Monodentate thiol group and hydroxyl group bridged double cobalt amide and preparation method and application of monodentate thiol group and hydroxyl group bridged double cobalt amide

Abstract

The invention discloses monodentate thiol group and hydroxyl group bridged double cobalt amides as well as a preparation method and application thereof, and belongs to the technical field of preparation of metal complexes. The complex takes a monodentate thiol group, an amino group, a hydroxyl group or a hydroxylamine group as a bridging group, and each cobalt atom is coordinated with a cyclopentadiene ligand. The monodentate thiol group and bromide ion bridged double-cobalt complex is used as a precursor to mediate hydroxylamine coordination activation to initiate NO bond breakage and capture amino and hydroxyl at the same time, and monodentate thiol group and hydroxyl bridged double-cobalt amide is generated. The monodentate thiol group and hydroxyl group bridged double cobalt amide provided by the invention is converted into an amide by removing one molecule of water through a proton coupling electron transfer process, and further efficiently produces ammonia at a yield of 88% under an acidic condition.

Description

Technical Field

[0001] The present invention relates to a method for preparing a monodentate thiol group and a hydroxyl-bridged dicobalt amide using hydroxylamine, and the application of the amide in synergistic dehydration through a proton-coupled electron transfer process and in the directional conversion to ammonia under acidic conditions. Background Art

[0002] Hydroxylamine (NH2OH) is not only a redox-active intermediate in the biogeochemical nitrogen cycle of the earth but also an important chemical raw material for the synthesis of caprolactam. High-concentration NH2OH wastewater generated from industrial applications will undergo a disproportionation reaction to obtain NH3, N2O, and N2 or be oxidized to form highly reactive substances (HNO or NO), and then undergo a series of chemical reactions to form stable nitrogen-containing compounds, thereby triggering the problem of water eutrophication. The traditional method for treating hydroxylamine-containing wastewater is a thermal catalytic deoxygenation process, which is restricted by harsh reaction conditions (>200 °C) and low selectivity (by-products such as NO x ), etc., facing the dual constraints of energy efficiency bottlenecks and environmental safety hazards, which prompts researchers in the field of organometallic chemistry to mediate the coordination activation of hydroxylamine by synthesizing metal complexes, reveal the selective activation law of the N-O bond of hydroxylamine at the molecular level, rationally design the coordination microenvironment of the metal center, and promote the directional conversion of industrial nitrogen-containing waste to clean energy ammonia.

[0003] It has been reported that the reduction conversion of hydroxylamine to ammonia mediated by transition metal complexes mainly includes: mononuclear iron complexes (J. Am. Chem. Soc. 2004, 126, 13432; J. Inorg. Biochem. 2010, 104, 30; Chem. Commun. 2019, 55, 11896; J. Am. Chem. Soc. 2025, 147, 8444), etc. The existing problems are: (1) poor reaction selectivity, and other by-products (N2O, NO, etc.) are generated during the reduction process; (2) low reaction efficiency, the efficiency of the reduction conversion of hydroxylamine to ammonia is only 29.8%, and the metal complex intermediate in the reduction process has not been obtained. Summary of the Invention

[0004] To solve the problems existing in the prior art, the present invention provides a method for preparing a monodentate thiol group and a hydroxyl-bridged dicobalt amide and its application in reducing ammonia release.

[0005] The technical solution of the present invention: A monodentate thiol group-bridged dicobalt amide has Structure I:

[0006]

[0007] Wherein:

[0008] R 1 Selected from aliphatic hydrocarbon groups with 1 to 4 carbon atoms, C6 to C11 aryl and adamantyl;

[0009] R 2 selected from cyclopentadiene ligands with or without substituents;

[0010] L 1 and L 2 selected from NH2 - 、NH2O - and OH - at least one of;

[0011] n is 0 or 1;

[0012] m is 1 or 2;

[0013] when n is 1, X - selected from Cl - 、Br - 、I - 、PF6 - 、SbF6 - 、BF4 - 、BPh4 - 、CF3SO3 - 、B(C6F5)4 - and B(3,5-(CF3)2C6H3)4 - at least one of;

[0014] Specific R 1 selected from C1-C4 aliphatic hydrocarbon groups and adamantyl (Ad).

