Planar annular tetradentate phosphine-molybdenum complex as well as preparation method and application thereof
By synthesizing the planar macrocyclic tetradentate phosphine-molybdenum complex without isomers using the sixth subgroup transition metal Mo as a template, the problem of synthesis of macrocyclic tetradentate phosphine ligands is solved, and a high efficiency of catalytic catalytic reaction is achieved under normal temperature and pressure is achieved to generate tri(trimethylsilyl)amine with high catalytic efficiency.
Patent Information
- Application Number
- CN202510479148.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-16
- Publication Date
- 2025-07-08
AI Technical Summary
There is no general method for synthesizing macrocyclic tetradentate phosphine ligands in the prior art, and it is difficult to remove template metals in the synthesis of macrocyclic tetradentate phosphine ligands, resulting in insufficient research on coordination chemistry, especially the study of plane macrocyclic tetradentate phosphine ligands, and the traditional nitrogen fixation method has high energy consumption and low catalytic efficiency.
The sixth subgroup transition metal Mo was used as a template to synthesize the planar macrocyclic tetradentate phosphine-molybdenum complex without isomers by the template method, and used as a catalyst for nitrogen silicoation reaction to form tri(trimethylsilyl)amine.
High-efficiency catalytic nitrogen silicolysis reaction is achieved under normal temperature and pressure to produce tri(trimethylsilyl)amine, with high catalytic efficiency, stable complex structure and excellent catalytic performance.
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Abstract
Description
Technical Field
[0001] The present invention belongs to the field related to organometallic chemistry, and specifically relates to a synthesis method and application of a planar macrocyclic tetradentate phosphine-molybdenum complex synthesized using molybdenum as a template. Background Art
[0002] Activating and converting nitrogen gas under normal temperature and pressure has always been a difficult problem that scientists have been striving to overcome. The traditional nitrogen fixation method is the Haber-Bosch process, which requires high temperature, high pressure, and an Fe compound catalyst, and this process is very energy-consuming; catalytic silylation of nitrogen gas to synthesize tris(trimethylsilyl)amine, and then tris(trimethylsilyl)amine is hydrolyzed by acid to synthesize ammonia, which is also regarded as a nitrogen fixation method. Synthesizing a catalyst with high catalytic efficiency for the silylation reaction of nitrogen gas is of great significance.
[0003] In the design and synthesis of homogeneous catalyst ligands, phosphine, as a strong and soft π-electron donor, is widely used. Especially for cyclic phosphine ligands, the macrocyclic effect generated will make the complex more stable. Edwards et al. synthesized a series of macrocyclic tridentate complexes using transition metals of the sixth subgroup as templates. Affected by the ring size, tridentate macrocyclic phosphine ligands often coordinate in a facial manner. The macrocyclic effect generated by the facial coordination of tridentate macrocyclic phosphine ligands is weaker than that generated by macrocyclic tetradentate phosphine ligands that can completely surround the metal center.
[0004] Regrettably, there is still no general method for synthesizing macrocyclic phosphine ligands to date, and there is no report on synthesizing planar macrocyclic tetradentate phosphine ligands using transition metals of the sixth subgroup as templates. The macrocyclic phosphine ligands synthesized by the template method are very difficult or even impossible to remove from the metal. Therefore, the coordination chemistry of macrocyclic tetradentate phosphine ligands has not been deeply studied.
[0005] Compared with oxacycle, azacycle, and thiacycle systems, the research on macrocyclic phosphine ligands is less, which may be related to the stereochemistry of phosphorus atoms. Different from tertiary amines, the inversion barrier of phosphine is very high (30 - 35 kcal / mol), and chiral phosphine molecules do not undergo inversion at room temperature. This means that macrocyclic phosphines (PR1R2R3) with asymmetric phosphine groups are chiral, and macrocyclic phosphine ligands usually contain three or more phosphorus atoms, resulting in multiple possible stereoisomers for each macrocycle, which is not conducive to product separation and purification. Summary of the Invention
[0006] To solve the problems existing in the prior art, the present invention provides a planar cyclic tetradentate phosphine-molybdenum complex, its synthesis method and application. Using the Group VI transition metal Mo as a template, a planar macrocyclic tetradentate phosphine ligand without isomers is synthesized by the template method. And through experiments, it is proved that this complex can catalyze the silylation of nitrogen to generate tris(trimethylsilyl)amine and has a high catalytic efficiency.
