Method for producing transition metal complex, method for purifying transition metal complex, transition metal complex and organic electroluminescence device

Abstract

To provide a method for producing a transition metal complex that enables a high-purity transition metal complex to be produced in simple and efficient manners.SOLUTION: A method for producing a transition metal complex includes the step for thermally aging a solution containing a transition metal complex and a coordinating compound to purify the transition metal complex.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for conveniently producing a high-purity transition metal complex, and in particular to a method for conveniently producing an iridium complex for use in an organic electroluminescent device. [Background technology]

[0002] In recent years, various electronic devices using organic electroluminescent elements (hereinafter sometimes referred to as "organic EL elements"), such as organic electroluminescent lighting (organic EL lighting) and organic electroluminescent displays (organic EL displays) (Patent Document 1), are being put into practical use. Organic EL elements have a low applied voltage, low power consumption, surface emission, and are capable of emitting the three primary colors, and therefore are being actively studied for application to lighting and displays. Therefore, there is a demand for further improvement in the luminous efficiency of organic EL elements. In order to improve the luminous efficiency, for example, it has been proposed to use a phosphorescent material in the luminescent layer of an organic EL element. Examples of phosphorescent materials include bis(2-phenylpyridinato-N,C2')iridium acetylacetonate (Ir(ppy) 2 (acac)) and tris(2-phenylpyridinato-N,C2') (Ir(ppy) 3 Orthometalated iridium complexes, including 1,2-dichloro-1,2-triazolidinediamine (1,2-diazolidinediamine), are widely known.

[0003] These complexes are generally synthesized by mixing and igniting the raw materials, iridium salt, ligand, silver salt, etc. During the process of producing the desired iridium complex, it is known that various side reactions occur, such as unintended coupling between the added ligands and complex formation with the added silver (Non-Patent Document 1).

[0004] Transition metal complexes used in organic EL devices and the like are required to have extremely high purity in order to stabilize their performance, and it is necessary to remove impurities contained in the transition metal complexes after the synthesis process (Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5459447 [Patent Document 2] Patent No. 4913059 [Patent Document 3] Patent Publication No. 2021-73692 [Patent Document 4] JP 2014-111613 A [Patent Document 5] JP 2010-285372 A [Non-patent literature]

[0006] [Non-Patent Document 1] Dalton.Trans.,2006,2468-2478 Summary of the Invention [Problem to be solved by the invention]

[0007] In order to obtain a product of the required high purity, chromatography (normal phase silica gel chromatography, reverse phase silica gel chromatography, size exclusion chromatography, paper chromatography), separation washing, recrystallization, reprecipitation, suspension washing, adsorbent treatment, and sublimation are usually used, and purification is generally performed multiple times or in combination. However, particularly in the purification of transition metal complexes, impurities produced as by-products during the reaction have a partial structure similar to that of the target complex, and it is very difficult to completely remove them (Non-Patent Document 1, Patent Document 3).

[0008] In particular, normal phase silica gel chromatography is preferably used for purifying transition metal complexes (Patent Document 4, Patent Document 5). However, in order to obtain a transition metal complex with a high purity required for application to an organic EL device or the like, purification by normal phase silica gel chromatography must usually be performed multiple times, which is costly and time-consuming and therefore unsuitable for industrialized large-scale production.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a transition metal complex, which can simply and efficiently produce a high-purity transition metal complex. [Means for solving the problem]

[0010] As a result of intensive research conducted by the present inventors to solve the above problems, they discovered a method for simply removing impurities without reducing the yield of the transition metal complex to be purified by adding a coordinating compound to a solution in which a transition metal complex has been dissolved and then heating and maturing the solution, thereby completing the present invention.

[0011] That is, the gist of the present invention is as follows.

[0012] Aspect 1 of the present invention is The method for producing a transition metal complex includes a step of purifying the transition metal complex by heating and aging a solution containing the transition metal complex and a coordinating compound.

[0013] A second aspect of the present invention relates to the production method of the first aspect, In the production method, the transition metal contained in the transition metal complex is a Group 8 or 9 metal element.

