A pincer-type ligand rare earth metal catalyst, a preparation method and application thereof

Abstract

The application discloses a Pincer ligand rare earth metal catalyst and a preparation method thereof, and application of the Pincer ligand rare earth metal catalyst in preparation of primary amine borane compounds and secondary amine compounds. The Pincer ligand rare earth metal catalyst can be bonded with a nitrogen atom in a borane ammonia complex, thereby activating a B-H bond, so that the preparation of the primary amine borane compounds and the secondary amine compounds can be completed by using the borane ammonia complex. Compared with pinacol borane (HBpin), the borane ammonia complex (H3NBH3) has the characteristics of high stability, small toxicity and convenient storage as a boron source, and can reduce energy consumption and be environment-friendly in the reaction. In addition, the Pincer ligand rare earth metal catalyst has the advantages of simple source, small dosage and low preparation difficulty.

Description

Technical Field

[0001] This invention relates to the field of rare earth metal catalysts, specifically to a Pincer-type ligand rare earth metal catalyst, its preparation method, and its application. Background Technology

[0002] Primary amine boranes are an important class of intermediates. They can react directly with acidic compounds to yield amides in high yields; they can also undergo hydrolysis to give amines; and they can polymerize into macromolecules, making them important materials for ceramics and photoresists. Secondary amines are another important class of compounds, serving as crucial intermediates in synthetic chemistry and widely used in agriculture, industry, and medicine. Both primary and secondary amine boranes have high economic value, and their preparation is a subject of widespread interest.

[0003] Generally, primary amine borane compounds are obtained by reacting sodium borohydride with amines in an aqueous solution of sodium bicarbonate (see reference "P. Veeraraghavan, R., Henry J, H., Shivani, C. Organic Letters 2020, 22(21), 8593-8597"), but the yield is low. To increase the yield, they can be prepared from nitriles, such as transition metal catalysts CuI or Cu(OTf)3 (see reference "Hao, S.; Yao, X., Taigang, ZJ Org. Chem. 2022, 87(1), 790-800"). Although the above catalysts can synthesize primary and secondary amine borane compounds from nitriles, the boron source used is an oxazolylborane-BF3 complex, which is obtained by reacting ethanolamine with BF3-THF at low temperature under argon protection for 12 h. However, this boron source needs to be prepared in advance, and the preparation process is cumbersome. Primary amine borane compounds can also be obtained by reacting nitrile with pinacolborane using a noble metal silver catalyst at 60°C for 12 h (see reference "Vipin, KP, Chandra, KT, Arnab, R. Organic Letters 2021, 23(5), 1681-1686").

[0004] In existing technologies, the reduction of imine compounds to secondary amines generally uses transition metal catalysts, and the boron source used is pinacolborane, also known as 4,4,5,5-tetramethyl-1,3,2-dioxoborane. This preparation method not only uses expensive catalysts, but also, similar to the preparation of primary amine borane compounds, the reactant pinacolborane is prone to dimerization and loss of reducing ability under high temperature heating. Therefore, it is generally used in excessive doses. Furthermore, pinacolborane is irritating to the eyes, respiratory system, and skin, and is environmentally unfriendly. In addition, the reduction reaction of nitrile or imine is catalyzed by rare earth carbene complexes, and the boron source used is pinacolborane. It is necessary to heat to 110℃ to achieve the reduction of nitrile and imine functional groups, which is energy-intensive (see reference "Zeming, H., Shaowu, W., Xiancui, Z. Inorg. Chem. 2018, 57(24), 15069-15078").

[0005] To address the issue of complex boron sources for primary and secondary amine boranes, borane-ammonia complexes (H3NBH3) can now be used as boron sources. Compared to pinacol borane (HBpin), borane-ammonia complexes (H3NBH3) offer advantages such as high stability, low toxicity, and convenient storage. However, due to the high stability of borane-ammonia complexes, their preparation requires more stringent conditions, such as high temperature and high pressure, which further increases energy consumption during preparation. Summary of the Invention

[0006] The purpose of this invention is to provide a Pincer-type ligand rare earth metal catalyst, its preparation method, and its application, in order to solve the technical problems of high energy consumption and complex processing in the preparation of primary amine borane compounds and secondary amine compounds in the prior art.

[0007] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution:

[0008] This invention provides a Pincer-type ligand rare earth metal catalyst, comprising a structure as shown in Formula A, Formula B, or Formula C.

[0009]

[0010] Wherein, RE is a rare earth metal ion; formula T is a heterocyclic compound or substituted heterocyclic compound with more than 4 carbon atoms, X is a heteroatom, Y is C or a heteroatom; formula Z is an aromatic compound; R1, R2, R3, R4, R5, R6, R7, R8 and R9 are each independently H, a C1-C30 hydrocarbon group or a C1-C30 substituted hydrocarbon group; n and m are both positive integers.

[0011] As a preferred embodiment of the present invention, the RE is selected from Y.3+ Yb 3+ Gd 3+ Or Lu 3+ Wherein, compound Y is a five-membered heterocyclic compound or a six-membered heterocyclic compound, X is selected from N or O, and Y is selected from C, N or O; R1, R2, R3, R4, R5, R6, R7, R8, and R9 are each independently selected from H, methyl, ethyl, or isopropyl; n is a positive integer from 1 to 3; and m is a positive integer from 1 to 2.

[0012] In a preferred embodiment of the present invention, compound Y is selected from tetrahydrofuran and tetrahydropyrrole; R1, R2, R3, R4, R5, R6, R7, R8 and R9 are each independently selected from H, methyl, ethyl or isopropyl; wherein the structural formula of the Pincer-type ligand rare earth metal catalyst is shown as shown in formula A1, A2, A3, A4, B1, B2, C1 or C2.

[0013]

[0014] This invention also provides a method for preparing a Pincer-type ligand rare earth metal catalyst, the method comprising the following steps:

[0015] In the presence of a protective gas, ligands with structures as shown in Formula D or Formula E and rare earth trialkyl complexes with structures as shown in Formula F are subjected to coordination reactions to obtain the Pincer-type ligand rare earth metal catalyst.

[0016]

[0017] Wherein, RE represents rare earth metal ions; R1, R2, R3, R4, R5, R6, R7, R8, and R9 are each independently selected from H, C1-C30 hydrocarbon groups, or C1-C30 substituted hydrocarbon groups; the heterocyclic compound Het shown in formula T represents a heterocyclic compound or substituted heterocyclic compound with more than 4 carbon atoms, X represents a heteroatom, Y represents C or a heteroatom, and n and m are each independently positive integers.

