7471-05-8Relevant academic research and scientific papers
Efficient Cp?Ir Catalysts with Imidazoline Ligands for CO2 Hydrogenation
Xu, Shaoan,Onishi, Naoya,Tsurusaki, Akihiro,Manaka, Yuichi,Wang, Wan-Hui,Muckerman, James T.,Fujita, Etsuko,Himeda, Yuichiro
, p. 5591 - 5594 (2015)
We report newly developed iridium catalysts with electron-donating imidazoline moieties as ligands for the hydrogenation of CO2 to formate in aqueous solution. Interestingly, these new complexes promote CO2 hydrogenation much more effectively than their imidazole analogues and exhibit a turnover frequency (TOF) of 1290 h-1 for the bisimidazoline complex compared to that of 20 h-1 for the bisimidazole complex at 1 MPa and 50 C. In addition, the hydrogenation proceeds smoothly even under atmospheric pressure at room temperature. The TOF of 43 h-1 for the bisimidazoline complex is comparable to that of a dinuclear complex (70 h-1, highest TOF reported) [Nat. Chem. 2012, 4, 383], which incorporates proton-responsive ligands with pendent-OH groups in the second coordination sphere. The catalytic activity of the complex with an N-methylated imidazoline moiety is much the same as that of the corresponding pyridylimidazoline analogue. This result and the UV/Vis titrations of the imidazoline complexes indicate that the high activity is not attributable to the deprotonation of NH on the imidazoline under the reaction conditions. A novel complex having imidazoline ligands shows much higher catalytic activity for CO2 hydrogenation than the conventional complex having imidazole ligands. The change from a double bond in imidazole to a single bond in imidazoline leads to a 60-fold increase in the catalytic activity.
Iridium-catalyzed chemoselective transfer hydrogenation of α, β-unsaturated ketones to saturated ketones in water
Chen, Jinxun,Chen, Yongsheng,Cui, Xiaofeng,Jiang, Xiaolan,Liu, Qixing,Zhou, Haifeng
supporting information, (2022/01/24)
A chemoselective iridium-catalyzed transfer hydrogenation of α, β-unsaturated ketones was realized in water. The C[dbnd]C double bonds of 2-benzylidene indanones and analogues were hydrogenated exclusively catalyzed by an iridium complex (0.1 mol%) bearin
Hydrogen production from formic acid catalyzed by a phosphine free manganese complex: Investigation and mechanistic insights
Léval, Alexander,Agapova, Anastasiya,Steinlechner, Christoph,Alberico, Elisabetta,Junge, Henrik,Beller, Matthias
supporting information, p. 913 - 920 (2020/02/27)
Formic acid dehydrogenation (FAD) is considered as a promising process in the context of hydrogen storage. Its low toxicity, availability and convenient handling make FA attractive as a potential hydrogen carrier. To date, most promising catalysts have been based on noble metals, such as ruthenium and iridium. Efficient non-noble metal systems like iron were designed but manganese remains relatively unexplored for this transformation. In this work, we present a panel of phosphine free manganese catalysts which showed activity and stability in formic acid dehydrogenation. The most promising results were obtained with Mn(pyridine-imidazoline)(CO)3Br yielding >14 l of the H2/CO2 mixture and proved to be stable for more than 3 days. Additionally, this study provides insights into the mechanism of formic acid dehydrogenation. Kinetic experiments, Kinetic Isotopic Effect (KIE), in situ observations, NMR labeling experiments and pH monitoring allow us to propose a catalytic cycle for this transformation.
Cooperative iridium complex-catalyzed synthesis of quinoxalines, benzimidazoles and quinazolines in water
Chakrabarti, Kaushik,Maji, Milan,Kundu, Sabuj
supporting information, p. 1999 - 2004 (2019/04/27)
Herein, an efficient methodology for the synthesis of a diverse class of N-heterocyclic moieties, such as quinoxalines, benzimidazoles and quinazolines, was developed in water using bio-renewable alcohols. The quinoxalines were successfully synthesized from a wide range of diamines and nitroamines with diols in air. Interestingly, benzimidazoles and quinazolines were synthesized with excellent isolated yields without using any external base. Finally, the preparative scale synthesis of various N-heterocycles and pharmaceutically active quinoxalines established the practicability of this protocol. For this iridium system, a metal-ligand cooperative mechanism was proposed based on kinetic and DFT studies.
