- Nanostructured IrOx Coatings for Efficient Oxygen Evolution Reactions in PV-EC Setup
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New heteroleptic iridium compounds exhibiting high volatility and defined thermal decomposition behavior were developed and tested in plasma-enhanced chemical vapor deposition (PECVD). The iridium precursor [(COD)Ir(TFB-TFEA)] (COD = 1,5-cyclooctadiene; TFB-TFEA = N-(4,4,4-Trifluorobut-1-en-3-on)-6,6,6-trifluoroethylamin) unifies both reactivity and sufficient stability through its heteroleptic constitution to offer a step-by-step elimination of ligands to provide high compositional purity in CVD deposits. The substitution of neutral COD ligands against CO groups further increased the volatility of the precursor. PECVD experiments with unambiguously characterized Ir compounds (single crystal X-ray diffraction analysis) demonstrated their suitability for an atom-efficient (high molecule-to-precursor yield) gas phase deposition of amorphous iridium oxide (IrOx) phases. Thin films of IrOx were well suited as electrocatalyst in oxygen evolution reaction so that an efficient coupled system in combination with solar cells is viable to perform water-splitting reaction without external bias.
- Jürgensen, Lasse,Frank, Michael,Graf, David,Gessner, Isabel,Fischer, Thomas,Welter, Katharina,J?germann, Wolfram,Mathur, Sanjay
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- Polymerization of phenylacetylene catalyzed by organoiridium compounds
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The compounds [Ir(cod)X]2 (cod = 1,5-cyclooctadiene; X = Cl, OMe) catalyze the polymerization of phenylacetylene, with negligible formation of oligomeric products. At variance, the monoolefin analogue [Ir(cot)2Cl]2 (cot = cyclooctene) only promotes alkyne cyclotrimerization. The polymerization reaction proceeds in various solvents such as tetrahydrofuran (THF), chloroform and benzene, but it is most favored when using NEt3 as reaction medium. The role of the diene in the catalytic reaction is investigated, also in relation to a deactivation process of the catalyst with time. Spectroscopic studies of the catalytic reaction indicate the formation of monomeric iridium-solvent adducts, which are likely to be the initiators of the polymerization reaction. A possible reaction mechanism is proposed, according to the data reported in the literature and the results of the present investigation.
- Marigo, Mauro,Marsich, Nazario,Farnetti, Erica
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- Subvalent Iridium Precursors for Atom-Efficient Chemical Vapor Deposition of Ir and IrO2 Thin Films
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A new heteroleptic Ir(I) compound exhibiting high volatility and defined thermal decomposition under CVD conditions is reported. The new iridium precursor [(COD)Ir(ThTFP)] (COD = cyclooctadiene, ThTFP = (Z)-3,3,3-trifluoro-1-(thiazol-2-yl)prop-1-en-2-olate) unifies both reactivity and sufficient stability through its heteroleptic constitution to provide a precise control over compositional purity in CVD deposits. The solution integrity of the monomeric Ir(I) complex was investigated by 1D and 2D NMR spectroscopy and EI mass spectrometry, whereas the molecular structure was confirmed by single-crystal diffraction. CVD experiments demonstrated the suitability of the iridium compound for an atom-efficient (high molecule-to-precursor yield) gas-phase deposition of nanocrystalline iridium films that could be converted into crystalline iridium dioxide upon heat treatment to demonstrate their electrocatalytic potential in the oxygen evolution reaction.
- Jürgensen, Lasse,Frank, Michael,Pyeon, Myeongwhun,Czympiel, Lisa,Mathur, Sanjay
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- Synthesis and characterisation of a novel mixed donor P,O,P' nixantphos ligand and its metal complex
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The complex [(NixC8OH)Ir(cod)Cl] 4 has been synthesized and structurally characterized by NMR, IR and single crystal X-ray diffraction. The synthesis and characterisation of the novel ligand NixC8OH is also presented. The coordination around Ir is trigonal bipyramidal with both P groups of the NixC8OH ligand bound in a bis-equatorial mode. The bis-chelating cod (C8H12) ligand occupies the remaining equatorial position and an axial position. This mode of bonding has resulted in a large bite angle (P1-Ir-P2) of 102.92(12)° for the title complex 4. The IR and NMR data further support the elucidated structure. Thermal analyses of 4 indicate that it is thermally stable up to a decomposition temperature of >400 °C.
