CN104130294A - Half-sandwich type polysubstituted nitrogen boron metallocene titanium metal chloride and synthetic method thereof - Google Patents

Abstract

The invention relates to a semi-sandwich type multi-substituted nitrogen borocene titanocene metal chloride and a synthesis method thereof, including the preparation of the corresponding multi-substituted mono nitrogen borocene ligand: 1,2,3,4-tetramethyl-1, 2-Azaboroles and 2,3,4-trimethyl-1-tert-butyl-1,2-azaborines; preparation of lithium salts of polysubstituted 1,2-azaborines and trimethyl Silicon-substituted multi-substituted 1,2-azaborine; adding titanium metal chloride MCl ₄ (M=Ti; Zr; Hf) in toluene solution to obtain multi-substituted 1,2-azaborine titanium metal Chloride, that is, the product obtained. The product obtained in the present invention exhibits excellent catalytic performance in catalyzing olefin polymerization. Due to the unique chemical coordination properties of the monoazaboroxene ligand, it can make the active center more stable, improve the catalytic activity and prolong the catalyst life.

Description

Semi-sandwich type multi-substituted nitrogen borazine titanocene metal chlorides and synthesis method thereof

technical field

The invention belongs to the field of olefin polymerization catalysts, and in particular relates to a semi-sandwich type multi-substituted titanocene borazine series metal chloride and a synthesis method thereof.

Background technique

In the early 1950s, the discovery of ferrocene and the elucidation of its sandwich structure, as well as the success of Ziegler-Natta catalysts in catalyzing ethylene polymerization under mild conditions, led to the gradual development of metal-organic olefin polymerization catalysis. For metallocene catalysts, the early catalytic system was low in activity and could not be applied to industrial production; its breakthrough was the use of methylaluminoxane as an auxiliary agent in the 1970s, which greatly improved the catalytic activity of metallocenes for ethylene polymerization , thus opening the door to the practical application of such catalysts. Metallocene catalysts have the following characteristics. First, they have a single active site in the homogeneous catalytic reaction process. Compared with traditional heterogeneous Ziegler-Natta catalysts, the obtained polymer molecular weight distribution is narrower, and the copolymer has a uniform composition. distribution, showing better performance than traditional polyolefins; second, it has higher catalytic efficiency; third, the controllability of the product, the catalytic characteristics of the metallocene catalyst and the central metal type, ligand structure and complex structure There is a direct relationship between the structure of the catalyst and its catalytic performance by changing the structure of the catalyst artificially, so as to obtain a polyolefin with a controllable molecular structure.

Polyolefin elastomers are a type of crystalline ethylene-α-olefin copolymers. It is characterized by a high mass fraction of α-olefin, low density, and its main properties are close to that of rubber, but it has a certain degree of crystallinity. The crystallizable polyethylene segments in the elastomeric structure form physical crosslinks to bear the load, and the non-crystalline random copolymer segments provide elasticity. This special morphological structure makes the elastomer have special properties and a wide range of uses. It can be used not only as rubber, but also as a thermoplastic elastomer, and as a toughener for general-purpose plastics such as polypropylene. The series of products that have been commercialized so far are all based on ethylene-α-olefin copolymers.

The structure and properties of the polymer can be controlled by changing the ligand structure and central metal species of the catalyst. In 1998, Brookhark and Gibson et al. (J.Am.Chem.Soc., 1998, 120, 4049-4050; Chem.Commun.1998, 849-850) reported pyridinediimine Fe(II) and Co(II) The complex of ethylene can be well oligomerized or polymerized by adjusting the substituent on the benzene ring, and the structure is shown in formula 1.

Fujita et al. (Chem.Lett., 2000, 358-359; Organometallics, 2001, 20, 4793-4799) reported a series of titanium-based early transition metal complexes with phenimine or pyrrole imine as ligands. The compound can catalyze the polymerization of olefins with high activity, and control the molecular weight of the polymer by changing the reaction conditions or selecting different cocatalysts; in addition, under some specific conditions, it can also realize the active polymerization of olefins, and the structures are as shown in formula 2 and formula 3 shown.

For vanadium-based monophenolimine and bisphenolimine complexes, they can efficiently catalyze ethylene polymerization at room temperature; and for bisphenolimine complexes, electron-withdrawing groups or alkyl substituents are introduced on N-, It can still efficiently catalyze ethylene polymerization at 70°C, and obtain a polymer with narrow molecular weight distribution, indicating that the catalyst has good thermal stability; the structures are shown in formula 4 and formula 5.