Thermally triggered solid-state single-crystal-to-single-crystal structural transformation accompanies property changes
Li, Quan-Quan,Ren, Chun-Yan,Huang, Yang-Yang,Li, Jian-Li,Liu, Ping,Liu, Bin,Liu, Yang,Wang, Yao-Yu
supporting information, p. 4703 - 4711 (2015/03/18)
The 1D complex [(CuL0.5H2O)·H2O]n (1) (H4 L = 2,2′-bipyridine-3,3′ ,6,6′-tetracarboxylic acid) undergoes an irreversible thermally triggered single-crystal-to-single-crystal (SCSC) transformation to produce the 3D anhydrous complex [CuL0.5]n (2). This SCSC structural transformation was confirmed by single-crystal X-ray diffraction analysis, thermogravimetric (TG) analysis, powder X-ray diffraction (PXRD) patterns, variable-temperature powder X-ray diffraction (VT-PXRD) patterns, and IR spectroscopy. Structural analyses reveal that in complex 2, though the initial 1D chain is still retained as in complex 1, accompanied with the Cu-bound H2O removed and new O(carboxyl)-Cu bond forming, the coordination geometries around the CuII ions vary from a distorted trigonal bipyramid to a distorted square pyramid. With the drastic structural transition, significant property changes are observed. Magnetic analyses show prominent changes from antiferromagnetism to weak ferromagnetism due to the new formed Cu1-O-C-O-Cu4 bridge. The catalytic results demonstrate that, even though both solid-state materials present high catalytic activity for the synthesis of 2-imidazolines derivatives and can be reused, the activation temperature of complex 1 is higher than that of complex 2. In addition, a possible pathway for the SCSC structural transformations is proposed.
Efficient synthesis of 2-imidazolines in the presence of molecular iodine under ultrasound irradiation
Chen, Guo-Feng,Li, Hong-Yang,Xiao, Nan,Chen, Bao-Hua,Song, Ya-Li,Li, Ji-Tai,Li, Zhi-Wei
, p. 1516 - 1521 (2014/12/11)
An efficient one-pot synthesis process for preparing 2-imidazolines from aldehydes and ethylenediamine using molecular iodine and potassium carbonate in absolute ethanol at 25-30°C under ultrasound irradiation is described. The synthetic strategy has the following advantages: mild conditions and low costs requirements, readily available catalyst, short reaction times, simplicity of operation, and good-to-excellent yields.
Palladium-catalyzed multicomponent synthesis of 2-aryl-2-imidazolines from aryl halides and diamines
Geden, Joanna V.,Pancholi, Alpa K.,Shipman, Michael
, p. 4158 - 4164 (2013/05/22)
An efficient palladium-catalyzed three-component reaction that combines aryl halides, isocyanides, and diamines provides access to 2-aryl-2-imidazolines in yields up to 96%. Through variation of the diamine component, the reaction can be extended to the s
Novel diversely substituted 1-heteroaryl-2-imidazolines for fragment-based drug discovery
Krasavin, Mikhail
scheme or table, p. 2876 - 2880 (2012/07/28)
A palladium-catalyzed Buchwald-Hartwig arylation protocol has been applied to achieve high-yielding N-heteroarylation of a diverse set of privileged 2-imidazolines. The resulting compounds are of interest as a novel type of molecular tool for fragment-bas
Trichloroisocyanuric acid as an efficient homogeneous catalyst for the chemoselective synthesis of 2-substituted oxazolines, imidazolines and thiazolines under solvent-free condition
Hojati, Seyedeh Fatemeh,Nezhadhoseiny, Seyede Atefe
, p. 1181 - 1189,9 (2020/09/14)
Trichloroisocyanuric acid, as a commercially available and inexpensive catalyst, was used in a new, facile and efficient procedure for the synthesis of 2-oxazolines, 2-imidazolines and 2-thiazolines through the reaction of nitriles with 2-aminoethanol, ethylenediamine or 2-aminoethanethiol under solvent-free conditions.
Synthesis, characterisation and application of iridium(III) photosensitisers for catalytic water reduction
Gaertner, Felix,Cozzula, Daniela,Losse, Sebastian,Boddien, Albert,Anilkumar, Gopinatan,Junge, Henrik,Schulz, Thomas,Marquet, Nicolas,Spannenberg, Anke,Gladiali, Serafino,Beller, Matthias
experimental part, p. 6998 - 7006 (2011/07/29)
The synthesis of novel, monocationic iridium(III) photosensitisers (Ir-PSs) with the general formula [IrIII(C^N)2(N^N)]+ (C^N: cyclometallating phenylpyridine ligand, N^N: neutral bidentate ligand) is described. The structures obtained were examined by cyclic voltammetry, UV/Vis and photoluminescence spectroscopy and X-ray analysis. All iridium complexes were tested for their ability as photosensitisers to promote homogeneously catalysed hydrogen generation from water. In the presence of [HNEt 3][HFe3(CO)11] as a water-reduction catalyst (WRC) and triethylamine as a sacrificial reductant (SR), seven of the new iridium complexes showed activity. [Ir(6-iPr-bpy)(ppy)2]PF 6 (bpy: 2,2′-bipyridine, ppy: 2-phenylpyridine) turned out to be the most efficient photosensitiser. This complex was also tested in combination with other WRCs based on rhodium, platinum, cobalt and manganese. In all cases, significant hydrogen evolution took place. Maximum turnover numbers of 4550 for this Ir-PS and 2770 for the Fe WRC generated in situ from [HNEt 3][HFe3(CO)11] and tris[3,5- bis(trifluoromethyl)phenyl]phosphine was obtained. These are the highest overall efficiencies for any Ir/Fe water-reduction system reported to date. The incident photon to hydrogen yield reaches 16.4 % with the best system. Copyright
