Article
Chemistry, Multidisciplinary
Kaixue Xie, Martin Oestreich
Summary: Readily available cyclohexa-2,5-dien-1-ylcarbonyl chloride derivatives were used as stable HCl surrogates for transfer hydrochlorination of alkenes and alkynes. B(C6F5)(3) facilitated the stepwise fragmentation of acyl chlorides, allowing the addition of HCl across C-C double and triple bonds with Markovnikov selectivity at room temperature.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Nils Ansmann, Deborah Hartmann, Sonja Sailer, Philipp Erdmann, Rezisha Maskey, Marcel Schorpp, Lutz Greb
Summary: In this study, hypercoordinated silicon anions were characterized using a new donor-free polymeric form of Lewis superacidic bis(perchlorocatecholato)silane 1. The results provide insights into the role of silicon hypercoordination in synthesis and catalysis, and suggest pronounced substrate activation.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Rezisha Maskey, Thaddaeus Thorwart, Simone F. Ebel, Angelina Jocic, Deborah Hartmann, Lutz Greb
Summary: Stable metal-free diradicaloids with modifiable nitrogen-containing frameworks can be synthesized through Lewis acid-base pair formation. This method allows for the one-step synthesis of diradicaloids with rationally adjustable diradical character, presenting great potential for various applications.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Multidisciplinary Sciences
Jason P. G. Rygus, Dennis G. Hall
Summary: This study reports a class of easily synthesized cyclic hemiboronic acid catalysts which can be applied in both nucleophilic and electrophilic modes of alcohol activation. Boronic acids have emerged as valuable catalysts for the functionalization of hydroxy groups in a mild and selective fashion. The utility of these catalysts is demonstrated in the monophosphorylation of vicinal diols and the reductive deoxygenation of benzylic alcohols and ketones respectively.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Li-Ya Cao, Jian-Nan Luo, Jia-Sheng Yao, De-Ku Wang, Yuan-Qing Dong, Chao Zheng, Chun-Xiang Zhuo
Summary: The study describes a Mo-catalyzed regiospecific deoxygenative cyclopropanation reaction using readily available 1,2-dicarbonyl compounds, which efficiently produces substituted cyclopropanes with high selectivity and synthetic utility. Preliminary mechanistic studies suggest that phosphine (or silane) acts as both a mild reductant and a good oxygen acceptor, efficiently regenerating the catalytically active Mo catalyst.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Florian S. Tschernuth, Thaddaus Thorwart, Lutz Greb, Franziska Hanusch, Shigeyoshi Inoue
Summary: This study introduces a Lewis superacid based on perfluorinated pinacol substituents, demonstrating its superacidic nature through experiments and showcasing its potential in catalytic properties.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Review
Chemistry, Multidisciplinary
Alexey Y. Timoshkin
Summary: This article highlights new developments in the field of Lewis acidity, focusing on novel Lewis acids and Lewis superacids of group 2, 13, 14, and 15 elements. It emphasizes the general nature of Lewis acidity phenomena and their vital role in different areas of chemistry. The basic principles of Donor-Acceptor (DA) interactions are presented to underscore the importance of Lewis acidity from weak intermolecular interactions to strong DA complexes. Recent advances in the synthesis and characterization of novel Lewis acids and Lewis superacids of group 2, 13, 14, and 15 elements are discussed.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Martin Hejda, Daniel Duvinage, Enno Lork, Antonin Lycka, Zdenck Cernosek, Jan Machacek, Sergey Makarov, Sergey Ketkov, Stefan Mebs, Libor Dostal, Jens Beckmann
Summary: The aryltellurenyl cation and the weakly coordinating carborane anion form an isolable ion pair complex, in which the Bronsted acidity of the formally hydridic B-H bonds is dramatically increased, leading to a proton transfer reaction at slightly elevated temperatures. The isolation of zwitterionic isomers further confirms the electrophilic activation of B-H bonds in the carborane moiety.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Multidisciplinary
Susannah A. A. Miller, Damien Guironnet
Summary: Functionalizing inorganic particles with organic ligands is a common technique for heterogenizing organometallic catalysts. We studied the unexpected latency in catalytic activity of molecular platinum coordinated to silica nanoparticles functionalized with norbornene ligands. We found that this latency is related to ligand density, chemical structure of the norbornene, and nanoparticle topology. Additionally, we demonstrated the benefit of this latency for triggering curing of silicone elastomers.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Marian Olaru, Stefan Mebs, Jens Beckmann