Some nickel-based late transition metal catalysts with phenimines as ligands can not only efficiently catalyze ethylene polymerization, but also have good tolerance to some polar functional groups; the structure is shown in formula 6 (Organometallics, 1998, 17, 3149 -3151; Science, 2000, 287, 460). And changing some groups of the catalyst can significantly affect its catalytic properties, such as the phenolic imine nickel complex shown in formula 7 (ACS Cata.2014, 4, 999-1003), under the same conditions, when X is -SO2- , its catalytic activity is 18 times that when X is -CH2-, the molecular weight and branching degree of the obtained polyethylene are 3.2 times and 1.5 times respectively when X is -CH2-, and the thermal stability is higher.

In a broad sense, metallocene catalysts are divided into double metallocene catalysts and single metallocene catalysts, namely sandwich type and semi-sandwich type. For the double metallocene catalyst, the molecular weight of the polymer obtained by catalysis is relatively large, and the molecular weight distribution is relatively narrow. Although its physical properties, especially mechanical properties, are improved, its molding process becomes difficult. The constrained-geometry catalysts (Constrained-Geometry Catalysts, CGC) and its Insite technology developed by Dow in the late 1980s have obtained long-chain branching with a novel structure and excellent mechanical properties and processing properties. Narrow copolymers of ethylene and alpha-olefins. However, this type of catalyst contains an unstable Si-N bond, which is easily broken by the attack of nucleophiles during the preparation or polymerization process, which limits its large-scale promotion.

In recent years, more and more attention has been paid to single metallocene catalysts with electron-donating side groups, which have a similar structure to CGC catalysts and are easier to synthesize than CGC catalysts. A large number of such metal complexes have been reported in the literature, and they have their own specific catalytic properties. For example, Formula 8 contains a phenol side group -OAr (Organometallics, 1998, 17, 2152-2154), and Formula 9 shows -N= CRR' side group (J.Am.Chem.Soc., 2000, 122, 5499-5509), -N≡PR ₃ side group shown in formula 10 (Organometallics, 2003, 22, 1937-1947), shown in formula 11 The imidazolium side group shown in (DaltonTrans., 2006, 459-467), the pyrrole side group shown in formula 12 (Organometallics, 2009, 28, 111-122).

1,2-azaborolyl (1,2-azaborolyl, Ab) is the isoelectronic body of cyclopentadienyl (Cyclopentadienyl, Cp), and its coordination chemistry is similar to that of Cp, and it can also form metal organic compounds with transition metals. Complexes. Ab can be regarded as the C=C unit in Cp is replaced by N-B bond, and N-B bond also has the property of double bond; but compared with the complete delocalization of π electrons in Cp, the N-B bond in Ab is due to the electronegativity of nitrogen and boron The difference makes the π electrons more concentrated on the nitrogen atom; the properties of the highest occupied orbital (HOMO) in Ab are similar to the filled nitrogen atomic orbital, and the lowest unoccupied orbital (LUMO) is similar to the 2P empty orbital of boron atom. The difference shown is that Ab is more electron-donating than the corresponding Cp. Therefore, it can make the active center more stable, improve the catalytic activity and prolong the life of the catalyst. So far, there are few reports on the related research based on Ab-titanium complexes and their derivatives, especially the research on catalyzed olefin polymerization. Theoretical and practical significance.

Contents of the invention

Purpose of the present invention is exactly to provide a kind of in order to overcome the defective that above-mentioned prior art exists.

The purpose of the present invention can be achieved through the following technical solutions:

The semi-sandwich type multi-substituted titanocene borazine series metal chloride has the following structural formula:

Respectively 1,2,3,4-tetramethyl-1,2-azaborine titanium trichloride; 2,3,4-trimethyl-1-tert-butyl-1,2-azaborine Titanocene trichloride; 2,3,4-trimethyl-1-tert-butyl-1,2-azaborocene zirconium trichloride; 2,3,4-trimethyl-1-tert-butyl - 1,2-Azaborocene hafnium trichloride.