[0015] Specific R 2 selected from cyclopentadiene ligand, monomethylcyclopentadiene ligand, dimethylcyclopentadiene ligand, trimethylcyclopentadiene ligand, tetramethylcyclopentadiene ligand, pentamethylcyclopentadiene ligand and 1,2,4-tri-tert-butylcyclopentadiene ligand.

[0016] As shown in Table 1, where: Ad, Cp, Cp 1 、Cp 2 、Cp 3 、Cp 4 、Cp*, Cp' represent the following structures:

[0017]

[0018] Specific monodentate thiolato-bridged dicobalt amide structure in Table 1

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030] In a preferred embodiment of the present invention, R 1 = Et or Ad;

[0031] In another preferred embodiment, R 2 = Cp* or Cp';

[0032] In another preferred embodiment, X - = PF6 - or BPh4 - ;

[0033] In another preferred embodiment, L 1 and L 2 are OH – 、NH2O – 、NH2 – ;

[0034] More preferably, the complexes of the present invention are selected from:

[0035] Complex 1: R 1 = Ad, R 2 = Cp*, m = 1, n = 1, L 1 = NH2 – ,L 2 = OH – ,X - = BPh4 - ;

[0036] Complex 2: R 1 = Ad, R 2 = Cp*, m = 1, n = 1, L 1 = NH2 – ,L 2 = NH2O – ,X- = BPh4 - ;

[0037] Table 2 Specific structures of preferred monodentate thiolato-bridged dicobalt amides

[0038]

[0039] An object of the present invention is to provide a preparation method of a monodentate thiolato and hydroxo-bridged dicobalt amide, which is prepared according to the following route:

[0040]

[0041] (1) Preparation of Complex 1

[0042] At 0 - 30 °C, 1 - 3 equivalents of tetraphenylborate and 0.5 - 1 equivalent of hydroxylamine are successively added to Complex A and reacted for 4 - 8 h to obtain Complex 1;

[0043] The reaction is carried out in at least one solvent selected from tetrahydrofuran and ethers with 6 or fewer carbon atoms. The reaction solvent is preferably tetrahydrofuran, and the hydroxylamine is preferably a 50% by mass aqueous hydroxylamine solution;

[0044] (2) Preparation of Complex 2

[0045] At 0 - 30 °C, 1 - 3 equivalents of hydroxylamine are added to adamantylthiolato and hydroxo-bridged dicobalt amide 1 and reacted for 4 - 8 h to obtain Complex 2;

[0046] The reaction is carried out in at least one solvent selected from tetrahydrofuran and ethers with 6 or fewer carbon atoms. The reaction solvent is preferably tetrahydrofuran, and the hydroxylamine is preferably a 50% by mass aqueous hydroxylamine solution;

[0047] The application of the present invention is to provide a monodentate thiolato-bridged dicobalt amide to achieve ammonia liberation upon acidification, which is transformed according to the route shown in the following formula:

[0048]

[0049] (1) Conversion of Complex 1 to Complex B

[0050] At - 80 - 0 °C, 2 - 4 equivalents of a reducing agent and 1 - 2 equivalents of a protonic acid salt are added to Complex 1 and reacted to room temperature to obtain Complex B;

[0051] The reaction solvent is preferably tetrahydrofuran, the reducing agent is preferably cobaltocene, and the protonic acid salt is preferably lutidine tetraphenylborate;

[0052] (2) At 20 - 40 °C, 2 - 5 equivalents of a protonic acid salt are added to Complex B and reacted for 3 h to obtain an ammonium salt;

[0053] The reaction solvent is preferably tetrahydrofuran; the protonic acid salt is preferably lutidine hydrochloride.

[0054] The method provided by the present invention further includes steps for product purification such as distillation, extraction, filtration, etc. The purification steps are all common knowledge in the art, well-known to those skilled in the art, and will not be elaborated herein.

[0055] Compared with the prior art, the advantages of the present invention are as follows:

[0056] (1) Hydroxylamine coordination activation is achieved through an earth-abundant metal cobalt-containing organic complex, and the N-O bond of hydroxylamine is selectively cleaved directionally instead of the O-H bond, thereby suppressing the formation of by-products (such as N2O, NO).