- Marimuthu, Thashree,Bala, Muhammad D.,Friedrich, Holger B.
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- A kinetic investigation of the oxidative addition reactions of the dimeric Bu4N[Ir2(μ-Dcbp)(cod)2] complex with iodomethane
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The kinetic results of the oxidative addition of iodomethane to Bu4N[Ir2(μ-Dcbp)(cod)2] (Dcbp = 3,5-dicarboxylatepyrazolate anion) show that oxidative addition can occur via a direct equilibrium pathway (K1 = 88(22) acetone, 51(3) 1,2-dichloroethane, 55(4) dichloromethane, 52(12) acetonitrile and 43(5) M-1 chloroform) or a solvent-assisted pathway (k2, k3). Oxidative addition occurs mainly along the direct pathway, which is a factor 10-40 faster than the solvent-assisted pathway. The observed solvent effect cannot be attributed to the donosity or polarity of the solvents. The fairly negative ΔS≠ value (-110(7) J K-1 mol-1) and the positive ΔH≠ value (+47(2) kJ mol-1) for the oxidative addition step are indicative of an associative process.
- Grobbelaar, Ebeth,Purcell, Walter,Basson, Stephen S.
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- Vapor pressure of some volatile iridium(I) compounds with carbonyl, acetylacetonate and cyclopentadienyl ligands
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Volatile compounds of iridium(I): (acetylacetonato)(1,5-cyclooctadiene) iridium(I) Ir(acac)(cod), (methylcyclopentadienyl) (1,5-cyclooctadiene) iridium(I) Ir(Cp')(cod), (pentamethylcyclopentadienyl)(dicarbonyl) iridium(I) Ir(Cp*)(CO)2 and (acet
- Morozova,Semyannikov,Trubin,Stabnikov,Bessonov,Zherikova,Igumenov
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- Luminescent iridium(III) complexes supported by a tetradentate trianionic ligand scaffold with mixed O, N, and C donor atoms: Synthesis, structures, photophysical properties, and material applications
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A panel of tetradentate H3-O^N^C^O ligands has been synthesized and employed as a trianionic scaffold for preparing [IrIII(O^N^C^O)(L)2], with L = a wide variety of neutral ligands, and also [IrIII(O^N^C^O)(C≡NAr)(NH2Ar)], [IrIII(O^N^C^O)(C≡NAr)(X)] (Ar = 2,6-Me2C6H3; X = 1-methylimidazole, PPh3, pyridine), and [IrIII(O^N^C^O)- (NHC)]2 (NHC = N-heterocyclic carbene). X-ray crystal structure analysis and photophysical studies (including variable-temperature emission lifetime measurements and nanosecond time-resolved emission and absorption spectroscopy) were performed. [Ir(O^N^C^O)(L)2] display a moderately strong phosphorescence at room temperature (emission quantum yields up to 18% in solution, 51% in PMMA film), with the luminescent properties being strongly affected by axial L ligands. The use of [Ir(O^N^C^O)(NHC)2] as a phosphorescent emitter in a solution-processed organic light-emitting diode device generated a red electrophosphorescence with an EQE of 10.5% and CIE chromaticity coordinates of (0.64, 0.36).