The preparation method of semi-sandwich type multi-substituted nitrogen borazine titanium series metal chlorides adopts the following steps:

1) Mix 2-methyl-3-chloropropene with aqueous sodium hydroxide solution, then add methylamine or tert-butylamine dropwise, condense in an ice bath, and react the mixture overnight;

2) The product obtained in step 1) is placed in a cold bath at -35°C with ether as a solvent, and a hexane solution of butyl lithium is added. The molar ratio of the product obtained in step 1) to butyl lithium is controlled to be 1:2-2.2, React in a cold bath for 1 h, and stir overnight at room temperature;

3) Add the ether solution of di-tert-butyltin dichloride to the mixture in step 2), and react overnight at room temperature to obtain a white suspension;

4) Add the product of step 3) into dichloromethane, add a boron trichloride solution in dichloromethane at a low temperature of -35°C, stir the brown solution for 1 h at low temperature, and 4 h at room temperature;

5) Take the product of step 4), add ether to dissolve, add methyl Grignard reagent dropwise, and stir overnight at room temperature;

6) Take the product of step 5), use tetrahydrofuran as a solvent, add a pentane solution of methyl iodide, add LDA at a low temperature and stir for 2 hours, and control the molar ratio of the product of step 5) to methyl iodide and LDA to be 1:1-1.2: 1-1.2, then stirred at 55°C-60°C for 24h to obtain the lithium salt of polysubstituted 1,2-azaborine;

7) Take the product of step 6), add a diethyl ether solution of trimethylchlorosilane, and stir overnight at room temperature;

8) Add a toluene solution of _MCl4 to the product of step 7), heat and stir the mixture for 72 hours to obtain a semi-sandwich type multi-substituted titanocene borazine metal chloride.

In step 1), the molar ratio of 2-methyl-3-chloropropene, sodium hydroxide and methylamine is 1:1:3 to obtain a methyl-substituted nitrogen borocene; 2-methyl-3-chloropropene, hydrogen The molar ratio of sodium oxide and tert-butylamine is 1:1:3 to obtain tert-butyl substituted azoborine; the rate of methylamine addition is maintained at 1 drop/second

In step 3), the molar ratio of the product in step 2) to di-tert-butyltin dichloride is 1:1-1.3. After the reaction, the ether is vacuumed off, hexane is added to stir, the mixture is left to filter, and the solvent is removed under reduced pressure.

In step 4), the molar ratio of the product of step 3) to boron trichloride is 1: 1.1-1.3, and the volume ratio of dichloromethane added is 3: 2, the solvent is removed, and a colorless liquid is obtained by distillation under reduced pressure , Acicular crystals were obtained at -35°C.

In step 5), the mol ratio of the product of step 4) to the methyl Grignard reagent is 1: 1-1.3, and the solvent is diethyl ether. After the reaction, the mixture is two-phase, the solvent is removed, and the residue is extracted with hexane, usually Hexane was evaporated under pressure, and a colorless liquid was obtained by distillation under reduced pressure.

Step 6) The lithium salt of the multi-substituted 1,2-BN heterocene prepared is 1,2,3,4-tetramethyl-1,2-azaborolelithium salt or 2,3,4-trimethyl Lithium-1-tert-butyl-1,2-azaborolelithium salt.

In step 7), the molar ratio of lithium salt of multi-substituted 1,2-BN heterocene to trimethylchlorosilane is 1:1.5-2, the reaction solvent is ether and tetrahydrofuran with a volume ratio of 4:1, and the reaction time is 24 hours , the resulting reaction solution was vacuum-evacuated to remove the solvent, the residue was extracted with hexane, filtered, and the solvent was removed in vacuum to prepare 1,2,3,4-tetramethyl-5-trimethylsilyl-1,2-boronazide Zolocene or 2,3,4-trimethyl-3-trimethylsilyl-1-tert-butyl-1,2-azaborole.

As a preferred embodiment, in step 7):

The molar ratio of 1,2,3,4-tetramethyl-1,2-azaborolelithium salt to trimethylchlorosilane is 1:1.5-2 to obtain 1,2,3,4-tetramethyl -5-trimethylsilyl-1,2-azaborole;

The molar ratio of 2,3,4-trimethyl-1-tert-butyl-1,2-azoborolithium salt to trimethylchlorosilane is 1:1.5-2 to obtain 2,3,4-tri Methyl-1-tert-butyl-3-trimethylsilyl-1,2-azaborole.

In step 8), the MCl ₄ is titanium metal chloride, selected from TiCl ₄ , ZrCl ₄ or HfCl ₄ .

