O-aminothiophenol bridged bimetallic complex and preparation method thereof

Abstract

The invention belongs to the technical field of preparation of sulfur-bridged bimetallic complexes, and discloses an o-aminothiophenol bridged bimetallic complex and a preparation method thereof. The bimetal complex comprises a ferrocobalt complex and a bicobalt complex, and each metal atom is coordinated with a cyclopentadiene ligand or substituted cyclopentadiene ligand. An o-amino thiophenol mononuclear cobalt complex reacts with mononuclear iron or a cobalt precursor, and the bimetallic complex is prepared through a directional assembly strategy. The two novel complexes are clear in structure, simple in synthesis step and easy in post-treatment, and have application potential in the field of hydrogen production through catalytic proton reduction.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of sulfur-bridged bimetallic complexes, and relates to o-aminothiophenol-bridged bimetallic complexes and their preparation methods, specifically to two o-aminothiophenol-bridged binuclear metal complexes with different coordination modes and their preparation methods. Background Art

[0002] o-Aminothiophenol (abt) and its derivatives are redox non-conservative ligands. At the same time, the amino group of this ligand can be protonated, deprotonated, and alkylated, so that its complexes are widely used in the research of biomimetic metal sulfur clusters. Existing research has shown that bdt-bridged dicobalt complexes exhibit excellent performance in the field of catalytic proton reduction to produce hydrogen (Dalton Trans. 2016, 45, 18559).

[0003]

[0004] The abt ligand can transfer protons in the catalytic cycle, so abt-bridged bimetallic complexes with similar structures may exhibit better catalytic performance. However, its complex redox activity makes it extremely challenging to construct abt-bridged bimetallic complexes directionally.

[0005] The reported preparations of o-aminothiophenol-bridged bimetallic complexes mainly include: binuclear manganese complexes (Inorg. Chem. 2001, 40, 3468), binuclear iron complexes (Dalton Trans. 2009, 17, 3298), binuclear iron complexes (Inorg. Chem. 2003, 42, 3208), binuclear ytterbium complexes (Organometallics 2005, 24, 738), binuclear dysprosium complexes (Organometallics 2006, 25, 4571), binuclear cobalt complexes (Eur. J. Inorg. Chem. 2002, 8, 1957; Z. Anorg. Chem. 2010, 637, 430), binuclear molybdenum complexes (Inorg. Chem. 2012, 51, 7284; Organometallics 2014, 33, 1181), etc.

[0006] Most of the reported binuclear complexes are coordinatively saturated dimers, and it is difficult to achieve functional transformation. Therefore, it is of great significance to explore the synthesis method of abt-bridged bimetallic complexes with both stability and reactivity. Summary of the Invention

[0007] In order to make up for the deficiencies of the prior art, the present invention aims to provide two o-aminothiophenol-bridged bimetallic complexes and their preparation methods.

[0008] The technical solution of the present invention is as follows:

[0009] The o-aminothiophenol-bridged binuclear metal complex has the following structure:

[0010]

[0011] In the general structural formula:

[0012] M is selected from Fe and Co;

[0013] R 1 is selected from a hydrogen atom, a methyl group, and a p-toluenesulfonyl group (Ts);

[0014] R 2 is selected from a cyclopentadiene ligand, a monomethylcyclopentadiene ligand, a dimethylcyclopentadiene ligand, a trimethylcyclopentadiene ligand, a tetramethylcyclopentadiene ligand, a pentamethylcyclopentadiene ligand, and a 1,2,4-tri-tert-butylcyclopentadiene ligand;

[0015] X - is an anti-anion and is selected from Cl - 、Br - 、I - 、PF6 - 、SbF6 - 、BF4 - 、BPh4 - 、CF3SO3 - and B(C6F5)4 - any one of them;

[0016] n is 0 or 1;

[0017] m is 0 or 1.

[0018] According to the above description, the specific complex structures are listed in Table 1, where: Ts, Cp, Cp 1 、Cp 2 、Cp 3 、Cp 4 、Cp*, Cp' represent the following structures:

[0019]

[0020] Table 1 Structures of o-aminothiophenol-bridged bimetallic complexes

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034] In a preferred embodiment of the present invention, R 1 = H or Me;

[0035] In another preferred embodiment, R 2 = Cp* or Cp';

[0036] In another preferred embodiment, X - = PF6 - or BPh4 - .