[0018] As a preferred embodiment of the present invention, the coordination reaction satisfies at least the following conditions: the reaction temperature is 15-35°C, and the reaction time is 0.5-2 h; wherein the coordination reaction is carried out in a solvent selected from toluene or n-hexane; the protective gas is selected from at least one of nitrogen, helium, and argon; when preparing the Pincer-type ligand rare earth metal catalysts as shown in Formula A1, Formula A2, Formula A3, and Formula A4, the molar ratio of ligand D to rare earth trialkyl complex F is 1:(1-1.1); when preparing the Pincer-type ligand rare earth metal catalysts as shown in Formula B1 and Formula B2, the molar ratio of ligand E to rare earth trialkyl complex F is 1:(1-1.1); when preparing the Pincer-type ligand rare earth metal catalysts as shown in Formula C1 and Formula C2, the molar ratio of ligand E to rare earth trialkyl complex F is 2:(1-1.1).

[0019] As a preferred embodiment of the present invention, the preparation of the ligand D includes the following steps: directly reacting an o-fluoroaromatic aldehyde compound with a heterocyclic amine compound J1 to obtain ligand precursor G; under nitrogen protection, reacting an aromatic amine with n-butyllithium in a first solvent; after the reaction is completed, adding the ligand precursor G to react and obtain the ligand D;

[0020] The preparation of the ligand E includes the following steps: a fluoroaromatic aldehyde compound and an aromatic amine compound are directly reacted to obtain ligand precursor H; under nitrogen protection, a heterocyclic amine compound J2 and n-butyllithium are reacted in a second solvent; after the reaction is completed, the ligand precursor H is added to react and obtain the ligand E.

[0021] Wherein, the structure of the ligand precursor G is shown as Formula G, the structure of the ligand precursor H is shown as Formula H, the structure of the o-fluoroaromatic aldehyde compound is shown as Formula I, the structure of the heterocyclic amine is shown as Formula J1 or Formula J2, and the structure of the aromatic amine is shown as Formula K.

[0022]

[0023] The molar ratio of the o-fluoroaromatic aldehydes to the aromatic amines and heterocyclic amines is 1:1;

[0024] The reaction of the o-fluoroaromatic aldehydes with aromatic amines and heterocyclic amines must meet at least the following conditions: the reaction time is 2 hours, and there is no solvent reaction during the reaction.

[0025] The molar ratio of the aromatic amine to the n-butyllithium is 1:1.3;

[0026] The molar ratio of the heterocyclic amine to the n-butyllithium is 1:1.5;

[0027] The molar ratio of the ligand precursor G to the aromatic amine lithium salt is 1:1.3;

[0028] The molar ratio of the ligand precursor H to the lithium heterocyclic amine salt is 1:2.5;

[0029] The reaction between the ligand precursor G and the aromatic amine lithium salt shall at least satisfy the following conditions: 60°C, 24h;

[0030] The reaction between the ligand precursor H and the lithium heterocyclic amine salt shall at least satisfy the following conditions: room temperature, 10 h;

[0031] The aromatic amine compound: the ratio of the first solvent to the first solvent is 10 mmol / L: 10-20 mL, and the first solvent is tetrahydrofuran;

[0032] The heterocyclic amine compound: the ratio of the second solvent to the amount of solvent is 10 mmol / L: 10-20 mL, and the second solvent is n-hexane.

[0033] As a preferred embodiment of the present invention, the RE is Y 3+ Yb 3+ Gd 3+ Or Lu 3+ ;

[0034] Wherein, the formula T is a five-membered heterocyclic compound or a six-membered heterocyclic compound, where X is N or O, Y is C, N or O; n is a positive integer from 1 to 3, and m is a positive integer from 1 to 2;

[0035] The heterocyclic compound is tetrahydrofuran or tetrahydropyrrole;

[0036] R1, R2, R3, R4, R5, R6, R7, R8, and R9 are each independently selected from H, methyl, ethyl, or isopropyl.

[0037] The structure of the ligand is shown in Formula D1 or Formula E1; the rare earth trialkyl complex is shown in Formula F1, F2, F3 or Formula F4:

[0038]

[0039] This invention provides an application of a Pincer-type ligand rare earth metal catalyst, including the application of the Pincer-type ligand rare earth metal catalyst in the preparation of primary amine borane compounds with the structure shown in Formula N or secondary amine compounds with the structure shown in Formula O.

[0040] The primary amine borane compound is obtained by reducing a nitrile compound with a borane-amine complex of the structure shown in Formula L under the catalysis of the Pincer-type ligand rare earth metal catalyst.

[0041] The secondary amine compounds are obtained by reducing an imine compound with a borane-ammonia complex as shown in Formula M under the catalysis of a Pincer-type ligand rare earth metal catalyst.

[0042]

[0043] R 1 R 2 R 3 Each is independently selected from H, H, C1-C30 hydrocarbon groups or C1-C30 substituted hydrocarbon groups.

[0044] In a preferred embodiment of the present invention, the nitrile compound is selected from at least one of benzonitrile, p-methylbenzonitrile, p-tert-butylbenzonitrile, p-trifluoromethylbenzonitrile, 2-naphthonitrile, and cyclopropylnitrile, and the imine compound is selected from at least one of N-benzylaniline, N-(4-methylbenzylaniline), N-(4-methoxybenzylaniline), and N-benzyl-m-methylaniline;

[0045] The structures of the primary amine borane compounds are shown as those of formulas N1, N2, N3, N4, N5, or N6, and the structures of the amine compounds are shown as those of formulas O1, O2, O3, or O4.

[0046]

[0047] In a preferred embodiment of the present invention, in the reaction for preparing the primary amine borane compound, the molar ratio of the nitrile compound, the boronine complex, and the Pincer-type ligand rare earth metal catalyst is 1.0 mmol: 2.5 mmol: (0.07-0.09) mmol, and the reaction temperature is 60°C and the reaction time is 2.5 h.

[0048] In the reaction for preparing the secondary amine compound, the molar ratio of the imine compound, the boronine complex, and the Pincer-type ligand rare earth metal catalyst is 1.0 mmol:1.0 mmol:0.03 mmol, and the reaction temperature is 60 °C for 1 h.

[0049] Compared with the prior art, the present invention has the following advantages:

[0050] 1. This invention provides a rare earth catalyst, where rare earth elements are Lewis strong acids that can catalyze the formation of stable and low-activity borane-ammonia complexes (H3NBH3). The catalyst bonds with nitrogen atoms in the borane-ammonia complexes, thereby activating the BH bonds. This enables the preparation of primary and secondary amine boranes using borane-ammonia complexes. Compared to pinacol borane (HBpin), borane-ammonia complexes (H3NBH3) have the advantages of high stability, low toxicity, and convenient storage as a boron source, making it convenient for the preparation of primary and secondary amine boranes.

[0051] 2. This invention discloses a Pincer-type ligand rare earth metal catalyst. This catalyst acts in borane-amine complexes to reduce the unsaturated double and triple bonds of CN, thereby preparing primary amine boranes and secondary amines. It effectively avoids the dangers of using high-pressure hydrogen equipment and the limitations of precious metal and heavy metal catalysts in the prior art. It also requires less material, has a simple reaction process, reduces energy consumption, and is environmentally friendly.