- Chen, Daqing,Li, Kai,Guan, Xiangguo,Cheng, Gang,Yang, Chen,Che, Chi-Ming
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- Fluorine-free blue-green emitters for light-emitting electrochemical cells
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There is presently a lack of efficient and stable blue emitters for light-emitting electrochemical cells (LEECs), which limits the development of white light emitting systems for lighting. Cyclometalated iridium complexes as blue emitters tend to show low photoluminescence efficiency due to significant ligand-centred character of the radiative transition. The most common strategy to blue-shift the emission is to use fluorine substituents on the cyclometalating ligand, such as 2,4-difluorophenylpyridine, dFppy, which has been shown to decrease the stability of the emitter in operating devices. Herein we report a series of four new charged cyclometalated iridium complexes using methoxy- and methyl-substituted 2,3′-bipyridine as the main ligands. The combination of donor groups and the use of a cyclometalated pyridine has been recently reported for neutral complexes and found electronically equivalent to dFppy. We describe the photophysical and electrochemical properties of the complexes in solution and use DFT and TDDFT calculations to gain insights into their properties. The complexes exhibit bluish-green emission with onsets around 450 nm, which correspond to the maximum emission at 77 K. Furthermore, photoluminescence quantum yields in solution are all above 40%, with the brightest in the series at 66%. Finally, LEECs were prepared using these complexes as the emissive material to evaluate the performance of this particular design. Compared to previously reported devices with fluorine-containing emitters, the emitted colours are slightly red-shifted due to methyl substituents on the coordinating pyridine of the main ligand and overall device performances, unfortunately including the stability of devices, are similar to those previously reported. Interestingly within the series of complexes there appears to be a positive effect of the methoxy-substituents on the stability of the devices. The poor stability is therefore attributed to the combination of cyclometalated pyridine and methoxy groups. the Partner Organisations 2014.
- Evariste, Sloane,Sandroni, Martina,Rees, Thomas W.,Roldan-Carmona, Cristina,Gil-Escrig, Lidon,Bolink, Henk J.,Baranoff, Etienne,Zysman-Colman, Eli
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- Preparation method of iridium catalyst
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The invention discloses a preparation method of an iridium catalyst [IrCl(C8H12)]2. The preparation method comprises following steps: a compound containing iridium and chlorine is dissolved in water in an oxygen-free environment, and an iridium solution is prepared; cyclooctadiene is added to the iridium solution, a reducing agent is slowly dropwise added for a reduction reaction, and the reducingagent is dropwise added until no precipitates are produced; the solution is filtered, evaporative crystallization is performed after solids are washed with water, and [IrCl(C8H12)]2 is obtained. According to the method, the reaction time is short, and the product is high in purity and yield.
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Paragraph 0026; 0027; 0032-0036
(2019/09/17)
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- Preparation method of (1,5-cyclooctadiene) methoxy iridium (I) dimer
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The invention discloses a preparation method of a (1,5-cyclooctadiene)methoxy iridium (I) dimer, which comprises the following steps: (1) mixing iridium powder and sodium chloride, purging the mixturewith N2, performing chlorination, dissolving the obtained solid powder in a hydrochloric acid solution, and stirring the solution to obtain a sodium chloroiridate water solution; (2) enabling the sodium chloroiridate aqueous solution to pass through acidic cation exchange resin to obtain a chloroiridic acid aqueous solution; (3) under the protection of N2, adding 1,5-cyclooctadiene into ethanol,increasing the temperature, dropwise adding a chloroiridic acid aqueous solution into the ethanol, stirring the mixture for reaction after dropwise adding is finished, cooling a reaction product to room temperature, and performing crystallization and filtration to obtain a (1,5-cyclooctadiene) iridium chloride (I) dimer; and (4) adding potassium hydroxide into methanol, heating and stirring the mixture, adding the (1,5-cyclooctadiene) iridium chloride (I) dimer, performing a reaction for 3-6 hours, cooling and filtering the reaction product, washing the reaction product with water, and carrying out vacuum drying to obtain the product. The method provided by the invention has the advantages of high product yield and high purity.
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Paragraph 0017-0023
(2019/12/02)
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- Iridium(I)-Catalyzed C?H Borylation in Air by Using Mechanochemistry
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Mechanochemistry has been applied for the first time to an iridium(I)-catalyzed C?H borylation reaction. By using either none or just a catalytic amount of a liquid, the mechanochemical C?H borylation of a series of heteroaromatic compounds proceeded in air to afford the corresponding arylboronates in good-to-excellent yields. A one-pot mechanochemical C?H borylation/Suzuki–Miyaura cross-coupling sequence for the direct synthesis of 2-aryl indole derivatives is also described. The present study constitutes an important milestone towards the development of industrially attractive solvent-free C?H bond functionalization processes in air.