[0037] More preferably, the complexes of the present invention are selected from:

[0038] Complex 1: M = Fe, R 1 = H, R 2 = Cp*, m = 0, n = 1, X - = PF6 - ;

[0039] Complex 2: M = Co, R 1 = H, R 2 = Cp*, m = 1, n = 1, X - = BPh4 - ;

[0040] The preferred o-aminothiophenol-bridged binuclear metal complex has the following structure:

[0041]

[0042] Another object of the present invention is to provide a method for preparing an o-aminothiophenol-bridged binuclear metal complex, which is prepared according to the following route.

[0043]

[0044] (1) Preparation of o-aminothiophenol-bridged cobalt-iron complex 1

[0045] Under the condition of -100 to 0 °C, 1 to 3 equivalents of mononuclear iron complex was added to the o-aminothiophenol mononuclear cobalt complex A, and the reaction was carried out for 0.5 to 2 h. After the temperature was raised to room temperature, the reaction was continued for 1 to 8 h to obtain o-aminothiophenol-bridged cobalt-iron complex 1;

[0046] The reaction was carried out in ethers with carbon number C 10 the following ethers, benzene, ethers with carbon number C 10 the following alkylbenzenes, alkanes with carbon number C5 - C 10 alkanes, haloalkanes with carbon number C6 or less, alcohols with carbon number C5 or less, chlorobenzene, fluorobenzene, acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide, preferably tetrahydrofuran, dichloromethane, methanol; the mononuclear iron complex was preferably [Cp*Fe(MeCN)3][PF6];

[0047] (2) Preparation of o-aminothiophenol-bridged bis-cobalt complex 2

[0048] Under the condition of -100 to 0 °C, 0.5 to 1.5 equivalents of binuclear cobalt complex and 1 to 10 equivalents of ion salt exchange anti-anion were added to the o-aminothiophenol mononuclear cobalt complex A, and the reaction was carried out for 0.5 to 2 h. After the temperature was raised to room temperature, the reaction was continued for 1 to 8 h to obtain o-aminothiophenol-bridged bis-cobalt complex 2.

[0049] The reaction was carried out in ethers with carbon number C 10 the following ethers, benzene, ethers with carbon number C 10 the following alkylbenzenes, alkanes with carbon number C5 - C 10 alkanes, haloalkanes with carbon number C6 or less, alcohols with carbon number C5 or less, chlorobenzene, fluorobenzene, acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide, preferably tetrahydrofuran, dichloromethane, methanol; the binuclear cobalt precursor was preferably [Cp*Co(μ-Cl)2(μ-Cl)2CoCp*]; the metal salt was preferably sodium tetraphenylborate.

[0050] The method provided by the present invention also includes steps for product purification such as distillation, extraction, filtration, etc. The purification steps are all well-known common knowledge in the art and are familiar to those skilled in the art, so they will not be elaborated here.

[0051] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0052] (1) Most of the reported ABT-bridged bimetallic complexes are coordinatively saturated dimers, and some of them are prone to decomposition into mononuclear complexes due to insufficient stability, making it difficult to achieve functional transformation. Through the strategy of directed assembly of mononuclear precursors, two novel bimetallic complexes were successfully synthesized, avoiding the by-product problems caused by the traditional oxidative substitution strategy and significantly improving the selectivity and yield of the synthesis.

[0053] (2) The reported BDT-bridged complexes can achieve electrocatalytic proton reduction to produce ammonia. Since the two bimetallic complexes invented in this patent are derived from a simple modulation of the bridging atom, we have reason to believe that they have similar catalytic potential. At the same time, the protonation performance of the amino group of the ABT ligand helps with proton transfer in the electrocatalytic process. In addition, by analyzing and comparing the characterization data, the distance between the bimetallic centers of Complex 1 and 2 is shorter, indicating a stronger bimetallic synergistic effect.

[0054] (3) The bis-cobalt complex of this invention has a bridging chloride ion, which can serve as a potential reaction site, providing active sites for subsequent functionalization reactions, giving full play to the bimetallic synergistic effect, and expanding the function to other small molecule activation fields (such as carbon dioxide reduction, water oxidation, etc.). Compared with the synthesis method of the reported BDT-bridged bis-cobalt complex, this method does not require the addition of external base and can be carried out at room temperature, meeting the concept of green chemistry.