[0052] 3. This invention discloses a method for preparing Pincer-type ligand rare earth metal catalysts. The steps are simple and the conditions are relatively mild, enabling the catalyst to be prepared under relatively simple conditions, thereby reducing the cost of the reaction. Attached Figure Description

[0053] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0054] Figure 1 This is the single-crystal diffraction pattern of metal catalyst A1 in Example 1;

[0055] Figure 4 This is the single-crystal diffraction pattern of metal catalyst A2 in Example 2;

[0056] Figure 5 This is the single-crystal diffraction pattern of metal catalyst A3 in Example 3;

[0057] Figure 8 This is the single-crystal diffraction pattern of metal catalyst A4 in Example 4;

[0058] Figure 9 This is the single-crystal diffraction pattern of metal catalyst B1 in Example 5;

[0059] Figure 12 This is the single-crystal diffraction pattern of metal catalyst B2 in Example 6;

[0060] Figure 13 This is the single-crystal diffraction pattern of the metal catalyst C1 in Example 7;

[0061] Figure 16 This is the single-crystal diffraction pattern of the metal catalyst C2 in Example 8;

[0062] Figure 2 This is the 1H NMR spectrum of metal catalyst A1 in Example 1;

[0063] Figure 3 This is the carbon NMR spectrum of metal catalyst A1 in Example 1;

[0064] Figure 6 This is the 1H NMR spectrum of metal catalyst A3 in Example 3;

[0065] Figure 7 This is the carbon NMR spectrum of metal catalyst A3 in Example 3;

[0066] Figure 10 This is the 1H NMR spectrum of metal catalyst B1 in Example 5;

[0067] Figure 11 This is the carbon NMR spectrum of metal catalyst B1 in Example 5;

[0068] Figure 14 This is the 1H NMR spectrum of the metal catalyst C1 in Example 7;

[0069] Figure 15 This is the carbon NMR spectrum of the metal catalyst C1 in Example 7. Detailed Implementation

[0070] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0071] This invention provides a method for preparing a primary amine borane compound with the structure shown in Formula N or a secondary amine compound with the structure shown in Formula O, comprising: the primary amine borane compound being obtained by a reduction reaction of a nitrile compound with a borane-amine complex with the structure shown in Formula L under the catalysis of a Pincer-type ligand rare earth metal catalyst.

[0072] The secondary amine compounds are obtained by reducing an imine compound with a borane-amine complex as shown in Formula M with a rare earth metal ligand catalyst of the Pincer type.

[0073]

[0074] R 1 R 2 R 3 Each is independently selected from H, H, C1-C30 hydrocarbon groups or C1-C30 substituted hydrocarbon groups.

[0075] This invention discloses methods for preparing primary amine borane compounds and secondary amine compounds, both of which can be reacted under the catalysis of Pincer-type ligand rare earth metal catalysts. The reaction steps are simple, require no secondary processing, and do not require complex boron sources, making them environmentally friendly and reducing energy consumption.

[0076] In the above reduction reaction, the amount of each raw material is not specifically limited. To further improve the yield, preferably, in the reaction for preparing the primary amine borane compound, the molar ratio of the nitrile compound, the boronine complex, and the Pincer-type ligand rare earth metal catalyst is 1.0 mmol: 2.5 mmol: (0.07-0.09) mmol, and the reaction temperature is 60°C and the reaction time is 2.5 h.

[0077] In the above reaction to obtain primary ammonia borane compounds, the reaction conditions are not specifically limited. To further improve the yield, preferably, in the reaction to prepare the secondary amine compounds, the molar ratio of the imine compound, the boron ammonia complex, and the Pincer-type ligand rare earth metal catalyst is 1.0 mmol:1.0 mmol:0.03 mmol, and the reaction temperature is 60°C and the reaction time is 1 h.

[0078] Because Pincer-type ligand rare earth metal catalysts have excellent performance, they require small amounts in the reaction process, have low preparation costs, and the reaction temperature is relatively mild with a short reaction time, which helps to reduce energy consumption in production and improve its economic benefits.

[0079] In this invention, the R 1 R 2 R 3 The type is not specifically limited, but considering the yield, preferably, the R... 1 R 2 R 3Each compound is independently selected from at least one of phenyl, p-methylphenyl, p-fluorophenyl, p-methoxy, and furanyl. More preferably, the nitrile compound is selected from at least one of benzonitrile, p-methylbenzonitrile, p-tert-butylbenzonitrile, p-trifluoromethylbenzonitrile, 2-naphthonitrile, and cyclopropylnitrile, and the imine compound is selected from at least one of N-benzylaniline, N-(4-methylbenzylaniline), N-(4-methoxybenzylaniline), and N-benzyl-m-methylaniline.

[0080] In this invention, nitrile compounds can be selected from a wide range. Preferably, in order to reduce production costs, the nitrile compounds are selected from at least one of benzonitrile, p-methylbenzonitrile, p-tert-butylbenzonitrile, p-trifluoromethylbenzonitrile, 2-naphthonitrile, and cyclopropylnitrile. The imine compounds are selected from at least one of N-benzylaniline, N-(4-methylbenzylaniline), N-(4-methoxybenzylaniline), and N-benzyl-m-methylaniline.

[0081] In this invention, primary amine borane compounds can be selected from a wide range. Preferably, in order to reduce production costs, the primary amine borane compounds have structures as shown in formulas N1, N2, N3, N4, N5, or N6, and the amine compounds have structures as shown in formulas O1, O2, O3, or O4.

[0082]

[0083] In the above preparation scheme, the Pincer-type ligand rare earth metal catalyst plays a crucial role. This invention also provides a Pincer-type ligand rare earth metal catalyst for the production of primary amine borane compounds and amine compounds. The structure of the Pincer-type ligand rare earth metal catalyst is shown in Formula A, Formula B, or Formula C.

[0084]

[0085] RE represents rare earth metal ions, compounds with the structure shown in formula T represent heterocyclic compounds with more than 4 Cs or substituted heterocyclic compounds, X represents heteroatoms, Y represents C or heteroatoms, and n and m are each independent positive integers.

[0086] R1, R2, R3, R4, R5, R6, R7, R8, and R9 are each independently selected from H, C1-C30 hydrocarbon groups, or C1-C30 substituted hydrocarbon groups.

[0087] In this invention, n represents the length of the carbon chain. The specific value of n is not limited, such as it can be 1-10. However, considering the difficulty of synthesis, n is preferably a positive integer from 1 to 3.

[0088] In this invention, m represents the length of the carbon chain. The specific value of m is not limited, such as it can be 1-10. However, considering the difficulty of synthesis, m is preferably a positive integer of 1-2.

