- Cationic Iridium(III) complexes with two carbene-based cyclometalating ligands: Cis versus trans isomers
-
A series of cationic iridium(III) complexes with two carbene-based cyclometalating ligands and five different N^N bipyridine and 1,10-phenanthroline ancillary ligands is presented. For the first time-in the frame of a rarely studied class of bis(heterolep
- Monti, Filippo,La Placa, Maria Grazia I.,Armaroli, Nicola,Scopelliti, Rosario,Gr?tzel, Michael,Nazeeruddin, Mohammad Khaja,Kessler, Florian
-
-
Read Online
- Phenyl and thienyl functionalized imidazolium iodides for highly efficient quasi-solid-state dye-sensitized solar cells
-
To enhance the ionic conductivity of imidazolium iodide based ionic conductors, the π conjugation of the imidazolium cation is expanded via N-substitution with aromatic groups of phenyl and thienyl. Three ionic conductors (ICs) of MPhII, MT2II
- Zhang, Meirong,Jin, Zhitong,Feng, Chuanqi,Wang, Min,Wang, Zhong-Sheng
-
-
Read Online
- ORGANIC ELECTROLUMINESCENT MATERIALS AND DEVICES
-
Provided is a compound of Formula Ir(LA)(LB)(LC), wherein LA is a ligand of LB is a ligand of and LC is a ligand of wherein a structure of is fused to the ligand LB of Formula II
- -
-
Paragraph 0144-0146
(2021/04/17)
-
- NHC ligand-based half-sandwich iridium complexes: synthesis, structure and catalytic activity in acceptorless dehydrogenation and transfer hydrogenation
-
A set of neutral C,C-chelate half-sandwich iridium(iii) complexes have been prepared with NHC ligands that contain pendant aromatic rings as potentially chelating donor sites. The catalytic activity of such iridium complexes has been investigated for the acceptorless dehydrogenation (AD) reactions of alcohols and for the transfer hydrogenation reactions of ketones. The prepared iridium(iii) complexes show excellent catalytic activity for AD reactions of a wide range of secondary alcohols, and they are also shown to be effective for the synthesis of aldehydes from primary alcohols without the observation of undesired byproducts such as esters. Additionally, these complexes are also highly efficient in transfer hydrogenation of ketones and aldehydes, which give the alcohols in good yields under mild conditions. The exact structure and bonding mode of the NHC-based iridium complexes was identified using various spectroscopic methods and single crystal X-ray analysis.
- Deng, Wei,Jin, Yan,Li, Rong-Jian,Liu, Zhen-Jiang,Wang, Yang,Yao, Zi-Jian
-
p. 19002 - 19010
(2021/10/29)
-
- Steric effect of NHC ligands in Pd(II)–NHC-catalyzed non-directed C–H acetoxylation of simple arenes
-
Although there has been a lot of progress in oxidative arene C–H functionalization reactions catalyzed by Pd(II/IV) system, the non-directed, site-selective functionalization of arene molecules is still challenging. It has been established that ligands play a pivotal role in controlling rate- as well as selectivity-determining step in a catalytic cycle involving well-defined metal-ligand bonding. N-heterocyclic carbene (NHC) ligands have had a tremendous contribution in the recent extraordinary success of achieving high reactivity and excellent selectivity in many catalytic processes including cross-coupling and olefin-metathesis reactions. However, the immense potential of these NHC ligands in improving site-selectivity of non-directed catalytic C–H functionalization reactions of simple arenes is yet to be realized, where overriding the electronic bias on deciding selectivity is a burdensome task. The presented work demonstrated an initiative step in this regard. Herein, a series of well-defined discrete [Pd(NHCR′R)(py)I2] complexes with systematically varied degree of spatial congestion at the Pd centre, exerted through the R and R’ substituents on the NHC ligand, were explored in controlling the activity as well as the site-selectivity of non-directed acetoxylation of representative monosubstituted and disubstituted simple arenes (such as toluene, iodobenzene and bromobenzene, naphthalene and 1,2-dichlorobenzene). The resulting best yields were found to be 75% for toluene and 65% for bromobenzene with [Pd(NHCMePh)(py)I2], 75% for iodobenzene and 79% for naphthalene with [Pd(NHCMeMe)(py)I2], and 41% for 1,2-dichlorobenzene with [Pd(NHCCyCy)(py)I2]. Most importantly, with increasing the bulkiness of the NHC ligand in the complexes, the selectivity of the distal C-acetoxylated products in comparison to the proximal ones, was enhanced to a great extent in all cases. Considering the vast library of NHC ligands, this study underscores the future opportunity to develop more strategies to improve the activity and the crucial site-selectivity of C–H functionalization reactions in simple as well as complex organic molecules.
