- Synthesis of conjugated Mn porphyrin polymers with p-phenylenediamine building blocks and efficient aerobic catalytic oxidation of alcohols
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A series of conjugated metalloporphyrin polymers (MnP-AMPs) were synthesized based on Buchwald-Hartwig aromatic amination with p-phenylenediamine and manganese tetraphenylporphyrin as building blocks, and N-heterocyclic carbene-palladium complex as cataly
- Li, Yongjin,Sun, Baoshuai,Yang, Weijun
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Read Online
- Dilithium Amides as a Modular Bis-Anionic Ligand Platform for Iron-Catalyzed Cross-Coupling
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Dilithium amides have been developed as a bespoke and general ligand for iron-catalyzed Kumada-Tamao-Corriu cross-coupling reactions, their design taking inspiration from previous mechanistic and structural studies. They allow for the cross-coupling of alkyl Grignard reagents with sp2-hybridized electrophiles as well as aryl Grignard reagents with sp3-hybridized electrophiles. This represents a rare example of a single iron-catalyzed system effective across diverse coupling reactions without significant modification of the catalytic protocol, as well as remaining operationally simple.
- Neate, Peter G.N.,Zhang, Bufan,Conforti, Jessica,Brennessel, William W.,Neidig, Michael L.
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supporting information
p. 5958 - 5963
(2021/08/18)
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- Aluminum nanoparticle preparation: Via catalytic decomposition of alane adducts-influence of reaction parameters on nanoparticle size, morphology and reactivity
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Al nanoparticles represent one of the most challenging classes of metal nanoparticles in synthesis and handling due to their high chemical reactivity and their affinity to oxidation. A promising wet chemical preparation route is the catalytic decomposition of alane adducts. In the current systematic study, we investigated the influence of various reaction parameters, such as precursors, catalysts, solvents, reaction temperatures, capping agents, and concentrations of the reactants on the size and morphology of the resulting Al nanoparticles. One major goal was the optimization of the reaction parameters towards short reaction times. Our studies revealed that Ti alkoxides, such as Ti(OiPr)4, are much more efficient decomposition catalysts compared to other related metal catalysts. Optimized conditions for full conversion times smaller than 15 min are temperatures between 90-100 °C and non-polar solvents such as toluene. Amine alanes containing short alkyl chains, for example H3AlNMe2Et or H3AlNEt3, were the most suitable precursors, leading to the formation of the smallest nanoparticles. The use of weakly coordinating capping agents like amines and phosphines should be preferred over the commonly employed carboxylic acids because they do not accelerate the formation of an amorphous oxide shell upon binding to the particle surface. In conclusion, the best reaction parameters for a fast synthesis of Al nanoparticles via a catalytic decomposition approach are the combination of sterically less hindered amine alanes applying a Ti catalyst in toluene solutions in the presence of amine or phosphine stabilizers at elevated temperatures.
- Kickelbick, Guido,Klein, Thomas
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supporting information
p. 9820 - 9834
(2020/07/30)
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- Synthesis of pentafluorobenzene-based NHC adducts and their catalytic activity in the microwave-assisted reactions of aldehydes
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N-Heterocyclic carbenes (NHCs) have been widely used in organometallic chemistry as ligands, as well as standalone organocatalysts in various reactions, mostly using aromatic aldehydes as substrates. We have previously demonstrated the efficiency of azolium-2-carboxylate zwitterions in the hydroxymethylation of aldehydes, especially aliphatic aldehydes, under microwave irradiation. In the present work, we report a series of pentafluorobenzene-based NHC adducts and their efficiency in the hydroxymethylation and self-condensation of aliphatic and aromatic aldehydes using microwave irradiation. The free carbenes are released under the reaction conditions and 1,3-dimesityl-2-(perfluorophenyl)imidazolidine and 1,3-bis(2,6-dimethylphenyl)-2-(perfluorophenyl)imidazolidine proved to be the most potent precatalysts.
- Papadaki, Evanthia,Magrioti, Victoria
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supporting information
(2019/12/24)
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- Method for preparing substituted aryl ketone by ketone arylation (by machine translation)
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The invention provides a method, for preparing substituted aryl ketone, by using a nitrogen heterocyclic carbene catalyst, with a saturated nitrogen heterocyclic carbene structure in an oxygen-containing atmosphere at, through α - catalysis of a nitrogen heterocyclic carbene structure, in a nitrogen heterocyclic carbene catalyst with a saturated nitrogen heterocyclic carbene structure under an alkaline condition, in an oxygen-containing atmosphere and can efficiently prepare various substituted, aryl ketones α - under the condition of containing an oxygen. atmosphere. (by machine translation)
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Paragraph 0026-0028; 0036; 0038
(2020/03/05)
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- BIS-IMINE TITANIUM COMPLEX, CATALYTIC SYSTEM COMPRISING SAID BIS-IMINE TITANIUM COMPLEX AND PROCESS FOR THE (CO)POLYMERIZATION OF CONJUGATED DIENES
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Bis-imine titanium complex having general formula (I): wherein: R1 and R2, mutually identical or different, represent a hydrogen atom; or are selected from linear or branched, optionally halogenated, C1-C20 alky
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Page/Page column 33
(2019/04/26)
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- Direct intramolecular carbon(sp2)-nitrogen(sp2) reductive elimination from gold(iii)
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The reactivity of bidentate AuIII-Cl species, [(C^N)AuCl2], with a bisphosphine or carbon donor ligands results in reductive elimination. Combined experimental and computational investigations lead to the first evidence of a direct intramolecular C(sp2)-N(sp2) bond formation from a monomeric [(C^N)AuCl2] gold(iii) complex. We show that bidentate ligated Au(iii) systems bypass transmetallation to form C(sp2)-N(sp2) species and NHC-Au-Cl. Mechanistic investigations of the reported transformation reveal a ligand-induced reductive elimination via a key AuIII intermediate. Kinetic studies of the reaction support a second-order rate process.
