4 with a diameter of 8 mm and 4 with a diameter of 10 mm were added. The ball mill was sealed and placed on a planetary ball mill and ball milled at a speed of 450 r / min for 90 min. After the reaction was completed, a black powder was obtained; wherein the molar amounts of the nitrogen heterocyclic carbene precursor salt, silver oxide and alkali were 0.189 mmol, 0.189 mmol and 1.132 mmol, respectively;

[0063] (2) The black powder obtained in step (1) was dissolved in 10 mL of solvent (acetonitrile), centrifuged, and the clear liquid was concentrated to 0.5 mL under reduced pressure. The obtained clear liquid was added to 10 mL of precipitant (ether), and a large amount of white precipitate was immediately precipitated. The precipitate was collected by centrifugation and vacuum dried to obtain 92.5 mg of white solid powder, that is, the nitrogen heterocyclic carbene metal assembly was obtained. (Yield 99%)

[0064] Reaction equation see Figure 3 ;

[0065] The product H NMR spectrum is shown in Figure 4 , 1 H NMR (400MHz, CD3CN): δ = 7.65 (s, 4H), 7.53 (d, J = 1.7Hz, 2H), 7.39 (d, J = 1.7Hz, 2H), 3.98 (s, 6H) ppm. ESI-TOFMS: m / z = 837.0099 (calcd for2 + :837.0173).

[0066] Embodiment 3:

[0067] Synthesis method of tridentate imidazolium salt ligand L3:

[0068] Tris(4'-bromomethyl)-[1,1'-biphenyl]-4-yl)amine (217 mg, 0.29 mmol) was added to a 50 mL Schlenk tube, and then 2 mL of N,N-dimethylformamide solution was added thereto, and finally bromobutyl (119 mg, 0.96 mmol) was added. The mixture was placed in a sand bath at 110°C for 24 hours. After the reaction was completed, it was cooled to room temperature. Subsequently, 50 mL of ethyl acetate solution was added to the reaction product, and a light yellow compound was obtained by filtration. The compound was redissolved in methanol (20 mL) and ammonium hexafluorophosphate (293 mg, 1.8 mmol) solid was added to the obtained solution, and stirred at room temperature for 12 hours. An off-white solid product was precipitated from the methanol solution, and the target compound L3 (330 mg, 0.25 mmol, 86%) was obtained by filtration.

[0069] 1 H NMR (400MHz, CD3CN): δ = 8.53 (s, 1H), 7.71 (d, J = 8.0Hz, 2H), 7.64 (d, J = 8.2Hz, 2H), 7.45 (d, J = 8.2Hz, 2H), 7.41 (m, 1 H),7.20(d,J=7.5Hz,2H),5.35(s,2H),4.13(t,J=7.3Hz,2H),1.82(m,2H),1.33(m,2H),0.94(t,J=7.3Hz,3H)ppm. 13 C{ 1 H}NMR (100MHz, CD3CN): δ = 148.0, 141.8, 136.3, 135.4, 133.4, 130.1, 128.9, 128.1, 125.4, 123.7, 123.3, 53.4, 50.4, 32.4, 19.9, 13.6ppm. HRMS (ESI, positive ions):m / z=514.7504(calcd for[L3-2PF6] 2+ 514.7505).

[0070] A mechanochemical synthesis method of a nitrogen heterocyclic carbene metal assembly comprises the following steps:

[0071] (1) In a 50 mL zirconium oxide ball mill, a nitrogen heterocyclic carbene precursor salt (tridentate imidazolium salt ligand L3), silver oxide and alkali (potassium carbonate) were added and mixed, and 36 zirconium oxide grinding balls with a diameter of 5 mm, 4 with a diameter of 8 mm and 4 with a diameter of 10 mm were added. The ball mill was sealed and placed on a planetary ball mill and ball milled at a speed of 450 r / min for 90 min. After the reaction was completed, a black powder was obtained; wherein the molar amounts of the nitrogen heterocyclic carbene precursor salt, silver oxide and alkali were 0.023 mmol, 0.069 mmol and 0.207 mmol, respectively;