[0007] The first object of the present invention is to provide a planar cyclic tetradentate phosphine-molybdenum complex, which has a unique electronic structure and spatial properties. The planar macrocycle is very stable and firm, and shows excellent catalytic performance in the catalytic silylation reaction of nitrogen.
[0008] The second object of the present invention is to provide a synthesis method of the above planar cyclic tetradentate phosphine-molybdenum complex. This complex uses the Group VI transition metal Mo as a template, and a planar macrocyclic tetradentate phosphine ligand without isomers is synthesized by the template method, deepening the exploration of the synthesis method of the macrocyclic tetradentate phosphine ligand.
[0009] The third object of the present invention is to provide the application of the above planar cyclic tetradentate phosphine-molybdenum complex. This complex has a high catalytic efficiency for the silylation reaction of nitrogen, inspiring people's design and thinking of homogeneous catalysts.
[0010] The technical solution adopted by the present invention is as follows: A planar cyclic tetradentate phosphine-molybdenum complex, the structural formula of this complex is: ; Among them, , are each independently selected from: , ; is a substituted or unsubstituted C3-C8 cycloalkane, or a substituted or unsubstituted 3-8 membered heterocyclic compound; R is hydrogen or a C1-C10 alkane; m1, n1, m2, n2 are each an integer from 1 to 3.
[0011] Furthermore, has the same structure as .
[0012] Furthermore, has the same structure as ; m1, n1, m2, n2 are each an integer from 1 to 3, and m1 is equal to n1, and m2 is equal to n2.
[0013] Furthermore, among them, , are each independently selected from , , .
[0014] A planar cyclic tetradentate phosphine-molybdenum complex, and the structural formula of the complex is: .
[0015] Application of a planar cyclic tetradentate phosphine-molybdenum complex, and the application of the planar cyclic tetradentate phosphine-molybdenum complex as a catalyst for the silylation reaction of nitrogen.
[0016] Furthermore, the planar cyclic tetradentate phosphine-molybdenum complex is used as a catalyst for the reaction of nitrogen with trimethylchlorosilane to produce tris(trimethylsilyl)amine.
[0017] Preferably, a preparation method of a planar cyclic tetradentate phosphine-molybdenum complex includes the following steps:
[0018] S1. Under nitrogen protection, compound A and 1,1-diiodomethylcyclopropane are heated in N , N -dimethylformamide to precipitate a solid, and compound B is obtained; S2. Under nitrogen protection, compound B and THF are mixed and placed at -30 o °C to -20 o °C, sodium dihydrobis(2-methoxyethoxy) aluminate is added, stirred, the reaction is quenched and then distilled under reduced pressure, and then extracted with n-hexane to obtain an open-chain tetradentate phosphine ligand H2L; S3. Under nitrogen protection, Mo(O)Cl2(PPh2Me)3, the open-chain tetradentate phosphine ligand H2L and MeOLi are mixed in MeOH, reacted at room temperature, the solvent is removed under vacuum and then extracted with acetonitrile to obtain a pale yellow clear liquid; NaPF 6, is added to the pale yellow clear liquid to precipitate a solid, and filtered; the solvent is removed from the filtrate under vacuum, and the product is extracted with dichloromethane to obtain a dichloromethane solution of ML1; hexane is added and diffused into the dichloromethane solution of ML1 to obtain yellow block crystals ML1.
[0019] S4. Under nitrogen protection, ML1 and tetrahydrofuran are cooled to -60 o °C, potassium bis(trimethylsilyl)amide is added, and then 1,1-diiodomethylcyclopropane is added, and the temperature is raised to room temperature to precipitate a solid, washed, extracted with acetonitrile, the solvent is removed under vacuum and dried to obtain a planar cyclic tetradentate phosphine-molybdenum complex ML2.
[0020] Furthermore, in the step S1, the molar ratio of the amount of compound A to 1,1-diiodomethylcyclopropane is 2:1.