- Kim, Jong Hyun,Mertens, R. Tyler,Agarwal, Amal,Parkin, Sean,Berger, Gilles,Awuah, Samuel G.
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supporting information
p. 6273 - 6282
(2019/05/17)
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- Synthesis of cobalt(II)-α-diimines complexes and their activity as mediators in organometallic mediated radical polymerization of vinyl acetate
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This study describes the synthesis and characterization of three α-diimine-cobalt complexes of the type [CoCl2(R-DAB)] (R-DAB = R–N[dbnd]CH–CH[dbnd]N–R; R = Mes, Dipp and Dipp?) and their application as mediators for the cobalt-media
- Riga, Beatriz A.,Neves, Marina D.,Machado, Antonio E.H.,Araújo, Diesley M.S.,Souza, Jhonathan R.,Nascimento, Otaciro R.,Santana, Vinícius T.,Cavalheiro, Carla C.S.,Carvalho-Jr, Valdemiro P.,Goi, Beatriz E.
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p. 620 - 629
(2018/01/11)
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- A more sustainable and efficient access to IMes·HCl and IPr·HCl by ball-milling
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Herein is described a mechanochemical one-pot two-step procedure giving access to various NHC (N-heterocyclic carbene) precursors. This original approach enabled the production of the widely used IPr·HCl, IMes·HCl, Io-Tol·HCl and ICy·HCl in much better yields than conventional solvent-based procedures, while the environmental impact was drastically reduced.
- Beillard, Audrey,Bantreil, Xavier,Métro, Thomas-Xavier,Martinez, Jean,Lamaty, Frédéric
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supporting information
p. 964 - 968
(2018/03/13)
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- NON-IONIC BLOCK COPOLYMERS AND PHARMACEUTICAL COMPOSITIONS DERIVED THEREFROM
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There are provided PVP-PLA block copolymers as defined in Formula (I): I wherein, x is an initiator alcohol having a boiling point greater than 145°C, n is, on average, from 20 and 40, and m is, on average, from 10 and 40, wherein the block copolymers hav
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Paragraph 00242; 00264; 00165
(2018/10/25)
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- N-heterocyclic carbene ruthenium catalyst containing electron donating group and preparation method of N-heterocyclic carbene ruthenium catalyst
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The invention provides an N-heterocyclic carbene ruthenium catalyst containing an electron donating group and a preparation method of the N-heterocyclic carbene ruthenium catalyst. The electron donating group is connected to an N-heterocyclic carbene ligand on the basis of the original structure of the N-heterocyclic carbene ruthenium catalyst, so that the electron donating ability of the N-heterocyclic carbene ligand is enhanced, and the catalytic efficiency and the structural stability of the catalyst are improved.
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Paragraph 0102; 0105; 0106
(2018/03/28)
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- Mechanochemistry for facilitated access to N,N-diaryl NHC metal complexes
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A user-friendly and solvent-free mechanosynthetic strategy allowed light-sensitive silver(i) complexes featuring N,N-diaryl N-heterocyclic carbenes (NHC), including challenging and sterically hindered ligands, to be yielded efficiently. The first transmet
- Beillard, Audrey,Bantreil, Xavier,Métro, Thomas-Xavier,Martinez, Jean,Lamaty, Frédéric
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supporting information
p. 1057 - 1063
(2017/02/10)
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- Synthesis, Antitumor Activity, and Docking Study of 1,3-Disubstituted Imidazolium Derivatives
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A series of 1,3-disubstituted imidazolium salts were synthesized through a convenient synthetic approach based on the reaction of 1,4-diazabuta-1,3-dienes with HClO4. Their antitumor activity was evaluated in vitro against a number of human cancer cells. 1,3-Bis[(3,5-bis(trifluoromethyl)phenyl]imidazolium perchlorate turned out to be the most active against A549 and MCF-7 cancer cell lines with IC50 values of 5.24 and 4.21 μM, respectively. The results of structure–activity relationship study indicated that substituents on the imidazole derivatives play an important role in their cytotoxic activities. Finally, molecular docking of some tested compounds was carried out in order to investigate their binding pattern with the CDK2.