[0057] (2) Traditional thermal decomposition of hydroxylamine requires high temperature and is prone to explosion risks. However, the monodentate thiolato-bridged dicobalt precursor complex enables efficient conversion of hydroxylamine to ammonia under mild conditions. This process does not require external strong acids / strong bases, and the by-product is only water, meeting the principle of atom economy and providing a green path for the resource treatment of industrial hydroxylamine-containing wastewater.

[0058] (3) The monodentate thiolato- and bromide-bridged dicobalt complex mediates hydroxylamine coordination activation to initiate N-O bond cleavage and simultaneously capture amino and hydroxyl groups, generating a monodentate thiolato- and hydroxyl-bridged dicobalt amide. The monodentate thiolato- and hydroxyl-bridged dicobalt amide provided by the present invention is converted into an amide by removing one molecule of water through a proton-coupled electron transfer process, and it efficiently produces ammonia with an 88% yield under acidic conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 is the preparation route diagram of the monodentate thiolato- and hydroxyl-bridged dicobalt amide.

[0060] Figure 2 is the application of the monodentate thiolato- and hydroxyl-bridged dicobalt amide.

[0061] Figure 3 is the crystal structure of complex 1.

[0062] Figure 4 is the crystal structure of complex 2. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0063] The following examples can enable those of ordinary skill in the art to understand the present invention more comprehensively, but do not limit the present invention in any way. The methods adopted in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained through commercial channels.

[0064]

[0065] Example 1 Preparation of Complex 1

[0066] In an argon atmosphere, the complex [Cp*Co(μ-SAd)(μ-Br)CoCp*] (A, 63.6 mg, 0.10 mmol) was dissolved in 7 mL of tetrahydrofuran solution. One equivalent of sodium tetraphenylborate (34.3 mg, 0.10 mmol) and 0.9 equivalent of hydroxylamine (6 μL, 0.090 mmol, wt. 50%) were added successively. The reaction was carried out at 25 °C for 8 h. The color of the solution changed from light yellow to dark red. The solvent was removed by vacuum drying. The reaction product was extracted with dichloromethane (3 × 5 mL), and then washed with diethyl ether (3 × 5 mL) after vacuum drying to obtain a black-purple powder [Cp*Co(μ-SAd)(μ-NH2)(μ-OH)CoCp*][BPh4] (1, 38.2 mg, 0.065 mmol, 65%). Single crystals suitable for X-ray single crystal diffraction were obtained by the dichloromethane / n-hexane dual-solvent diffusion method.

[0067] 1 1H NMR (400 MHz, CD2Cl2, ppm): δ 7.31 (br, 8H, Ph-H), 7.03 (br, 8H, Ph-H), 6.88 (br, 4H, Ph-H), 2.20 (br, 9H, Ad-H), 1.81 (br, 6H, Ad-H), 1.31 (s, 30H, Cp*-CH3), -0.89 (br, 1H, OH), -1.37 (br, 1H, NH2), -7.12 (br, 1H, NH2). IR (Film, cm –1 ): 3605, 3567 (v OH ), 3348 (v NH ), 3275 (v NH ), 3034, 2912, 2851, 1580, 1478, 1376, 1036, 731. HRMS (ESI, m / z) Calcd. for [1-BPh4] + , 588.2120, Found 588.2114. Anal. Calcd. for C 54 H 68 Co2BNOS: C, 71.44; H, 7.55; N, 1.54. Found: C, 71.70; H, 7.20; N, 1.06.

[0068] Example 2 Preparation of Complex 2

[0069] In an argon atmosphere, the complex [Cp*Co(μ-SAd)(μ-NH2)(μ-OH)CoCp*][BPh4] (1, 58.8 mg, 0.10 mmol) was dissolved in 7 mL of tetrahydrofuran, and 1.5 equivalents of hydroxylamine (10 μL, 0.15 mmol, wt. 50%) was added. The reaction was carried out at 25 °C for 6 h. The solvent was removed by vacuum drying. The product was extracted with dichloromethane (3 × 5 mL), and after vacuum drying, it was washed with diethyl ether (3 × 5 mL) to obtain a black-purple powder [Cp*Co(μ-SAd)(μ-η 1 :η 1 -NH2O)(μ-NH2)CoCp*][BPh4] (2, 38 mg, 0.063 mmol, 63%). Crystals suitable for X-ray single crystal diffraction were obtained by the double-solvent diffusion method of dichloromethane / n-hexane.