In step 8), the molar ratio of the product of step 7) to _MCl is 1: 1-1.5, the reaction solvent is toluene, the post-treatment is solvent vacuum extraction, and the remaining solid is extracted with toluene until there is no color, and the extract is filtered , vacuum solvent concentration, prepared 1,2,3,4-tetramethyl-1,2-azaborine titanium trichloride; 2,3,4-trimethyl-1-tert-butyl-1 , 2-azaborine titanium trichloride; 2,3,4-trimethyl-1-tert-butyl-1,2-azaborine zirconium trichloride; 2,3,4-trimethyl - 1-tert-butyl-1,2-azaborocene hafnium trichloride.

As a preferred embodiment, in step 8):

The molar ratio of 1,2,3,4-tetramethyl-5-trimethylsilyl-1,2-azaboroxine to titanium tetrachloride is 1:1-1.5, and 1,2,3 , 4-Tetramethyl-1,2-azaborine titanium trichloride;

The molar ratio of 2,3,4-trimethyl-1-tert-butyl-3-trimethylsilyl-1,2-azaborolene ligand to TiCl ₄ , ZrCl ₄ , and HfCl ₄ is 1: 1-1.5, prepared 2,3,4-trimethyl-1-tert-butyl-1,2-azaborine titanium trichloride; 2,3,4-trimethyl-1-tert-butyl - 1,2-azaborocene zirconium trichloride; 2,3,4-trimethyl-1-tert-butyl-1,2-azaborocene hafnium trichloride.

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

(1) The multi-substituted monoazoborocene titanocene metal chlorides provided are due to the N-B bond of the multi-substituted monoazaborocene ligands replacing the traditional C=C unit of the azolocene ring, and at the same time, 1,2-nitroboron 1,2-azaborolyl (Ab) is the isoelectronic body of cyclopentadienyl (Cyclopentadienyl, Cp), and its coordination chemical properties are similar to those of Cp, and the N-B bond also has the property of a double bond. However, compared with the complete delocalization of π electrons in Cp, the N-B bond in Ab makes π electrons more concentrated on nitrogen atoms due to the difference in electronegativity between nitrogen and boron elements. The difference in properties is that Ab is more concentrated than the corresponding Cp have stronger electron-donating properties. Therefore, it can make the positively charged metal active center more stable, improve the catalytic activity and prolong the life of the catalyst.

(2) The electron-donating ability of multi-substituted monoazaborine ligands can be regulated by the steric effect and electronic effect of multiple substituents, so it is possible to control the multi-substituted monoazaborine metallocene chlorine properties and catalytic performance of the compounds.

(3) The monoazoborocene semi-sandwich catalyst prepared by the present application can efficiently catalyze the polymerization of olefins under the action of a very small amount of cocatalyst methylaluminoxane (Methylaluminoxane, referred to as MAO). It is of great significance to study the production cost and the mechanism of homogeneous polymerization of olefins.

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments.

The semi-sandwich type multi-substituted nitrogen borazine titanocene metal chloride synthesized by this patent has the following structural formula:

The attached picture of the reaction is as follows:

The first few preparation steps are roughly the same, as follows:

1) Mix 2-methyl-3-chloropropene with aqueous sodium hydroxide solution, then add methylamine or tert-butylamine drop by drop, condense in an ice bath, and react the mixture overnight, wherein 2-methyl-3-chloropropene, hydroxide The molar ratio of sodium and methylamine is 1:1:3 to obtain methyl-substituted azoborine; the molar ratio of 2-methyl-3-chloropropene, sodium hydroxide and tert-butylamine is 1:1:3 to obtain tertiary Butyl substituted azoborine; because the reaction is exothermic, the rate of methylamine addition remains 1 drop/second;

2) The product obtained in step 1) is placed in a cold bath at -35°C with ether as a solvent, and a hexane solution of butyl lithium is added. The molar ratio of the product obtained in step 1) to butyl lithium is controlled to be 1:2-2.2, React in a cold bath for 1 h, and stir overnight at room temperature;

3) Add the ether solution of di-tert-butyl tin dichloride to the mixture of step 2), the molar ratio of the product of step 2) to di-tert-butyl tin dichloride is 1: 1-1.3, vacuum Remove the ether, add hexane to stir, stand and filter, remove the solvent under reduced pressure, and react overnight at room temperature to obtain a white suspension;

4) Take the product of step 3) and add it to dichloromethane, and add a solution of boron trichloride in dichloromethane at a low temperature of -35°C. The molar ratio of the product of step 3) to boron trichloride is 1: 1.1-1.3, The volume ratio to the added dichloromethane was 3:2, the brown solution was stirred at low temperature for 1 h, and at room temperature for 4 h, the solvent was removed, and a colorless liquid was obtained by distillation under reduced pressure, and needle-shaped crystals were obtained at -35°C;