[0021] Further, in the step S2, the molar ratio of compound B to sodium bis(2-methoxyethoxy)aluminate is 1:4.
[0022] Further, in the step S3, the molar ratio of the open-chain tetradentate phosphine ligand H2L, Mo(O)Cl2(PPh2Me)3 to MeOLi is 1:1:1.
[0023] Further, in the step S4, the molar ratio of the complex ML1, potassium bis(trimethylsilyl)amide to 1,1-diiodomethylcyclopropane is 1:2:1.
[0024] The silylation of nitrogen to form tris(trimethylsilyl)amine is also regarded as a way of nitrogen fixation. The application of the cyclic tetradentate phosphine-molybdenum complex provided by the present invention as a catalyst for the silylation of nitrogen with a planar cyclic tetradentate phosphine-Mo complex is characterized in that it catalyzes the reaction of nitrogen with Me3SiCl to form tris(trimethylsilyl)amine, and has excellent catalytic performance. The specific reaction is as follows:
[0025] Based on the above technical solutions, preferably, metallic potassium is used as the reducing agent.
[0026] Based on the above technical solutions, preferably, THF is used as the solvent for this reaction.
[0027] Based on the above technical solutions, preferably, the silylation reaction of nitrogen is carried out at normal temperature and pressure.
[0028] Compared with the prior art, the present invention has the following beneficial effects 1. A cyclic tetradentate phosphine-molybdenum complex provided by the present invention, in which the strong and soft π electrons of the phosphine ligand have a strong chelating effect, can coordinate with the metal precursor smoothly and the coordination yield is relatively high. And due to the macrocycle effect, the ring-closing reaction has certain advantages; the introduction of two side rings increases the ring rigidity, making the whole structure very stable; the unique electronic structure and spatial properties of the complex make it have certain catalytic activity, so it is a highly potential efficient catalyst for the silylation reaction of nitrogen.
[0029] 2. A preparation method of a cyclic tetradentate phosphine-molybdenum complex provided by the present invention, first synthesizing an open-chain tetradentate phosphine ligand, coordinating with the metal precursor MoOCl2(PPhMe)3, and then using KHMDS to deprotonate and close the ring, successfully obtaining the target complex. The reaction needs to be carried out in an inert atmosphere and does not require harsh conditions.
[0030] 3. The application of a cyclic tetradentate phosphine-molybdenum complex provided by the present invention as an efficient catalyst for the silylation reaction of nitrogen can catalyze nitrogen to form tris(trimethylsilyl)amine under normal temperature and pressure conditions. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Figure 1 This is the phosphorus NMR spectrum of the tetradentate phosphine-molybdenum complex ML1 of the present invention.
[0032] Figure 2 This is the phosphorus NMR spectrum of the cyclic tetradentate phosphine-molybdenum complex ML2 of the present invention.
[0033] Figure 3 This is the phosphorus NMR spectrum of the cyclic tetradentate phosphine-molybdenum complex ML3 of the present invention.
[0034] Figure 4 This is the phosphorus NMR spectrum of the cyclic tetradentate phosphine-molybdenum complex ML4 of the present invention.
[0035] Figure 5 This is the GC-MS spectrum of the reaction for catalytic synthesis of tris(trimethylsilyl)amine. The target product has a retention time of 14.3 min. DETAILED DESCRIPTION OF THE INVENTION
[0036] The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.
[0037] In certain specific embodiments, a method for synthesizing a planar cyclic tetradentate phosphine-molybdenum complex using molybdenum as a template uses the Group VI transition metal Mo as a template and Mo(O)Cl2(PMePh2)3 as a metal precursor. After coordination with an open-chain tetradentate phosphine ligand, ring closure occurs. Taking ML2 as an example, the synthesis route of the planar macrocyclic tetradentate phosphine ligand is as follows:
[0038] Based on the above technical solution, preferably, compound B is synthesized from compound A, and 1,1-diiodomethylcyclopropane is selected as the linker.
[0039] Based on the above technical solution, preferably, compound B is reduced to the open-chain tetradentate phosphine ligand H2L, and sodium bis(2-methoxyethoxy)aluminum dihydride (Red-Al) is used as the reducing agent.