[0014] A third aspect of the present invention relates to the production method of the second aspect, The method for producing the present invention is characterized in that the Group 8 or 9 metal element is iridium.

[0015] A fourth aspect of the present invention relates to a production method according to any one of the first to third aspects, The process for producing said transition metal complex is a triscyclometallated iridium complex.

[0016] A fifth aspect of the present invention relates to the production method of the fourth aspect, The method for producing said triscyclometallated iridium complex is a homotriscyclometallated iridium complex.

[0017] A sixth aspect of the present invention relates to a production method according to any one of the first to fifth aspects, The method is such that the coordinating compound is a compound containing a nitrogen atom.

[0018] A seventh aspect of the present invention is a production method according to any one of the first to sixth aspects, In the production method, the mass of the coordinating compound contained in the solution is 0.01 times or more the mass of the transition metal complex.

[0019] An eighth aspect of the present invention is a production method according to any one of the first to seventh aspects, The heat aging is carried out at 70°C or higher.

[0020] A ninth aspect of the present invention is a production method according to any one of the first to eighth aspects, The method of manufacturing, wherein the solution further comprises a solvent.

[0021] A tenth aspect of the present invention relates to the production method of the ninth aspect, In the production method, the solubility of the transition metal complex in the solvent at 25° C. is 10 mg / mL or more.

[0022] An eleventh aspect of the present invention is In a liquid chromatography analysis under the following conditions, when the relative retention time of a peak exhibited by the transition metal complex is taken as 1.0, the area ratio of the total area of ​​a group of peaks appearing in the relative retention time range of 0.3 to 0.9 to the total peak area is 0.49% or less. (Liquid Chromatography Analysis Conditions) Analytical column: A column with a silica gel base and an octadecyl group as the chemical bond. (Average particle size 3μm, average pore size 10nm, length 250mm x inner diameter 4.6mm) Sample concentration: 0.1% by mass (dilution solvent: tetrahydrofuran) Column oven temperature: 40℃ Career: Acetonitrile:2-propanol = 75:25 (volume ratio) mixed solution Column flow rate: 1.0mL / min

[0023] A twelfth aspect of the present invention is An organic electroluminescence device using the transition metal complex of embodiment 11.

[0024] A thirteenth aspect of the present invention is The method for purifying a transition metal complex includes a step of heating and aging a solution containing the transition metal complex and a coordinating compound. Effect of the Invention

[0025] According to the present invention, it is possible to remove trace impurities that are generated during the synthesis of a complex and that are difficult to remove by a purification method that is usually used, without reducing the yield of the transition metal complex to be purified, and thus it is possible to simply and efficiently produce a high-purity transition metal complex. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The following describes in detail the embodiments of the present invention, but the present invention is not limited to the following embodiments and can be modified in various ways within the scope of the gist of the present invention. In this specification, when the expression "to" is used, it is used as an expression including the numerical values ​​or physical property values ​​before and after it.

[0027] <Method of producing transition metal complex> The method for producing a transition metal complex according to the present invention is characterized by a purification step of the transition metal complex, and may include a synthesis step, an analysis step, and the like in addition to the purification step.

[0028] [Transition metal complex synthesis process] The synthesis method used in the synthesis step of the transition metal complex is not particularly limited, but specific examples thereof include a method using stirring with a stirring blade or a magnetic stirrer, a method using microwaves, a method utilizing shaking, grinding, pressing, dispersing, kneading, and crushing using a shaker, ball mill, bead mill, kneader, or the like (mechanochemical synthesis), a method using an electrode to pass electricity (electrolytic synthesis), a continuous flow synthesis method, and a combination of these as necessary.

[0029] [Transition metal complex purification step] The method for producing a transition metal complex according to the present invention includes a step of purifying the transition metal complex by heating and aging a solution containing the transition metal complex and a coordinating compound. In this specification, heat aging means heating a solution containing a transition metal complex and a coordination compound to make the impurities in a removable state. Examples of the removable state include decomposition and derivatization. The solution containing a transition metal complex and a coordination compound may contain a solvent described later as a component other than the transition metal complex and the coordination compound, but it is preferable that the coordination compound dissolves the transition metal complex and forms a solution without using a solvent.