[0089] In this invention, the specific type of RE is not required; however, in order to obtain a wider variety of catalysts, the RE is preferably selected from Y. 3+ Yb 3+ Gd 3+ Or Lu 3+ .

[0090] In this invention, the specific type of compound Y is not required. However, to obtain a wider variety of catalysts, preferably, compound Y is a five-membered or six-membered heterocyclic compound, where X is selected from N or O, and Y is selected from C, N, or O. Substituents, such as 3-methyltetrahydrofuran, may be present on the five-membered and six-membered heterocyclic compounds, and this is not limited. Considering the difficulty of synthesis and the availability of raw materials, more preferably, compound Y is selected from tetrahydropyrrole or tetrahydrofuran.

[0091] In this invention, the specific types of R1, R2, R3, R4, R5, R6, R7, R8, and R9 are not limited. However, considering the difficulty of catalyst preparation, preferably, R1, R2, R3, R4, R5, R6, R7, R8, and R9 are each independently selected from H, C1-C10 hydrocarbon groups, or C1-C10 substituted hydrocarbon groups; more preferably, R1, R2, R3, R4, R5, R6, R7, R8, and R9 are each independently selected from H, methyl, ethyl, or isopropyl.

[0092] Based on the above-mentioned embodiments, in order to further facilitate the obtaining of the Pincer-type ligand rare earth metal catalyst, preferably, the structure of the Pincer-type ligand rare earth metal catalyst is as shown in Formula A1, Formula A2, Formula A3, Formula A4, Formula B1, Formula B2, Formula C1 or Formula C2.

[0093]

[0094] The present invention also provides a method for preparing the Pincer-type ligand rare earth metal catalyst as described above. The method is as follows: in the presence of a protective gas, a ligand with a structure as shown in Formula D or Formula E and a rare earth trialkyl complex with a structure as shown in Formula F are subjected to a coordination reaction to obtain the Pincer-type ligand rare earth metal catalyst.

[0095]

[0096] Wherein, RE is a rare earth metal ion, Het of the structure shown in formula D and formula E represents a heterocyclic compound or substituted heterocyclic compound with more than 4 carbon atoms, X is a heteroatom, Y is C or a heteroatom, n and m are each independently positive integers; R1, R2, R3, R4, R5, R6, R7, R8, and R9 are each independently selected from H, C1-C30 hydrocarbon groups or C1-C30 substituted hydrocarbon groups.

[0097] In the above preparation method, n represents the length of the carbon chain. The specific value of n is not limited, such as it can be 1-10. However, considering the difficulty of preparation, it is preferable that n is a positive integer from 1 to 2.

[0098] In this invention, m represents the length of the carbon chain. The specific value of m is not limited, such as it can be 1-10. However, considering the difficulty of synthesis, m is preferably a positive integer of 1-2.

[0099] In the above preparation method, the specific type of RE is not required, but for the sake of yield, it is preferable that the RE is selected from Y. 3+ Yb 3+ Gd 3+ Or Lu 3+ .

[0100] In the above preparation method, the specific type of compound Het is not required. However, for the sake of yield, compound Het is a five-membered or six-membered heterocyclic compound, where X is selected from S, N, or O, and Y is selected from C, S, N, or O. Substituents, such as 3-methyltetrahydrofuran, may be present on the five-membered and six-membered heterocyclic compounds, and this is not limited. More preferably, considering the difficulty of synthesis and the availability of raw materials, compound Het is selected from tetrahydropyrrole or tetrahydrofuran.

[0101] In the above preparation method, the specific types of R1, R2, R3, R4, R5, R6, R7, R8, and R9 are not limited. However, for the sake of yield, each of R1, R2, R3, R4, R5, R6, R7, R8, and R9 is independently selected from H, C1-C10 hydrocarbon groups, or C1-C10 substituted hydrocarbon groups; each of R1, R2, R3, R4, R5, R6, R7, R8, and R9 is independently selected from H, methyl, ethyl, or isopropyl.

[0102] In the above preparation method, the specific type of RE is not required; however, considering the radius difference, it is preferable that the RE is selected from Y. 3+ Yb 3+ Gd 3+ Or Lu 3+ .

[0103] The structure of the ligand is shown in Formula D1 or Formula E1, and the rare earth trialkyl complex is shown in Formula F1, F2, F3 or Formula F4.

[0104]

[0105] Furthermore, in this invention, the amounts of the ligands and the rare earth trialkyl complexes are not specifically limited. However, to further ensure that the reactants react as completely as possible, preferably, the molar ratio of the ligand D and the rare earth trialkyl complex F in the preparation of Pincer-type ligand rare earth metal catalysts A1, A2, A3, and A4 is 1:(1-1.1); the molar ratio of the ligand E and the rare earth trialkyl complex F in the preparation of multidentate β-diimine ligand rare earth metal catalysts B1 and B2 is 1:(1-1.1); and the molar ratio of the ligand E and the rare earth trialkyl complex F in the preparation of Pincer-type ligand rare earth metal catalysts C1 and C2 is 2:(1-1.1).

[0106] Meanwhile, in this invention, the conditions for the coordination reaction are not specifically limited. However, in order to further ensure that the reactants react as completely as possible, preferably, the coordination reaction meets at least the following conditions: the reaction temperature is 15-35℃ and the reaction time is 0.5-2h.

[0107] The present invention provides a method for preparing Pincer-type ligand rare earth metal catalysts where the reactants are readily available, the preparation steps are simple, the preparation temperature is low, the preparation time is short, the energy consumption is low, and it is cleaner and more environmentally friendly.

[0108] Furthermore, in the above method, to further improve the yield, preferably, the coordination reaction is carried out in a solvent selected from toluene or n-hexane. The amount of solvent can be selected within a wide range, but to further improve the yield, the ratio of the rare earth trialkyl complex to the ligand is 1 mmol: 1-5 mL.

[0109] In the above preparation method, the type of protective gas is not specifically limited. However, in order to further improve the protective effect, the protective gas is preferably selected from at least one of nitrogen, helium and argon.

[0110] In the above preparation method, the ligand is prepared and used immediately. To further improve the purity of the ligand, preferably, the ligand D is prepared by the following method:

[0111] The ligand precursor G is obtained by direct contact reaction of o-fluoroaromatic aldehydes and heterocyclic amines J1; the ligand precursor G is obtained by contact reaction of aromatic amines and n-butyllithium in solvent under nitrogen protection.

[0112] Preferably, the ligand E is prepared by the following method:

[0113] The ligand precursor H is obtained by direct contact reaction of o-fluoroaromatic aldehydes and aromatic amines; the heterocyclic amine J2 is obtained by contact reaction of n-butyllithium with a solvent under nitrogen protection, followed by the addition of ligand precursor H.

[0114] The structures of the ligand precursors are shown in Formula G and Formula H, the structures of the o-fluoroaromatic aldehydes are shown in Formula I, the structures of the heterocyclic amines are shown in Formula J1 and Formula J2, and the structures of the aromatic amines are shown in Formula K.