5) get the product of step 4), add ether to dissolve, add methyl Grignard reagent dropwise, the mol ratio of the product of step 4) and methyl Grignard reagent is 1: 1-1.3, solvent is ether, after reaction, The mixture was two phases, the solvent was removed, the residue was extracted with hexane, the hexane was evaporated under normal pressure, and the colorless liquid was obtained by distillation under reduced pressure;

6) Take the product of step 5), use tetrahydrofuran as a solvent, add a pentane solution of methyl iodide, add LDA at a low temperature and stir for 2 hours, and control the molar ratio of the product of step 5) to methyl iodide and LDA to be 1:1-1.2: 1-1.2, then stirred at 55°C-60°C for 24h to obtain the lithium salt of multi-substituted 1,2-BN heterocene;

7) Take the product of step 6), add the ether solution of trimethylchlorosilane, the molar ratio of lithium salt of multi-substituted 1,2-BN heterocene to trimethylchlorosilane is 1: 1.5-2, and the reaction solvent is The volume ratio of diethyl ether to tetrahydrofuran is 4:1, and the reaction time is 24 hours. The resulting reaction solution is vacuum-extracted to remove the solvent, the residue is extracted with hexane, filtered, and the solvent is removed by vacuum to prepare 1,2,3,4-tetramethyl- 5-trimethylsilyl-1,2-azaborine or 2,3,4-trimethyl-3-trimethylsilyl-1-tert-butyl-1,2-azaborine.

Next is the preparation method of the final product, the following steps can be used.

Example 1

Synthesis of 1,2,3,4-Tetramethyl-1,2-azaborocene Titanium Trichloride

Method one: add 1,2,3,4-tetramethyl-1,2-BN heterocene lithium salt (1.29g, 10mmol) in the Schlenk bottle of 100mL, add TiCl ₄ (2.85g, 15mmol) toluene ( 30mL) solution. The mixture was heated and stirred for 72h, and the color of the reaction solution turned dark blue. The solvent was extracted in vacuo, and the remaining dark blue solid was extracted with toluene until there was no color, the extract was filtered, and the solvent was concentrated in vacuo. Recrystallization at -35°C gave dark blue needle crystals (1.51 g, 55%).

Method 2: 1,2,3,4-tetramethyl-1,2-azaborine lithium salt (4.64g, 36mmol), trimethylchlorosilane (3.9g, 36mmol) was added to 30ml of ether as a solvent, The reaction was stirred overnight at room temperature. The solvent was removed from the reactant in vacuo, the residue was extracted with hexane (30ml*5), and the yellow liquid obtained after removing the hexane was 1,2,3,4-tetramethyl-5-trimethylsilyl-1,2-nitrogen Borocene 4.90g, yield 70%. Take 1,2,3,4-tetramethyl-5-trimethylsilyl-1,2-azaborole (0.7g, 3.6mmol), add TiCl ₄ (1.7g, 9mmol) in toluene (20mL ) solution was stirred overnight at room temperature. The solvent was removed in vacuo, the residue was extracted with toluene, and the product was recrystallized from hexane at -35°C to obtain 1.47 g of the product 1,2,3,4-tetramethyl-1,2-azaborine titanium trichloride, yield 73 %.

¹ H NMR (400MHz, CDCl ₃ ): δ6.71(s, 1H), 3.44(s, 3H), 2.37(s, 3H), 2.16(s, 3H), 0.96(s, 3H). ¹³ C NMR (100MHz, CDCl ₃ ): δ144.5, 123.0, 38.4, 16.4, 15.6. ¹¹ B NMR (96.3MHz, CDCl ₃ ): δ38.8.HRMS(EI) m/z calcd for C ₇ H ₁₃ BC ₁₃ NTi : 271.9769, found: 271.9732.

Example 2

Synthesis of 2,3,4-trimethyl-1-tert-butyl-1,2-azaborolene titanium trichloride

Method 1: Add 2,3,4-trimethyl-1-tert-butyl-1,2-azaborine lithium salt (1.71g, 10mmol) into a 100mL Schlenk bottle, add TiCl ₄ (2.85g, 15mmol) in toluene (30mL). The mixture was heated and stirred for 72h, and the color of the reaction solution turned dark blue. The solvent was extracted in vacuo, and the remaining solid was extracted with toluene until there was no color, the extract was filtered, and the solvent was concentrated in vacuo. Recrystallization at -35°C gave dark blue needle crystals (2.13 g, 67%).