- Mandal, Tanmoy,Yadav, Sudha,Choudhury, Joyanta
-
-
- Efficient transfer hydrogenation of carbonate salts from glycerol using water-soluble iridium N-heterocyclic carbene catalysts
-
The transfer hydrogenation of CO2and carbonates from biomass-derived alcohols, such as glycerol, to afford formic and lactic acid is a highly attractive path to valorizing two waste streams, and is significantly more thermodynamically favorable than direct carbonate hydrogenation. Expanding on our seminal report of the first homogeneous catalyst for this process, here we show that thermally-robust and water-soluble Ir(i) and Ir(iii) N-heterocyclic carbene (NHC) complexes with sulfonate-functionalized wingtips are highly prolific and robust catalysts for carbonate transfer hydrogenation from glycerol, requiring no additives in aqueous media. The most prolific catalyst of the nine examined, [Ir(NHC-Ph-SO3?)2CO2]Na (cat7), effectively facilitates the reaction at low catalyst loading (10 ppm) at 150 °C using microwave or conventional heating. The cation of the carbonate salt significantly impacts catalytic activity, with highest activity observed with Cs2CO3(27?850 and 13?350 TONs for lactate and formate respectively in 6 hours, compared to 15?400 and 8120 with K2CO3). Catalytic amounts of Cs+were found to significantly enhance activity with K2CO3. Catalyst7is even more prolific with conventional heating under a positive N2pressure, reaching TOFs of >3000 h?1and >2100 h?1respectively for lactate and formate with K2CO3. The high activity of this catalyst compared to non-sulfonated and cyclooctadiene analogs is attributed to a combination of catalyst solubility in aqueous media and presence of π-acceptor carbonyl ligands. A catalytic mechanism is proposed for7involving O-H oxidative addition of glycerol, β-hydride elimination, bicarbonate dehydroxylation, insertion and reductive elimination.
- Ainembabazi, Diana,Finn, Matthew,Ridenour, James,Voutchkova-Kostal, Adelina,Wang, Kai
-
supporting information
p. 6093 - 6104
(2020/10/18)
-
- Simple and reactive Ir(i) N-heterocyclic carbene complexes for alkyne activation
-
Two simple unsymmetrical monometallic Ir(i) complexes with an N-heterocyclic carbene ligand and an analogous bimetallic Ir(i) complex were synthesised. These complexes were found to be extremely active catalysts for a range of C-X (X = N or O) and Si-N bond forming reactions involving alkyne and imine activation for dihydroalkoxylation, hydroamination and hydrosilylation reactions. These catalysts exhibited reaction rates far exceeding those of other Rh(i) and Ir(i) complexes previously reported. In addition, a small change to the ligand design (phenyl vs. mesityl) substantially affected both the reactivity and product selectivity of the catalyst. The Ir(i) complex bearing a mesitylene wingtip provided unprecedented regioselectivity in the dihydroalkoxylation reaction and a new kinetic product from the typical hydrosilylation protocol of 2-benyzlpyrroline to produce an N-silylaminoalkene. Our mechanistic studies indicated that this transformation proceeded via a dehydrogenative coupling mechanism.
- Gatus, Mark R. D.,Pernik, Indrek,Tompsett, Joshua A.,Binding, Samantha C.,Peterson, Matthew B.,Messerle, Barbara A.
-
supporting information
p. 4333 - 4340
(2019/04/01)
-
- Remote coordination approach for electronic tuning of a rhodium(I)-N-heterocyclic carbene (NHC)-complex
-
A simple Lewis acid coordination at the remote binding site installed within a modular N-heterocyclic carbene (NHC) ligated rhodium(I) complex could induce desired electronic influence and thereby enhance the activity of the complex in a model styrene hyd
- Thenarukandiyil, Ranjeesh,Maji, Babulal,Choudhury, Joyanta
-
supporting information
p. 419 - 423
(2019/01/08)
-
- Cation-π interactions secure aggregation induced emission of planar organic luminophores
-
The use of non-covalent intermolecular π+-π interactions between quaternary pyridinium or imidazolium cations and aromatic π systems is an efficient approach to achieve AIE in planar purely organic luminophores.