[0040] Based on the above technical solution, preferably, the tetravalent molybdenum oxide Mo(O)Cl2(PMePh2)3 is used as the metal precursor to obtain the complex ML1.
[0041] Based on the above technical solution, preferably, KHMDS is used to deprotonate the complex ML1.
[0042] Based on the above technical solutions, preferably, the deprotonation of the complex ML1 is carried out at -60 o °C.
[0043] Based on the above technical solutions, preferably, 1,1-diiodomethylcyclopropane is used for ring closure to synthesize the planar macrocyclic tetradentate phosphine-molybdenum complex ML2.
[0044] Based on the above technical solutions, preferably, the ring closure for synthesizing the molybdenum complex ML2 of the planar macrocyclic tetradentate phosphine ligand is carried out at -60 o °C.
[0045] Furthermore, the synthesis method of the H2L ligand used is as follows:
[0046] 1) Under nitrogen protection, compound A and 1,1-diiodomethylcyclopropane are heated to 50 N , N in N,N-dimethylformamide (DMF) and reacted for 1 h. A large amount of white solid precipitates, which is compound B. The white solid is washed with diethyl ether and dried by vacuum distillation to obtain pure compound B. The crystal of compound B is obtained by recrystallization with methanol and is in the form of colorless blocks. o C to react for 1 h, and a large amount of white solid precipitates, which is compound B. The white solid is washed with diethyl ether and dried by vacuum distillation to obtain pure compound B. The crystal of compound B is obtained by recrystallization with methanol and is in the form of colorless blocks.
[0047] 2) Under nitrogen protection, compound B and THF are mixed in a 100 mL Schlenk tube and placed at -30 o °C. Red-Al is added, and after stirring for half an hour, it is quenched with methanol until no bubbles emerge. The solvent is removed by vacuum distillation, and the open-chain tetradentate phosphine ligand H2L is extracted with n-hexane.
[0048] The dosage ratio of compound A, 1,1-diiodomethylcyclopropane, and DMF in the above reaction steps is 0.2 mmol : 0.1 mmol : 5 mL; the dosage ratio of compound B, Red-Al, and THF is 0.2 mmol : 0.8 mmol : 5 mL.
[0049] The synthesis method of the used ML1 is as follows:
[0050] 1) Under nitrogen protection, Mo(O)Cl2(PPh2Me)3, ligand H2L, and MeOLi are mixed in MeOH. After 1 h at room temperature, the green solid gradually dissolves and turns into a brown clear solution. The solvent is removed under vacuum, and the product is extracted with acetonitrile to obtain a yellow-brown clear solution; 2) NaPF 6, is added to the yellow-brown clear solution, and a white solid precipitates. After filtration, the solvent of the filtrate is removed under vacuum, and the product is extracted with dichloromethane to obtain a dichloromethane solution of ML1. n-Hexane is diffused into the dichloromethane solution of ML1 to obtain yellow block crystals.
[0051] In the above reaction, the reaction temperature is room temperature, and the dosage ratio of ligand H2L, Mo(O)Cl2(PPh2Me)3, MeOLi, and MeOH is 0.02 mmol : 0.02 mmol : 0.02 mmol : 1 mL. The dosage ratio of NaPF6 and dichloromethane in step 2) of the reaction is 0.05 mmol : 1 mL.
[0052] A planar cyclic tetradentate phosphine-molybdenum complex uses the transition metal molybdenum in Group VI as a template, and a planar macrocyclic tetradentate phosphine ligand without isomers is synthesized by the template method. The reaction equation is as follows:
[0053] Under nitrogen protection, a Schlenk tube containing ML1 and tetrahydrofuran (THF) was cooled to -60 o °C, potassium bis(trimethylsilyl)amide (KHMDS) was added, the yellow solid dissolved, and the liquid phase turned dark green. 1,1-Diiodomethylcyclopropane was added under low-temperature conditions, and it immediately became a brown suspension. During the slow recovery to room temperature, a large amount of yellow solid precipitated, the color of the liquid phase became lighter, and it was light yellow. The orange-yellow solid was first washed with THF, and then the cyclization product was extracted with acetonitrile. The solvent was removed under vacuum and then dried to obtain ML2.