[0072] (2) The black powder obtained in step (1) was dissolved in 5 mL of solvent (acetonitrile), centrifuged, and the clear liquid was concentrated under reduced pressure to 0.5 mL. The obtained clear liquid was added to 10 mL of precipitant (ether), and a large amount of white precipitate was immediately precipitated. The precipitate was collected by centrifugation and vacuum dried to obtain 26.2 mg of gray solid powder, that is, the nitrogen heterocyclic carbene metal assembly was obtained. (Yield 91%)

[0073] Reaction equation see Figure 5 :

[0074] The product H NMR spectrum is shown in Figure 6 , 1H NMR (400MHz, CD3CN): δ = 7.40 (d, J = 7.0Hz, 4H), 7.28-7.26 (m, 2H), 7.17 (d, J = 8.2Hz, 2H), 6.95 (d, J = 8.6Hz, 2H) ,5.34(s,2H),4.21(t,J=7.1Hz,2H),1.90-1.83(m,2H),1.41-1.32(m,2H),0.95(t,J=7.4Hz,3H)ppm.ESI-TOF MS: m / z=695.9291(calcd for 3 3+ :695.9142).

[0075] Embodiment 4:

[0076] A mechanochemical synthesis method of a nitrogen heterocyclic carbene metal assembly comprises the following steps:

[0077] (1) In a 50 mL zirconium oxide ball mill, a nitrogen heterocyclic carbene precursor salt (tridentate imidazolium salt ligand L4), silver oxide and a base (potassium carbonate) were added and mixed, and 36 zirconium oxide grinding balls with a diameter of 5 mm, 4 with a diameter of 8 mm and 4 with a diameter of 10 mm were added. The ball mill was sealed and placed on a planetary ball mill and ball milled at a speed of 450 r / min for 90 min. After the reaction was completed, a black powder was obtained; wherein the molar amounts of the nitrogen heterocyclic carbene precursor salt, silver oxide and base were 0.026 mmol, 0.078 mmol and 0.234 mmol, respectively;

[0078] (2) The black powder obtained in step (1) was dissolved in 5 mL of solvent (acetonitrile), centrifuged, and the clear liquid was concentrated under reduced pressure to 0.5 mL. The obtained clear liquid was added to 10 mL of precipitant (ether), and a large amount of white precipitate was immediately precipitated. The precipitate was collected by centrifugation and vacuum dried to obtain 26.6 mg of gray solid powder with a yield of 92%, that is, the nitrogen heterocyclic carbene metal assembly was obtained. (Yield 92%)

[0079] Reaction equation see Figure 7 ;

[0080] The product H NMR spectrum is shown in Figure 8 , 1H NMR (400MHz, CD3CN): δ = 8.25 (d, J = 8.3Hz, 2H), 7.27 (d, J = 1.7Hz, 1H), 7.17 (d, J = 1.7Hz, 1H), 7.12 (d, J = 8.3Hz, 2 H),5.34(s,2H),4.24(t,J=7.1Hz,2H),1.91-1.87(m,2H),1.46-1.36(m,2H),1.01(t,J=7.4Hz,3H)ppm.ESI-TOF MS:m / z=952.2679(calcd for 4 2+ :952.2658).

[0081] Embodiment 5:

[0082] A mechanochemical synthesis method of a nitrogen heterocyclic carbene metal assembly comprises the following steps:

[0083] (1) In a 50 mL zirconium oxide ball mill, a nitrogen heterocyclic carbene precursor salt (tetradentate imidazolium salt ligand L5), silver oxide and alkali (potassium carbonate) were added and mixed, and 36 zirconium oxide grinding balls with a diameter of 5 mm, 4 with a diameter of 8 mm and 4 with a diameter of 10 mm were added. The ball mill was sealed and placed on a planetary ball mill and ball milled at a speed of 450 r / min for 90 min. After the reaction was completed, a black powder was obtained; wherein the molar amounts of the nitrogen heterocyclic carbene precursor salt, silver oxide and alkali were 0.0364 mmol, 0.255 mmol and 0.437 mmol, respectively;

