- Luminescence properties of cyclometalated platinum(II) complexes in a dichloromethane/n-hexane system
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The luminescence properties of three neutral cyclometalated Pt(II) complexes were investigated in a CH2Cl2/n-hexane system. The diphenylamino and trifluoromethyl modified Pt2 exhibits aggregation-induced phosphorescent emission (AIPE
- Tao, Weitong,Chen, Yan,Lu, Lu,Liu, Chun
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- Structural Insights into the Nature of Fe0 and FeI Low-Valent Species Obtained upon the Reduction of Iron Salts by Aryl Grignard Reagents
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Mechanistic studies of the reduction of FeIII and FeII salts by aryl Grignard reagents in toluene/tetrahydrofuran mixtures in the absence of a supporting ligand, as well as structural insights regarding the nature of the low-valent iron species obtained at the end of this reduction process, are reported. It is shown that several reduction pathways can be followed, depending on the starting iron precursor. We demonstrate, moreover, that these pathways lead to a mixture of Fe0 and FeI complexes regardless of the nature of the precursor. M?ssbauer and 1H NMR spectroscopies suggest that diamagnetic 16-electron bisarene complexes such as (η4-C6H5Me)2Fe0 can be formed as major species (85% of the overall iron quantity). The formation of a η6-arene-ligated low-spin FeI complex as a minor species (accounting for ca. 15% of the overall iron quantity) is attested by M?ssbauer spectroscopy, as well as by continuous-wave electron paramagnetic resonance (EPR) and pulsed-EPR (HYSCORE) spectroscopies. The nature of the FeI coordination sphere is discussed by means of isotopic labeling experiments and density functional theory calculations. It is shown that the most likely low-spin FeI candidate obtained in these systems is a diphenylarene-stabilized species [(η6-C6H5Me)FeIPh2]- exhibiting an idealized C2v topology. This enlightens the nature of the lowest valence states accommodated by iron during the reduction of FeIII and FeII salts by aryl Grignard reagents in the absence of any additional coligand, which so far remained rather unknown. The reactivity of these low-valent FeI and Fe0 complexes in aryl-heteroaryl Kumada cross-coupling conditions has also been investigated, and it is shown that the zerovalent Fe0 species can be used efficiently as a precursor in this reaction, whereas the FeI oxidation state does not exhibit any reactivity.
- Clémancey, Martin,Cantat, Thibault,Blondin, Geneviève,Latour, Jean-Marc,Dorlet, Pierre,Lefèvre, Guillaume
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- Synthesis, characterization, and electroluminescent properties of iridium(III) 2-phenylpyridine-type complexes containing trifluoromethyl substituents and various main-group moieties
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New heteroleptic cyclometalated iridium(III) 2-phenylpyridine-type complexes with trifluoromethyl substituents and various main-group moieties were synthesized and their photophysical, electrochemical, and electroluminescent (EL) properties studied. The emission color can be tuned by a facile derivatization of the phenyl moiety of 2-phenylpyridine with various main-group moieties, and we have prepared new yellowish-green to orange triplet emitters with enhanced charge injection/charge transporting features, which can furnish attractive EL performance in phosphorescent organic light-emitting devices (OLEDs). Attempts were also made to fabricate two-color white-light OLEDs based on a combination of fluorescent blue and phosphorescent orange emitters.
- Ho, Cheuk-Lam,Lam, Ching-Shan,Sun, Ning,Ma, Dongge,Liu, Li,Yu, Zhen-Qiang,Xue, Liqin,Lin, Zhenyang,Li, Hua,Lo, Yih Hsing,Wong, Wai-Yeung
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- Importance of Two-Electron Processes in Fe-Catalyzed Aryl-(hetero)aryl Cross-Couplings: Evidence of Fe0/FeIICouple Implication
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We demonstrate in this work that two drastically distinct mechanisms can be involved in aryl-(hetero)aryl Fe-mediated cross-couplings between Grignard reagents and organic halides, depending on the nature of the latter. (Hetero)aryl electrophiles, which easily undergo one-electron reduction, can be involved in a FeII/FeIII coupling sequence featuring an in situ generated organoiron(II) species, akin to their aliphatic analogues. On the other hand, less easily reduced substrates can be activated by transient Fe0 species formed by the reduction of the precatalyst. In this case, the coupling mechanism relies on two-electron elementary steps involving the Fe0/FeII redox couple and proceeds by an oxidative addition/reductive elimination sequence. Hammett analysis shows that both those elementary steps are faster for electrophiles substituted by electron-withdrawing groups. The two mechanisms discussed herein can be involved concomitantly for electrophiles displaying an average oxidative power. Attesting to the feasibility of the aforementioned bielectronic mechanism, high-spin organoiron(II) intermediates formed by two-electron oxidative addition onto (hetero)aryl halides in catalytically relevant conditions were also characterized for the first time. Those results are sustained by paramagnetic 1H NMR, kinetics monitoring, and density functional theory (DFT) calculations.