- Pang, Yadong,Ishiyama, Tatsuo,Kubota, Koji,Ito, Hajime
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supporting information
p. 4654 - 4659
(2019/03/17)
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- A new synthetic route to acylnitroso intermediates and their applications in HDA and ene reactions
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Background: Acylnitroso intermediates are considered as highly reactive and useful transient that have been used to synthesize a broad class of biological active compounds and synthetic drugs. Although there are some reported methods for the generation of these intermediates, but still challenge for mild and environmental benign protocol. Herein, we report the facile in situ synthesis of acylnitroso intermediates and their efficient hetero Diels-Alder (HDA) and ene reactions. Methods: Acylnitroso intermediates were readily obtained by hydrogen peroxide oxidation of hydroxamic acids catalyzed by Cu(I)-, Ir(I)- or Ru(II)-complexes and easily reacted with symmetric and asymmetric conjugated dienes beside their reaction with different alkenes which converted to biological active products. Results: The resulted acylnitroso intermediates were efficiently afforded the hetero Diels-Alder cycloadducts in the presence of cyclopentadiene, cyclohexadiene or α-terpinene in high yields along with good regioselectivity for the later. In case of N-dienyl lactams, the cycloadducts were formed in the yield up to 89% with complete regioselectivity. In the presence of optically active N-dienyl pyroglutamates, diastereoisomers were formed in high yields with up to 72 de. In addition, the transient acylnitroso species were trapped with alkene to form the ene product in yield up to 95 %. As an interesting transformation, the halocyclization of the ene products gave substituted oxazolidone in 77% yield which considered as one of the effective antimicrobial and antibiotic compounds. Conclusion: In a brief, we introduce a mild and effective route to deliver acylnitroso intermediates in situ by using environmentally benign, cost effective, and non-toxic hydrogen peroxide oxidant catalyzed by Cu(I)-, Ir(I)- or Ru(II)-complexes. Good to excellent yields, regio- and diastereoselectivity were obtained by trapping these intermediates in symmetric and asymmetric HDA and ene reactions. Interestingly, the ene products easily transformed to potent drugs.
- Fakhruddin, Ahmad,Abu-Elfotoh, Abdel-Moneim,Shibatomi, Kazutaka,Iwasa, Seiji
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supporting information
p. 196 - 205
(2018/03/09)
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- One-step synthesis method of (1,5-cyclooctadiene)-dichloro iridium dipolymer
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The invention discloses a one-step synthesis method of a (1,5-cyclooctadiene)-dichloro iridium dipolymer. The method comprises the following steps: introducing nitrogen into hydrated iridous chloride; then mixing with absolute ethyl alcohol and 1,5-cyclooctadiene under a stirring condition, and carrying out a refluxing reaction, wherein a large amount of red crystals are generated on the wall of a three-necked flask after the reaction is over; after the refluxing reaction is over, naturally cooling to a room temperature, washing the red crystals with iced absolute ethyl alcohol, and drying the washed red crystals, thereby obtaining the (1,5-cyclooctadiene)-dichloro iridium dipolymer; and performing vacuum concentration treatment on filtrate so as to respectively recover noble metal iridium and a solvent. Compared with an existing synthesis method, the synthesis method disclosed by the invention has the advantages that the reaction time is greatly shortened, the synthesis method is simple in operation with one-step reaction, and the productivity is greatly improved; the one-step synthesis method can be used for solving the defects of overlong reaction time, strict reaction conditions, raw material waste and the like in an existing synthesis process, and has the advantages of environmental conservation, economical efficiency, simplicity and convenience in operation, relatively short reaction time and the like.