- Leduskrasts, Kaspars,Kinens, Artis,Suna, Edgars
-
supporting information
p. 12663 - 12666
(2019/10/28)
-
- Ionic liquid containing electron-rich, porous polyphosphazene nanoreactors catalyze the transformation of CO2 to carbonates
-
We show that ionic liquids (ILs) interact with electron-rich, porous polyphosphazene (PPZ), to form hybrid PPZ-IL nanoreactors able to simultaneously capture and transform CO2 into carbonates. The PPZ nanospheres swell in organic solvents and e
- Huang, Zhangjun,Uranga, Jorge G.,Zhou, Shiliu,Jia, Haiyan,Fei, Zhaofu,Wang, Yefeng,Bobbink, Felix D.,Lu, Qinghua,Dyson, Paul J.
-
p. 20916 - 20925
(2018/11/20)
-
- Harnessing asymmetric N-heterocyclic carbene ligands to optimise SABRE hyperpolarisation
-
The catalytic signal amplification by reversible exchange process has become widely used for the hyperpolarisation of small molecules to improve their magnetic resonance detectability. It harnesses the latent polarisation of parahydrogen, and involves the
- Wong, Chin Min,Fekete, Marianna,Nelson-Forde, Rhianna,Gatus, Mark R. D.,Rayner, Peter J.,Whitwood, Adrian C.,Duckett, Simon B.,Messerle, Barbara A.
-
p. 4925 - 4933
(2018/10/17)
-
- Small “Yaw” Angles, Large “Bite” Angles and an Electron-Rich Metal: Revealing a Stereoelectronic Synergy To Enhance Hydride-Transfer Activity
-
Cyclometalated complexes are an important class of (pre)catalysts in many reactions including hydride transfer. The ring size of such complexes could therefore be a relevant aspect to consider while modulating their catalytic activity. However, any correl
- Semwal, Shrivats,Mukkatt, Indulekha,Thenarukandiyil, Ranjeesh,Choudhury, Joyanta
-
supporting information
p. 13051 - 13057
(2017/09/26)
-
- N -heterocyclic carbenes: Versatile second cyclometalated ligands for neutral iridium(III) heteroleptic complexes
-
With 2-(2,4-difluorophenyl)pyridine (dfppy) as the first cyclometalated ligand and different monoanionic N-heterocyclic carbenes (NHCs) as the second cyclometalated ligands, 16 blue or greenish-blue neutral iridium(III) phosphorescent complexes, (dfppy)s
- Li, Tian-Yi,Liang, Xiao,Zhou, Liang,Wu, Chen,Zhang, Song,Liu, Xuan,Lu, Guang-Zhao,Xue, Li-Sha,Zheng, You-Xuan,Zuo, Jing-Lin
-
p. 161 - 173
(2015/03/03)
-
- Blue phosphorescent N-heterocyclic carbene chelated Pt(ii) complexes with an α-duryl-β-diketonato ancillary ligand
-
C^C chelated Pt(ii) compounds that contain an N-heterocyclic carbene (NHC) donor have recently attracted great interest as blue or white phosphorescent emitters for organic light-emitting devices (OLEDs). To overcome the tendency for excimer formation in Pt(ii) compounds, an α-duryl-β-diketonato ligand was selected as the ancillary ligand for blue phosphorescent C^C chelated Pt(ii) compounds. Using this approach, a series of NHC-based C^C chelated Pt(ii) compounds has been designed and synthesized. The chelate ligands used in the new C^C chelated Pt(ii) compounds include 1-phenylimidazol-2-ylidene in Pt1, 1-phenyl-1,2,4-triazol-5-ylidene in Pt2, p-TMS-1-phenylimidazol-2-ylidene in Pt3, and p-TMS-1-phenyl-1,2,4-triazol-5-ylidene in Pt4. A single-crystal X-ray diffraction analysis revealed that the presence of the α-duryl-β-diketonato ligand in the Pt(ii) compounds effectively suppresses the dimer formation in the crystal lattice. Pt1, Pt2, Pt3, and Pt4 display blue phosphorescence at room temperature. The p-TMS substituted complex Pt3 was found to display the most efficient blue phosphorescence at λem = 468 nm with a ΦPL of 0.68. Spectroscopic and computational studies established that the blue phosphorescence in the phenyl-imidazolylidene chelated complexes originates mainly from a 3MLCT state while that in the phenyl-triazolylidene chelated compounds arises from a 3ILCT state. Electroluminescent devices using Pt1 and Pt3 as the dopant were fabricated which display both monomer and exciplex emission, leading to pure white light electroluminescence with CIE coordinates of (0.32, 0.31).
