Article
Chemistry, Multidisciplinary
Constantin Eisen, Jia Min Chin, Michael R. Reithofer
Summary: Solid supported or ligand capped gold nanomaterials (AuNMs) have emerged as versatile and recyclable heterogeneous catalysts for a broad variety of conversions in the ongoing catalytic 'gold rush'. AuNMs, existing at the border of homogeneous and heterogeneous catalysis, have the potential to merge high catalytic activity with significant substrate selectivity. This work summarizes well-defined catalytically active NHC capped AuNMs, including spherical nanoparticles and atom-precise nanoclusters, as well as the important NHC design choices towards activity and (stereo-)selectivity enhancements.
CHEMISTRY-AN ASIAN JOURNAL
(2021)
Article
Chemistry, Multidisciplinary
Qun Zhao, Guangrong Meng, Guangchen Li, Carol Flach, Richard Mendelsohn, Roger Lalancette, Roman Szostak, Michal Szostak
Summary: This study reports the synthesis, catalytic activity, and full structural and electronic characterization of novel, sterically-bulky NHC ligands based on the hash peralkylation concept. The new ligands have been commercialized and show broad activity in various cross-coupling reactions. The generality of the approach in ligand design is demonstrated through facile synthesis of different NHC ligands.
Article
Multidisciplinary Sciences
Tong Liu, Sha Bai, Le Zhang, F. Ekkehardt Hahn, Ying-Feng Han
Summary: Tuning the surface-embellishing ligands of metal nanoparticles can impact their catalytic activity and selectivity. The design and synthesis of a polytriazolium organic cage in this study stabilized PdNPs and showed excellent catalytic performance and recyclability.
NATIONAL SCIENCE REVIEW
(2022)
Article
Polymer Science
Rui Tan, Xiaochun Mu, Haiyang Wang, Yang Li
Summary: By using (i)Pr(2)Im as a Lewis base ligand, beta-H elimination reactions in propylene polymerization were suppressed, resulting in high molecular weight polypropylene and block copolymers. DFT calculations showed that the delocalized electrons in (i)Pr(2)Im could decrease the electro positivity of active sites, providing a convenient strategy for tuning their electronic properties.
Article
Chemistry, Multidisciplinary
Hui Shen, Zhen Xu, Maryam Sabooni Asre Hazer, Qingyuan Wu, Jian Peng, Ruixuan Qin, Sami Malola, Boon K. Teo, Hannu Hakkinen, Nanfeng Zheng
Summary: Deciphering the atomic arrangement of hybrid surface ligands on metal nanoparticles is a key step towards understanding their complex geometrical and electronic structures, which can have potential bio-applications.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Hang Shen, Michael B. Larsen, Allison G. Roessler, Paul M. Zimmerman, Andrew J. Boydston
Summary: A new flex-activated mechanophore has been discovered, which releases an N-heterocyclic carbene (NHC) under mechanical load. This design demonstrates a promising first step towards flex-activated designs with downstream reactivities, allowing for iterative activation increases in the material through non-destructive compression cycles. The potential modularity of the mechanophore design is highlighted by the demonstration of two different NHC structures.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Organic
Zhen Li, Pengju Ji, Jin-Pei Cheng
Summary: A Brønsted basicity scale was established for nine representative N-heterocyclic olefins (NHOs) using an UV-visible spectroscopic method. The unsaturated NHOs were found to have stronger basicities compared to their N-heterocyclic carbene (NHC) analogues, while the basicities of the saturated NHOs were weaker. The nucleophilicity of the NHOs was also stronger than commonly used Lewis bases but weaker than their NHC analogues.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Ludwig Zapf, Udo Radius, Maik Finze
Summary: The paper describes the synthesis of 1,3-bis(tricyanoborane)imidazolate anion and its derivatives, including a novel dianionic N-heterocyclic carbene. These compounds exhibit unique electronic and steric properties, making them promising ligands and building blocks for coordination chemistry.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Marcos A. S. Francisco, Felipe Fantuzzi, Thiago M. Cardozo, Pierre M. Esteves, Bernd Engels, Ricardo R. Oliveira