- Fan,Zhong,Yan
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p. 3023 - 3028
(2018/02/21)
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- Tuning the Catalyst Reactivity of Imidazolylidene Catalysts through Substituent Effects on the N-Aryl Groups
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A series of imidazolium salts with various N-aryl groups were synthesized, and their catalytic activities were evaluated to investigate the contribution of the N-aryl groups to the catalytic activity in the synthesis of γ-butyrolactone through an a3
- Kyan, Ryuji,Sato, Kohei,Mase, Nobuyuki,Watanabe, Naoharu,Narumi, Tetsuo
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supporting information
p. 2750 - 2753
(2017/05/24)
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- Selective Oxygen Atom Insertion into an Aryl-Palladium Bond
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The chemistry of a palladium(II) complex containing both an alkyl- and an aryl-palladium bond is reported. The reaction of [Pd(CH2CMe2C6H4)(MesN=CHCH=NMes)] with bromine or iodine leads to reductive elimination of 1,1-dimethylcyclobutabenzene with formation of [PdX2(MesN=CHCH=NMes)] (X = Br, I). However, the reaction with hydrogen peroxide gives [Pd(CH2CMe2C6H4O)(MesN=CHCH=NMes)] by overall oxygen atom insertion into the aryl-palladium rather than the alkyl-palladium bond. This complex [Pd(CH2CMe2C6H4O)(MesN=CHCH=NMes)] reacts with bromine, iodine, or hydrogen peroxide to give 3,3-dimethyl-2,3-dihydrobenzofuran and the corresponding complex [PdX2(MesN=CHCH=NMes)]. The mechanisms of reaction and basis for selectivity are discussed. The results support the view that oxygen atom insertion is a mechanistically viable pathway for selective catalytic oxidation of hydrocarbons by the green oxidant hydrogen peroxide.
- Behnia, Ava,Boyle, Paul D.,Blacquiere, Johanna M.,Puddephatt, Richard J.
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p. 2645 - 2654
(2016/09/04)
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- Cross-metathesis reaction of functionalized and substituted olefins using group 8 transition metal carbene complexes as metathesis catalysts
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The invention pertains to the use of Group 8 transition metal carbene complexes as catalysts for olefin cross-metathesis reactions. In particular, ruthenium and osmium alkylidene complexes substituted with an N-heterocyclic carbene ligand are used to catalyze cross-metathesis reactions to provide a variety of substituted and functionalized olefins, including phosphonate-substituted olefins, directly halogenated olefins, 1,1,2-trisubstituted olefins, and quaternary allylic olefins. The invention further provides a method for creating functional diversity using the aforementioned complexes to catalyze cross-metathesis reactions of a first olefinic reactant, which may or may not be substituted with a functional group, with each of a plurality of different olefinic reactants, which may or may not be substituted with functional groups, to give a plurality of structurally distinct olefinic products. The methodology of the invention is also useful in facilitating the stereoselective synthesis of 1,2-disubstituted olefins in the cis configuration.
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Page/Page column 40; 41
(2016/08/29)
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- Unraveling the synthesis of homoleptic [Ag(N, N -diaryl-NHC)2]Y (Y = BF4, PF6) complexes by ball-milling
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A user-friendly and general mechanochemical method was developed to access rarely described NHC (N-heterocyclic carbene) silver(i) complexes featuring N,N-diarylimidazol(idin)ene ligands and non-coordinating tetrafluoroborate or hexafluorophosphate counter anions. Comparison with syntheses in solution clearly demonstrated the superiority of the ball-milling conditions.
- Beillard, Audrey,Bantreil, Xavier,Métro, Thomas-Xavier,Martinez, Jean,Lamaty, Frédéric
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supporting information
p. 17859 - 17866
(2016/11/18)
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- Heteroatom-substituted secondary phosphine oxides for Suzuki-Miyaura cross-coupling reactions
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Several di-substituted diimines (3a–3f) and heteroatom-substituted unsaturated secondary phosphine oxides (HASPO, 6a–6f) were prepared and characterized. Compounds 6a–6f are regarded as pre-ligands because of their ability of tautomerization to heteroatom-substituted phosphinous acid (HAPA, 7a–7f). An unexpected 3e-coordinated palladium dibromide 8e was observed from the reaction of compound 6e with PdBr2. Molecular structures of pre-ligands 6a, 6c, and 6e, as well as palladium complexes 8e were determined by single crystal X-ray diffraction methods. When pre-ligand 6a was applied to palladium-catalyzed Suzuki-Miyaura cross-coupling reactions, satisfactory yields were obtained. Density functional theory were employed to examine the electronic properties of HASPO 6a–6f pre-ligands, their corresponding 1,3-di-N-substituted tautomers 7a–7f, and the saturated counterpart 7as of 7a. Compound 7a is the most effective and genuine ligand in Suzuki-Miyaura reaction that is confirmed by its higher-lying lone-pair (LP) molecular orbital (HOMO-1). The LP orbital of 7c–7f is lower-lying HOMO-5. For each 7c–7f, two conformational rotamers with minute energy difference were located. Hirshfeld charge and population analysis of 7c–7f were also calculated in order to comprehend the electronic properties for these two rotamers for each HAPAs. Besides, the steric effect of HAPAs was estimated in terms of the Percent Buried Volume (%Vbur). This model has shown that 7a has similar steric property to that of PCy3, which is an effective ligand in Suzuki-coupling reactions.