- Ko, Soo-Byung,Park, Hee-Jun,Gong, Shaolong,Wang, Xiang,Lu, Zheng-Hong,Wang, Suning
-
p. 8433 - 8443
(2015/05/20)
-
- Bimetallic N-Heterocyclic Carbene Rh(I) Complexes: Probing the Cooperative Effect for the Catalyzed Hydroelementation of Alkynes
-
A series of bimetallic N-heterocyclic carbene Rh(I) complexes (13, 14, 16, 18, 19, and 21) were prepared, in which two metal fragments are linked to a central organic scaffold. These complexes were investigated as catalysts for the hydroelementation of al
- Diachenko, Vera,Page, Michael J.,Gatus, Mark R. D.,Bhadbhade, Mohan,Messerle, Barbara A.
-
p. 4543 - 4552
(2015/10/06)
-
- Iridium complexes of N-heterocyclic carbene ligands: Investigation into the energetic requirements for efficient electrogenerated chemiluminescence
-
A series of five heteroleptic Ir(III) complexes of the general form Ir(ppy)2(C∧C:) have been prepared (C∧C represents a bidentate cyclometalated phenyl-substituted imidazolylidene ligand). The five complexes arise from the
- Stringer, Bradley D.,Quan, Linh M.,Barnard, Peter J.,Wilson, David J.D.,Hogan, Conor F.
-
p. 4860 - 4872
(2015/04/27)
-
- Exploring a unique reactivity of N-heterocyclic carbenes (NHC) in rhodium(III)-catalyzed intermolecular C-H activation/annulation
-
Disclosed herein is the unique conjugative role of N-heterocyclic carbene (NHC) ligands as a directing group in aromatic C-H activation, coupled with a facile NHC-alkenyl annulative reductive elimination which guided the RhIII-catalyzed intermo
- Ghorai, Debasish,Choudhury, Joyanta
-
supporting information
p. 15159 - 15162
(2014/12/11)
-
- Luminescent biscarbene iridium(iii) complexes as living cell imaging reagents
-
Five iridium(iii) complexes with two N-heterocyclic carbene (NHC) ligands and an ancillary ligand have been designed and successfully synthesized. With multicolor photoluminescence and low toxicity, these carbene complexes were tested, for the first time,
- Zhou, Yuyang,Jia, Junli,Li, Wanfei,Fei, Hao,Zhou, Ming
-
supporting information
p. 3230 - 3232
(2013/05/08)
-
- [NiX2(NHC)2]complexes in the hydrosilylation of internal alkynes
-
A number of nickel(II) dihalide complexes with small monodentate N-heterocyclic carbene ligands was synthesized and tested for their catalytic activity in the hydrosilylation of internal alkynes. The nickel(0) active species was obtained from the starting
- Berding, Joris,Van Paridon, John A.,Van Rixel, Vincent H. S.,Bouwman, Elisabeth
-
experimental part
p. 2450 - 2458
(2011/08/03)
-
- An acidity scale of 1,3-dialkylimidazolium salts in dimethyl sulfoxide solution
-
(Chemical Equation Presented) Equilibrium acidities of 16 1,3-dialkylimidazolium-type ionic liquid (IL) molecules (1-16) were systematically measured by the overlapping indicator method at 25°C in dimethyl sulfoxide (DMSO) solution. The pKa values were observed to range from 23.4 for IL 12 to 19.7 for IL 6 (Tables 1 and 2), responding mainly to structural variations on the cation moiety. Excellent agreement between the spectrophotometrically determined pKa and that derived from NMR titration for 1,3,4,5-tetramethylimidazolium bis(trifluoromethanesulfonyl)imide (12) and the close match of the obtained pK values with the reported data in literature provide credence to the acidity measurements of the present work. The substituent effects at the imidazolium ring and the effects of counterions on the acidities of ionic liquids are discussed.
- Chu, Yuan,Deng, Hui,Cheng, Jin-Pei
-
p. 7790 - 7793
(2008/02/13)
-