- Wowk, Vincent,Rousseau, Lidie,Lefèvre, Guillaume
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supporting information
p. 3253 - 3266
(2021/10/12)
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- Nickel-Catalyzed Reductive 2-Pyridination of Aryl Iodides with Difluoromethyl 2-Pyridyl Sulfone
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A novel nickel-catalyzed reductive cross-coupling between aryl iodides and difluoromethyl 2-pyridyl sulfone (2-PySO2CF2H) enables C(sp2)-C(sp2) bond formation through selective C(sp2)-S bond cleavage, which demonstrates the new reactivity of 2-PySO2CF2H reagent. This method employs readily available nickel catalyst and sulfones as cross-electrophile coupling partners, providing facile access to biaryls under mild reaction conditions without pregeneration of arylmetal reagents.
- Miao, Wenjun,Ni, Chuanfa,Xiao, Pan,Jia, Rulong,Zhang, Wei,Hu, Jinbo
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p. 711 - 715
(2021/01/26)
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- A facile and versatile electro-reductive system for hydrodefunctionalization under ambient conditions
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A general electrochemical system for reductive hydrodefunctionalization is described, employing the inexpensive and easily available triethylamine (Et3N) as a sacrificial reductant. This protocol is characterized by facile operation, sustainable conditions, and exceptionally wide substrate scope covering the cleavage of C-halogen, N-S, N-C, O-S, O-C, C-C and C-N bonds. Notably, the selectivity and capability of reduction can be conveniently switched by simple incorporation or removal of an alcohol as a co-solvent.
- Huang, Binbin,Guo, Lin,Xia, Wujiong
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supporting information
p. 2095 - 2103
(2021/03/26)
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- Base-Activated Latent Heteroaromatic Sulfinates as Nucleophilic Coupling Partners in Palladium-Catalyzed Cross-Coupling Reactions
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Heteroaromatic sulfinates are effective nucleophilic reagents in Pd0-catalyzed cross-coupling reactions with aryl halides. However, metal sulfinate salts can be challenging to purify, solubilize in reaction media, and are not tolerant to multi-step transformations. Here we introduce base-activated, latent sulfinate reagents: β-nitrile and β-ester sulfones. We show that under the cross-coupling conditions, these species generate the sulfinate salt in situ, which then undergo efficient palladium-catalyzed desulfinative cross-coupling with (hetero)aryl bromides to deliver a broad range of biaryls. These latent sulfinate reagents have proven to be stable through multi-step substrate elaboration, and amenable to scale-up.
- Blakemore, David C.,Cook, Xinlan A. F.,Moses, Ian B.,Pantaine, Lo?c R. E.,Sach, Neal W.,Shavnya, Andre,Willis, Michael C.
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p. 22461 - 22468
(2021/09/09)
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- Selective Defluoroallylation of Trifluoromethylarenes
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We report a fluoride-initiated coupling reaction between trifluoromethylarenes and allylsilanes to access allylated α,α-difluorobenzylic compounds. This method's utility is demonstrated through a 30 mmol scale reaction, a sequential allylation/derivatization protocol and multiple examples of site-selective trifluoromethylarene allylation. Initial mechanistic studies suggest a base-induced single electron transfer pathway is responsible for the high efficiency and selectivity of this novel C-F substitution process.
- Luo, Chaosheng,Bandar, Jeffrey S.