[0070] 1 1H NMR (400 MHz, CD2Cl2, ppm): δ 7.34 (s, 8H, Ph-H), 7.04 (t, 8H, Ph-H), 6.89 (t, 4H, Ph-H), 6.12 (d, 1H, NH2O-H), 5.74 (d, 1H, NH2O-H), 2.16 (t, 9H, Ad-H), 1.78 (br, 6H, Ad-H), 1.36 (s, 15H, Cp*-CH3), 1.29 (s, 15H, Cp*-CH3), -0.30 (br, 1H, NH2), -0.81 (br, 1H, NH2). IR (Film, cm –1 ): 3353 (v NH ), 3328 (v NH ), 3256 (v NH ), 3206 (v NH ), 3052, 2907, 2851, 1479, 1425, 1378, 1033, 704. HRMS (ESI, m / z) Calcd for [2–BPh4] + , 603.2230, Found 603.2270. Anal. Calcd for C 54 H 69 Co2BN2OS: C, 70.28; H, 7.54; N, 3.04. Found: C, 70.73; H, 7.516; N, 3.25.

[0071]

[0072] Example 3 Reduction of Complex 1 to Complex B

[0073] In an argon atmosphere, at -78 °C, the complex [Cp*Co(μ-SAd)(μ-NH2)(μ-OH)CoCp*][BPh4] (1, 58.8 mg, 0.10 mmol) was dissolved in 6 mL of tetrahydrofuran. To the solution were successively added the protonate lutidinium proton acid (42.7 mg, 0.10 mmol) and the one-electron reducing agent cobaltocene (37.8 mg, 0.20 mmol). At -78 °C, the color of the solution changed from purple-red to green, and when the temperature was slowly raised to room temperature, there was no obvious change in the color of the solution. The solvent was removed by vacuum drying, and the product was extracted with n-hexane (3 × 5 mL). After vacuum drying, the complex [Cp*Co(μ-SAd)(μ-NH2)CoCp*] (B, 38.8 mg, 0.068 mmol, 68%) was obtained.

[0074] Example 4 Acidolysis of Complex B to Produce Ammonia

[0075] In an argon atmosphere, the complex [Cp*Co(μ-SAd)(μ-NH2)CoCp*] (B, 57.1 mg, 0.1 mmol) was dissolved in 5 mL of tetrahydrofuran. Lutidinium hydrochloride (29 mg, 0.2 mmol) was added to the solution, and the reaction was carried out at 25 °C for 3 h. The solution changed from green to brown-red. The solvent was removed by vacuum drying, and the complex part was extracted with n-hexane (3 × 5 mL). The remaining solid was added with an internal standard (ferrocene), and 1H NMR was measured with DMSO-d6 to determine the yield of NH4Cl (0.088 mmol, 88%).

[0076] The structures of Complexes 1 and 2 were characterized by X-ray single crystal diffraction (instrument used: Bruker Smart Apex CCD single crystal diffractometer). The important crystallographic data are shown in Table 3, and their crystal structures are as Figure 3 and 4 , and the main structural parameters are shown in Tables 4 and 5.

[0077] Table 3 Crystallographic Data of Complexes 1 and 2

[0078]

[0079] Table 4 Main Bond Lengths, Bond Angles and Dihedral Angles of Complex 1

[0080]

[0081] Table 5 Main Bond Lengths, Bond Angles and Dihedral Angles of Complex 2

[0082]

[0083] The above embodiments are only used to illustrate the present invention. Any equivalent transformation and improvement made on the basis of the technical solution of the present invention should not be excluded from the protection scope of the present invention.

Claims

1. Monodentate thiol group and amino group bridged bicoordinate cobalt complex, characterized in that The structure of the complex is as shown in General Formula I: ； Wherein: R 1 an aliphatic hydrocarbon group selected from C1 to C4, an aryl group of C6 to C 11 or an adamantyl group; R 2 selected from cyclopentadiene ligands with or without substituents; L 1 and L 2 at least one of which is selected from NH2 − , NH2O − or OH − , and L 1 and L 2 are different; n is 0 or 1; m is 1 or 2; When n is 1, X − is selected from Cl − , Br − , I − , PF6 − , SbF6 − , BF4 − , BPh4 − , CF3SO3 − , B(C6F5)4 − and B(3,5-(CF3)2C6H3)4 − and at least one of them.