Method two: 2,3,4-trimethyl-1-tert-butyl-1,2-azaborine lithium salt (5.5g, 32.22mmol) was used as solvent in 10ml toluene, trimethylchlorosilane (7.0 g, 64.66mmol) was added 10ml of toluene as a solvent, and the reactant was stirred at room temperature for 48h. The solvent was removed from the reactant in vacuo, the residue was extracted with pentane (30ml*5), and the yellow liquid obtained after removing the pentane was 2,3,4-trimethyl-1-tert-butyl-3-trimethylsilyl-1 , 2-azaborole 4.64g, yield 60%. Take 2,3,4-trimethyl-1-tert-butyl-3-trimethylsilyl-1,2-azaborole (1.1g, 4.65mmol), add 20ml of toluene as solvent, add TiCl ₄ (0.96g, 5.11mmol) in toluene (20mL) was reacted at 110°C for 72h. The solvent was extracted in vacuo, and the remaining solid was extracted with toluene until there was no color, the extract was filtered, and the solvent was concentrated in vacuo. Recrystallization at -35°C gave dark blue needle crystals (1.06 g, 72%).

¹ H NMR (300MHz, C ₆ D ₆ ): δ6.38(s, 1H), 1.93(s, 3H), 1.92(s, 3H), 1.15(s, 9H), 1.09(s, 3H). ¹³ C NMR (75.5MHz, CDCl ₃ ): δ146.2 (bs), 144.0, 119.9, 61.3, 30.4, 16.7, 15.9, 1.96 (bs). ¹¹ B NMR (96.3MHz, C ₆ D ₆ ): δ38.8 .HRMS(EI) m/zcalcd for C ₁₀ H ₁₉ BCl ₃ NTi: 317.0161, found: 317.0141. Anal. Calcd. For C ₁₀ H ₁₉ BCl ₃ NTi: C, 37.73; H, 6.02; N, 4.40. Found: C , 38.03; H, 6.37; N, 4.41.

Example 3

Synthesis of 2,3,4-trimethyl-1-tert-butyl-1,2-azaborocene zirconium trichloride

Method 1: Add 1-tert-butyl-2,3,4-trimethyl-1,2-azaborine lithium salt (1.71g, 10mmol) to a 100mL Schlenk bottle, add ZrCl ₄ (3.50g, 15mmol) in toluene (30mL). The mixture was heated and stirred for 72h, and the color of the reaction solution turned dark brown. The solvent was extracted in vacuo, and the remaining brown solid was extracted with toluene until there was no color, the extract was filtered, and the solvent was concentrated in vacuo. Recrystallization at -35°C gave dark brown cubic crystals (1.95 g, 54%).

Method two: 2,3,4-trimethyl-1-tert-butyl-1,2-azaborine lithium salt (5.5g, 32.22mmol) was used as solvent in 10ml toluene, trimethylchlorosilane (7.0 g, 64.66mmol) was added 10ml of toluene as a solvent, and the reactant was stirred at room temperature for 48h. The solvent was removed from the reactant in vacuo, the residue was extracted with pentane (30ml*5), and the yellow liquid obtained after removing the pentane was 2,3,4-trimethyl-1-tert-butyl-3-trimethylsilyl-1 , 2-azaborole 4.64g, yield 60%. Take 2,3,4-trimethyl-1-tert-butyl-3-trimethylsilyl-1,2-azaborole (1.1g, 4.65mmol), add 20ml of toluene as solvent, add ZrCl ₄ (1.19g, 5.11mmol) in toluene (20mL) was reacted at 110°C for 72h. The solvent was extracted in vacuo, and the remaining solid was extracted with toluene until there was no color, the extract was filtered, and the solvent was concentrated in vacuo. Recrystallization at -35°C gave dark brown cubic crystals (1.09, 65.5%).

¹ H NMR (300MHz, CDCl ₃ ): δ6.64(s, 1H), 2.12(s, 3H), 1.94(s, 3H), 1.42(s, 9H), 0.93(s, 3H). ¹³ C NMR (75.5MHz, C ₆ D ₆ ): δ142.2, 110.6, 59.9, 30.9, 30.7, 14.4, 13.9. ¹¹ B NMR (96.3MHz, C ₆ D ₆ ): δ37.0.HRMS(EI) m/z calcd for C ₁₀ H ₁₉ ¹⁰ BCl ₃ NZr: 357.9765, found: 357.9758. Anal. Calcd. For C ₁₀ H ₁₉ BCl ₃ NTi: C, 33.20; H, 5.30; N, 3.87. Found: C, 32.86; H, 5.04 ; N, 3.53.

