JP2005104958A - Method for synthesizing fluorine-containing metal complex - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for synthesizing a fluorine-containing metal complex which is excellent in volatility and stability and is useful as a raw material for forming a thin film by chemical vapor deposition (CVD). <P>SOLUTION: The method for synthesizing the fluorine-containing metal complex is for synthesizing a β-diketone complex of Zr or Hf and comprises suspending anhydrous chloride of Zr or Hf in an anhydrous aprotic solvent, adding a fluorine-containing β-diketone and reacting, refluxing the mixture at 60-120°C while reacting it under a pressure of 100-700 Pa, removing generated hydrogen chloride gas, removing the solvent composing the upper layer of a solution separated into two layers, adding the aprotic solvent again, refluxing the mixture at 60-120°C, cooling it to from -20 to 5°C to separate out a crystal, collecting the crystal through filtering, adding the aprotic solvent again, refluxing the mixture at 60-120°C and cooling it to from -20 to 5°C to separate out a crystal in the lower layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for synthesizing a fluorine-containing metal complex which is useful as a raw material for forming a thin film by vapor phase chemical reaction (CVD) and has excellent vaporization and stability.

In recent years, the CVD method has been used as one of the means for depositing various materials on a large-area substrate at a high speed, but in order to be used in the CVD method, it has excellent vaporization, vaporization stability, and reactivity. Compound materials are needed.

  For example, there is a β-diketone complex using Zr or Hf as a CVD raw material for optical fibers or thin films. The complex is synthesized by various methods, one of which is a method of synthesizing a complex by reacting with acetylacetone in an aqueous solution using a water-soluble inorganic salt (Patent Document 1), and starting from anhydrous chlorides of Zr and Hf. And a method of synthesizing a complex by reacting with acetylacetone in an inert gas under an anhydrous solvent (Patent Documents 2 and 3). However, with these synthesis methods, it is difficult to remove moisture from the crystals, and crystals exhibiting good vaporization characteristics cannot be obtained.

In addition, E.I. M.M. Larsen is a method for synthesizing trifluoroacetylacetone of Zr and Hf using oxychloride as a starting material, but it is difficult to dehydrate and dry even if it contains crystallization water and is processed in high vacuum. It does not show good vaporization characteristics (Non-Patent Document 1).
A complex synthesized by a conventional method is a method in which fluorine-containing β-diketone is added and reacted, followed by solvent extraction and recrystallization in ether, followed by drying under high vacuum for a long time and then sublimation under high vacuum. Is described. This method has a low yield of 50 to 60% and is not only inefficient under high vacuum, but also has a problem that it is difficult to remove moisture and the original excellent vaporization characteristics cannot be obtained.
Japanese Patent Laid-Open No. 3-141118 JP-A-6-9660 Japanese Patent Laid-Open No. 6-87868 J. et al. Amer. Chem. Soc. , 75, 5107 (1953)

  As a result of intensive investigations in view of the above-mentioned drawbacks, the present inventors have suspended anhydrous metal chloride in an aprotic anhydrous solvent, gradually dropped fluorine-containing β-diketone, allowed to react under sealed pressure, The present inventors have found that a fluorine-containing metal complex having excellent vaporization characteristics can be efficiently synthesized through a purification step by repeating liquid crystal treatment and cooling and recrystallization twice.

That is, when synthesizing a fluorine-containing β-diketone complex of Zr or Hf, the present invention suspends an anhydrous chloride of Zr or Hf in an anhydrous aprotic solvent and adds the fluorine-containing β-diketone to the reaction. Then, the reaction is carried out under a pressure of 100 to 700 Pa while refluxing in a temperature range of 60 to 120 ° C., and the generated hydrogen chloride gas is removed. After adding a protic solvent and refluxing in a temperature range of 60 to 120 ° C., cooling in a temperature range of −20 to 5 ° C. to precipitate crystals, filtering the crystals, adding an aprotic solvent again. And then refluxing in a temperature range of 60 to 120 ° C., and then cooling in a temperature range of −20 to 5 ° C. to precipitate crystals in the lower layer. The diketone is A β- diketone compound represented by the ¹ COCH ^₂ COR ₂ (provided that, R ^1, R ² each represent an alkyl group or fluorinated alkyl group of 1 to 8 carbon atoms.), The fluorine-containing β- The diketone is trifluoroacetylacetone or hexafluoroacetylacetone, and the aprotic solvent is any one of toluene, benzene, xylene, dichloromethane, chloroform, n-hexane, n-heptane, or cyclohexane. The present invention provides a method for synthesizing a fluorine-containing metal complex characterized by the following.