[0084] (2) The black powder obtained in step (1) was dissolved in 8 mL of solvent (acetonitrile), centrifuged, and the clear liquid was concentrated under reduced pressure to 0.5 mL. The obtained clear liquid was added to 10 mL of precipitant (ether), and a large amount of white precipitate was immediately precipitated. The precipitate was collected by centrifugation and vacuum dried to obtain 57.1 mg of khaki solid powder, that is, the nitrogen heterocyclic carbene metal assembly was obtained. (Yield 99%)

[0085] Reaction equation see Fig. 9 ;

[0086] The product H NMR spectrum is shown in Fig.10 , 1 H NMR (400MHz, DMSO-d6): δ = 7.81 (d, J = 3.5Hz, 8H), 7.68 (d, J = 8.0Hz, 8H), 7.14 ( d,J=8.0Hz,8H),6.93(s,4H),4.36(m,8H),1.52(t,J=7.3Hz,12H)ppm.ESI-TOF MS:m / z=717.7814(calcd for5 3+ 717.7984).

[0087] Embodiment 6:

[0088] A mechanochemical synthesis method of a nitrogen heterocyclic carbene metal assembly comprises the following steps:

[0089] (1) In a 50 mL zirconium oxide ball mill, a nitrogen heterocyclic carbene precursor salt (tridentate imidazolium salt ligand L6), silver oxide and a base (potassium carbonate) were added and mixed, and 36 zirconium oxide grinding balls with a diameter of 5 mm, 4 with a diameter of 8 mm and 4 with a diameter of 10 mm were added. The ball mill was sealed and placed on a planetary ball mill and ball milled at a speed of 450 r / min for 90 min. After the reaction was completed, a black powder was obtained; wherein the molar amounts of the nitrogen heterocyclic carbene precursor salt, silver oxide and base were 0.403 mmol, 0.605 mmol and 2.419 mmol, respectively;

[0090] (2) The black powder obtained in step (1) was dissolved in 10 mL of solvent (acetonitrile), centrifuged, and the clear liquid was concentrated under reduced pressure to 0.5 mL. The obtained clear liquid was added to 10 mL of precipitant (ether), and a large amount of white precipitate was immediately precipitated. The precipitate was collected by centrifugation and vacuum dried to obtain 275.6 mg of khaki solid powder, that is, the nitrogen heterocyclic carbene metal assembly was obtained. (Yield 99%)

[0091] Reaction equation see Fig.11 ;

[0092] The product H NMR spectrum is shown in Fig.12 , 1 H NMR (400MHz, DMSO-d6): δ = 8.17 (s, 2H), 7.61 (s, 2H), 7.52 (s, 2H), 4.27 (s, 6H), 3.91 (s, 6H) ppm.

[0093] Embodiment 7:

[0094] A mechanochemical synthesis method of a nitrogen heterocyclic carbene metal assembly comprises the following steps:

[0095] (1) Add the nitrogen heterocyclic carbene precursor salt (tridentate imidazolium salt ligand L) to a 50 mL zirconium oxide ball mill. 7D and tridentate imidazolium ligand L 7AA mixture of 2,4-dimethyl-1-nitropropene (2,4-dimethyl-1-nitropropene) and 2,4-dimethyl-1-nitropropene (2,4-dimethyl-1-nitropropene) was prepared by mixing silver oxide and alkali (potassium carbonate), adding 36 zirconia grinding balls with a diameter of 5 mm, 4 zirconia grinding balls with a diameter of 8 mm and 4 zirconia grinding balls with a diameter of 10 mm, sealing the ball mill and placing it on a planetary ball mill, and milling at a speed of 450 r / min for 90 min. After the reaction, a black powder was obtained; wherein the molar amounts of the nitrogen heterocyclic carbene precursor salt, silver oxide and alkali were 0.064 mmol, 0.193 mmol and 0.58 mmol, respectively;