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Paragraph 0016; 0018; 0020
(2017/12/01)
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- Method for preparing chloro(1,5-cyclooctadiene)iridium(I) dimer
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The invention relates to the field of noble metal catalyst synthesis, and discloses a method for preparing chloro(1,5-cyclooctadiene)iridium(I) dimer. The method includes the step that under the oxygen-free condition, an iridium-containing and chlorine-containing compound, aldehyde, 1,5-cyclooctadiene and solvent are subjected to a contact reaction. Traditionally used reactants (alcohol) are abandoned, and new reactants (aldehyde) are used, so the yield of chloro(1,5-cyclooctadiene)iridium(I) dimer can be as high as 75% in short reaction time. Consumption of water and 1,5-cyclooctadiene is low, waste liquid treatment loss is greatly reduced, and production cost is reduced.
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Paragraph 0049-0051
(2017/05/12)
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- Synthesis and reactivity of rhodium and iridium alkene, alkyl and silyl complexes supported by a phenyl-substituted PNP pincer ligand
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New rhodium and iridium complexes supported by the phenyl-substituted PNP pincer ligand PNPPhH (HN(2-PPh2-4-Me-C6H 3)2) (1) were synthesized. The reaction of 2 equiv. of 1 with [(COD)IrCl]2 afforded the coordination complex [(PNP PhH)Ir(COD)]Cl (2) featuring hydrogen bonding between the N-H group and the chloride anion, as characterized by NMR spectroscopy and X-ray crystallography. Reaction of 1 with [(COE)2IrCl]2 or [(COE)2RhCl]2 in benzene provided a mixture of complexes including (PNPPhH)MHCl2 (M = Ir (4), M = Rh (7)) and (PNP)M(COE) (M = Ir (5), M = Rh (8)). Alkene complexes of the type (PNP Ph)M(L) (M = Ir, L = COD (3) and COE (5); M = Rh, L = COE (8) and L = ethylene (9)) were synthesized by reaction of (PNPPh)Li with the appropriate alkene chloride complexes. Reactions of silanes with 5, 8 or 9 produced silyl hydride complexes (PNPPh)MH(SiR3) (M = Ir, R = Ph (16) and R = Et (17); M = Rh, R = Ph (18), Et (19) and Ph2Cl (20)) via Si-H oxidative addition. The JSiH coupling constants for rhodium complexes 18, 19 and 20 were determined to be ca. 35 Hz, while iridium complexes 16 and 17 exhibited coupling constants less than 10 Hz. X-Ray crystal structures of 16 and 18 reveal isostructural complexes featuring a trigonal bipyramidal geometry about iridium with a mer binding of the PNPPh ligand. A hydride ligand, located from the Fourier map for 18, has a short contact of 1.83(3) A with the silicon atom. Oxidative addition of iodomethane to 5 and 8 afforded (PNPPh)M(Me)(I)(THF) (M = Rh (14), M = Ir (12)), respectively. Arene C-H activation upon thermolysis of 12 in benzene produced (PNPPh)M(Ph)(I)(THF). Iridium silyl iodide complexes (PNPPh)IrI(SiR3) (SiR3 = SiPh3 (21), SiH2Mes (22) and SiH2Xyl (23)) resulted from addition of organosilanes to 12, via elimination of CH4. The Royal Society of Chemistry.
- Calimano, Elisa,Tilley, T. Don
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p. 9250 - 9263
(2011/01/06)
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- Iridium-catalyzed asymmetric allylic substitutions-very high regioselectivity and air stability with a catalyst derived from dibenzo[a,e]cyclooctatetraene and a phosphoramidite
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A final tweak: A new phosphoramidite iridium catalyst (see scheme) allows allylic substitutions to be run with a higher degree of regioselectivity than with other iridium catalysts and under aerobic conditions. Mechanistic aspects, in particular, the reversibility of the catalyst formation by C-H activation, are also presented. LL=dibenzocyclooctatetraene.