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supporting information
p. 14120 - 14125
(2019/10/11)
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- Transition-Metal-Free Desulfinative Cross-Coupling of Heteroaryl Sulfinates with Grignard Reagents
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A mild cross-coupling reaction of heteroaryl sulfinates with Grignard reagents has been developed under transition-metal-free conditions. This study provides an example of the SO22- as a leaving group in an aromatic system and an effective methodology for the construction of C-C bond.
- Wei, Jun,Liang, Huamin,Ni, Chuanfa,Sheng, Rong,Hu, Jinbo
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supporting information
(2019/02/05)
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- Synthesis and catalytic activity of N-heterocyclic silylene (NHSi) cobalt hydride for Kumada coupling reactions
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The electron-rich silylene Co(i) chloride 5 was obtained through the reaction of CoCl(PMe3)3 with chlorosilylene. Complex 5 reacted with 1,3-siladiazole HSiMe(NCH2PPh2)2C6H4 to give the silylene Co(iii) hydride 6 through chelate-assisted Si-H activation. To the best of our knowledge, complex 6 is the first example of Co(iii) hydride supported by N-heterocyclic silylene. Complexes 5 and 6 were fully characterized by spectroscopic methods and X-ray diffraction analysis. Complex 6 was used as an efficient precatalyst for Kumada cross-coupling reactions. Compared with the related complex 3 supported by only trimethylphosphine, complex 6 as a catalyst supported by both chlorosilylene and trimethylphosphine exhibits a more efficient performance for the Kumada cross-coupling reactions. A novel catalytic radical mechanism was suggested and experimentally verified. As an intermediate silylene cobalt(ii) chloride 6d was isolated and structurally characterized.
- Qi, Xinghao,Sun, Hongjian,Li, Xiaoyan,Fuhr, Olaf,Fenske, Dieter
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p. 2581 - 2588
(2018/02/28)
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- Based on pyridine ring metal-ligand-platinum complex and its preparation method and application
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The invention relates to a novel cyclometal ligand-platinum complex and a preparation method and application thereof, and belongs to the technical field of electronic materials. The novel cyclometal ligand-platinum complex is convenient in template design and easy to obtain. Triphenylaminyl, quinolyl and trifluoromethyl are introduced in a material, and the electron structure and the hole injection and transmission performance of the material can be conveniently adjusted by adjusting substituents on an aza heteroaromatic ring. The complex provided by the invention is good in thermal stability and hole injection and transmission performance, and has wide application prospect in the fields of organic electroluminescent materials, oxygen sensing materials, dyes and medicines and the like. The oxygen sensor prepared by the complex has the advantages of simple structure, low cost, reliable work and the like; and the complex can be prepared into a portable oxygen sensor to be popularized and used.
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Paragraph 0069
(2016/11/07)
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- Room-temperature palladium-catalysed Suzuki-Miyaura coupling of arylboric acid with aryl chlorides
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An efficient room-temperature Pd-catalyzed Suzuki-Miyaura cross-coupling reaction of aryl-boronic acids with aryl chlorides is communicated here. The Pd(OAc)2/NiXantphos catalyst system enables the coupling reaction at room temperature in good
- Wang, Dan,Chen, Hong-Guan,Tian, Xin-Chuan,Liang, Xiao-Xia,Chen, Feng-Zhen,Gao, Feng
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p. 107119 - 107122
(2016/01/08)
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- Trifluoromethyl-substituted cyclometalated iridiumIII emitters with high photostability for continuous oxygen sensing
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Trifluoromethyl-substituted cyclometalated Ir(III) complexes have been prepared and fully characterized. The photophysical and electrochemical properties of the complexes were investigated systematically. All iridium complexes exhibit high photoluminescence quantum yields, high oxidation potentials and good photostability against continuous irradiation. The optimum loading level of the Ir(III) complexes incorporated into oxygen-sensitive films has been discussed. Three different polymers were investigated for the development of efficient oxygen-sensitive films. All Ir(III) complexes immobilized in ethyl cellulose demonstrated quick responses to various oxygen concentrations and high sensitivity upon changes of oxygen partial pressure. These cyclometalated Ir(III) complexes with high photostability are potential candidates for online continuous monitoring of oxygen concentrations.