[0115]

[0116] In the above-described method for preparing the ligands, the amount of each raw material is not specifically limited. However, to improve the yield, preferably, the molar ratio of the o-fluoroaromatic aldehyde to the amine is 1:1; the molar ratio of the aromatic amine to n-butyllithium is 1:1.3; the molar ratio of the heterocyclic amine to n-butyllithium is 1:1.5; the molar ratio of the ligand precursor G to the aromatic amine lithium salt is 1:1.3; and the molar ratio of the ligand precursor H to the heterocyclic amine lithium salt is 1:2.5.

[0117] In the above-mentioned method for preparing ligands, the conditions for the contact reaction are not specifically limited. However, in order to improve the yield, preferably, the contact reaction between the o-fluoroaromatic aldehyde and the amine satisfies at least the following conditions: 2 h, solvent-free reaction; the contact reaction between the ligand precursor G and the aromatic amine lithium salt satisfies at least the following conditions: 60 °C, 24 h; and the contact reaction between the ligand precursor H and the heterocyclic amine lithium salt satisfies at least the following conditions: room temperature, 10 h.

[0118] In the above-mentioned method for preparing ligands, the amount and type of solvent are not specifically limited. However, in order to improve the yield, preferably, the ratio of the aromatic amine compound to the solvent is 10 mmol / L: 10-20 mL, wherein the solvent is selected from tetrahydrofuran; the ratio of the heterocyclic amine compound to the solvent is 10 mmol / L: 10-20 mL, wherein the solvent is selected from n-hexane.

[0119] The present invention will be described in detail below through examples. In the following examples, the proton and carbon NMR spectra were measured using a Bruker AV400MHz and Bruker AV500MHz NMR spectra, respectively, and the single-crystal diffraction patterns were measured using a Bruker AXS SMART APEX II single-crystal diffractometer.

[0120] The structural formulas of the lutetium trialkyl complex, ytterbium trialkyl complex, yttrium trialkyl complex, and gadolinium trialkyl complex are F1, F2, F3, and F4, respectively:

[0121]

[0122] Preparation Example 1

[0123] Preparation of ligand precursor G:

[0124]

[0125] In a 100 mL round-bottom flask, o-fluorobenzaldehyde (4.96 g, 40 mmol) and 1-(2-aminoethyl)pyrrolidine (4.56 g, 40 mmol) were added sequentially and stirred at room temperature. The solution gradually changed from colorless to a pale greenish-yellow liquid. After 24 h, the solution was distilled under reduced pressure, and the pale yellow oily substance (yield = 95%) at approximately 120 °C was collected.

[0126] The characterization results are as follows: 1 H NMR (400MHz, CDCl3, ppm): δ8.62(s,1H),7.98-7.93(m,1H),7.40–7.34(m,1H),7.15(t,J=7.6Hz,1H), 7.08-7.03(m,1H),3.83-3.79(m,2H),2.81(t,J=7.0Hz,2H),2.60-2.57(m,4H),1.80–1.76(m,4H).13C NMR (100MHz, CDCl3, ppm): δ162.0(d,J F-C =250.0Hz),154.6(d),131.9(d),127.5(d),124.1(d),123.7(d),115.5(d),61.3,56.8,54.5,23.4.

[0127] Preparation of ligand precursor H:

[0128]

[0129] In a 100 mL round-bottom flask, o-fluorobenzaldehyde (4.96 g, 40 mmol) and 2,6-diisopropylaniline (7.09 g, 40 mmol) were added sequentially and stirred at room temperature. The solution gradually changed from colorless to a pale green liquid, and finally to a pale yellow liquid. After 2 hours, a pale yellow solid (yield > 99%) was obtained. No further treatment was required, and it could be used directly for the next reaction.

[0130] The characterization results are as follows: 1H NMR (500MHz, CDCl3, ppm): δ8.51 (s, 1H), 8.22 (dd, J1=J2=7.5Hz, 1H), 7.50-7.47 (m, 1H), 7. 29(dd,J1=J2=7.5Hz,1H),7.17-7.10(m,4H),2.99-2.91(m,2H),1.17(d,J=6.5Hz,12H).13C NMR (125MHz, CDCl3, ppm): δ163.2(d,J F-C =251.2Hz),156.0(d),149.6,137.9,133.4(d),128.1,124.9(d),124.7,124.1(d),123.4,116.4,116.3,28.3,23.8.

[0131] Preparation Example 2

[0132] Preparation of ligand D:

[0133]

[0134] Under argon protection, 2,6-2-isopropylaniline (1.79 mL, 10.0 mmol) and 20 mL of tetrahydrofuran were added to a 250 mL round-bottom flask. Under an ice-water bath, n-BuLi (9.13 mL, 1.6 M stored in n-hexane, 13.0 mmol) was slowly added, and the mixture was slowly brought to room temperature. The solution gradually changed from colorless to a white turbid liquid. After 8 h, the ligand precursor solution (1.60 g, 7.7 mmol, dissolved in tetrahydrofuran) was slowly added, and the mixture was slowly brought to room temperature. The reaction was carried out at 60 °C for 24 h. The solvent was removed under vacuum, and the mixture was recrystallized from methanol to give a colorless solid weighing 2.15 g, with a yield of 74%.

[0135] The characterization results are as follows: 1 H NMR (400MHz, CDCl3): δ10.54(s,1H),8.49(s,1H),7.28–7.23(m,4H),7.09–7.05(m,1H),6.65(t,J=7.4Hz,1H),6.21(d,J=8.0Hz,1H),3.80(t,J=7 .2Hz,2H),3.16-3.05(m,2H),2.79(t,J=7.2Hz,2H),2.59–2.56(m,4H),1 .79–1.76(m,4H),1.15(d,J=6.8Hz,CH3,6H),1.13(d,J=7.2Hz,CH3,6H). 13C NMR (100MHz, CDCl3, ppm): δ164.9,149.4,147.5,135.1,133.5,131.0,127.1,123.7,116.6,114.9,111.6,61.2,57.4,54.7,28.4,24.9,23.5,22.9.

[0136] Preparation of ligand E:

[0137]

[0138] Under argon protection, tetrahydrofurfurylamine (1.03 mL, 10.0 mmol) and 20 mL of n-hexane were added to a 250 mL round-bottom flask. Under an ice-water bath, n-BuLi (9.37 mL, 1.6 M stored in n-hexane, 15.0 mmol) was slowly added, and the mixture was slowly brought to room temperature. The solution changed from pale yellow to a yellow turbidity. After 12 h, the mixture was allowed to stand, the supernatant was removed, and the solid was washed with n-hexane (2 × 30 mL) to remove excess n-butyllithium as much as possible. Under an ice-water bath, the ligand precursor solution (1.13 g, 4 mmol, dissolved in n-hexane) was slowly added, and the mixture was brought to room temperature. The solution changed from yellow to brick red, then back to yellow. After 10 h, 20 mL of ethyl acetate was added, and the mixture was concentrated under vacuum to obtain a yellow oily liquid. Recrystallization from methanol yielded a yellow solid weighing 1.03 g, with a yield of 71%.