[0030] The purification step of the transition metal complex in the present invention is a step of purifying a transition metal complex synthesized according to a conventional method into a high-purity transition metal complex by treating the transition metal complex with the purification method described below. This makes it possible to purify even a transition metal complex containing impurities that are difficult to remove on an industrial scale, and to produce a high-purity transition metal complex with high production efficiency. The purification method (purification step) of the transition metal complex will be described in detail below.

[0031] {Method for obtaining a solution containing a transition metal complex and a coordination compound} In the purification step, first, the transition metal complex and the coordinating compound are mixed to obtain a solution containing them.

[0032] There is no particular limitation on the order in which the transition metal complex and the coordinating compound are mixed.

[0033] The temperature at which the transition metal complex and the coordinating compound are mixed is not particularly limited, but from the viewpoint of promoting dissolution of the transition metal complex, it is preferably 0° C. or higher, more preferably 15° C. or higher. Also, from the viewpoint of suppressing generation of the coordinating compound or the solvent as vapor, it is preferably 120° C. or lower, more preferably 90° C. or lower. In order to increase the amount of the transition metal complex dissolved in the coordinating compound, the mixture may be mixed while heating the mixing temperature to about 40 to 90° C. There is no particular limitation on the method for confirming whether the transition metal complex is dissolved, but visual inspection, spotting of the solution, or confirmation using a microscope are preferably used.

[0034] (coordination compound) The coordinating compound may be any compound that does not chemically react with the transition metal complex to be purified and has coordination ability with a transition metal atom, and from the viewpoint of efficiency in rendering the impurities in a state capable of being removed, it is preferable that the coordinating compound is a compound that contains a nitrogen atom in the molecule.

[0035] The coordination compound is not particularly limited, and examples thereof include aromatic compounds, aromatic heterocyclic compounds, alicyclic compounds, heterocyclic compounds, or linear or branched hydrocarbon compounds in which at least one carbon atom is replaced with a nitrogen atom, amine compounds, amide compounds, cyan compounds, isocyan compounds, thiocyan compounds, isothiocyan compounds, and azides.Specific examples thereof include ammonium chloride, trimethylamine, N,N'-dimethylethylenediamine, aniline, triphenylamine, pyridine, 2,2'-bipyridyl, pyrimidine, piperidine, pyrrole, imidazole, pyrrolidine, quinoline, acetonitrile, benzonitrile, dimethylacetamide, dimethylformamide, sodium cyanide, sodium azide, potassium thiocyanate, 4-fluorophenyl thiocyanate, phenyl isocyanate, phenyl isocyanide, phenyl isocyanate, and phenyl cyanate. From the viewpoints of safety and efficiency in rendering impurities removable, ammonium chloride, trimethylamine, aniline, triphenylamine, pyridine, pyrimidine, piperidine, pyrrole, imidazole, pyrrolidine, quinoline, acetonitrile, and benzonitrile are preferred, and from the viewpoint of efficiency in rendering impurities removable, pyridine and benzonitrile are more preferred.

[0036] The amount of the coordinating compound used is not particularly limited, but from the viewpoint of improving the efficiency of aging, the mass of the coordinating compound contained in the solution is preferably 0.01 times or more, more preferably 0.1 times or more, relative to the mass of the transition metal complex. In addition, when a solvent described later is not added, from the viewpoint of promoting dissolution of the transition metal complex, the mass of the coordinating compound is preferably 0.01 times or more, more preferably 0.1 times or more, and even more preferably 1 times or more, relative to the mass of the transition metal complex. From the viewpoint of process efficiency, the content is preferably 50 times or less, and more preferably 20 times or less.