  Hereinafter, the present invention will be described in more detail.

In the present invention, ZrCl ₄ , HfCl _4, etc. may be mentioned as the raw material Zr or Hf anhydrous chloride. In addition, since the synthesized compound needs to extremely suppress moisture, the anhydrous salt as a raw material is easy to absorb moisture and is handled in a glow box, and the fluorine-containing β-diketone is dehydrated in advance. It should be noted that the organic solvent should be completely dehydrated with molecular sieves.

Next, the fluorine-containing β-diketone used in the present invention is a β-diketone compound represented by R ¹ COCH ₂ COR ² (however, R ¹ and R ² are an alkyl group having 1 to 8 carbon atoms or fluorine. Each represents an alkyl group. Particularly preferred fluorine-containing β-diketones include trifluoroacetylacetone (CF ₃ COCH ₂ COCH ₃ ), hexafluoroacetylacetone (CF ₃ COCH ₂ COCF ₃ ) and the like.

  In the present invention, first, an anhydrous chloride of Zr or Hf is suspended in an anhydrous aprotic solvent. Solvents include toluene, benzene, xylene, dichloromethane, chloroform, hexane or its isomers, heptane or its isomers, cyclohexane, methylcyclohexane, methylcyclopentane, acetonitrile, etc. Especially, toluene, benzene, xylene, dichloromethane, chloroform , N-hexane, n-heptane, or cyclohexane are preferred. If a solvent other than aprotic is used here, the anhydrous metal salt acts as a strong Lewis acid and partially reacts with the solvent, or the resulting complex decomposes or generates adducts, resulting in a decrease in yield. However, the solvent is not particularly limited as long as it does not react with a metal chloride or a metal complex of the product or generate an adduct. Next, the fluorine-containing β-diketone that has been dehydrated in advance is gradually added and reacted at room temperature (10 to 30 ° C.) for 1 to 6 hours. The addition amount of the fluorine-containing β-diketone is based on Zr metal or Hf metal. Add 1.0-1.5 equivalent excess. Outside this range, unreacted chloride raw material remains if it is less than 1.0 equivalent, and if it exceeds 1.5 equivalent, it is necessary to remove the unreacted fluorine-containing β-diketone ligand. Is expensive and not preferred.

  Next, after adding the fluorine-containing β-diketone, the solution is reacted in a closed system while heating and refluxing in a temperature range of 60 to 120 ° C. That is, when heated, the concentration of hydrogen chloride gas dissolved in the solvent becomes extremely small in inverse proportion to the liquid temperature.

The reaction proceeds as follows.
MCl ₄ + 4R ¹ COCH ₂ COR ² → M (R ¹ COCHCOR ² ) ₄ + 4HCl
(Here, M represents a group 4 metal Zr or Hf, R ¹ COCH ₂ COR ² represents a fluorine-containing ligand, and R ¹ and R ² represent an alkyl group having 1 to 8 carbon atoms or a fluorinated alkyl. Each group is shown.)
Here, in order to proceed the reaction, it is necessary to quickly exhaust the generated hydrogen chloride gas. The heating reflux time depends on the amount of synthesis, but 1 to 5 days is appropriate.

In order to dislike moisture extremely, the inside of the system is kept at a positive pressure (100 to 700 Pa), and the dried gas is sealed. As the gas, it is necessary to use an inert gas that does not react with raw materials and products such as Ar and He. The generated hydrogen chloride gas has a constant rate of reaction between anhydrous chloride and fluorine-containing ligand by providing a check valve on the exhaust side as a method for shutting off the outside air or completely shutting it off from the outside air through a cooling trap. In this way, hydrates and side reactions are suppressed, and a high-purity complex is obtained.
If the outside air blocking treatment is insufficient, the raw material generates hydrates due to the influence of moisture, the fluorine-containing ligand itself generates hydrates, or some multimers are vaporized. Problems with extremely inferior properties and yields arise.