- Liu, Chun,Lv, Xin,Xing, Yang,Qiu, Jieshan
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supporting information
p. 8010 - 8017
(2015/08/06)
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- Practical iron- and cobalt-catalyzed cross-coupling reactions between n-heterocyclic halides and aryl or heteroaryl magnesium reagents
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The reaction scope of iron- and cobalt-catalyzed cross-coupling reactions in the presence of isoquinoline (quinoline) in the solvent mixture tBuOMe/THF has been further investigated. Various 2-halogenated pyridine, pyrimidine, and triazine derivatives were arylated under these mild conditions in excellent yields. The presence of isoquinoline allows us to perform Fe-catalyzed cross-coupling reactions between 6-chloroquinoline and aryl magnesium reagents. Furthermore, it was found that the use of 10% N,N-dimethylquinoline-8-amine increases the yields of some Co-catalyzed cross-coupling reactions with chloropyridines bearing electron-withdrawing substituents. Iron out your coupling! The use of iron and cobalt catalysts in a combination with only 10% isoquinoline represents a practical method for the cross-coupling reactions of various 2-halogenopyridines, -pyrimidines, and -triazines, as well as 6-halogenoquinolines with functionalized aryl or heteroaryl Grignard reagents (see scheme).
- Kuzmina, Olesya M.,Steib, Andreas K.,Fernandez, Sarah,Boudot, Willy,Markiewicz, John T.,Knochel, Paul
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supporting information
p. 8242 - 8249
(2015/05/27)
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- Palladium-catalyzed cross-coupling reaction of functionalized aryl- and heteroarylbismuthanes with 2-halo(or 2-Triflyl)azines and -diazines
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The palladium-catalyzed cross-coupling of highly functionalized organobismuthanes with 2-halo(or 2-triflyl)pyridines, -pyrimidines, -pyrazines, and -pyridazines is reported. The reaction tolerates numerous functional groups, including aldehydes. The synthesis of a shelf-stable (formylphenyl)bismuth reagent and its use in a cross-coupling reaction is also described. The palladium-catalyzed cross-coupling of highly functionalized organobismuthanes with 2-halo(or 2-triflyl)pyridines, -pyrimidines, -pyrazines, and -pyridazines is reported. The reaction tolerates numerous functional groups, including aldehydes. The synthesis of a shelf-stable (formylphenyl)bismuth reagent and its use in cross-coupling reactions is also described. Copyright
- Petiot, Pauline,Gagnon, Alexandre
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supporting information
p. 5282 - 5289
(2013/09/02)
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- Room-temperature Suzuki-Miyaura coupling of heteroaryl chlorides and tosylates
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Suzuki-Miyaura coupling of heteroaryls is an important method for the preparation of compound libraries for medicinal chemistry and materials research. Although many catalysts have been developed, none of them have been generally applicable to the coupling reactions of heteroaryl chlorides and tosylates at room temperature. We discovered that a catalyst combination of Pd(OAc)2 and XPhos (2-dicyclohexylphosphanyl-2',4',6'- triisopropylbiphenyl) could efficiently catalyze these couplings. Besides the choice of catalyst, the use of hydroxide bases in an aqueous alcoholic solvent was essential for fast couplings. These conditions promoted fast release of active catalyst (XPhos)Pd0, and accelerated the transmetalation in the catalytic cycle. Most of the major families of heteroaryl chlorides (31 examples) and tosylates (17 examples) reached full conversion within minutes to hours at room temperature. The method could be easily scaled up for gram-scale synthesis. Furthermore, we examined the relative reactivity of coupling partners in whole reactions. Electron-rich heteroaryl chlorides and tosylates reacted more slowly than electron-deficient ones, in the order of indole, pyrrole furan, thiophene > pyridine. Similarly, electron-deficient arylboronic acids were less reactive than electron-neutral and electron-rich ones. The reactivity trends from this study can help to choose appropriate coupling partners for Suzuki reactions.