[0096] (2) The black powder obtained in step (1) was dissolved in 10 mL of solvent (acetonitrile), centrifuged, and the clear liquid was concentrated to 0.5 mL under reduced pressure. The obtained clear liquid was added to 10 mL of precipitant (ether), and a large amount of yellow precipitate was immediately precipitated. The precipitate was collected by centrifugation and vacuum dried to obtain 48.0 mg of yellow solid powder, that is, the nitrogen heterocyclic carbene metal assembly was obtained. (Yield 78%)

[0097] Reaction equation see Fig.13 ;

[0098] The product H NMR spectrum is shown in Fig.14 , 1 H NMR (400MHz, DMSO-d6): δ = 8.50 (d, J = 8.6Hz, 3H), 8.12-7.53 (m, 36H), 6.01-5. 88(m,6H),5.26-5.14(m,12H),4.53-4.43(m,12H),2.77(q,12H)ppm.ESI-TOF MS:m / z=873.7089(calcd for7 2+ 873.6985).

[0099] Embodiment 8:

[0100] A mechanochemical synthesis method of a nitrogen heterocyclic carbene metal assembly comprises the following steps:

[0101] (1) In a 50 mL zirconium oxide ball mill, a nitrogen heterocyclic carbene precursor salt (bidentate imidazolium salt ligand L8), silver oxide and alkali (potassium carbonate) were added and mixed, and 36 zirconium oxide grinding balls with a diameter of 5 mm, 4 with a diameter of 8 mm and 4 with a diameter of 10 mm were added. The ball mill was sealed and placed on a planetary ball mill and ball milled at a speed of 450 r / min for 90 min. After the reaction was completed, a black powder was obtained; wherein the molar amounts of the nitrogen heterocyclic carbene precursor salt, silver oxide and alkali were 0.043 mmol, 0.085 mmol and 0.255 mmol, respectively;

[0102] (2) The black powder obtained in step (1) was dissolved in 10 mL of solvent (acetonitrile), centrifuged, and the clear liquid was concentrated under reduced pressure to 0.5 mL. The obtained clear liquid was added to 10 mL of precipitant (ether), and a large amount of yellow precipitate was immediately precipitated. The precipitate was collected by centrifugation and vacuum dried to obtain 37.8 mg of khaki solid powder, that is, the nitrogen heterocyclic carbene metal assembly was obtained. (Yield 98%)

[0103] Reaction equation see Fig.15 ;

[0104] The product H NMR spectrum is shown in Fig.16 , 1 H NMR (400MHz, CD3CN):

[0105] δ=8.83(s,2H),8.62(s,2H),8.45(s,2H),8.37(s,2H),7.73-7.71(m,4 H),7.66(s,2H),7.64-7.57(m,8H),7.51(d,2H,J=9.2Hz),7.46(d,2H, J=7.4Hz),7.31-7.29(m,4H),7.29(s,2H),7.24(d,2H,J=9.2Hz),7.22(d,2H,J=9.2Hz),7.16(s,4H),7.14-7.12(m,4H),7.12-7.08(m,4H),7 .10-7.07(m,4H),7.04-7.03(m,4H),6.96(s,2H),6.93-6.85(m,6H),6 .75(d,2H,J=7.4Hz),6.63(s,2H),6.36(d,2H,J=7.4Hz),6.17(d,2H,J =7.4Hz),2.53(s,36H),2.24(s,6H),2.17(s,6H),2.02(s,6H),1.82(s,6H),1.62(s,6H),1.54(s,6H),1.52(s,6H),1.49(s,6H)ppm.ESI-TOF MS:m / z=1658.3565(calcd for[8 -2PF6] 2+ 1658.3546).

[0106] Test example

[0107] 1. Yield

[0108] The yield of the product, i.e. the dried silver carbene compound, was calculated by dividing its mass by the theoretical equivalent yield of the ligand to obtain the yield. Meanwhile, Examples 1, 2 and 5-8 were tested by liquid phase method as a control, and the results are shown in Table 1.