Example 4

Synthesis of 2,3,4-trimethyl-1-tert-butyl-1,2-azaborocene hafnium trichloride

Method 1: Add 1-tert-butyl-2,3,4-trimethyl-1,2-azaborole lithium salt (1.71g, 10mmol) into a 100mL Schlenk bottle, add HfCl ₄ (4.8g, 15mmol) in toluene (30mL). The mixture was heated and stirred for 72h, and the color of the reaction solution turned dark red. The solvent was extracted in vacuo, and the remaining brown solid was extracted with toluene until there was no color, the extract was filtered, and the solvent was concentrated in vacuo. -35°C gave needle crystals (3.0 g, 67%).

Method two: 2,3,4-trimethyl-1-tert-butyl-1,2-azaborine lithium salt (5.5g, 32.22mmol) was used as solvent in 10ml toluene, trimethylchlorosilane (7.0 g, 64.66mmol) was added 10ml of toluene as a solvent, and the reactant was stirred at room temperature for 48h. The solvent was removed from the reactant in vacuo, the residue was extracted with pentane (30ml*5), and the yellow liquid obtained after removing the pentane was 2,3,4-trimethyl-1-tert-butyl-3-trimethylsilyl-1 , 2-azaborole 4.64g, yield 60%. Take 2,3,4-trimethyl-1-tert-butyl-3-trimethylsilyl-1,2-azaborole (1.1g, 4.65mmol), add 20ml of toluene as solvent, add HfCl ₄ (1.64g, 5.11mmol) in toluene (20mL) was reacted at 110°C for 72h. The solvent was extracted in vacuo, and the remaining solid was extracted with toluene until there was no color, the extract was filtered, and the solvent was concentrated in vacuo. Recrystallization at -35°C gave light yellow needle crystals (1.50 g, 72%).

¹ H NMR (300MHz, CDCl ₃ ): δ6.02(s, 1H), 2.00(s, 3H), 1.86(s, 3H), 1.10(s, 9H), 1.05(s, 3H). ¹³ C NMR (75.5MHz, C ₆ D ₆ ): δ140.70, 128.06, 109.03, 59.25, 30.37, 13.71, 12.93. ¹¹ B NMR (96.3MHz, C ₆ D ₆ ): δ36.20

In summary, it should be understood that these examples are only used to illustrate the present invention and are not intended to limit the protection scope of the present invention. In addition, it should also be understood that after reading the technical content of the present invention, those skilled in the art can make various changes, modifications and/or variations to the present invention, and all these equivalent forms also fall within the appended claims of the present application. limited scope of protection.

Claims (10)