[0139] The characterization results are as follows: 1 H NMR (400MHz, CDCl3, ppm): δ9.26(s,1H),8.24(s,1H),7.35-7.26(m,2H),719-7.1 0(m,3H),6.82(d,J=8.4Hz,1H),6.69(dd,J1=7.2Hz,J2=7.6Hz,1H,),4.21-4.15(m ,1H),3.89-3.83(m,1H),3.76-3.70(m,1H),3.48-3.35(m,2H),3.09-2.99(m,2H) ,2.07-1.98(m,1H),1.95-1.83(m,2H),1.78-1.69(m,1H),1.17(d,J=6.8Hz,12H). 13 CNMR (100MHz, CDCl3, ppm): δ165.6,149.9,149.0,138.2,134.9,132.4,124.2,123.0,116.8,114.5,110.3,68.3,46.8,29.3,27.9,25.8,23.6.

[0140] Example 1

[0141] Preparation of rare earth metal catalyst A1:

[0142] Ligand D (0.65 g, 1.72 mmol) was mixed with a rare earth lutetium trialkyl complex (1.0 g, 1.72 mmol) in 1.5 mL of toluene and 2.5 mL of n-hexane. The mixture was reacted at room temperature for 0.5 h, allowed to stand, filtered, and then allowed to stand at -30 °C for several hours to obtain 0.81 g of yellow crystals, with a yield of 65%.

[0143] The characterization results are as follows: 1 H NMR (500MHz, C6D6, ppm): δ7.79(s,1H),7.34–7.30(m,3H),7.06-7.04(m,1H),6.91–6.87(m ,1H),6.41-6.36(m,2H),3.44-3.38(m,2H),3.21–3.17(m,2H),2.92(t,J=6.0Hz,2H),2.29– 2.25(m,2H),2.21(t,J=6.0Hz,2H),1.56-1.50(m,2H),1.46(d,J=7.0Hz,6H),1.24–1.22(m, 2H),1.16(d,J=7.0Hz,6H),0.12(s,18H),-0.93(d,J=12.0Hz,2H),-1.05(d,J=12.0Hz,2H).

[0144] 13 C NMR (125MHz, CDCl3, ppm): δ169.6,157.7,145.4,144.1,137.3,134.5,126.3,1 25.1,119.1,118.1,113.8,57.2,54.6,53.0,43.3,28.3,25.8,25.0,22.5,4.6.

[0145] Anal.Calcd for C 33 H 56 N3Si2Lu:C,54.60;H,7.78;N,5.79.Found:C,54.68;H,7.43;N,5.29.

[0146] See single crystal diffraction pattern Figure 1 The proton NMR spectrum is shown below. Figure 9 See the carbon NMR spectrum. Figure 10 .

[0147] Example 2

[0148] Preparation of rare earth metal catalyst A2:

[0149] Ligand D (0.65 g, 1.72 mmol) was mixed with a rare earth ytterbium trialkyl complex (1.00 g, 1.72 mmol) in 1.5 mL of toluene and 2.5 mL of n-hexane. The mixture was reacted at room temperature for 0.5 h, allowed to stand, filtered, and then allowed to stand at -30 °C for several hours to obtain 0.87 g of yellow crystals, with a yield of 70%.

[0150] The characterization results are as follows: Anal.Calcd for C 33 H 56 N3Si2Yb:C,54.74;H,7.80;N,5.80.Found:C,54.45;H,7.80;N,5.67.

[0151] See single crystal diffraction pattern Figure 2 .

[0152] Example 3

[0153] Preparation of rare earth metal catalyst A3:

[0154] Ligand D (0.76 g, 2.02 mmol) was mixed with a rare earth ytterbium trialkyl complex (1.00 g, 2.02 mmol) in 1.5 mL of toluene and 2.5 mL of n-hexane. The mixture was reacted at room temperature for 0.5 h, allowed to stand, filtered, and then allowed to stand at -30 °C for several hours to obtain 0.77 g of yellow crystals, with a yield of 60%.

[0155] The characterization results are as follows: 1 H NMR (500MHz, C6D6, ppm): δ7.80 (s, 1H), 7.35–7.29 (m, 3H), 7.07 (dd, J1=8.0Hz, J2=1.6Hz, 1H), 6.91-6. 71(m,1H),6.43–6.39(m,1H),6.31(d,J=11Hz,1H),3.41-3.30(m,2H),3.24–3.18(m,2H),2.94(t,J=7. 5Hz,2H),2.25(t,J=7.5Hz,4H),1.60–1.51(m,2H),1.42(d,J=8.5Hz,6H),1.28–1.24(m,2H),1.14(d,J =8.5Hz, 6H), 0.14 (s, 18H), -0.77 (dd, J1 = 14.0Hz, J2 = 3.5Hz, 2H), -0.91 (dd, J1 = 14.5Hz, J2 = 4.0Hz, 2H).

[0156] 13C NMR (125MHz, CDCl3, ppm): δ169.0,156.5,145.5,141.8,137.1,134.1,126.3,124.9,117 .9,117.6,113.3,56.9,54.8,53.0,32.4(d,JY-C=51.3Hz),28.1,25.4,24.7,22.3,4.1.

[0157] Anal.Calcd for C 33 H 56 N3Si2Y:C,61.94;H,8.82;N,6.57.Found:C,61.70;H,8.94;N,6.54.

[0158] See single crystal diffraction pattern Figure 3 The proton NMR spectrum is shown below. Figure 11 See the carbon NMR spectrum. Figure 12 .

[0159] Example 4

[0160] Preparation of rare earth metal catalyst A4:

[0161] Ligand D (0.67 g, 1.77 mmol) was mixed with a rare earth gadolinium trialkyl complex (1.00 g, 1.77 mmol) in 1.5 mL of toluene and 2.5 mL of n-hexane. The mixture was reacted at room temperature for 0.5 h, allowed to stand, filtered, and then allowed to stand at -30 °C for several hours to obtain 0.81 g of yellow crystals, with a yield of 65%.

[0162] The characterization results are as follows: Anal.Calcd for C 33 H 56 N3Si2Gd:C,55.96;H,7.97;N,5.93.Found:C,54.59;H,7.88;N,5.79.

[0163] See single crystal diffraction pattern Figure 4 .

[0164] Example 5

[0165] Preparation of rare earth metal catalyst B1:

[0166] Ligand E (0.36 g, 1.0 mmol) was mixed with a rare earth lutetium trialkyl complex (0.58 g, 1.0 mmol) in 1 mL of toluene and reacted at room temperature for 2 hours. After standing, 0.34 g of yellow crystals were obtained, with a yield of 48%.

