CN108822152A - Osmium bidentate N base complex and preparation method thereof with catalysis ammonia borine dehydrogenation activity - Google Patents

Abstract

The invention discloses an osmium bidentate N-base complex with catalytic activity for ammonia borane dehydrogenation and a preparation method thereof, belonging to the technical field of inorganic synthesis and catalysis. A series of osmium nitrogen complexes can be produced by reacting OsCl ₂ (PPh ₃ ) ₃ with phenanthroline bidentate N-based active ligands in an organic solvent at room temperature. This method has mild conditions, easy separation of products and high yield. When it is applied to catalyze the dehydrogenation reaction of ammonia borane, it has high catalytic activity.

Description

Osmium bidentate N-base complex with catalytic ammonia borane dehydrogenation activity and preparation method thereof

technical field

The invention relates to an osmium bidentate N-base complex with catalytic activity for ammonia borane dehydrogenation and a preparation method thereof, belonging to the technical field of inorganic synthesis and catalysis.

Background technique

In recent years, with the increasing energy and environmental problems, it is imminent to develop a sustainable and clean energy system to replace the existing energy carriers. Hydrogen energy has become the preferred new energy due to its many advantages such as large reserves, wide distribution, high combustion value, and zero pollution to the environment. However, safe and efficient hydrogen storage and transportation methods are the key to the large-scale application of hydrogen energy. Chemical hydrogen storage has the advantages of high hydrogen storage density and good safety, and has received extensive attention in recent years. Among them, ammonia borane (NH ₃ BH ₃ , AB) has become the most potential chemical hydrogen storage material by virtue of its theoretical hydrogen storage capacity of up to 19.6 wt%, and being a stable solid at room temperature.

However, although ammonia borane has various advantages as a potential hydrogen storage material, there are still problems such as high hydrogen release temperature during the hydrogen release process, the generation of impurity gases, volume expansion, and difficult regeneration during the hydrogen release process. To this end, a series of research work on improving the hydrogen release performance of ammonia borane has been rapidly carried out worldwide, such as loading ammonia borane on porous materials, metal substitution chemical activation, and the use of additives or catalysts. Among many measures, the use of metal-catalyzed ammonia borane dehydrogenation is one of the most effective methods to improve the amount of hydrogen released, the selectivity and kinetics of the hydrogen released reaction.

At present, the ammonia borane dehydrogenation catalysts that have been studied in the world involve a variety of metals in the front, middle and back transition systems [Chem. Rev. 2010, 110, 4023-4078]. Among them, the three transition metal catalysts of ruthenium, rhodium and iridium have shown relatively excellent performance [Synthesis and Application of Organoboron Compounds.Topics in Organometallic Chemistry.2015,49,153-220.], their introduction changed the reaction path and reduced the The activation energy of the reaction effectively increases the hydrogen release reaction rate and reduces the hydrogen release temperature. The third transition metal osmium and ruthenium, rhodium, and iridium are both in the VIII group of the periodic table, and have certain similarities in properties. The wide application of the latter three in the catalytic ammonia borane dehydrogenation reaction makes the osmium metal It has a great possibility to be applied to this kind of reaction, and it is expected to become a new catalyst for the dehydrogenation of ammonia borane.

Therefore, the development of new and efficient osmium catalysts with catalytic activity for the dehydrogenation of ammonia borane is worthy of further exploration and excavation.

Contents of the invention

The technical problem solved by the present invention is to provide a class of osmium bidentate N-based complex catalysts and a preparation method thereof. By selecting a suitable active N-based ligand, designing and optimizing the synthesis route, a catalyst with high-efficiency catalytic ammonia borane dehydrogenation is obtained. A new class of osmium bidentate N-group catalysts.

The method of the osmium bidentate N-base complex of the present invention is characterized in that: after reacting OsCl ₂ (PPh ₃ ) ₃ with an active bidentate N-base ligand in an organic solvent, the osmium bidentate N-base complex can be obtained. base complexes.

The structures of such osmium bidentate diamine complexes are as follows:

Further, in the above technical scheme, the bidentate N ligand is selected from 1,10-phenanthroline or substituted 1,10-phenanthroline.

Preferably,

Further, in the above technical scheme, the reaction is carried out under anhydrous and oxygen-free conditions.

Further, in the above technical solution, the molar ratio of OsCl ₂ (PPh ₃ ) ₃ to the active bidentate N ligand is 1:1-2, preferably 1:1.2, and the reaction temperature is 20-25°C.

Further, in the above technical solution, the reaction solvent is selected from dichloromethane, chloroform, tetrahydrofuran or 1,2-dichloroethane. The dichloromethane solvent is preferred.