[0037] (Transition metal complex to be purified) There is no particular restriction on the transition metal complex to be purified, but since particularly high purity is required when the transition metal complex is used for applications such as organic electroluminescent materials and photocatalysts, the purification step of the present invention for the transition metal complex is particularly useful for the embodiment in which the transition metal contained in the transition metal complex is a Group 8 or Group 9 metal element. Among these, the purification step of the present invention for the transition metal complex is even more useful for the embodiment in which the Group 8 or Group 9 metal element is iridium, i.e., the transition metal complex is an iridium complex, since it is difficult to remove impurities generated in the synthesis step. In addition, since the complex is thermally and chemically stable, the purification step of the present invention for the transition metal complex is most useful for the embodiment in which the transition metal complex is a triscyclometallated iridium complex, particularly the embodiment in which the triscyclometallated iridium complex is a homotriscyclometallated iridium complex.

[0038] The iridium complex to be purified as the transition metal complex is not particularly limited. Specific examples of the iridium complex that can be highly purified by the purification step of the present invention include complexes having at least one, preferably two or more, chemical structures in which at least one selected from aromatic rings and aromatic heterocycles are bonded as ligands.

[0039] Specific examples of transition metal complexes suitable for purification according to the present invention are shown below, but the invention is not limited to these.

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[0058] (solvent) In the method for producing a transition metal complex according to the present invention, the solution containing the transition metal complex and the coordinating compound may further contain a solvent. By containing a solvent, the amount of the coordinating compound used can be reduced compared to the case where no solvent is used, which is preferable. In the present specification, a solvent means a component that does not have a coordinating ability for a transition metal complex. That is, in the present specification, a compound that has a coordinating ability for a transition metal complex is considered to be a coordinating compound even if it is a component that can be used as a solvent.

[0059] There is no particular limit to the type of solvent that can be used, but from the viewpoint of process efficiency, the solubility of the transition metal complex to be purified in the solvent at 25° C. is preferably 10 mg / mL or more, more preferably 50 mg / mL or more. In addition, as described below, since heating is performed during aging, the boiling point of the solvent is preferably 70° C. or more, more preferably 100° C. or more. Examples of solvents that can be used include acetophenone, benzene, dimethyl sulfoxide, methyl ethyl ketone, butyl acetate, ethyl acetate, cresol, 1,2-dichloroethane, 2-ethoxyethanol, ethylene glycol monomethyl ether, glycerin, 1,1,2,2-tetrachloroethane, toluene, and xylene.

[0060] When a solvent is used, the amount of the solvent is not particularly limited, but from the viewpoint of easily maintaining the solubility of the transition metal complex in the solution during heating, the amount of the solvent is preferably 0.5 times or more, more preferably 2 times or more, based on the mass of the transition metal complex to be purified, and from the viewpoint of process efficiency, the amount of the solvent is preferably 50 times or less, more preferably 20 times or less.

[0061] {Method of heating and aging the solution} In the purification step of the present invention, a solution containing a transition metal complex to be purified and a coordination compound is heated and aged. The heating and aging is preferably performed while stirring the solution. By the heating and aging, the transition metal complex to be purified can be brought into a state in which impurities contained therein can be removed. The present invention also relates to a method for purifying a transition metal complex, which comprises a step of heating and aging a solution containing the transition metal complex and a coordinating compound.

[0062] (heating ripening temperature) From the viewpoint of efficiency in heat-aging impurities contained in the transition metal complex to be purified, the temperature for heat-aging is preferably 70° C. or higher, and more preferably 100° C. or higher. Moreover, from the viewpoint of shortening the time required for heating and cooling, the temperature is preferably 230° C. or lower, and more preferably 200° C. or lower.

[0063] (Heat maturation time) From the viewpoint of efficiency in heat-aging impurities contained in the transition metal complex to be purified, the heat-aging time is preferably 15 minutes or more, more preferably 30 minutes or more, and from the viewpoint of preventing decomposition of the transition metal complex to be purified, the heat-aging time is preferably 600 minutes or less, more preferably 300 minutes or less.