[0167] The characterization results are as follows: 1H NMR (500MHz, C6D6, ppm): δ8.02(s,1H),7.26-7.16(m,4H),7.02(dd,J1=J2=1.5Hz,1H),6.51(d,J=9.0Hz,1H),6.45-6.42(m ,1H),4.28-4.22(m,1H),4.03-4.00(m,1H),3.87-3.82(m,1H),3.67-3.62(m,1H),3.27-3.17(m,2H),2.90-2.87(m,1H),1.5 4(d,J=6.5Hz,3H),1.40(d,J=7.0Hz,3H),1.38-1.28(m,3H),1.15(d,J=6.5Hz,3H),1.12-1.09(m,1H),0.87(d,J=7.0Hz),0 .13(s,9H),0.05(s,9H),-0.28(d,J=11.5Hz),-0.73(d,J=11.5Hz,1H),-0.82(d,J2=11.5Hz,2H),-0.85(d,J2=11.5Hz,2H).

[0168] 13 C NMR (125MHz, C6D6, ppm): δ171.6,158.3,146.8,142.0,138.9,136.2,124.5,124.4,118.0,11 3.8,113.6,82.2,71.9,56.3,45.5,39.9,29.3,28.8,28.4,26.2,25.8,22.9,22.5,4.3,3.9.

[0169] Anal.Calcd for C 32 H 53 N2OSi2Lu:C,53.91;H,7.49;N,3.93.Found:C,53.54;H,7.82;N,3.86.

[0170] See single crystal diffraction pattern Figure 1 The proton NMR spectrum is shown below. Figure 9 See the carbon NMR spectrum. Figure 10 .

[0171] Example 6

[0172] Preparation of rare earth metal catalyst B2:

[0173] Ligand E (0.36 g, 1.0 mmol) was mixed with a rare earth ytterbium trialkyl complex (0.58 g, 1.0 mmol) in 1.1 mL of toluene and reacted at room temperature for 2 hours. After standing, 0.38 g of red crystals were obtained, with a yield of 53%.

[0174] The characterization data is as follows: Anal.Calcdfor C 32 H 53 N2OSi2Yb:C,54.06;H,7.51;N,3.94.Found:C,53.76;H,7.63;N,4.11.

[0175] See single crystal diffraction pattern Figure 2 .

[0176] Example 7

[0177] Preparation of rare earth metal catalyst C1:

[0178] Ligand E (0.72 g, 2.0 mmol) was mixed with a rare earth yttrium trialkyl complex (0.49 g, 1.0 mmol) in 1.2 mL of toluene and reacted at room temperature for 2 hours. After standing, 0.37 g of brick-red crystals were obtained, with a yield of 62%.

[0179] The characterization data are as follows: 1 H NMR (400MHz, C6D6, ppm): δ8.04(d),7.32-7.27(m,1H),7.21-7.19(m,2H ),7.11-7.04(m,4H),7.02-6.97(m,2H),6.84-6.73(m,1H),6.71-6.61(m ,2H),6.54-6.35(m,2H),4.18-4.07(m,2H),3.09-3.72(m,3H),3.62-3. 48(m,2H),3.47-3.36(m,3H),3.33-3.25(m,1H),3.20-3.10(m,2H),2.99 -2.61(m,2H),2.33-2.27(m,1H),1.57(d,J=6.8Hz,1H),1.51(t,J=6.4H z,3H),1.46(d,J=6.4Hz,2H),1.42(d,J=6.8Hz,1H),1.38-1.33(m,4H),1 .32-1.26(m,3H),1.25-1.22(m,3H),1.19-1.15(m,2H),1.10-1.03(m,7H ),0.79(d,J=6.8Hz,3H),0.70-0.66(m,3H),-0.03(s,5H),-0.08(s,4H).

[0180] 13 C NMR (125MHz, C6D6, ppm): δ169.9,169.3,158.7,156.0,152.4,151.5,147.6,147.2,142.8,142.4,141.6,139.6 ,137.9,134.5,129.3,125.7,126.1,125.7,123.6,123.2,122.4,122.2,122.1,119.6,119.2,114.5,114.3,112 .1,111.2,110.7,107.4,88.5,85.7,85.3,85.6,71.4,71.2,70.6,69.3,68.9,58.3,57.8,49.39,32.0,30.3,29.6,28.8,28.6,28.3,28.1,27.4,27.1,26.8,26.2,25.7,25.2,23.6,23.0,22.6,21.8,21.4,20.5,14.4,-0.17.

[0181] Anal.Calcd for C 52 H 73 N4O2SiY:C,69.15;H,8.15;N,6.20.Found:C,69.33;H,8.52;N,3.86.

[0182] See single crystal diffraction pattern Figure 3 The proton NMR spectrum is shown below. Figure 11 See the carbon NMR spectrum. Figure 12 .

[0183] Example 8

[0184] Preparation of rare earth metal catalyst C2:

[0185] Ligand E (0.72 g, 2.0 mmol) was mixed with a rare earth gadolinium trialkyl complex (0.49 g, 1.0 mmol) in 1.2 mL of toluene and reacted at room temperature for 2 hours. After standing, 0.36 g of brick-red crystals were obtained, with a yield of 54%.

[0186] The characterization data is as follows: Anal.Calcdfor C 52 H 73 N4O2SiGd:C,64.29;H,7.57;N,5.77.Found:C,64.54;H,7.52;N,5.75.

[0187] See single crystal diffraction pattern Figure 4 .

[0188] Application Example 1

[0189] Under argon protection and at 25°C, a boronamine alkyl complex (substrate 1, 2.5 mmol), a rare earth metal complex (0.07 mmol), and THF (2 mL) were added to a 15 mL Schlenk reaction flask. The mixture was stirred at 60°C for 10 min, followed by the addition of a nitrile compound (substrate 2, 1.0 mmol). The mixture was stirred at 60°C for 2.5 h. After the reaction was completed, the product was purified by column chromatography using ethyl acetate:petroleum ether = 1:8 as the mobile phase. The specific raw materials and product results are shown in Table 1.

[0190] Table 1

[0191]

[0192]

[0193] Application Example 2

[0194] Under argon protection and at 25°C, a boronamine alkyl complex (substrate 1, 1.0 mmol), a rare earth metal complex (0.03 mmol), and THF (2 mL) were added to a 15 mL Schlenk reaction flask. The mixture was stirred at 60°C for 10 min, followed by the addition of an imine compound (substrate 2, 1.0 mmol), and the mixture was stirred at 60°C for 1.0 h. After the reaction was completed, the product was purified by column chromatography using ethyl acetate:petroleum ether as the mobile phase. The specific results are shown in Table 2.