Its concrete reaction steps comprise as follows:

(1) Preparation of the crude product of osmium bidentate N-group complex: add OsCl ₂ (PPh ₃ ) ₃ and bidentate N-group ligand into the reaction flask, then add anhydrous solvent to dissolve, stir and react, then concentrate under reduced pressure to obtain Osmium bidentate N-ligand complex crude product;

(2) Purification of the crude product of the osmium bidentate N-base complex: the crude product is washed with an anhydrous solvent, filtered, and dried to obtain the solid of the purified osmium bidentate N-base complex;

In step (1), the molar ratio of OsCl ₂ (PPh ₃ ) ₃ to the bidentate N-based ligand is 1:1-2, and the reaction condition is stirring at 15-30° C. for 1-10 h. The preferred reaction conditions are stirring at 20-25°C for 4h;

The organic solvent washing solvent in step (2) is selected from n-pentane, n-hexane or n-heptane. The preferred solvent is n-hexane, and the number of washings is preferably 4 times.

Preferably, drying in the step (2) adopts vacuum/high-purity nitrogen flow switching, and the switching frequency is 0.5-1h/time;

In the present invention, the high-purity nitrogen used in drying refers to nitrogen with a purity of 99.95%-99.99%.

Beneficial effects of the present invention:

The preparation method of the osmium bidentate N-base complex of the invention has simple steps, mild reaction conditions and low energy consumption, and is suitable for large-scale production. The obtained complex exhibits excellent catalytic activity in catalyzing the dehydrogenation reaction of ammonia borane.

Detailed ways

The above-mentioned contents of the present invention are described in further detail below through the embodiments, but this should not be interpreted as the scope of the above-mentioned themes of the present invention being limited to the following embodiments, and all technologies realized based on the above-mentioned contents of the present invention all belong to the scope of the present invention.

Example 1

Weigh 1,10-phenanthroline (45mg, 0.25mmol) and _{OsCl 2} (PPh ₃ ) ₃ (220mg, 0.21mmol) into a 25mL reaction flask with a magnet, and add 15mL of dichloro Methane solvent, stirred and reacted at 20-25°C for 4h, the solution changed from dark green to purple-black. After the reaction was completed, the reaction solution was concentrated, and 20 mL of anhydrous n-hexane was added to form a purple-red precipitate, which was the crude product of 1,10-phenanthroline substituted osmium nitrogen complex. The crude product was washed with n-hexane (4 times, 40 mL), filtered and dried to obtain a purplish red solid of osmium nitrogen complex with a yield of 148 mg and a yield of 73%.

The result of NMR analysis is ¹ H NMR (400MHz, CDCl ₃ ): 8.9(s, 2H, Ar), 7.9(d, J=8.0Hz, 2H, Ar), 7.8(s, 2H, Ar), 7.0(d ,J=5.6Hz,2H,Ar),7.3(t,J=7.2Hz,12H,PPh ₃ ),7.1(t,J=7.0Hz,6H,PPh ₃ ),6.9(t,J=7.2Hz, 12H,PPh ₃ ). ¹³ C{ ¹ H}NMR(101MHz,DMSO)}: 157.0(s,Ar),150.1(s,Ar),136.2(s,Ar),135.7(s,PPh ₃ ),130.3 (s,Ar),129.4(s,PPh ₃ ),127.8(s,Ar),127.3(broad s,PPh ₃ ),124.6(s,Ar). ³¹ P{ ¹ H}NMR(162MHz,CDCl ₃ ) }:-16.2(s,PPh ₃ ).

Elemental analysis (%) Theoretical value (OsC ₄₈ H ₃₈ N ₂ P ₂ Cl ₂ ): C, 59.69; H, 3.97; N, 2.90. Found value: C, 70.48; H, 4.11; N, 2.88.

Example 2

Weigh 4-methyl-1,10-phenanthroline (49mg, 0.25mmol) and OsCl ₂ (PPh ₃ ) ₃ (220mg, 0.21mmol) into a 25mL reaction bottle with a magnet, under the protection of N ₂ , add 15mL of dichloromethane solvent, stir and react at 20-25°C for 4h, the solution turns from dark green to purple-black. After the reaction was completed, the reaction solution was concentrated, and 20 mL of anhydrous n-hexane was added to form a purple-red precipitate, which was the crude product of 4-methyl-1,10-phenanthroline substituted osmium nitrogen complex. The crude product was washed with n-hexane (4 times, 40 mL), filtered and dried to obtain a purplish red solid of the purified osmium nitrogen complex, with a yield of 158 mg and a yield of 77%.