[0064] [Method for recovering transition metal complexes after thermal aging] The method for producing a transition metal complex according to the present invention may include, as an operation included in the purification step, recovery of the transition metal complex after heat aging. There are no particular limitations on the recovery method, but preferred methods include distilling off the solvent under reduced pressure or by heating, reprecipitation followed by filtration, crystallization, etc.

[0065] In the purification step of the present invention, the recovered transition metal complex may be subjected to purification procedures such as chromatography (e.g., normal phase silica gel chromatography, reverse phase silica gel chromatography, size exclusion chromatography, paper chromatography), separation washing, reprecipitation, recrystallization, suspension washing, drying under reduced pressure, sublimation, etc. The purification procedures may be carried out multiple times under different conditions.

[0066] [Analysis process of transition metal complexes] The method for producing a transition metal complex according to the present invention preferably includes an analysis step of the transition metal complex. The analysis step of the transition metal complex is a step of analyzing and measuring the purity of the transition metal complex. There is no particular limitation on the analysis method, but specific examples include X-ray powder diffraction (XRPD), single crystal X-ray diffraction, infrared (IR) and Raman spectroscopy, solid-state and solution nuclear magnetic resonance (NMR) spectroscopy, solubility measurement, dissolution measurement, elemental analysis, melting point measurement, high performance liquid chromatography (HPLC), gas chromatography (GC), ion chromatography, and size exclusion chromatography, and high performance liquid chromatography (HPLC) is preferably used. There is no particular limitation on the detection method for high performance liquid chromatography analysis, but examples include the use of an ultraviolet-visible detector, a fluorescence detector, a differential refractive index detector, a photodiode array detector, an electrical conductivity detector, an electrochemical detector, and an evaporative light scattering detector, and from the viewpoint of detection sensitivity, a photodiode array detector is preferably used.

[0067] (Purity of transition metal complex) In the present invention, from the results of liquid chromatography analysis measured under the following specific conditions, it has been found that when the relative retention time of a peak exhibited by a transition metal complex to be purified is taken as 1.0, the area ratio of a group of peaks appearing within a certain range of relative retention times is particularly correlated with the luminescence characteristics of an organic electroluminescent device. The area ratio of the total area of ​​the peak group appearing in the range of relative retention times of 0.3 to 0.9 to the total peak area is preferably 0.49% or less, more preferably 0.25% or less, and even more preferably 0.10% or less, from the viewpoint of the luminous efficiency of the organic electroluminescent device, and is preferably 0.0001% or more, more preferably 0.0005% or more, and even more preferably 0.001% or more, from the viewpoint of purification efficiency.

[0068] (Liquid Chromatography Analysis Conditions) Analytical column: A column with a silica gel base and an octadecyl group as the chemical bond. (Average particle size 3μm, average pore size 10nm, length 250mm x inner diameter 4.6mm) Sample concentration: 0.1% by mass (dilution solvent: tetrahydrofuran) Column oven temperature: 40℃ Career: Acetonitrile:2-propanol = 75:25 (volume ratio) mixed solution Column flow rate: 1.0mL / min

[0069] [Transition metal complexes, organic electroluminescent devices] The present invention relates to a transition metal complex in which, when the relative retention time of a peak exhibited by the transition metal complex is taken as 1.0, the area ratio of the total area of ​​a group of peaks appearing in the relative retention time range of 0.3 to 0.9 to the total peak area falls within the above range in liquid chromatography analysis under the above conditions. The present invention also relates to an organic electroluminescence device using such a transition metal complex. EXAMPLES

[0070] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples, and the present invention can be practiced with any modifications without departing from the gist of the present invention.