1. The semi-sandwich type multi-substituted titanocene borazine series metal chloride is characterized in that it has the following structural formula: Respectively 1,2,3,4-tetramethyl-1,2-azaborine titanium trichloride; 2,3,4-trimethyl-1-tert-butyl-1,2-azaborine Titanocene trichloride; 2,3,4-trimethyl-1-tert-butyl-1,2-azaborocene zirconium trichloride; 2,3,4-trimethyl-1-tert-butyl - 1,2-Azaborocene hafnium trichloride. 2. the preparation method of semi-sandwich type multi-substituted titanocene borazine series metal chlorides as claimed in claim 1, is characterized in that, the method adopts the following steps: 1) Mix 2-methyl-3-chloropropene with aqueous sodium hydroxide solution, then add methylamine or tert-butylamine dropwise, condense in an ice bath, and react the mixture overnight; 2) The product obtained in step 1) is placed in a cold bath at -35°C with ether as a solvent, and a hexane solution of butyl lithium is added. The molar ratio of the product obtained in step 1) to butyl lithium is controlled to be 1:2-2.2, React in a cold bath for 1 h, and stir overnight at room temperature; 3) Add the ether solution of di-tert-butyltin dichloride to the mixture in step 2), and react overnight at room temperature to obtain a white suspension; 4) Add the product of step 3) into dichloromethane, add a boron trichloride solution in dichloromethane at a low temperature of -35°C, stir the brown solution for 1 h at low temperature, and 4 h at room temperature; 5) Take the product of step 4), add ether to dissolve, add methyl Grignard reagent dropwise, and stir overnight at room temperature; 6) Take the product of step 5), use tetrahydrofuran as a solvent, add a pentane solution of methyl iodide, add LDA at a low temperature and stir for 2 hours, and control the molar ratio of the product of step 5) to methyl iodide and LDA to be 1:1-1.2: 1-1.2, then stirred at 55°C-60°C for 24h to obtain the lithium salt of multi-substituted 1,2-BN heterocene; 7) Take the product of step 6), add a diethyl ether solution of trimethylchlorosilane, and stir overnight at room temperature; 8) Add a toluene solution of _MCl4 to the product of step 7), heat and stir the mixture for 72 hours to obtain a semi-sandwich type multi-substituted titanocene borazine metal chloride. 3. the preparation method of the semi-sandwich type multi-substituted azaborine titanocene metal chlorides according to claim 2, is characterized in that, in step 1), 2-methyl-3-chloropropene, sodium hydroxide, formazan The molar ratio of amines is 1:1:3 to obtain methyl-substituted azaborole; the molar ratio of 2-methyl-3-chloropropene, sodium hydroxide and tert-butylamine is 1:1:3 to obtain tert-butyl-substituted Nitrogen; Methylamine drop rate to maintain 1 drop / second. 4. the preparation method of semi-sandwich type multi-substituted nitrogen borazine titanocene metal chlorides according to claim 2, is characterized in that, in step 3), the product of step 2) and di-tert-butyl tin dichloride The molar ratio of the mixture is 1:1-1.3. After the reaction, the ether is vacuumed off, hexane is added to stir, and the solvent is removed under reduced pressure. 5. the preparation method of semi-sandwich type multi-substituted titanocene boron azocene metal chlorides according to claim 2, is characterized in that, in step 4), the mol ratio of the product of step 3) and boron trichloride is 1:1.1-1.3, the volume ratio to the added dichloromethane was 3:2, the solvent was removed, and a colorless liquid was obtained by distillation under reduced pressure, and needle-like crystals were obtained at -35°C. 6. the preparation method of semi-sandwich type multi-substituted azaborine titanocene metal chlorides according to claim 2, is characterized in that, in step 5), get the mole of the product of step 4) and methyl Grignard reagent The ratio is 1:1-1.3, the solvent is diethyl ether, after the reaction, the mixture is two-phase, the solvent is removed, the residue is extracted with hexane, the hexane is evaporated under normal pressure, and a colorless liquid is obtained by distillation under reduced pressure. 7. The preparation method of the semi-sandwich type multi-substituted nitrogen borocene titanocene metal chlorides according to claim 2, characterized in that, the multi-substituted 1,2-BN heterocene lithium salt prepared in step 6) is 1,2,3,4-Tetramethyl-1,2-lithium azaboride or 2,3,4-trimethyl-1-tert-butyl-1,2-lithium azaboride. 8. The preparation method of the semi-sandwich type multi-substituted nitrogen borocene titanocene metal chloride according to claim 7, characterized in that, in step 7), the lithium salt of multi-substituted 1,2-BN heterocene and three The molar ratio of methylchlorosilane is 1:1.5-2, the reaction solvent is diethyl ether and tetrahydrofuran with a volume ratio of 4:1, and the reaction time is 24 hours. Remove the solvent to prepare 1,2,3,4-tetramethyl-5-trimethylsilyl-1,2-azaborole or 2,3,4-trimethyl-3-trimethylsilyl Base-1-tert-butyl-1,2-azaborole. 9. The preparation method of the semi-sandwich type multi-substituted azaborocene titanocene metal chlorides according to claim 8, characterized in that, in step 8), the _MCl4 is a titanium metal chloride selected from TiCl ₄ , ZrCl ₄ or HfCl ₄ . 10. the preparation method of semi-sandwich type multi-substituted titanocene borazine series metal chlorides according to claim 8, is characterized in that, in step 8), the product of step 7) and MCl _The mol ratio is 1: 1-1.5, the reaction solvent is toluene, the post-treatment is vacuum pumping of the solvent, the remaining solid is extracted with toluene until there is no color, the extract is filtered, the solvent is concentrated by vacuum pumping, and 1,2,3,4-tetramethyl -1,2-azaborine titanium trichloride; 2,3,4-trimethyl-1-tert-butyl-1,2-azaborine titanium trichloride; 2,3,4-tri Methyl-1-tert-butyl-1,2-azaborocene zirconium trichloride; 2,3,4-trimethyl-1-tert-butyl-1,2-azaborocene hafnium trichloride .