The result of nuclear magnetic resonance analysis is ¹ H NMR (600MHz, CDCl ₃ ) δ: 8.9(d, J=7.8Hz, 1H, Ar), 8.8(d, J=8.4Hz, 1H, Ar,), 8.0(d, J =13.2Hz,1H,Ar),7.9(d,J=12.0Hz,1H,Ar),7.8(d,J=13.8Hz,1H,Ar),7.3(d,J=10.2Hz,12H,PPh ₃ ), 7.1(t, J=10.8Hz, 6H, PPh ₃ ), 7.0(t, J=10.5Hz, 13H, PPh ₃ and Ar), 6.9(d, J=7.8Hz, 1H, Ar), 2.8( s,3H,CH ₃ ). ¹³ C{ ¹ H}NMR (151MHz, CDCl ₃ )δ:156.2(s,Ar),155.3(s,Ar),150.0(s,Ar),149.4(s,Ar) ,143.1(s,Ar),134.9(broad s,PPh ₃ ),133.1(s,Ar),131.1(s,Ar),128.7(s,Ar),127.6(s,PPh ₃ ),125.9(d, J＝2.2Hz,,PPh ₃ ),125.6(s,Ar),123.7(s,Ar),122.6(s,Ar),122.4(s,Ar),17.3(s,CH ₃ ). ³¹ P{ ¹ H}NMR(243MHz,CDCl ₃ )δ:-14.5(s,PPh ₃ ).

Elemental analysis (%) Theoretical value (OsC ₄₉ H ₄₀ N ₂ P ₂ Cl ₂ ): C, 60.06; H, 4.11; N, 2.86. Found value: C, 60.11; H, 4.08; N, 2.78.

Example 3

Weigh 4,7-dimethyl-1,10-phenanthroline (52mg, 0.25mmol) and OsCl ₂ (PPh ₃ ) ₃ (220mg, 0.21mmol) into a 25mL reaction bottle with a magnetic sub, in N _2. Under the protection of 2, 15 mL of dichloromethane solvent was added, and the reaction was stirred at 20-25° C. for 4 h, and the solution changed from dark green to purple-black. After the reaction was completed, the reaction solution was concentrated, and 20 mL of anhydrous n-hexane was added to form a purple-red precipitate, which was the crude product of 4,7-dimethyl-1,10-phenanthroline substituted osmium nitrogen complex. The crude product was washed with n-hexane (4 times, 40 mL), filtered and dried to obtain a purplish red solid of osmium nitrogen complex with a yield of 148 mg and a yield of 71%.

The result of nuclear magnetic resonance analysis is ¹ H NMR (600MHz, CD ₂ Cl ₂ ) δ: 8.8(s, 2H, Ar), 8.0(s, 2H, Ar), 7.3 (d, J=6.0Hz, 12H, PPh ₃ ) ,7.1(t,J=6.6Hz,6H,PPh ₃ ),7.0(t,J=6.6Hz,12H,PPh ₃ ),6.9(broad s,2H,Ar),2.8(s,6H,CH ₃ ) ^.13 C{ ¹ H}NMR (151MHz,CD ₂ Cl ₂ )δ:156.4(s,Ar),150.2(s,Ar),144.5(s,Ar),136.0(s,PPh ₃ ),129.7(s ,Ar),128.6(s,PPh ₃ ),126.7(broad s,PPh ₃ ),124.6(s,Ar),123.3(s,Ar),18.4(s,CH ₃ ). ³¹ P{ ¹ H}NMR (243MHz,CD ₂ Cl ₂ )δ:-14.5(s,PPh ₃ ).

Elemental analysis (%) Theoretical value (OsC ₅₀ H ₄₂ N ₂ P ₂ Cl ₂ ): C, 60.42; H, 4.26; N, 2.82. Found value: C, 60.55; H, 4.16; N, 2.66.

Example 4

Weigh 4,7-dichloro-1,10-phenanthroline (63mg, 0.25mmol) and OsCl ₂ (PPh ₃ ) ₃ (220mg, 0.21mmol) into a 25mL reaction bottle with a magnetic sub, under N ₂ Under protection, 15 mL of dichloromethane solvent was added, and the reaction was stirred at 20-25° C. for 4 h, and the solution changed from dark green to blue-purple. After the reaction was completed, the reaction solution was concentrated, and 20 mL of anhydrous n-hexane was added to form a blue-purple precipitate, which was the crude product of 4,7-dichloro-1,10-phenanthroline substituted osmium nitrogen complex. The crude product was washed with n-hexane (4 times, 40 mL), filtered and dried to obtain a purplish red solid of the purified osmium nitrogen complex, with a yield of 150 mg and a yield of 69%.