- Chang, Yu-Chang,Lee, Yi-Chang,Chang, Meng-Fan,Hong, Fung-E.
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- IMIDAZOLIDINE-BASED METAL CARBENE METATHESIS CATALYSTS
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The present invention relates to novel metathesis catalysts with an imidazolidine-based ligand and to methods for making and using the same. The inventive catalysts are of the formula wherein: M is ruthenium or osmium;X and X1 are each independently an anionic ligand;L is a neutral electron donor ligand; and,R, R1, R6, R7, R8, and R9 are each independently hydrogen or a substituent selected from the group consisting of C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, aryl, C1-C20 carboxylate, C1-C20 alkoxy, C2-C20 alkenyloxy, C2-C20 alkynyloxy, aryloxy, C2-C20 alkoxycarbonyl, C1-C20 alkylthiol, aryl thiol, C1-C20 alkylsulfonyl and C2-C20 alkylsulfinyl, the substituent optionally substituted with one or more moieties selected from the group consisting of C1-C10 alkyl, C1-C10 alkoxy, aryl, and a functional group selected from the group consisting of hydroxyl, thiol, thioether, ketone, aldehyde, ester, ether, amine, imine, amide, nitro, carboxylic acid, disulfide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate, and halogen. The inclusion of an imidazolidine ligand to the previously described ruthenium or osmium catalysts has been found to dramatically improve the properties of these complexes. The inventive catalysts maintains the functional group tolerance of previously described ruthenium complexes while having enhanced metathesis activity that compares favorably to prior art tungsten and molybdenum systems.
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Paragraph 0054
(2016/09/12)
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- Synthesis and reactivity of: N, N ′-1,4-diazabutadiene derived borocations
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A series of borocations have been synthesised from the addition of haloboranes to synthetically accessible N,N′-1,4-diazabutadiene precursors, which are derived from commercially available anilines. The synthesis and structural studies of the borocations
- Lawson, James R.,Wilkins, Lewis C.,André, Manon,Richards, Emma C.,Ali, Mohammed N.,Platts, James A.,Melen, Rebecca L.
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supporting information
p. 16177 - 16181
(2016/10/31)
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- Synthesis, characterization, electrochemical properties and catalytic reactivity of N-heterocyclic carbene-containing diiron complexes
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(μ-dmedt)[Fe(CO)3]2 (I, dmedt = 2,3-butanedithiol) was chosen as the parent complex. A series of new model complexes, N-heterocyclic carbene (NHC) substituted (μ-dmedt)[Fe-Fe]-NHC (II, (μ-dmedt)[Fe(CO)2]2[IMe(CH2)2IMe], IMe = 1-methylimidazol-2-ylidene; III, {(μ-dmedt)[Fe2(CO)5]}2[IMe(CH2)2IMe]; IV, (μ-dmedt)[Fe2(CO)5]IMes, IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene; V, (μ-dmedt)[Fe2(CO)5]IMe, IMe = 1,3-dimethylimidazol-2-ylidene) as mimics of the [Fe-Fe]-H2ase active site were synthesized from I and characterized using solution IR spectroscopy, NMR spectroscopy, elemental analysis and single-crystal X-ray diffraction. The electrochemical properties of complexes I-V, with and without the addition of HOAc, were investigated by cyclic voltammetry in the coordinating solvent CH3CN to evaluate the effects of different NHC ligands on the redox properties of the iron atoms of the series of complexes. It was concluded that all the new complexes are electrochemical catalysts for proton reduction to hydrogen. The symmetrically substituted cisoid basal/basal coordination complex II displays the most negative reduction potential owing to the stronger δ-donating ability of the NHC and the orientation of the NHC donor carbon as a result of the constraints of the bridging bidentate ligands. A new application for the [Fe-Fe]-NHC model complexes in the direct catalytic hydroxylation of benzene to phenol was also studied. Under the optimized experimental conditions (II, 0.01 mmol; benzene, 0.1 mL; CH3CN, 2.0 mL; H2O2, 6.0 mmol; 60 °C, 3 h), the maximal phenol yield was 26.7%.
- Wang, Yanhong,Zhang, Tianyong,Li, Bin,Jiang, Shuang,Sheng, Liao
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p. 29022 - 29031
(2015/04/14)
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- Rhodium-NHC hybrid silica materials as recyclable catalysts for [2+2+2] cycloaddition reactions of alkynes
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Bis-silylated dihydroimidazolium salt 1 and monosilylated imidazolium salt 2 are transformed to (NHC)RhCl(COD) complexes 3 and 4, allowing the preparation of hybrid silica materials either by sol-gel or grafting processes. Full characterization of the materials by means of solid state NMR, N2-sorption measurements, thermogravimetric analysis (TGA) and elemental analysis was followed by evaluation of catalytic activity in the [2+2+2] cycloaddition of alkynes. Excellent yields of the cycloadducts are obtained for up to six consecutive cycles with the grafted material, using simple filtration to recover the catalyst. Both conventional and microwave heating prove effective for the process described.