Summary: The article discusses the stabilization of phosphenium and arsenium ions through the judicious choice of aromatic substituents, resulting in molecules with specific electronic structures.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Kurt F. Hoffmann, Anja Wiesner, Simon Steinhauer, Sebastian Riedel
Summary: This article presents the preparation and characterization of the dimeric Lewis superacid [Al(OTeF5)(3)](2) and its solvent adducts, as well as the evaluation of their acidity. The experimental proof of their Lewis acidity and their reactivity in various reactions are demonstrated.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Chemistry, Physical
Md Jabed Hossain, Brij Kumar Shah, Shabana Khan
Summary: In this study, a convenient method for the synthesis of amines using accessible Ce[N(SiMe3)(2)](3)(THF)(3) catalyst under mild conditions was developed. The reduction of 1 degrees and 2 degrees amides to amines was achieved with high yields. This methodology was also successfully applied for the synthesis of indole derivatives.
Article
Chemistry, Inorganic & Nuclear
Daniel Duvinage, Lorraine A. Malaspina, Simon Grabowsky, Stefan Mebs, Jens Beckmann
Summary: In this study, the molecular and electronic structures of five divalent bis(m-terphenyl)element cations were investigated using experimental and computational methods. The preparation and characterization of some of these cations have been previously reported, while one was prepared and characterized for the first time. Quantum chemical calculations were used to analyze their electronic structures and compare them to a similar group of compounds previously studied. The results showed that these compounds have high fluoride ion affinities, classifying them as Lewis superacids.
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
(2023)
Article
Engineering, Environmental
Myungwon Oh, Mingyu Jin, Kyungho Lee, Jeong-Chul Kim, Ryong Ryoo, Minkee Choi
Summary: In this study, the catalytic effects of Pt/Al2O3 on triglyceride deoxygenation were rigorously investigated. The results showed that the γ-Al2O3 and θ-Al2O3 phases effectively stabilized highly dispersed Pt particles and exhibited high catalytic activity. Additionally, large mesopores were essential for achieving maximum catalytic activity and suppressing catalyst fouling. Comparatively, the θ-Al2O3 phase generally had larger pore sizes and fewer Lewis acid sites, which inhibited the formation of heavy products and coke.
CHEMICAL ENGINEERING JOURNAL
(2022)
Article
Chemistry, Physical
Anne K. Ravn, Nomaan M. Rezayee
Summary: This study investigates a switchable Cp*-iridium catalyst supported by a 1,10-phenanthroline-2,9-diol for the hydrogenation of amides. The catalyst can selectively induce either C-O or C-N bond scission of the amide depending on the reaction conditions. The addition of base can switch the selectivity to favor C-N bond-cleaved products. These studies provide fundamental insights for the rational design of hydrogenation catalysts.
Article
Chemistry, Multidisciplinary
Philipp Erdmann, Lutz Greb
Summary: The global Lewis acidity and effective Lewis acidity often have poor correlation, mainly due to the influence of deformation energy. Through theoretical and experimental analysis, the relationship between global Lewis acidity and effective Lewis acidity is identified.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Heiko Ruppert, Lutz Greb
Summary: In this paper, the isolation and characterization of the first tetraamido tin(II) dianion and its properties as a ligand and nucleophile were described. Experimental and computational results showed that the compound possesses high electron-donating ability and can form stable complexes with transition metals. Furthermore, it can undergo hydride substitution reactions with aldehydes to yield valuable acyl stannates. In addition, facile redox pathways mediated by halogen bond interaction were observed in the reductive dehalogenation of iodobenzene.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Inorganic & Nuclear
Lutz Greb
Summary: Valence tautomerism has a significant impact on transition metal chemistry, and its applicability to p-block elements is still at an early stage. However, considering the substantial disparity in the properties of p-block elements in different redox states, this concept may offer a valid extension for future developments in main group catalysis.