[0054] The dosage ratio of ML1, KHMDS, 1,1-diiodomethylcyclopropane, and THF is 0.01 mmol : 0.02 mmol : 0.01 mmol : 1 mL.
[0055] Furthermore, the THF used was deoxygenated and dehydrated, MeOH, acetonitrile, DMF, n-hexane, and dichloromethane were all purchased ultra-dry solvents, and MeOLi and 1,1-diiodomethylcyclopropane were deoxygenated.
[0056] Example 1 Preparation of open-chain tetradentate phosphine-molybdenum complex
[0057] Synthesis of compound B Under nitrogen protection, compound A (3.9 mmol) and 1,1-diiodomethylcyclopropane (1.95 mmol) were heated to 50 o °C in DMF and reacted for one day. A large amount of white solid precipitated, which was compound B. The white solid was washed with diethyl ether and dried by vacuum distillation to obtain pure compound B. Yield: 87% (1.7 mmol). 31 P{H} NMR (162 MHz, DMF): δ= 79.6 (dt, 2P), -50.0 (dt, 2P) ppm.
[0058] Compound A used was synthesized by the method reported in the literature. Reference: Issleib K, Thorausch P. Bildung und reaktionsverhalten substituierter 1,2-diphospholaneund des 1,5-diphosphabicyclo[3.3.0]octans. Phosphorus and Sulfur and the RelatedElements. 1978, 4(2): 137-144.
[0059] Synthesis of the open-chain tetradentate phosphine ligand H2L Under nitrogen protection, compound B (0.2 mmol) and Red-Al (0.4 mmol) were mixed in THF (5 mL). After stirring at low temperature for half an hour, it was quenched with methanol until no bubbles emerged. After drying the solvent, it was extracted with n-hexane to obtain the open-chain tetradentate phosphine ligand H2L. Yield: 80% (0.16 mmol).
[0060] Synthesis of the complex ML1 Under nitrogen protection, Mo(O)Cl2(PMePh2)3 (0.12 mmol), ligand H2L (0.12 mmol) and lithium methoxide (0.24 mmol) were mixed in MeOH (5 mL). After stirring at room temperature for 2 h, the solvent was removed under vacuum. The product was extracted with acetonitrile, NaPF6 (0.12 mmol) was added and stirred vigorously, then the solvent was removed under vacuum. The product was extracted with dichloromethane and dried to obtain the complex ML1. Yield: 60% (0.072 mmol). 31 P{H} NMR (162 MHz, CD2Cl2): δ = 0.9~-1.0 (m, 2P), -34.5~-36.3 (m, 2P), -144.5 (heptet, 1P) ppm.
[0061] The used Mo(O)Cl2(PPh2Me)3 was synthesized by the method reported in the literature.
[0062] References: (a) Butcher A V, Chatt J. Complexes of tertiary phosphines and tertiary arsines with molybdenurn(IV). Journal of the American Chemical Society. 1970: 2652-2656. (b) Butcher A V, Chatt J. Some oxo-complexes of molybdenum(IV) and (V) with 1,2-bisdiphenyl-phosphinoethane. Journal of the American Chemical Society. 1971: 2356-2358。
[0063] Example 2 Preparation of macrocyclic tetradentate phosphine-molybdenum complex ML2
[0064] Mix ML1 (0.03 mmol) and THF (2 mL), cool down to -60 o °C, add twice the amount of potassium hexamethyldisilazide (KHMDS, 0.06 mmol), the yellow solid dissolves, and the liquid phase turns dark green. Add 1,1-diiodomethylcyclopropane (0.03 mmol) at low temperature, the liquid phase turns yellow, and a large amount of orange-yellow solid gradually precipitates. React at room temperature for 12 h, and the amount of orange-yellow precipitate increases. Wash the yellow solid with THF, then extract the product with acetonitrile, and dry to obtain complex ML2. The separation yield is 50% (0.015 mmol). 31 P{H} NMR (162 MHz, CD2Cl2): δ δ = 5.0 (s, 4P), -144.5 (heptet, 1P) ppm。
[0065] Example 3 Preparation of macrocyclic tetradentate phosphine-molybdenum complex ML3
[0066] Mix ML1 (0.03 mmol) and THF (2 mL), cool down to -60 oCompound C (0.03 mmol) was added with twice the amount of potassium hexamethyldisilazide (KHMDS, 0.06 mmol). The yellow solid dissolved and the liquid phase turned dark green. 3,3-Diiodomethyloxetane (0.03 mmol) was added at low temperature, and the liquid phase turned yellow. A large amount of orange-yellow solid gradually precipitated. The reaction was carried out at room temperature for 12 h, and the amount of orange-yellow precipitate increased. The yellow solid was washed with THF, and the product was extracted with acetonitrile and dried to obtain the complex ML3. The isolated yield was 49% (0.015 mmol). 31 P{H} NMR (162 MHz, CD2Cl2): δ δ = 5.4 (s, 4P), -144.5 (heptet, 1P) ppm.