- Fernndez, Mart,Ferr, Meritxell,Pla-Quintana, Anna,Parella, Teodor,Pleixats, Roser,Roglans, Anna
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supporting information
p. 6242 - 6251
(2015/02/19)
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- Rhodium-NHC hybrid silica materials as recyclable catalysts for [2+2+2] cycloaddition reactions of alkynes
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Bis-silylated dihydroimidazolium salt 1 and monosilylated imidazolium salt 2 are transformed to (NHC)RhCl(COD) complexes 3 and 4, allowing the preparation of hybrid silica materials either by sol-gel or grafting processes. Full characterization of the materials by means of solid state NMR, N2-sorption measurements, thermogravimetric analysis (TGA) and elemental analysis was followed by evaluation of catalytic activity in the [2+2+2] cycloaddition of alkynes. Excellent yields of the cycloadducts are obtained for up to six consecutive cycles with the grafted material, using simple filtration to recover the catalyst. Both conventional and microwave heating prove effective for the process described.
- Fernndez, Mart,Ferr, Meritxell,Pla-Quintana, Anna,Parella, Teodor,Pleixats, Roser,Roglans, Anna
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supporting information
p. 6242 - 6251
(2015/03/30)
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- Introduction of bulky tert-butyl substituents on the core of N,N′-diaryl N-heterocyclic carbenes through the corresponding vicinal diamines
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Highly bulky N,N′-diaryl imidazolinium salts substituted by one or two tert-butyl groups on the heterocyclic backbone and the corresponding silver N-heterocyclic carbene complexes are obtained by the addition of tert-butyl magnesium chloride or tert-butyl lithium on symmetrical 1,2-bisimines derived from 2,6-diisopropylaniline, 2,6-diethylaniline and 2,4,6-trimethylaniline.
- Jacquemard, Ulrich,Harpainter, Phoebe,Roland, Sylvain
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supporting information
p. 4793 - 4795
(2013/08/23)
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- Synthesis and characterization of sterically enlarged hoveyda-type olefin metathesis catalysts
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A series of four ruthenium-based olefin metathesis catalysts has been prepared. These new complexes were designed with nanofiltration in organic media in mind; steric enlargement and functionalisation by means of polar ethylene glycol chains were incorporated. New complexes based on the stable 2nd generation Hoveyda-type architecture and featuring substitution either on the NHC backbone or on the N-aryl substituent of the NHC have been prepared and fully characterized. The application of these complexes in a series of olefin metathesis transformations revealed that these modified catalysts retained activity on par with the parent Hoveyda catalyst thus validating the disclosed ligand design.
- Shahane, Saurabh,Toupet, Loic,Fischmeister, Cedric,Bruneau, Christian
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- Rhodium(I) and silver(I) complexes of 4,5-Dicyano-1,3-dimesityl- and 4,5-dicyano-1, 3-dineopentylimidazol-2-ylidene
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The new N-heterocyclic carbene (NHC) precursors 4, -dicyano-1, -dimesityl- (9) and 4, 5-dicyano-1, 3-dineopentyl-2-(pentafluorophenyl)imidazoline (14) were synthesized. The structure of 9 could be determined by X-ray crystallography. With the 2-pentafluorophenyl-substituted imidazolines 9 and 14, the [AgCl(NHC)], [RhCl(COD)(NHC)], and [RhCl(CO)2(NHC)] complexes [NHC = 4, 5-dicyano-1, 3-dimesitylimidazol-2-ylidene (3) and 4, 5-dicyano-1, 3-dineopentylimidazol-2-ylidene (4)] were obtained. Crystal structures of [AgCl(3)] (15), [RhCl(COD)(3)] (17), [RhCl(COD)(4)] (18), and [RhCl(CO) 2(3)] (19) were solved and with the crystal data of 19, the percent buried volume (%Vbur) of 31.8(±0.1) % was determined for NHC 3. Infrared spectra of the imidazolines 9 and 14 and of the complexes 15-20 were recorded and the CO stretching frequencies of complexes 19 and 20 were used to determine the Tolman electronic parameters of the newly obtained NHCs 3 (TEP: 2060 cm-1) and 4 (TEP: 2061 cm-1), thus proving that 1, 3-substitution of maleonitrile-NHCs does not have a significant effect for the high π-acceptor strength of these carbenes. Copyright
- Baier, Heiko,Kelling, Alexandra,Jackstell, Ralf,Holdt, Hans-Juergen
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p. 1731 - 1739
(2013/09/02)
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- A direct and practical approach for the synthesis of Au(I)-NHC complexes from commercially available imidazolium salts and Au(III) salts
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A direct and practical approach for the synthesis of Au(I)-NHC complexes from imidazolium salts and commercially available aurate salt (MAuCl 4·2H2O) is described. The reaction proceeded without sacrificing carbene transfer agent (Ag
- Zhu, Shifa,Liang, Renxiao,Chen, Lijuan,Wang, Chao,Ren, Yanwei,Jiang, Huanfeng
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supporting information; experimental part
p. 815 - 818
(2012/03/10)
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- A direct and practical approach for the synthesis of N-heterocyclic carbene coinage metal complexes
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A novel direct and practical synthetic route leading to N-heterocyclic carbene coinage metal complexes has been developed by using air stable, commercial available Au(III) salt [MAuCl4·2H2O], CuCln (n=1,2) or AgCl, and imidazolium salts as starting materials. The reaction proceeded without sacrificing carbene transfer agent (Ag 2O) or using highly sensitive free NHC.