[0055] The structures of the two novel complexes are well-defined, the synthesis steps are simple, and the post-treatment is easy, showing potential applications in the field of catalytic proton reduction to produce hydrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 For the crystal structure of [Cp*Co(μ-η 2 :η 4 -abt)FeCp*][PF6] (1);

[0057] Figure 2 For the crystal structure of [Cp*Co(μ-η 2 :η 2 -abt)(μ-Cl)CoCp*][PF6] (2). DETAILED DESCRIPTION OF THE INVENTION

[0058] 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 used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained through commercial channels.

[0059] Example 1 Preparation of Complex 1

[0060] In an argon or nitrogen atmosphere, at -78 °C, [Cp*Co(abt)] (A, 34.6 mg, 1.0 mmol) was added to a dichloromethane (5 mL) solution of [Cp*Fe(MeCN)3][PF6] (50.0 mg, 1.09 mmol). The solution gradually changed from blue to purple-red, and the reaction was carried out for 2 h. After the temperature was raised to room temperature, the reaction was continued for 1 h. The solvent was removed under vacuum, and the product was washed with n-hexane (3 × 5 mL) and dried under reduced pressure to obtain a black powder [Cp*Co(μ-η 2 :η 4 -abt)FeCp*][PF6] (1, 64.7 mg, 0.99 mmol, 91%). Suitable crystals for X-ray single crystal diffraction were obtained by the dichloromethane / n-hexane double-solvent diffusion method.

[0061] 1 1H NMR (400 MHz, CDCl3, ppm, 298 K): 1.42 (s, 15H, Cp*-H), 1.87 (s, 15H, Cp*-H), 7.16 (d, J = 8.69 Hz, 1H, abt-H), 7.44 (m, 2H, abt-H), 7.92 (d, J = 8.62 Hz, 1H, abt-H), 8.61 (s, 1H, NH). IR (KBr; cm -1 ): 3318 (v N-H ), 2936, 2922, 2854, 1651, 1471, 1381, 1261, 1023, 842, 756, 558; HRMS (ESI, m / z): Calcd. For C 26 H 35 CoFeNS[1] + , 508.1172, Found 508.1168. Anal. Calcd. For C 26 H 35 CoF6FeNPS: C, 47.80; H, 5.40; N, 2.14. Found: C, 46.88; H, 5.74; N, 2.02.

[0062] Example 2 Preparation of Complex 1

[0063] Same as Example 1, except that the reaction solvent was changed from dichloromethane to tetrahydrofuran, and the yield was 83%.

[0064] Example 3 Preparation of Complex 2

[0065] In an argon or nitrogen atmosphere, at -78 °C, [Cp*Co(abt)] (A, 29.8 mg, 0.94 mmol) and sodium tetraphenylborate (32.3 mg, 0.94 mmol) were added to a methanol (5 mL) solution of [Cp*Co(μ-Cl)2(η-Cl)2CoCp*] (50.0 mg, 0.94 mmol). The reaction was carried out for 2 h, and then continued for 1 h after the temperature was raised to room temperature. The solvent was removed under vacuum, and the product was extracted with dichloromethane (2 × 5 mL) and dried by suction. The product was washed with n-hexane (3 × 5 mL) and dried under reduced pressure to obtain a black powder [Cp*Co(μ-η 2 :η 2 -abt)(μ-Cl)CoCp*][PF6] (2, 53.3 mg, 0.77 mmol, 82%). Suitable crystals for X-ray single crystal diffraction were obtained by the dichloromethane / n-hexane double solvent diffusion method.

[0066] 1 1H NMR (400 MHz, CDCl3, ppm, 298 K) δ: 1.15 (s, 30H, Cp*-H), 5.65 (br, 2H, abt-H), 6.86 (br, 2H, abt-H); IR (KBr; cm -1 ): 3312 (v N-H ), 3064, 2987, 2914, 1564, 1472, 1377, 1020, 841, 730, 557; HRMS (ESI, m / z): Calcd. For C 26 H 35 Co2NS[2] + , 546.0843, Found 546.0838. Anal. Calcd. For C 26 H 35 Co2F6NPS: C, 45.13; H, 5.10; N, 2.02. Found: C, 45.28; H, 5.42; N, 1.95.

[0067] Preparation of Complex 2 in Example 4

[0068] Same as Example 2, except that the reaction solvent was changed from methanol to ethanol, and the yield was 73%.

[0069] The structures of Complexes 1 and 2 were determined by X-ray single crystal diffraction characterization (instrument used: Bruker Smart Apex CCD single crystal diffractometer). The important crystallographic data are shown in Table 2, and their crystal structures are as shown in Figure 1 and 2 shown, and the main structural parameters are shown in Tables 3 and 4.