Summary: This study discusses the design principles and computational investigation of new organometallic platforms containing stable manganese-manganese bonds. The analysis focuses on the metal-carbene interaction and auxiliary coordination to generate short metal-metal bonds, closed-shell singlet multiplicities, and positive singlet-triplet energy gaps. The research identifies two classes of viable synthetic targets with thoroughly investigated electrostructural properties.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Multidisciplinary
Junbeom Park, Jaelim Kim, Gu Yoon Jeong, Youngsuk Kim, Eunsung Lee
Summary: This study investigates the electron and proton transfer chemistry of N-heterocyclic carbene nitric oxide radical compounds and prepares a variety of nitrosyl derivatives. The reactions of these derivatives resemble those of transition metal nitrosyl complexes.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Chaohuang Chen, Constantin G. Daniliuc, Gerald Kehr, Gerhard Erker
Summary: Deprotonation of [(NHC)(Fmes)B-allyl](+) borenium cations provides access to NHC-stabilized 1-bora-1,3-butadienes, which undergo various organic transformations and serve as precursors for metal complexes.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Biochemical Research Methods
Fady Nahra, Nikolaos Tzouras, Alba Collado, Steven P. Nolan
Summary: N-heterocyclic carbene gold(I) chloride and hydroxide complexes are commonly used as synthetic reagents and efficient catalysts. This study describes a straightforward and practical method for synthesizing mononuclear gold complexes with high yields, as well as the synthesis of a mononuclear gold(I) hydroxide complex and an improved synthesis method for a dinuclear gold(I) hydroxide complex. This methodology offers advantages such as the use of sustainable reaction solvents and commercially available starting materials.
Review
Chemistry, Multidisciplinary
Tingting Li, Zhichao Jin, Yonggui Robin Chi
Summary: This review discusses N-heterocyclic carbene-catalyzed reactions for the formation of aromatic compounds, categorizing them into 4 types based on activation modes. The achievements, challenges, and future research directions in NHC-catalyzed arene construction processes are summarized. The outlook is based on the authors' opinions and knowledge on the trends of NHC organocatalysis development.
SCIENCE CHINA-CHEMISTRY
(2022)
Review
Chemistry, Multidisciplinary
Kun-Quan Chen, He Sheng, Qiang Liu, Pan-Lin Shao, Xiang-Yu Chen
Summary: In recent years, NHC-catalyzed radical reactions have been gaining attention for their potential to create new activation modes previously inaccessible. Further research and understanding of this emerging area is warranted to explore its synthetic techniques and advantages.
SCIENCE CHINA-CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Nadine Weyer, Myron Heinz, Julia I. Schweizer, Clemens Bruhn, Max C. Holthausen, Ulrich Siemeling
Summary: The N-heterocyclic silylene shows a remarkable combination of thermal stability and reactivity towards small molecules, producing different follow-up products in reactions with CO2, N2O, H2O, NH3, and FcPH(2). Unexpectedly, the reaction with H3BNH3 results in B-H activation instead of N-H activation. DFT results suggest dramatically different mechanisms for these H-X insertions.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Ramapada Dolai, Rahul Kumar, Benedict J. Elvers, Pradeep Kumar Pal, Benson Joseph, Rina Sikari, Mithilesh Kumar Nayak, Avijit Maiti, Tejender Singh, Nicolas Chrysochos, Arumugam Jayaraman, Ivo Krummenacher, Jagannath Mondal, U. Deva Priyakumar, Holger Braunschweig, Cem B. Yildiz, Carola Schulzke, Anukul Jana
Summary: A new type of carbodicarbene (CDC) with two different classes of carbenes has been reported, which shows promising potential as organic electron donors and n-dopants. These compounds exhibit notable redox properties and can form carbon-carbon sigma bonds through reactions with [NO][SbF6].