  It is preferable to keep the inside of the system at a slightly positive pressure (100 to 700 Pa) for shutting off the outside air. When the pressure in the system is less than 100 Pa or on the reduced pressure side, the solvent or the complex fluorine-containing ligand is hydrogen chloride or inert. It is not preferable because it is scattered with gas and lost, and hydrogen chloride dissolves in moisture.

 Conversely, when the pressure in the system exceeds 700 Pa, the generation of hydrogen chloride gas is suppressed, the concentration of hydrogen chloride gas in the solution rises and the reaction does not proceed smoothly, and the system pressure increases further, causing bumping and ejection. This is not preferable for safety.

  Next, it is gradually refluxed for 1 to 5 days while exhausting hydrogen chloride gas under a slightly positive pressure. In other words, if the pressure is not adjusted, hydrogen chloride gas is generated abruptly at the initial stage, and it is difficult to shut off the outside air. Shutting off a cooling trap or the like causes the reaction of hydrogen chloride with water to generate hydrates quickly. It becomes difficult to suppress. Under slightly increased pressure, the initial generation of hydrogen chloride gas is suppressed, and the complex formation reaction proceeds at a constant rate. When refluxed for 1 to 5 days, hydrogen chloride gas is not detected from the system and the reaction is completed. In order to remove hydrogen chloride gas during or near the end of the reaction, a dry inert gas may be appropriately blown. Hydrogen chloride gas can be detected by a simple method by which white smoke is not generated when the exhaust gas is exposed to ammonia gas.

  When the reflux is stopped and the temperature is lowered to room temperature, the solution eventually separates into two layers. The upper layer is a black-brown solution, and the lower layer is separated into an oily brown solution. The upper layer of the solution is removed once with an evaporator. In this case, the water bath temperature is 30 to 45 ° C. If the water bath temperature is further increased, the lower oily metal complex is scattered and lost. When the aprotic solvent in the upper layer and the excess fluorine-containing ligand are removed, a brown oily slurry in the lower layer remains.

(First crystallization)
When 2-5 times the volume of aprotic solvent is added to the high viscosity oily slurry in the lower layer and refluxed again in the temperature range of 60-120 ° C., the impurities migrate to the upper solvent and turn brown. In the lower layer, it is separated into a pale yellow oily slurry of high viscosity. When cooled to -20 to 5 ° C and allowed to stand for 12 to 24 hours, the lower layer oily slurry crystallizes. The crystals are separated by filtration, washed with a small amount of cold aprotic solvent and dried to obtain pale yellow crystals.

(Second crystallization)
When a 2-5 times volume aprotic solvent is added to the crystals obtained in the first crystallization and refluxed again in the temperature range of 60-120 ° C., the upper solvent turns pale yellow, Into a highly viscous white oily slurry. When cooled to -20 to 5 ° C and allowed to stand for 24 hours, the lower layer oily slurry crystallizes. The crystals are separated by filtration, washed with a small amount of cold aprotic solvent and dried to obtain white crystals.

  By these two crystallization operations, unreacted substances, organic substances, tars, etc. are transferred to the upper layer and separated into white crystals in the lower layer, whereby a fluorine-containing metal complex can be obtained with high purity and high yield. .

  The method of the present invention can obtain a high-purity fluorine-containing metal complex in a high yield by two recrystallizations without taking a complicated process like the sublimation purification method, and is extremely stable against moisture and has a high vapor pressure. And a complex suitable for film formation by CVD can be provided in large quantities at low cost.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to this Example.

Example 1
Synthesis of Hf (C ₅ F ₆ HO ₂ ) _{4 In} a 500 ml three-necked flask, 11.6 g (36.2 mmol) of raw material HfCl ₄ is collected in a glove box, and 300 ml of dehydrated toluene is added and suspended. . The container is sealed and previously sealed with dry nitrogen, and 34.35 g (1.14 equivalents) of hexafluoroacetylacetone previously dehydrated and distilled is slowly added dropwise at room temperature while stirring at room temperature. The white suspension changes from yellow to brown and begins to generate hydrogen chloride gas. The pressure is adjusted so that the pressure in the system is maintained at a positive pressure (100 to 700 Pa), and hydrogen chloride gas is appropriately discharged from the check valve. Exhaust is provided with a trap in two stages, paying sufficient attention to moisture. After the completion of the dropwise addition of hexafluoroacetylacetone in about 3 hours, when refluxing at 110 ° C. for 5 days, the reflux was stopped when no hydrogen chloride gas was detected in the exhaust gas (pH> 3). (After the exposure, no white smoke (NH ₄ Cl) is generated and the reflux is stopped.) When cooled to room temperature in a sealed state, two layers are separated into a blackish brown upper layer and a brownish brown lower layer. The water content of the solution by Karl Fischer was 430 ppm. Toluene solvent and excess β-diketone are distilled off from this solution in an evaporator on a 40 ° C. water bath. The residue was a brown high-viscosity oily slurry.