- Yang, Junfeng,Liu, Sijia,Zheng, Jian-Feng,Zhou, Jianrong
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supporting information
p. 6248 - 6259,12
(2020/09/16)
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- Negishi cross-coupling reactions catalyzed by an aminophosphine-based nickel system: A reliable and general applicable reaction protocol for the high-yielding synthesis of biaryls
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Treatment of NMP solutions of NiCl2 with 1,1′,1″- (phosphanetriyl)tripiperidine (≈2.05 equiv), dissolved in THF, in air at 25°C forms a highly active catalytic system for the cross-coupling of a large variety of electronically activated, non-activated, deactivated, and ortho-substituted, heterocyclic, and functionalized aryl bromides and aryl chlorides with diarylzinc reagents. Very high levels of conversion and yields were obtained within 2 h at 60°C in the presence of only 0.1 mol% of catalyst (based on nickel) and thus at catalyst loadings far lower than typically reported for nickel-catalyzed versions of the Negishi reaction. Various aryl halides-which may contain trifluoromethyl groups, fluorides, or other functional groups such as acetals, ketones, ethers, esters, lactones, amides, imines, anilines, alkenes, pyridines, quinolines, and pyrimidines-were successfully converted into the corresponding biaryls. Electronic and steric variations are tolerated in both reaction partners. Experimental observations indicate that a molecular (NiI/NiIII) mechanism is operative.
- Gerber, Roman,Frech, Christian M.
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experimental part
p. 11893 - 11904
(2011/11/29)
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- Simple mixed Fe-Zn catalysts for the Suzuki couplings of tetraarylborates with benzyl halides and 2-halopyridines
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Employing co-catalytic zinc reagents facilitates the iron-catalysed Suzuki cross-coupling of tetraarylborates with both benzyl and 2-heteroaryl halides.
- Bedford, Robin B.,Hall, Mark A.,Hodges, George R.,Huwe, Michael,Wilkinson, Mark C.
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supporting information; experimental part
p. 6430 - 6432
(2010/03/03)
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- Micellar catalysis of Suzuki-Miyaura cross-couplings with heteroaromatics in water
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(Chemical Equation Presented) Pd-catalyzed couplings involving several heteroaromatic halides (bromides and chlorides) as well as boronic acids can be done under exceedingly mild conditions (between rt and 40 °C) in pure water using commercially available Pd catalysts and PTS, a nanomicelle-forming amphiphile.
- Lipshutz, Bruce H.,Abela, Alexander R.
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supporting information; experimental part
p. 5329 - 5332
(2009/06/06)
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- Palladium Charcoal-Catalyzed Suzuki-Miyaura Coupling to Obtain Arylpyridines and Arylquinolines
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A phosphine ligand, such as PPh3 or 2-(dicyclohexylphosphino)biphenyl, is essential for the Pd/C-catalyzed Suzuki-Miyaura coupling of halopyridines and haloquinolines, although it has been reported that the reaction of phenyl chlorides can be catalyzed by nonprereduced Pd/C without any additives. In the reactions of bromopyridines, bromoquinolines, 2-chloropyridines, and 2-chloroquinolines, PPh3 was effective enough to provide coupling products in good yields. However, in the reactions of 3-chloropyridine, 4-chloropyridine, and 6-chloroquinoline, sterically hindered 2-(dicyclohexylphosphino)biphenyl was indispensable as a ligand.
- Tagata, Tsuyoshi,Nishida, Mayumi
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p. 9412 - 9415
(2007/10/03)
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- Luminescence device, display apparatus and metal coordination compound
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A luminescence device is principally constituted by a pair of electrodes and an organic compound layer disposed therebetween. The layer contains a metal coordination compound represented by the following formula (1): wherein M denotes Ir, Rh or Pd; n is 2 or 3; and X1 to X8 independently denote hydrogen atom or a substituent selected from the group consisting of halogen atom; nitro group; trifluoromethyl group trialkylsilyl group having three linear or branched alkyl groups each independently having 1-8 carbon atoms; and a linear or branched alkyl group having 2-20 carbon atoms capable of including one or at least two non-neighboring methylene groups which can be replaced with —O—, —S—, —CO—, —CO—O—, —O—CO—, —CH═CH— or —C≡C— and capable of including hydrogen atom which can be replaced with fluorine atom; with the proviso that at least one of X1 to X8 is a substituent other than hydrogen atom, and X2 and X3 cannot be fluorine atom at the same time.
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