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Henric Steffenfauseweh, Dennis Rottschaefer, Yury V. Vishnevskiy, Beate Neumann, Hans-Georg Stammler, Dariusz W. Szczepanik, Rajendra S. Ghadwal
Summary: A bordeaux-red solid compound based on an anionic dicarbene (ADC) with a central six-membered C4Sb2 ring is reported. The compound undergoes 2 e-oxidation to form a brick-red solid with unpaired electrons and lone pairs. The diradical character of the compound is calculated to be 36-39% according to different methods.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Biochemistry & Molecular Biology
Hemant Kumar, Maryam Khosraneh, Siva S. M. Bandaru, Carola Schulzke, Silke Leimkuehler
Summary: This study investigates the reversible oxidation of formate to carbon dioxide catalyzed by molybdenum or tungsten-containing formate dehydrogenases. The formation of bicarbonate as the first intermediate during the reaction at the active site is discovered, contrary to previous reports. Bicarbonate formation occurs after an oxygen atom transfer reaction, where the oxygen is transferred from water to formate, followed by a proton-coupled electron transfer or hydride transfer reaction involving the sulfido ligand as the acceptor.
Article
Chemistry, Organic
Subhadip Jana, Benedict J. Elvers, Sebastian Patsch, Pallavi Sarkar, Ivo Krummenacher, Mithilesh Kumar Nayak, Avijit Maiti, Nicolas Chrysochos, Swapan K. Pati, Carola Schulzke, Holger Braunschweig, Cem B. Yildiz, Anukul Jana
Summary: We developed a new method for synthesizing different quinodimethane derivatives by oxidizing bis-N-heterocyclic olefins linked by pi-conjugated aromatic spacers. Stable diimidazolium para- and ortho-quinodimethane derivatives were obtained with para- and ortho-phenylene bridges, as well as with tetrafluoro-p-phenylene and p-anthracene spacers. The influence of imidazolium substituents on the air and moisture stability of the quinodimethane derivatives was emphasized. Different electron transfer processes were observed depending on the pi-conjugated aromatic spacer used, with two one-electron or one two-electron redox transitions between bis-N-heterocyclic olefins and diimidazolium-quinodimethanes. The formation of pi-conjugated radical-cations, which are transient redox intermediates, was confirmed by EPR investigation.
Review
Chemistry, Multidisciplinary
Rajendra S. Ghadwal
Summary: This review article aims to highlight recent advances in accessing stable iMICs, quantifying their properties, and exploring their applications in synthesis and catalysis. The synthetic viability and use of vicinal C4,C5-anionic dicarbenes (ADCs) based on a 1,3-imidazole framework are also presented. iMICs and ADCs have the potential to push the limit of classical NHCs by enabling access to conceptually new main-group heterocycles, radicals, molecular catalysts, ligand sets, and more.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Arne Merschel, Yury V. Vishnevskiy, Beate Neumann, Hans-Georg Stammler, Rajendra S. Ghadwal
Summary: Cyclic organoalane compounds [(ADC(Ar))AlH2](2) based on anionic dicarbene (ADC) frameworks have been reported. These compounds are stable crystalline solids and soluble in organic solvents. They exhibit annulated tricyclic structures with a planar central C4Al2-core embedded between two peripheral 1,3-imidazole rings.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Organic
Siva Sankar Murthy Bandaru, Carola Schulzke
Summary: The novel organic salt was synthesized through a Lewis acid and Lewis-base reaction and analyzed by various spectroscopic and crystallographic techniques.
Article
Chemistry, Inorganic & Nuclear
Siva Sankar Murthy Bandaru, Claudia Schindler, Felix Wenzek, Carola Schulzke
Summary: Several synthetic cross-coupling procedures were evaluated for tethering pyrazine to dithiocarbonates. The resulting compounds can serve as pro-ligands and can be converted into ene-dithiolate ligand systems resembling molybdopterin by removing the C=O moiety. The coupling of 2-iodopyrazine with stannylated dithiocarbonate units mediated by copper(I)-thiophene-2-carboxylate in stoichiometric equivalents proved to be the most efficient and reliable method for synthesizing the targeted compounds.