(First crystallization)
When a small amount of 80 ml of toluene is added and refluxed at 110 ° C. for 4 hours, it is separated into two layers, the upper layer is separated into a yellow transparent solution, and the lower layer is separated into a highly viscous yellow oily slurry. When this was allowed to stand at 0 ° C. for 15 hours, a brown transparent solution was deposited on the upper layer and yellow crystals were deposited on the lower layer.

(Second crystallization)
The lower layer crystal was separated by filtration, 50 ml of toluene was added, and the mixture was refluxed at 110 ° C. for 2 hours to obtain a slurry having two layers separated. When this slurry solution was cooled and allowed to stand again at 0 ° C. for 12 hours, white crystals were deposited in the lower layer. After washing by filtration, 33.31 g (yield 91.4%) of white crystals was obtained. The analysis results are shown below. The values in parentheses are theoretical values.

Hf metal: ICP analysis 17.39% (17.7%)
Elemental analysis: C: 23.94% (23.85%)
H: 0.45% (0.40%)
F: 45.6% (45.3%)
From these results, tetrakishexafluoroacetylacetonatohafnium (Hf (C ₅ F ₆ HO ₂ ) ₄ ) was identified. Moreover, the vaporization rate by TG-DTA showed a favorable vaporization characteristic of 100.2% (temperature increase 10 ° C./min, N ₂ gas flow rate 300 ml / min).

Example 2
Synthesis of Zr (C ₅ F ₆ HO ₂ ) _{4 In} a 500 ml three-necked flask, 9.57 g (41.07 mmol) of raw material ZrCl ₄ was fractionated in a glove box, and 250 ml of dehydrated n-hexane was added and suspended. Make it cloudy. The container is sealed and previously sealed with dry nitrogen, and 35.88 g (1.05 equivalents) of hexafluoroacetylacetone previously dehydrated and distilled is slowly added dropwise at room temperature while stirring at room temperature. The white suspension changes from yellow to brown and begins to generate hydrogen chloride gas. The pressure is adjusted so that the system maintains a positive pressure (100 to 700 Pa), and hydrogen chloride gas is appropriately discharged from the check valve. Exhaust is provided with a trap in two stages, paying sufficient attention to moisture. After completion of the dropwise addition of hexafluoroacetylacetone in about 4 hours, when refluxing at 69 ° C. for 4 days, the refluxing was stopped in a state where no hydrogen chloride gas was detected in the exhaust gas. Reflux is stopped after (NH ₄ Cl) is no longer generated. When cooled to room temperature while sealed, a solution having two layers separated into a brown upper layer and a brown lower layer was obtained. The water content of the solution by Karl Fischer was 210 ppm. This solution was taken out and the n-hexane solvent and excess hexafluoroacetylacetone were distilled off on a 43 ° C. water bath with an evaporator. The residue was a yellow-brown oily slurry.

(First crystallization)
When a small amount of n-hexane (60 ml) was added and the mixture was heated to reflux at 69 ° C. for 6 hours, it was separated into two layers, the upper layer was separated into a pale yellow transparent solution, and the lower layer was separated into a highly viscous pale yellow slurry. When this slurry solution was cooled and allowed to stand at 0 ° C. for 15 hours, crystals were deposited in the lower layer.

(Second crystallization)
The crystals were separated by filtration, 80 ml of n-hexane was added, and the mixture was heated to reflux at 69 ° C. for 3 hours to obtain a slurry solution separated into two layers. When the slurry solution was cooled and allowed to stand again at 0 ° C. for 12 hours, white crystals were deposited in the lower layer. After washing by filtration, 33.86 g (yield 89.7%) of white crystals was obtained. The analysis results are shown below. The values in parentheses are theoretical values.