- Zhu, Shifa,Liang, Renxiao,Jiang, Huanfeng
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supporting information; experimental part
p. 7949 - 7955
(2012/09/22)
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- Sol-gel immobilized Hoveyda-Grubbs complex through the NHC ligand: A recyclable metathesis catalyst
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The synthesis of a bis-silylated Hoveyda-Grubbs ruthenium alkylidene complex is described, as well as the preparation via the sol-gel process and the characterization of an organosilica by co-gelification with tetraethyl orthosilicate (TEOS). This material is an active supported catalyst for various metathesis reactions. The recyclability has been proven even for the formation of a trisubstituted olefin. This is the first example of an immobilized Hoveyda-Grubbs' type complex prepared by sol-gel co-gelification from a well-defined ruthenium alkylidene precursor bearing a silylated NHC moiety.
- Monge-Marcet, Amàlia,Pleixats, Roser,Catto?n, Xavier,Wong Chi Man, Michel
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scheme or table
p. 59 - 66
(2012/05/20)
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- Thiadiazolidine 1-oxide systems for phosphine-free palladium-mediated catalysis
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We herein report several highly active catalyst systems with thiadiazolidine 1-oxides as ligands for palladium in the Mizoroki-Heck reaction. Excellent yields of stilbenes derived from aryl iodides and bromides have been achieved using as little as 0.00002 mol % catalyst. The ligand/palladium system can be stored as a stock solution open to air at room temperature with no observable loss of activity for a period of several months.
- Buckley, Benjamin R.,Neary, Stephen P.
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experimental part
p. 7988 - 7994
(2010/10/21)
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- Switched stereocontrol in Grubbs - Hoveyda complex catalyzed ROMP utilizing proton-switched NHC ligands
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Grubbs-Hoveyda and Grubbs III type complexes with ferrocenyl- or -NEt 2-substituted NHC ligands were synthesized according to standard procedures. The electron donation of the NHC ligands in the respective ruthenium complexes can be modulated by oxidation of the ferrocenyl moiety or by protonation of the amino group. The neutral and the respective cationic (oxidized or protonated) ruthenium complexes were tested in the ROMP of norbornene. The change in the electron donation of the NHC ligands upon protonation leads to a significant change in the double-bond geometry (from E/Z ratio = 0.78 to E/Z = 1.04) and in the microstructure of the resulting polynorbornene. Consequently, addition of acid and protonation of the living catalyst attached to the polymer chain during the polymerization reaction allows fine-tuning the E/Z ratio of the resulting polynorbornene.
- Peeck, Lars H.,Leuthaeusser, Steffen,Plenio, Herbert
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scheme or table
p. 4339 - 4345
(2011/01/03)
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- The first thiadiazolidine 1-oxide system for phosphine-free palladium-mediated catalysis
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We herein report a highly active catalyst system using for the first time a thiadiazolidine 1-oxide as a ligand for palladium in the Mizoroki-Heck reaction. Excellent yields of stilbenes derived from aryl iodides and bromides have been achieved using as little as 0.00002 mol% catalyst. The ligand/ palladium system can be stored as a stock solution open to air at room temperature with no observable loss of activity for a period of several weeks/months.
- Buckley, Benjamin R.,Neary, Stephen P.
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supporting information; scheme or table
p. 71 - 77
(2009/08/07)
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- SYNTHESIS OF 1,3 DISUBSTITUTED IMIDAZOLIUM SALTS
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Imidazolium salts are the immediate precursors to N-heterocyclic carbenes (NHC) yet a simple, general synthetic route to a wide variety of imidazolium salts is not yet available. Such a straightforward route is described for two specific members of this family of ligand precursor: l,3-Bis(2,4,6-trimethylphenyl)imidazolium chloride (IMes-HCl) and l,3-Bis(2,6-diispropylphenyl)imidazolium chloride (IPrHCl). The procedure appears general and similar protocols can be used to isolate various imidazolium salts.
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Page/Page column 4; 6; 7-8
(2008/06/13)
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- N-Heterocyclic phosphenium cations: Syntheses and cycloaddition reactions
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A series of trifluoromethanesulfonate (OTf) salts of N-heterocyclic phospheniums (NHP) bearing phenyl (1a), para-methoxyphenyl (1b), 2,6-diisopropylphenyl (1c) and mesityl (1d) substituents is reported. The compounds 1b-d are made by a modification to a literature procedure that improves the overall yields for 1c and 1d by 15 and 23%, respectively. Two unwanted side-products in the synthesis of 1d, the diammonium salt, [(2,6-iPr-C6H3)N(H)2CH2CH 2N(H)2(2,6-iPr-C6H3)]Cl2 (4) and the bisphosphine (2,6-iPr-C6H3)N(PCl 2)CH2CH2N(PCl2)(2,6-iPr-C 6H3) (5), are crystallographically characterized, as is the intermediate cyclic chlorophosphine, C1PN(4-OMe-C6H 4)CH2CH2N(4-OMe-C6H4) (3b). The phenyl-substituted NHP 1a is fully characterized, including by X-ray crystallography, for the first time; this compound contains a short P-O contact of 2.1850(14) A Cycloaddition reactions of 1a-d with 2,3-dimethyl-1,3- butadiene give the expected spirocyclic phospholeniums, 7,8-dimethyl-1,4-diaryl- 1,4-diaza-5-phopshoniaspiro[4.4]non-7-ene, as their OTf salts (6a-d), while reactions with N,N′-dimesityl-1,4-diaza-1,3-butadiene give, except in the case of 1c, which is too bulky to react, the aza analogues, 1,4-dimesityl-6,9- diaryl-1,4,6,9-tetraaza-5-phosphoniaspiro[4.4]non-2-ene (7a, 7b and 7d). The sterically congested 7d is in thermal equilibrium with 1d and free diazadiene, and undergoes a substitution reaction with 2,3-dimethyl-1,3-butadiene to give 6d.