[0195] Table 2

[0196]

[0197]

[0198] Comparative Example 1

[0199] Under argon protection and at 25°C, substrate 1 (1.0 mmol) and substrate 2 (2.5 mmol) from Table 1 were added to a 15 mL Schlenk reaction flask, dissolved in 2 mL tetrahydrofuran, and stirred at 60°C for 2.5 h. Characterization showed that the yield of product 1 from Table 1 was only 24%.

[0200] Comparative Example 2

[0201] Under argon protection and at 25°C, 1.0 mmol each of substrate 1 and substrate 2 from item 1 in Table 2 were added to a 15 mL Schlenk reaction flask, dissolved in 2 mL tetrahydrofuran, and stirred at 60°C for 1.0 h. Characterization showed that the yield of product 1 from item 1 in Table 2 was only 35%.

[0202] The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. The scope of protection of this application is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this application within its substance and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this application.

Claims

1. A Pincer ligand rare earth metal catalyst, characterized in that, a structural formula of the Pincer ligand rare earth metal catalyst is shown in formula A1, formula A2, formula A3, formula A4, formula B1, formula B2, formula C1 or formula C2; 。 2. A process for the preparation of the Pincer-type ligand rare earth metal catalyst according to claim 1, characterized in that, the preparation method comprises the following steps: ligands with structures shown in formula D or formula E and rare earth trialkyl complexes with structures shown in formula F are subjected to a coordination reaction in the presence of a protective gas to prepare the Pincer ligand rare earth metal catalyst; 。 3.The preparation method according to claim 2, characterized in that, the coordination reaction at least meets the following conditions: a reaction temperature is 15-35 ℃, and a reaction time is 0.5-2 h; wherein, the coordination reaction is carried out in a solvent selected from toluene or n-hexane; the protective gas is at least one selected from nitrogen, helium and argon; in the preparation of the Pincer ligand rare earth metal catalysts shown in the formula A1, the formula A2, the formula A3 and the formula A4, a molar ratio of the ligand D to the rare earth trialkyl complex F is 1: (1-1.1) ; in the preparation of the Pincer ligand rare earth metal catalysts shown in the formula B1 and the formula B2, a molar ratio of the ligand E to the rare earth trialkyl complex F is 1: (1-1.1) ; in the preparation of the Pincer ligand rare earth metal catalysts shown in the formula C1 and the formula C2, a molar ratio of the ligand E to the rare earth trialkyl complex F is 2: (1-1.1). 4.The preparation method according to claim 2, characterized in that, the preparation of the ligand D comprises the following steps: an o-fluoro aromatic aldehyde compound is directly subjected to a contact reaction with a heterocyclic amine compound J1 to obtain a ligand precursor G; under nitrogen protection, an aromatic amine is subjected to a contact reaction with n-butyllithium in a first solvent to obtain an aromatic amine lithium salt, and after the reaction is completed, the ligand precursor G is added to react to obtain the ligand D; the preparation of the ligand E comprises the following steps: an o-fluoro aromatic aldehyde compound is directly subjected to a contact reaction with an aromatic amine compound to obtain a ligand precursor H; under nitrogen protection, a heterocyclic amine compound J2 is subjected to a contact reaction with n-butyllithium in a second solvent to obtain a heterocyclic amine lithium salt, and after the reaction is completed, the ligand precursor H is added to react to obtain the ligand E; wherein, a structure of the ligand precursor G is shown in formula G, a structure of the ligand precursor H is shown in formula H, a structure of the o-fluoro aromatic aldehyde compound is shown in formula I, a structure of the heterocyclic amine compound is shown in formula J1 or formula J2, and a structure of the aromatic amine is shown in formula K; a molar ratio of the o-fluoro aromatic aldehyde compound to the aromatic amine is 1:1; the contact reaction of the o-fluoro aromatic aldehyde compound with the aromatic amine and the heterocyclic amine compound at least meets the following conditions: a reaction condition is 2 h, and there is no solvent reaction in the reaction process; a molar ratio of the aromatic amine to the n-butyllithium is 1:1.3; a molar ratio of the heterocyclic amine to the n-butyllithium is 1:1.5; The molar ratio of the ligand precursor G to the aromatic amine lithium salt is 1:1.3; The molar ratio of the ligand precursor H to the heterocyclic amine lithium salt is 1:2.5; The contact reaction of the ligand precursor G with the aromatic amine lithium salt at least meets the following conditions: 60℃, 24h; The contact reaction of the ligand precursor H with the heterocyclic amine lithium salt at least meets the following conditions: room temperature, 10h; The molar ratio of the aromatic amine compound to the first solvent is 10mmol:10-20ml, and the first solvent is tetrahydrofuran; The molar ratio of the heterocyclic amine compound to the second solvent is 10mmol:10-20ml, and the second solvent is n-hexane.

5. The preparation method of claim 2, wherein the structure of the ligand is shown in formula D1 or formula E1; the rare earth trialkyl complex is shown in formula F1, F2, F3 or formula F4: The application of the Pincer-type ligand rare earth metal catalyst in the preparation of primary amine borane compounds with the structure shown in formula N or secondary amine compounds with the structure shown in formula O; 。 6. Use of a Pincer-type ligand rare earth metal catalyst as claimed in claim 1, wherein, The primary amine borane compound is obtained by reduction reaction of a nitrile compound with the structure shown in formula L and a boron amine complex under the catalysis of the Pincer-type ligand rare earth metal catalyst; The secondary amine compound is obtained by reduction reaction of an imine compound with the structure shown in formula M and a boron amine complex under the catalysis of the Pincer-type ligand rare earth metal catalyst; 7. The application of claim 6, wherein the nitrile compound is at least one selected from benzonitrile, p-methylbenzonitrile, p-tert-butylbenzonitrile, p-trifluoromethylbenzonitrile, 2-naphthalene carbonitrile, and cyclopropyl nitrile, and the imine compound is at least one selected from N-benzylidene aniline, N-(4-methylbenzylidene) aniline, N-(4-methoxybenzylidene) aniline, and N-benzylidene m-methylaniline; R 1 , R 2 , R 3 are each independently selected from H, C1-C30 hydrocarbyl. The structure of the primary amine borane compound is shown in formula N1, formula N2, formula N3, formula N4, formula N5 or formula N6, and the structure of the secondary amine compound is shown in formula O1, formula O2, formula O3 or formula O4:

8. The application of claim 6, wherein in the reaction for preparing the primary amine borane compound, the molar ratio of the nitrile compound, the boron amine complex and the Pincer-type ligand rare earth metal catalyst is 1.0mmol:2.5mmol:(0.07-0.09)mmol, and the reaction temperature is 60℃ and the reaction time is 2.5h; In the reaction for preparing the secondary amine compound, the molar ratio of the imine compound, the boron amine complex and the Pincer-type ligand rare earth metal catalyst is 1.0mmol:1.0mmol:0.03mmol, and the reaction temperature is 60℃ and the reaction time is 1h. 。 ​ ​ ​

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