2. The complex according to claim 1, characterized in that: R 1 An aliphatic hydrocarbon group selected from C1 to C4, an aryl group of C6 to C 11 or adamantyl Ad; R 2 selected from cyclopentadienyl ligand Cp, monomethylcyclopentadienyl ligand Cp 1 , dimethylcyclopentadienyl ligand Cp 2 , trimethylcyclopentadienyl ligand Cp 3 , tetramethylcyclopentadienyl ligand Cp 4 , pentamethylcyclopentadienyl ligand Cp*, and 1,2,4-tri-tert-butylcyclopentadienyl ligand Cp'; Ad, Cp, Cp 1 , Cp 2 , Cp 3 , Cp 4 , Cp*, Cp' have the structure: 。 3. The complex according to claim 1, characterized in that, The structure of the complex is as shown in General Formula I: ； Where: R 1 、R 2 、m, n, L 1 、L 2 Are as shown in the following table: Among them, Et is ethyl, i -Pr is isopropyl; Ad, Cp, Cp 1 , Cp 2 , Cp 3 , Cp 4 , Cp*, Cp' have the following structures: 。 4. The complex according to claim 3, characterized in that: The complex is Complex 1 and Complex 2: Complex 1: R 1 = Ad, R 2 = Cp*, L 1 = NH2 − , L 2 = OH − , X − = BPh4 − , n = 1, m = 1; Complex 2: R 1 = Ad, R 2 = Cp*, L 1 = NH2 − , L 2 = NH2O − , X − = BPh4 − , n = 1, m = 1。 5. The preparation method of the complex according to claim 4, characterized in that, Comprising the following steps: ； (1) Preparation of Complex 1 Under the condition of 0 - 30 °C, 1 - 3 equivalents of tetraphenylborate and 0.5 - 1 equivalent of hydroxylamine are successively added to Compound A and reacted for 4 - 8 h to obtain Complex 1; (2) Preparation of Complex 2 Under the condition of 0 - 30 °C, 1 - 3 equivalents of hydroxylamine are added to Complex 1 and reacted for 4 - 8 h to obtain Complex 2.

6. The preparation method of the complex according to claim 5, wherein In step (1), the reaction solvent is selected from at least one of tetrahydrofuran and ethers with 6 or less carbon atoms; the tetraphenylborate is sodium tetraphenylborate or potassium tetraphenylborate.

7. The preparation method of the complex according to claim 5, wherein, In step (2), the reaction is carried out in at least one solvent of tetrahydrofuran and ethers with 6 or less carbon atoms; the hydroxylamine is 30% by mass aqueous hydroxylamine solution or 50% by mass aqueous hydroxylamine solution.

8. Use of the complex according to any one of claims 1-4, characterized in that: The complex is applied to the reduction for ammonia production.

9. Use of the complex according to claim 8, characterized in that: Complex 1 is reductively transformed into Complex B, thereby achieving efficient reduction for ammonia production: ； (1) Transformation of Complex 1 into Complex B Under the condition of - 80 - 0 °C, 2 - 4 equivalents of a reducing agent and 1 - 2 equivalents of a protonic acid salt are added to Complex 1 and reacted to room temperature to obtain Complex B; (2) Acidolysis of Complex B for ammonia production Under the condition of 20 - 40 °C, 2 - 5 equivalents of an acidolysis protonic acid salt are added to Complex B and reacted for 2 - 5 h to obtain an ammonium salt.

10. Use of the complex according to claim 9, characterized in that, In step (1), the reaction solvent is at least one of tetrahydrofuran and acyclic ethers with 6 or less carbon atoms; the reducing agent is cobaltocene or chromocene; the protonic acid salt is lutidine tetraphenylborate or lutidine hexafluorophosphate; In step (2), the reaction solvent is tetrahydrofuran; the acidolysis protonic acid salt is lutidine hydrochloride, tetrafluoroboric acid or hexafluorophosphoric acid.

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