Article
Chemistry, Multidisciplinary
Priyanka Saha, Nicolas Chrysochos, Benedict J. Elvers, Sebastian Paetsch, Sk Imraj Uddin, Ivo Krummenacher, Muneshwar Nandeshwar, Anshika Mishra, Karthik V. Raman, Gopalan Rajaraman, Ganesan Prabusankar, Holger Braunschweig, Prince Ravat, Carola Schulzke, Anukul Jana
Summary: A modular approach for the synthesis of isolable crystalline Schlenk hydrocarbon diradicals from m-phenylene bridged electron-rich bis-triazaalkenes as synthons is demonstrated. The diradical nature and triplet electronic structure of the synthesized compounds are confirmed through EPR spectroscopy and computational analysis. The potential of the modular methodology is further illustrated through the utilization of 4,6-dimethyl-m-phenylene as a coupling unit.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Jevy V. Correia, Bruno Wilke, Carola Schulzke
Summary: A new alkyne functionalized pterin derivative was successfully synthesized and its purity and chemical structure were confirmed through various methods. The compound can be further modified by utilizing its alkyne moiety and exhibits good solubility in solvents except for water.
Article
Chemistry, Multidisciplinary
Benedict J. Elvers, Sebastian Paetsch, Siva S. M. Bandaru, Vera Krewald, Carola Schulzke, Christian Fischer
Summary: Heteroleptic molybdenum complexes with P2N2 and non-innocent dithiolene ligands were synthesized and electrochemically characterized. The reduction potentials of the complexes were adjusted by ligand-ligand cooperativity via non-covalent interactions. This finding was supported by electrochemical studies, UV/Vis spectroscopy, and temperature-dependent NMR spectroscopy. The observed behavior resembles enzymatic redox modulation through second ligand sphere effects.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Mithilesh Kumar Nayak, Benedict J. Elvers, Debdeep Mandal, Ayan Das, Raghunathan Ramakrishnan, Kaustubh R. Mote, Carola Schulzke, Cem Burak Yildiz, Anukul Jana
Summary: The reduction of 2-H-substituted pyrrolinium cations results in dimerisation or H-abstracted products, depending on the N-substituents. The dimerised 2,2'-bipyrrolidine derivatives with a central carbon-carbon single bond are stable and can be oxidised chemically or electrochemically. These dimers, which are air and moisture-stable, can serve as a source of two electrons in various chemical transformations.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Falk Ebeler, Yury V. Vishnevskiy, Beate Neumann, Hans-Georg Stammler, Rajendra S. Ghadwal
Summary: The decarbonylation of a cyclic bis-phosphaethynolatostannylene [(ADC)Sn(PCO)](2) based on an anionic dicarbene framework and under UV light results in the formation of a Sn2P2 cluster compound [(ADC)SnP](2). The [(ADC)SnP](2) compound binds reversibly with CO2 and enables catalytic hydroboration reaction with CO2. Additionally, it reacts with elemental selenium and Fe-2(CO)(9) to form corresponding compounds.
Article
Chemistry, Multidisciplinary
Arne Merschel, Yury V. Vishnevskiy, Beate Neumann, Hans-Georg Stammler, Rajendra S. Ghadwal
Summary: An unprecedented ring-opening of mesoionic carbenes (iMICs) based on an 1,3-imidazole scaffold to yield N-ethynylformimidamide (eFIM) derivatives as crystalline solids. The eFIMs are thermally stable under an inert atmosphere and show moderate air stability. They are excellent surrogates of iMICs and readily undergo ring-closing click reactions with a variety of main-group as well as transition metal Lewis acids to form challenging iMIC-compounds in good to excellent yields.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Nicolas Chrysochos, Sebastian Paetsch, Benedict J. Elvers, Ivo Krummenacher, Muneshwar Nandeshwar, Ganesan Prabusankar, Holger Braunschweig, Carola Schulzke, Prince Ravat, Anukul Jana
Summary: The synthesis of a twisted, push-pull, and electron-rich alkene is reported, providing a unique combination for alkene compounds. This newly synthesized alkene motif was used as a donor for the synthesis of a boron-containing pi-conjugated compound with zwitterionic properties through intramolecular charge transfer.
CHEMICAL COMMUNICATIONS
(2023)