[0109] The specific method of the liquid phase method is as follows: the synthesis is carried out in a nitrogen atmosphere, the nitrogen heterocyclic carbene precursor compound is added to a 100mL Schlenk tube, and completely dissolved with 30mL ultra-dry acetonitrile, the solution is light orange, and then Ag2O is added to the reaction bottle. After replacing the nitrogen three times, the reaction bottle is placed in a 65°C oil bath away from light, heated and stirred to react for 24 hours, cooled to room temperature, and after standing for a while, filtered with diatomaceous earth, washed with acetonitrile, and the obtained clear solution is concentrated to 2mL, and then 15mL of ether is added thereto, a large amount of gray solid is precipitated, and it is allowed to stand for a while, then filtered and vacuum dried to obtain the target product.

[0110] Table 1 Yield comparison

[0111] Yield Ball milling Liquid Phase Method Example 1 99％ 45％ Example 2 99％ 40％ Example 5 99％ 73％ Example 6 99％ 83％ Example 7 78％ 68％ Example 8 98％ 93％

[0112] two, Figure 17-Figure 23 The diagram is a structural formula of other nitrogen heterocyclic carbene metal assemblies prepared by the present invention.

[0113] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A mechanochemical synthesis method of a nitrogen heterocyclic carbene metal assembly, characterized in that: The following steps are involved: (1) mixing a nitrogen heterocyclic carbene precursor salt, silver oxide and a base, adding grinding balls, and ball milling to obtain a powder; (2) dissolving the powder obtained in step (1) in a solvent, centrifuging, and concentrating under reduced pressure, adding the obtained clear solution to a precipitant, centrifuging, and vacuum drying to obtain a nitrogen heterocyclic carbene metal assembly.

2. The mechanochemical synthesis method of the nitrogen heterocyclic carbene metal assembly according to claim 1, characterized in that: In step (1), the molar ratio of the nitrogen heterocyclic carbene precursor salt, silver oxide and base is 0.026-0.403:0.069-0.605:0.207-2.

419.

3. The mechanochemical synthesis method of the nitrogen heterocyclic carbene metal assembly according to claim 1, characterized in that: In step (1), the nitrogen heterocyclic carbene precursor salt is a hexafluorophosphate or a tetrafluoroborate of a nitrogen heterocyclic carbene precursor, and the nitrogen heterocyclic carbene precursor is an imidazole carbene, a triazole carbene, a benzimidazole carbene or an imidazole [1,5-α] pyridyl carbene.

4. The mechanochemical synthesis method of the nitrogen heterocyclic carbene metal assembly according to claim 1, characterized in that: In step (1), the base is potassium carbonate or cesium carbonate.

5. The mechanochemical synthesis method of the nitrogen heterocyclic carbene metal assembly according to claim 1, characterized in that: In step (1), the grinding ball is made of zirconium oxide.

6. The mechanochemical synthesis method of the nitrogen heterocyclic carbene metal assembly according to claim 1, characterized in that: In step (1), the ball milling is performed at a rotation speed of 430-470 r / min for 80-100 min.

7. The mechanochemical synthesis method of the nitrogen heterocyclic carbene metal assembly according to claim 1, characterized in that: In step (2), the solvent is N,N-dimethylformamide or acetonitrile.

8. The mechanochemical synthesis method of the nitrogen heterocyclic carbene metal assembly according to claim 1, characterized in that: In step (2), the volume ratio of the clear liquid to the precipitant is 0.5:

10.

9. The mechanochemical synthesis method of the nitrogen heterocyclic carbene metal assembly according to claim 1, characterized in that: In step (2), the precipitant is diethyl ether or isopropyl ether. 10 . The nitrogen heterocyclic carbene metal assembly obtained by the mechanochemical synthesis method of the nitrogen heterocyclic carbene metal assembly according to claim 1 .

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