- Caputo, Christine A.,Price, Jacquelyn T.,Jennings, Michael C.,McDonald, Robert,Jones, Nathan D.
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p. 3461 - 3469
(2008/09/21)
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- Synthesis of chromium N-heterocyclic carbene complexes using chromium Fischer carbenes as a source of chromium carbonyls
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Chromium Fischer carbene complexes, [Cr{{double bond, long}OMe(R)}(CO)5] have been utilized as a source of chromium carbonyls in the synthesis of chromium NHC complexes. Using the synthetic method, chromium complexes of various NHC ligands were isolated in reasonable yields. Moreover, the method can be employed for the synthesis of molybdenum and tungsten NHC compounds.
- Kim, Seongjin,Choi, Soo Young,Lee, Young Tak,Park, Kang Hyun,Sitzmann, Helmut,Chung, Young Keun
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p. 5390 - 5394
(2008/03/12)
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- trans-[1,3-Bis(2,4,6-trimethyl-phenyl)-imidazolidin-2-yl-idene] -dichlorido(triphenyl-phosphine-P)palladium(II)
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The title complex, [PdCl2(C21H26N2)(C18H15P)], shows slightly distorted square-planar coordination around the PdII metal centre. The Pd - C bond distance between the N-heterocyclic ligand and the metal atom is 2.028 (5) A. The dihedral angle be
- Sevincek, Resul,Tuerkmen, Hayati,Ayguen, Muhittin,Cetinkaya, Bekir,Garcia-Granda, Santiago
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p. m277-m279
(2008/03/11)
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- Tuning the electronic properties of N-heterocyclic carbenes
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The electron-donating properties of N-heterocyclic carbenes ([N,N′-bis(2,6-dimethylphenyl)imidazol]-2-ylidene and the respective dihydro ligands) with 4,4′-R-substituted aryl rings (4,4′-R = NEt2, OC12H25, Me, H, Br, S(4-t
- Leuthaeusser, Steffen,Schwarz, Daniela,Plenio, Herbert
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p. 7195 - 7203
(2008/03/12)
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- Synthesis of 1,3 distributed imidazolium salts
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Imidazolium salts are the immediate precursors to N-heterocyclic carbenes (NHC) yet a simple, general synthetic route to a wide variety of imidazolium salts is not yet available. Such a straightforward route is described for two specific members of this family of ligand precursor: 1,3-Bis(2,4,6-trimethylphenyl)imidazolium chloride (IMes.HCl) and 1,3-Bis(2,6-diispropylphenyl)imidazolium chloride (IPr.HCl). The procedure appears general and similar protocols can be used to isolate various imidazolium salts.
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Page/Page column 3; 5-7
(2008/06/13)
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- Synthesis and activity of ruthenium alkylidene complexes coordinated with phosphine and N-heterocyclic carbene ligands
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This paper reports the synthesis and characterization of a variety of ruthenium complexes coordinated with phosphine and N-heterocyclic carbene (NHC) ligands. These complexes include several alkylidene derivatives of the general formula (NHC)(PR3)(Cl)2Ru=CHR′, which are highly active olefin metathesis catalysts. Although these catalysts can be prepared adequately by the reaction of bis(phosphine) ruthenium alkylidene precursors with free NHCs, we have developed an alternative route that employs NHC-alcohol or -chloroform adducts as "protected" forms of the NHC ligands. This route is advantageous because NHC adducts are easier to handle than their free carbene counterparts. We also demonstrate that sterically bulky bis(NHC) complexes can be made by reaction of the pyridine-coordinated precursor (NHC)(py)2(Cl)2Ru=CHPh with free NHCs or NHC adducts. Two crystal structures are presented, one of the mixed bis(NHC) derivative (H2IMes)(IMes)(Cl)2Ru=CHPh, and the other of (PCy3)(Cl)(CO)Ru[η2-(CH2- C6H2Me2)(N2 C3H4)(C6H2Me3)], the product of ortho methyl C-H bond activation. Other side reactions encountered during the synthesis of new ruthenium alkylidene complexes include the formation of hydridocarbonyl-chloride derivatives in the presence of primary alcohols and the deprotonation of ruthenium vinylcarbene ligands by KOBut. We also evaluate the olefin metathesis activity of NHC-coordinated complexes in representative RCM and ROMP reactions.