[0071] Analysis and quantification were performed using high performance liquid chromatography (HPLC) under the following measurement conditions. <Measurement conditions> ·Device: Agilent 1260 Infinity II Quaternary Pump VL (G7111A) Agilent 1260 Infinity II Vial Sampler (G7129A) Agilent 1260 Infinity Diode Array Detector (G4212B) Analytical column: GLSciences Inertsil ODS-3 (Average particle size 3μm, average pore size 10nm, length 250mm x inner diameter 4.6mm) Column oven temperature: 40℃ Career: Acetonitrile:2-propanol = 75:25 (volume ratio) mixed solution Column flow rate: 1.0mL / min Sample concentration: 0.1% by mass (dilution solvent: tetrahydrofuran) Detector: Diode Array Detector Detection wavelength: 254nm

[0072] The retention time of the peak with the largest total peak area within the target relative retention time, obtained by the attached analysis software, was set to 1.0 (the relative retention time of the peak of the transition metal complex to be purified), and the retention time of each peak was normalized. The ratio of the peak area corresponding to the transition metal complex to be purified to the total peak area was taken as the complex purity (the item "Complex purity" in Table 1). The ratio of the sum of the peak areas within the relative retention time range of 0.3 to 0.9 to the total peak area was taken as the impurity content (the item "Impurity content" in Table 1).

[0073] In addition, peaks of the solvent used in the production or tetrahydrofuran used as a dilution solvent may be observed at relative retention times of 0.3 to 0.9, but these were excluded from the peak area. The minimum value of the area ratio that could be detected in this measurement was 0.01 ppm.

[0074] In the following Example 1 and Comparative Examples 1 and 2, purification of iridium complex A was carried out. Iridium complex A was synthesized according to the methods described in Reference Examples 1 and 2, and the obtained crude iridium complex A (complex purity: 55.38%) was purified by the respective methods.

[0075] [Reference Example 1] (Synthesis of dinuclear complex A)

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[0077] IrCl 3 The n-hydrate (1.00 g), water (5.43 g), diglyme (33.94 g) and ligand A (3.62 g) were mixed and heated to an external temperature of 165°C. The mixture was heated while distilling off the solvent, and after the internal temperature became constant at 165°C, the mixture was heated and stirred for 2.0 hours. After cooling, methanol (38.60 mL) was added, and the precipitated solid was collected by filtration after stirring. The obtained crude product (4.54 g) was quantified by HPLC, and it was found to contain 3.92 g of binuclear complex A.

[0078] [Reference Example 2] (Synthesis of Iridium Complex A)

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[0080] The crude product (4.40 g) containing the binuclear complex A synthesized above, ligand A (6.00 g), diglyme (40.80 g) and silver trifluoromethanesulfonate (1.00 g) were mixed and heated and stirred at an internal temperature of 120 ° C for 3 hours. After cooling, methanol (83.60 mL) was added, stirred and filtered. Dichloromethane (83.60 mL) was added to the collected solid to completely dissolve it, and then activated clay (2.10 g) was added, stirred and filtered. The obtained filtrate was distilled under reduced pressure to remove dichloromethane, and the residue was collected. The obtained crude product (7.50 g) was quantified using HPLC, and it was found to contain 3.31 g of iridium complex A, with a complex purity of 55.38% and an impurity content of 42.21%.

[0081] [Example 1] <Purification of iridium complex A by heat aging> Benzonitrile (50.00 g) was added as a coordinating compound to the crude product (2.50 g) containing iridium complex A obtained in Reference Example 2, and completely dissolved. The obtained solution was heated under a nitrogen atmosphere, and after the internal temperature became constant at 175°C, it was heated and stirred under reflux conditions for 3 hours. After cooling to room temperature, acetonitrile (125.00 mL) was added, and the solid precipitated after stirring was filtered and collected. The obtained iridium complex A (0.88 g) was purified by applying normal phase column chromatography using silica gel (10.02 g) and eluting with a 2:8 mixed solution of ethyl acetate / n-heptane. The column effluent was fractionated to collect a fraction containing iridium complex A, which was then concentrated and dried. The obtained dried product (0.76 g) was analyzed and quantified by HPLC, and it was found to contain 0.68 g of iridium complex A, with a yield of 61.5%, a complex purity of 98.53%, and an impurity content of 0.17%.