[0070] Table 2 Crystallographic data of Complexes 1 and 2

[0071]

[0072] Table 3 Main bond lengths, bond angles and dihedral angles of Complex 1

[0073]

[0074] Table 4 Main bond lengths, bond angles and dihedral angles of Complex 2

[0075]

[0076]

[0077] The above-described embodiments are only the preferred embodiments of the present invention, rather than all the feasible embodiments of the present invention. Any obvious modifications made by those of ordinary skill in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. o - aminothiophenol - bridged bimetallic complex, characterized in that, The bimetallic complexes include cobalt-iron and bis-cobalt complexes; the structural formula is as shown in I; Wherein: M is selected from Fe and Co; R 1 selected from a hydrogen atom, a methyl group, and a p-toluenesulfonyl group (Ts); R 2 selected from cyclopentadienyl ligand, monomethylcyclopentadienyl ligand, dimethylcyclopentadienyl ligand, trimethylcyclopentadienyl ligand, tetramethylcyclopentadienyl ligand, pentamethylcyclopentadienyl ligand and 1,2,4-tri-tert-butylcyclopentadienyl ligand; X - is an anion, selected from Cl - , Br - , I - , PF6 - , SbF6 - , BF4 - , BPh4 - , CF3SO3 - and B(C6F5)4 - ; any one of them n is 0 or 1; m is 0 or 1.

2. The o-aminothiophenol-bridged bimetallic complex according to claim 1, wherein: The bimetallic complexes are selected from Complex 1 and 2: Complex 1: M = Fe, R 1 = H, R 2 = Cp*, m = 0, n = 1, X - = PF6 - ; Complex 2: M = Co, R 1 = H, R 2 = Cp*, m = 1, n = 1, X - = BPh4 - .

3. Preparation method of o-aminothiophenol-bridged bimetallic complex, characterized in that, Prepared according to the following route:

4. The preparation method of the o-aminothiophenol-bridged binuclear metal complex according to claim 3, characterized in that, The specific preparation method includes the following steps: (1) Preparation of o-aminobenzenethiol-bridged cobalt-iron complex 1 Under the condition of -100 to 0 °C, 1 to 3 equivalents of mononuclear iron complex are added to the o-aminobenzenethiol mononuclear cobalt complex A, and the reaction is carried out for 0.5 to 2 h. After the temperature rises to room temperature, the reaction is continued for 1 to 8 h to obtain o-aminobenzenethiol-bridged cobalt-iron complex 1; (2) Preparation of o-aminobenzenethiol-bridged bis-cobalt complex 2 Under the condition of -100 to 0 °C, 0.5 to 1.5 equivalents of binuclear cobalt complex and 1 to 10 equivalents of ion salt exchange anti-anion are added to the o-aminobenzenethiol mononuclear cobalt complex A, and the reaction is carried out for 0.5 to 2 h. After the temperature rises to room temperature, the reaction is continued for 1 to 8 h to obtain o-aminobenzenethiol-bridged bis-cobalt complex 2.

5. The preparation method of the o-aminothiophenol-bridged bimetallic complex according to claim 4, characterized in that, The reactions described in steps (1) and (2) are carried out in any one of the following solvents: ethers, benzene, alkanes having C carbon atoms, 10 alkylbenzenes having C carbon atoms, 10 alkanes having C5 to C carbon atoms, 10 halogenated alkanes having C6 or fewer carbon atoms, alcohols having C5 or fewer carbon atoms, chlorobenzene, fluorobenzene, acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide.

6. The preparation method of the o-aminothiophenol-bridged bimetallic complex according to claim 4, characterized in that, The reactions described in steps (1) and (2) are carried out in any one of the solvents of tetrahydrofuran, dichloromethane, and methanol.

7. The preparation method of the o-aminothiophenol-bridged bimetallic complex according to claim 4, characterized in that, The mononuclear iron complex described in step (1) is [Cp*Fe(MeCN)3][PF6].

8. The preparation method of the o-aminothiophenol-bridged bimetallic complex according to claim 4, characterized in that, The binuclear cobalt complex described in step (2) is [Cp*Co(μ-Cl)2(η-Cl)2CoCp*].

9. The preparation method of the o-aminothiophenol-bridged bimetallic complex according to claim 4, characterized in that, The salt described in step (2) is sodium tetraphenylborate.

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