Zr metal: ICP analysis 9.86% (9.92%)
Elemental analysis: C: 26.42% (26.11%)
H: 0.43% (0.44%)
F: 49.2% (49.6%)
From these results, it was identified as tetrakishexafluoroacetylacetonatozirconium (Zr (C ₅ F ₆ HO ₂ ) ₄ ). Moreover, the vaporization rate by TG-DTA showed a favorable vaporization characteristic of 99.8% (temperature increase 10 ° C./min, N ₂ gas flow rate 300 ml / min).

Comparative Example 1
The raw material HfCl ₄ is collected in a 7.52 g (23.48 mmol) glove box, and 200 ml of dehydrated toluene is added and suspended. 20.12 g (1.03 equivalents) of hexafluoroacetylacetone previously dehydrated and distilled is slowly added dropwise at room temperature while stirring at room temperature for 2 hours. The white suspension changes from yellow to ocher and begins to generate hydrogen chloride gas. After completion of the dropwise addition of hexafluoroacetylacetone in about 2 hours, the system was heated to reflux for 5 days while adjusting the pressure in the system in the same manner as in Example 1.

When refluxed for 5 days, the reflux was stopped when no hydrogen chloride gas was detected in the exhaust gas (pH = 3). (For confirmation, the exhaust gas was exposed to ammonia gas and no white smoke (NH ₄ Cl) was generated. Refrain from reflux.) Upon cooling to room temperature with sealing, two layers were separated into a brown upper layer and a pale yellow lower layer. When the lower layer portion is collected with a separatory funnel and concentrated on a 40 ° C. water bath with an evaporator, the contained toluene solvent and excess β-diketone (hexafluoroacetylacetone) are distilled off. The residue gives a pale yellow oily slurry.

(First crystallization)
When a small amount of 70 ml of toluene is added and heated to reflux at 110 ° C. for 4 hours, it is separated into two layers, the upper layer is separated into a yellow transparent solution and the lower layer is separated into a highly viscous yellow oily slurry. When this was allowed to stand at room temperature (at 24 ° C.) for 16 hours, it was separated into a brown transparent solution in the upper layer and a yellow oily transparent solution in the lower layer.

(Second crystallization)
The oil solution in the lower layer was separated with a separatory funnel, 50 ml of toluene was added, and the mixture was heated to reflux at 110 ° C. for 3 hours to obtain a solution separated into two layers. This solution was separated, and the lower layer oily solution was allowed to stand at room temperature (24 ° C.). However, crystals remained as a highly viscous oil. When this was cooled to 0 ° C. and allowed to stand for 16 hours, white needle crystals precipitated. After filtering and washing, 16.19 g (yield 68.5%) of white crystals was obtained, but the yield was inferior to that of the Example.

Claims (4)

In synthesizing a fluorine-containing β-diketone complex of Zr or Hf, after suspending an anhydrous chloride of Zr or Hf in an anhydrous aprotic solvent, adding a fluorine-containing β-diketone and reacting, While reacting under a temperature of 120 ° C. under a pressure of 100 to 700 Pa, the generated hydrogen chloride gas is removed, the upper layer solvent is removed from the solution separated into two layers, and an aprotic solvent is added again. Then, after refluxing in a temperature range of 60 to 120 ° C., cooling is performed in a temperature range of −20 to 5 ° C. to precipitate crystals, and after filtering the crystals, an aprotic solvent is added again to 60 to 120 ° C. The method for synthesizing a fluorine-containing metal complex is characterized in that after refluxing in a temperature range of ˜20 to 5 ° C., the crystal is precipitated in a lower layer by cooling in a temperature range of −20 to 5 ° C. The method for synthesizing a fluorine-containing metal complex according to claim ^1, wherein the fluorine-containing β-diketone is a β-diketone compound represented by R ¹ COCH ₂ COR ² .
However, R ^1, R ² each represent an alkyl group or fluorinated alkyl group of 1 to 8 carbon atoms. The method for synthesizing a fluorine-containing metal complex according to claim 2, wherein the fluorine-containing β-diketone is trifluoroacetylacetone or hexafluoroacetylacetone. 4. The fluorine-containing metal according to claim 1, wherein the aprotic solvent is one of toluene, benzene, xylene, dichloromethane, chloroform, n-hexane, n-heptane, or cyclohexane. Complex synthesis method.