[0082] [Comparative Example 1] <Purification of Iridium Complex A by Crystallization> Benzonitrile (50.00 g) was added to the crude product (2.50 g) containing iridium complex A obtained in Reference Example 2, and completely dissolved. The obtained solution was kept at room temperature (25° C.) under a nitrogen atmosphere and stirred for 3 hours. Acetonitrile (125.00 mL) was added thereto, and the precipitated solid was collected by filtration. The obtained iridium complex A (1.53 g) was purified by applying normal phase column chromatography using silica gel (30.04 g) and eluting with a 2:8 mixed solution of ethyl acetate / n-heptane. The column effluent was fractionated to collect a fraction containing iridium complex A, which was then concentrated and dried. The obtained dried product (0.87 g) was analyzed and quantified by HPLC, and it was found to contain 0.85 g of iridium complex A, with a yield of 77.1%, a purity of 98.44%, and an impurity content of 0.50%.

[0083] [Comparative Example 2] <Purification of iridium complex A by column chromatography alone> The crude product (2.50 g) containing iridium complex A obtained in Reference Example 2 was purified by normal phase column chromatography using silica gel (150.00 g) and eluted with a 2:8 mixed solution of ethyl acetate / n-heptane. The column effluent was fractionated to recover a fraction containing iridium complex A, which was then concentrated to dryness. The obtained dry product (1.04 g) was analyzed and quantified by HPLC, and it was found to contain 0.97 g of iridium complex A, with a calculated yield of 88.2%, complex purity of 98.34%, and impurity content of 1.57%.

[0084] The results of Example 1 and Comparative Examples 1 and 2 are summarized in Table 1.

[0085] [Table 1]

[0086] From the above results, it is possible to easily remove impurities that are difficult to remove by purifying a transition metal complex synthesized according to a conventional method using the purification step included in the method for producing a transition metal complex according to the present invention. This shows that the method for producing a transition metal complex according to the present invention makes it possible to synthesize and purify a transition metal complex on an industrial scale, and to produce a high-purity transition metal complex with high production efficiency. [Industrial Applicability]

[0087] The production method according to the present invention enables a high-purity transition metal complex to be produced in a simple manner, and is therefore particularly applicable to the production of iridium complexes used in organic electroluminescent devices.

Claims

1. A method for producing a transition metal complex, comprising the step of purifying the transition metal complex by heating and aging a solution containing the transition metal complex and a coordinating compound.

2. The method according to claim 1 , wherein the transition metal contained in the transition metal complex is a Group 8 or 9 metal element.

3. The method according to claim 2 , wherein the Group 8 or 9 metal element is iridium.

4. The process according to claim 1 , wherein the transition metal complex is a triscyclometallated iridium complex.

5. The method according to claim 4, wherein the triscyclometallated iridium complex is a homotriscyclometallated iridium complex.

6. The method according to claim 1 , wherein the coordinating compound is a compound containing a nitrogen atom.

7. The method according to claim 1 , wherein the mass of the coordinating compound contained in the solution is 0.01 times or more the mass of the transition metal complex.

8. The method according to claim 1, wherein the heat aging is carried out at 70°C or higher.

9. The method of claim 1 , wherein the solution further comprises a solvent.

10. The method according to claim 9 , wherein the transition metal complex has a solubility in the solvent at 25° C. of 10 mg / mL or more.

11. A transition metal complex in which, when the relative retention time of a peak exhibited by the transition metal complex is taken as 1.0, the area ratio of the total area of ​​a group of peaks appearing in the relative retention time range of 0.3 to 0.9 to the total peak area is 0.49% or less in liquid chromatography analysis under the following conditions: (Liquid Chromatography Analysis Conditions) Analytical column: A column with a silica gel base and an octadecyl group as the chemical bond. (Average particle size 3 μm, average pore size 10 nm, length 250 mm x inner diameter 4.6 mm) Sample concentration: 0.1% by weight (dilution solvent: tetrahydrofuran) Column oven temperature: ４０℃ Career: Acetonitrile:2-propanol=75:25 (volume ratio) mixed solution Column liquid flow rate: 1.0mL / min

12. An organic electroluminescence device using the transition metal complex according to claim 11.

13. A method for purifying a transition metal complex, comprising a step of heating and maturing a solution containing the transition metal complex and a coordinating compound.

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