[0067] Example 4 Preparation of macrocyclic tetradentate phosphine-molybdenum complex ML4
[0068] ML1 (0.03 mmol) and THF (2 mL) were mixed and cooled to -60 o °C. Twice the amount of potassium hexamethyldisilazide (KHMDS, 0.06 mmol) was added. The yellow solid dissolved and the liquid phase turned dark green. α , α o'-Dibromo-o-xylene (0.03 mmol) was added at low temperature, and the liquid phase turned yellow. A large amount of orange-yellow solid gradually precipitated. The reaction was carried out at room temperature for 12 h, and the amount of orange-yellow precipitate increased. The yellow solid was washed with THF, and the product was extracted with acetonitrile and dried to obtain the complex ML4. The isolated yield was 45% (0.014 mmol). 31 P{H} NMR (162 MHz, CD2Cl2): δ δ = 3.3~-0.1 (m, 4P), -144.5 (heptet, 1P) ppm.
[0069] The technical solution described in the present invention has not been reported in relevant literature so far. The synthesized B, H2L, ML1, ML2, ML3, and ML4 are all new compounds.
[0070] Example 5 Application as a catalyst
[0071] Under a nitrogen atmosphere, ML2 (0.005 mmol), trimethylchlorosilane (2.5 mmol) and potassium (2.5 mmol) were mixed in THF (5 mL) and stirred vigorously at room temperature for 24 h. The precipitate was filtered, the supernatant was dried by evaporation of the solvent, and the product was extracted with n-hexane. The n-hexane was removed under reduced pressure to obtain tris(trimethylsilyl)amine with a yield of 25% (0.21 mmol).
[0072] The above are all the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A planar cyclic tetradentate phosphine-molybdenum complex, characterized in that, The structural formula of the complex is as follows: ； Among them, , are each independently selected from: , ; is a substituted or unsubstituted C3-C8 cycloalkane, or A substituted or unsubstituted 3- to 8-membered heterocyclic compound; R is hydrogen or an alkane with 1 to 10 carbon atoms; m1, n1, m2, and n2 are each integers from 1 to 3.
2. A planar cyclic tetradentate phosphine-molybdenum complex according to claim 1, wherein: Same as in structure.
3. A planar cyclic tetradentate phosphine-molybdenum complex according to claim 1, wherein: identical to in structure; m1, n1, m2, and n2 are each integers from 1 to 3, and m1 is equal to n1, and m2 is equal to n2.
4. A planar cyclic tetradentate phosphine-molybdenum complex according to claim 1, characterized in that: Among them, , are each independently selected from , , .
5. A planar cyclic tetradentate phosphine-molybdenum complex according to claim 1, characterized in that, The structural formula of the complex is as follows: 。 6. Use of a planar cyclic tetradentate phosphine-molybdenum complex according to any one of claims 1-5, characterized in that: Use of the planar cyclic tetradentate phosphine-molybdenum complex as a catalyst for the silylation reaction of nitrogen.
7. Use of a planar cyclic tetradentate phosphine-molybdenum complex according to claim 6, characterized in that: The planar cyclic tetradentate phosphine-molybdenum complex is used as a catalyst for the reaction of nitrogen with trimethylchlorosilane to produce tris(trimethylsilyl)amine.