- Trnka, Tina M.,Morgan, John P.,Sanford, Melanie S.,Wilhelm, Thomas E.,Scholl, Matthias,Choi, Tae-Lim,Ding, Sheng,Day, Michael W.,Grubbs, Robert H.
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p. 2546 - 2558
(2007/10/03)
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- Amination reactions of aryl halides with nitrogen-containing reagents mediated by palladium/imidazolium salt systems
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Nucleophilic N-heterocyclic carbenes have been conveniently used as catalyst modifiers in amination reactions involving aryl chlorides, aryl bromides, and aryl iodides with various nitrogen-containing substrates. The scope of a coupling process using a Pd(0) or Pd(II) source and an imidazolium salt in the presence of a base, KOtBu or NaOH, was tested using various substrates. The Pd2(dba)3/IPr·HCl (1, IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) system presents the highest activity with respect to electron-neutral and electron-rich aryl chlorides. The ligand is also effective for the synthesis of benzophenone imines, which can be easily converted to the corresponding primary amines by acid hydrolysis. Less reactive indoles were converted to N-aryl-substituted indoles using as supporting ligand the more donating SIPr·HCl (5, SIPr = 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidene). The Pd(OAc)2/SIPr·HCl/NaOH system is efficient for the N-arylation of diverse indoles with aryl bromides. The general protocol developed has been applied successfully to the synthesis of a key intermediate in the synthesis of an important new antibiotic. Mechanistically, palladium-to-ligand ratio studies strongly support an active species bearing one nucleophilic carbene ligand.
- Grasa,Viciu,Huang,Nolan
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p. 7729 - 7737
(2007/10/03)
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- Efficient and recyclable monomeric and dendritic Ru-based metathesis catalysts
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Several highly active, recoverable and recyclable Ru-based metathesis catalysts are presented. The crystal structure of Ru complex 5, beating a 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene and styrenyl ether ligand is disclosed. The heterocyclic ligand significantly enhances the catalytic activity, and the styrenyl ether allows for the easy recovery of the Ru complex. Catalyst 5 promotes ring-closing metathesis (RCM) and the efficient formation of various trisubstituted olefins at ambient temperature in high yield within 2 h; the catalyst is obtained in >95% yield after silica gel chromatography and can be used directly in subsequent reactions. Tetrasubstituted olefins can also be synthesized by RCM reactions catalyzed by 5. In addition, the synthesis and catalytic activities of two dendritic and recyclable Ru-based complexes are disclosed (32 and 33). Examples involving catalytic ring-closing, ring-opening, and cross metatheses are presented where, unlike monomer 5, dendritic 33 can be readily recovered.
- Garber, Steven B.,Kingsbury, Jason S.,Gray, Brian L.,Hoveyda, Amir H.
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p. 8168 - 8179
(2007/10/03)
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- Bis[N,N′-bis(2,4,6-trimethylphenyl)-1,2-ethanediylidenediamine] copper(I) tetrafluoroborate
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In the title compound, [Cu(C20)H24N2)2]BF4, the complex cation adopts a distorted tetrahedral structure, the dihedral angle between the least-squares planes of the chelating ligand backbones being 51.1 (2)°. This flattening of the tetrahedral coordination sphere may be driven by the presence of intramolecular π-π stacking interactions between mesityl groups on adjacent ligands.
- Foster, Caroline L.,Kilner, Colin A.,Thornton-Pett, Mark,Halcrow, Malcolm A.
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p. 319 - 320
(2007/10/03)
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- Imidazolylidenes, imidazolinylidenes and imidazolidines
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Starting from glyoxal, 1,3-diarylimidazolinium chlorides 3 were obtained in a three-step sequence via the diimines (1) and ethylene diamine dihydrochlorides (2). Reduction of 1,3-diarylimidazolinium chlorides (3) with lithium alumnium hydride furnished the 1,3- diarylimidazolidines (4) while their deprotonation with potassium hydride in thf gave access to stable carbenes (1,3-diarylimidazolin-2-ylidenes, 5). Similarly substituted imidazol-2-ylidenes are described for comparison.
- Arduengo III, Anthony J.,Krafczyk, Roland,Schmutzler, Reinhard,Craig, Hugh A.,Goerlich, Jens R.,Marshall, William J.,Unverzagt, Markus
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p. 14523 - 14534
(2007/10/03)
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- Synthesis and activity of a new generation of ruthenium-based olefin metathesis catalysts coordinated with 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene ligands.
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[formula: see text] A new family of 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene-substituted ruthenium-based complexes 9a-c has been prepared starting from RuCl2(=CHPh)(PCy3)2 2. These air- and water-tolerant complexes were shown to exhibit an increased ring-closing metathesis activity at elevated temperature when compared to that of the parent complex 2 and the previously developed complex 3. In many instances the activity of these complexes also rivaled or exceeded that of the alkoxy-imido molybdenum complex 1. Catalyst loadings of as low as 0.05 mol% could be used.
- Scholl,Ding,Lee,Grubbs
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p. 953 - 956
(2008/02/09)
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