The result of nuclear magnetic resonance analysis is ¹ H NMR (400MHz, CDCl ₃ ) δ: 8.9 (d, J=6.1Hz, 2H, Ar), 8.3 (s, 2H, Ar), 7.3 (broad s, 12H, PPh ₃ ), 7.2(t, J=6.8Hz, 6H, PPh ₃ ), 7.1(d, J=6.1Hz, 2H, Ar), 7.0(t, J=6Hz, 12H, PPh ₃ ). ¹³ C{ ¹ H}NMR (151MHz,CDCl ₃ )δ:156.8(s,Ar),151.7(s,Ar),141.0(s,Ar),135.9(s,PPh ₃ ),129.0(s,PPh ₃ ),128.7(s,Ar ),127.1(broad s,PPh ₃ ),124.5(s,Ar),124.2(s,Ar). ³¹ P{ ¹ H}NMR(243MHz,CDCl ₃ )δ:-17.8(s,PPh ₃ ).

Elemental analysis (%) Theoretical value (OsC ₅₂ H ₄₆ N ₂ P ₂ Cl ₂ ): C, 61.11; H, 4.54; N, 2.74. Found value: C, 61.38; H, 4.75; N, 2.66.

Example 5

Catalytic performance test

With the osmium bidentate N-group complex prepared in the described embodiment 1-4 as a catalyst, under anhydrous and anaerobic conditions, in a dry 25mL Schlenk bottle, a THF solution (5mL) of ammonia borane (1.77mmol) was first added. ), then add an ethylene glycol dimethyl ether solution (8 mL) of an osmium bidentate N-based complex catalyst (0.09 mmol), and after the two are mixed, the side branch port of the Schlenk bottle is closed. Then connect the side branch port with the plastic conduit attached to the burette for gas measurement, transfer the Schlenk bottle to an oil bath at 60°C, control the rotation speed of the magnet to 300rpm, open the branch port and stopwatch, collect hydrogen and record the time. The volume of hydrogen gas was recorded at various time intervals.

The osmium N-based complex catalyst prepared in Examples 1-4 catalyzes the hydrogen release results of ammonia borane in a tetrahydrofuran/ethylene glycol dimethyl ether mixed solution (volume ratio 1:1.6) at 60°C, when the catalyst loading is 5 mol%. As shown in Table 1, it can be seen from the above test results that the synthesized osmium N-based complex has good catalytic activity as a catalyst, and can release 2.12-2.29 equivalents of H ₂ from ammonia borane. It shows that this kind of osmium N-based complex has potential application as an efficient osmium catalyst for the dehydrogenation of ammonia borane.

^a Calculated based on the time required to release 1 equivalent of oxygen.

Table 1 Example 1-4 prepares osmium N-based complexes to catalyze the dehydrogenation of ammonia borane

The above embodiments describe the basic principles, main features and advantages of the present invention. Those skilled in the industry should understand that the present invention is not limited by the above-mentioned embodiments, and that described in the above-mentioned embodiments and the specification only illustrates the principle of the present invention, and the present invention also has various aspects without departing from the scope of the principle of the present invention. Changes and improvements, these changes and improvements all fall within the protection scope of the present invention.

Claims (9)

1. A class of osmium bidentate N-based complex catalysts, characterized in that the chemical structure is as follows: 2. according to the described osmium bidentate N base complex catalyst of claim 1, it is characterized in that: 3. The method for preparing the bidentate N-group complex of osmium according to claim 1, characterized in that it comprises the following operations: reacting OsCl ₂ (PPh ₃ ) ₃ and a bidentate N-group ligand in a solvent to obtain the complex. 4. The preparation method of the osmium bidentate N-base complex according to claim 3, characterized in that: the bidentate N-base ligand is selected from 1,10-phenanthroline or substituted 1,10-phenanthroline. 5. The preparation method of the osmium bidentate N-group complex according to claim 3, characterized in that: the reaction solvent is selected from dichloromethane, chloroform, tetrahydrofuran or 1,2-dichloroethane. 6. The preparation method of the osmium bidentate N-group complex according to claim 3, characterized in that: the reaction is carried out under anhydrous and oxygen-free conditions, and the reaction temperature is 20-25°C. 7. The preparation method of the bidentate N-group complex of osmium according to claim 3, characterized in that: the molar ratio of OsCl ₂ (PPh ₃ ) ₃ to the bidentate N-group ligand is 1:1-2. 8. according to the preparation method of the osmium bidentate N base complex described in any one of claim 3-7, it is characterized in that: the complex is purified after washing with anhydrous solvent and vacuum drying; the washing solvent is selected from n-pentane, n-hexane alkanes or n-heptanes. 9. The application of the osmium bidentate N-base complex in catalyzing the dehydrogenation of ammonia borane according to claim 1, characterized in that: the osmium bidentate N-base complex is used to catalyze the dehydrogenation of ammonia borane.