- Spiess, Stephanie,Welter, Carolin,Franck, Geraldine,Taquet, Jean-Philippe,Helmchen, Guenter
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p. 7652 - 7655
(2009/04/11)
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- Direct in situ synthesis of cationic N-heterocyclic carbene iridium and rhodium complexes from neat ionic liquid: Application in catalytic dehydrogenation of cyclooctadiene
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A direct synthetic route to cationic N-heterocyclic carbene (NHC) complexes of rhodium and iridium from neat dialkyl-imidazolium ionic liquids (ILs) has been found. The method uses complexes bearing basic anionic ligands, [M(COD)(PPh3)X], X = OEt, MeCO2, which react with the inactivated imidazolium cation in the absence of external bases yielding one M-NHC moiety and the free protonated base. This new one-pot synthesis leaving pure, catalytically active IL solutions is faster, cleaner and more efficient than traditional syntheses of such NHC complexes. The observed reactivity also gives insight into NHC incorporation of rhodium and iridium catalyzed reactions performed in common dialkyl-imidazolium ILs. The complexes synthesised in this manner are compared with their bis-phosphine analogues in terms of activity for catalytic dehydrogenation of 1,5-cyclooctadiene and 1,3-cyclooctadiene in neat [BMIM][NTf2] as solvent. Even at high temperature, no ligand exchange reaction is observed with [(COD)M(PPh3)2] [NTf2] catalysts. As expected, the yields of all the reactions were low, iridium was much more active in C-H activation than rhodium and the NHC ligands were more stable than triphenylphosphine. For all catalysts, the isomerisation of 1,5-cyclooctadiene is the major reaction. However, the phosphine-NHC complex of iridium seems to be more selective for dehydrogenation than its bis-phosphine counterpart, which is more active in transfer-hydrogenation and less stable under the applied conditions. Different reaction conditions were tried in order to optimise selectivity for dehydrogenation over isomerisation and transfer-hydrogenation. Surprisingly, with 1,3-cyclooctadiene as substrate selectivity for dehydrogenation is much higher than with 1,5-cyclooctadiene for all catalysts.
- Hintermair, Ulrich,Gutel, Thibaut,Slawin, Alexandra M.Z.,Cole-Hamilton, David J.,Santini, Catherine C.,Chauvin, Yves
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p. 2407 - 2414
(2008/09/20)
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- Reversible C-H bond activation of a bifunctional phosphine bridging ligand across two unbonded metal centers
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Reaction of [{Ir(μ-Cl)(cod)}2] with the short-bite bifunctional N,P-donor ligand (1-benzyl-2-imidazolyl) diphenylphosphine (Ph2PBzIm) gives the yellow complex [IrCl (Ph2PBzIm)(cod)] (2). A further addition of [{Ir (μ-Cl)(cod)}2] to 2 results in the reversible metalation of a phenyl ring across two unbonded iridium centers to give orange crystals of [IrCl(cod){μ-PPh(C6H4)-BzIm}IrHCl (cod)] (1). Complex 1 is in equilibrium with the mononuclear complex [IrCl(Ph2-PBzIm)(cod)] and the active species undergoing the sp2-C-H activation, [{IrCl(cod)}2 (μ-Ph2PBZIm)], in solution. Abstraction of one chloride ligand from 1 with AgBF4 produces the deinsertion of the C-H bond yielding the cationic complex [{Ir(cod)}2(μ-Ph2 PBzIm)(μ-Cl)]-BF4, which regenerates 1 upon addition of a chloride-soluble salt. The cationic complex [{Ir- (cod)}2(μ-Ph2PBzIm)(μ-Cl)]BF4 is inactive for the above-mentioned sp2-C-H bond activation and can be prepared alternatively from the reaction of 2 with [Ir(cod) (CH3CN)2]BF4. A related binuclear sp2-C-H bond activation across two unbonded metals also occurs in the reaction of dppm with [{Ir(μ-Cl)(cod)}2] in a 1:1 molar ratio. This reaction leads to a mixture in equilibrium of [{IrCl(cod)}2(μ-dppm)] and the hydride complex [IrCl(cod){μ-PPh(C6H4)CH2-PPh2)}IrHCl (cod)] in a 1.5:1 molar ratio, respectively, in dichloromethane at 20°C. The structure of the mixed-valence complex 1 was solved by X-ray diffraction studies.
- Tejel, Cristina,Bravi, Rita,Ciriano, Miguel A.,Oro, Luis A.,Bordonaba, Marta,Graiff, Claudia,Tiripicchio, Antonio,Burini, Alfrede
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p. 3115 - 3119
(2008/10/08)
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