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Lukas M. Sigmund, Rouven Maier, Lutz Greb
Summary: This study investigates the configurational inversion of tetrahedral compounds and reveals surprisingly low inversion barriers, while also developing a model to understand and predict the angular flexibility of tetrahedral species.
Article
Chemistry, Multidisciplinary
Florian Schoen, Lukas M. Sigmund, Friederike Schneider, Deborah Hartmann, Matthew A. Wiebe, Ian Manners, Lutz Greb
Summary: This study developed a transition metal-free catalyst for the preparation of high molar weight polyphosphinoboranes, overcoming the interference of transition metal impurities on the reproducibility of material properties.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Nils Ansmann, Deborah Hartmann, Sonja Sailer, Philipp Erdmann, Rezisha Maskey, Marcel Schorpp, Lutz Greb
Summary: In this study, hypercoordinated silicon anions were characterized using a new donor-free polymeric form of Lewis superacidic bis(perchlorocatecholato)silane 1. The results provide insights into the role of silicon hypercoordination in synthesis and catalysis, and suggest pronounced substrate activation.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Selina Hollstein, Philipp Erdmann, Andreas Ulmer, Henrik Loew, Lutz Greb, Max von Delius
Summary: The dynamic covalent chemistry of the Si-O bond has unique opportunities but is rarely used to assemble discrete molecular architectures, possibly due to the harsh conditions required for exchange reactions at silicon in aprotic solvents. In this study, we provide a comprehensive account on the reaction of trialkoxysilanes with alcohols and identify mild conditions for rapid exchange in aprotic solvents. We uncover, understand, and exploit the effects of substituents, solvent, and salt for the construction of sila-orthoester cryptates, which show a sharp, divergent pH-response attractive for future applications beyond host-guest chemistry, such as drug delivery.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Rezisha Maskey, Thaddaeus Thorwart, Simone F. Ebel, Angelina Jocic, Deborah Hartmann, Lutz Greb
Summary: Stable metal-free diradicaloids with modifiable nitrogen-containing frameworks can be synthesized through Lewis acid-base pair formation. This method allows for the one-step synthesis of diradicaloids with rationally adjustable diradical character, presenting great potential for various applications.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Inorganic & Nuclear
Qingqing Luo, Lutz Greb
Summary: Organosilanes are crucial products in the chemical industries, but their bulk production starting from silica has a significant ecological impact due to energy consumption and hazardous by-products. In this study, a redox-neutral, one-pot silicon-carbon bond formation process was developed using catechol-mediated SiO2 depolymerization and nucleophilic substitution. By optimizing the steps, a 76% yield of SiPh4 was achieved on a large scale. This success encourages further research on energy- and waste-efficient organosilane production.
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Nils Ansmann, Joshua Muench, Marcel Schorpp, Lutz Greb
Summary: A novel chelating Lewis acidic bis(amidophenolato)silane is introduced as a strong Z-type ligand in this study, enabling the characterization of the first anionic [Pd(0)-X]- ate complex. The compounds exhibit a highly unusual square planar coordination and have important implications in Pd-catalyzed cross-coupling reactions.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Ravi Yadav, Paul Janssen, Marcel Schorpp, Lutz Greb
Summary: Anti-van't Hoff-Le Bel configured p-blockelementspecies possess intrinsically high reactivity and are thus challenging to isolate. Consequently, numerous elements in this configuration, including square-planar germanium(IV), remain unexplored. Herein, we follow a concept to reach anti-van't Hoff-Le Bel reactivity by ligand dissociation from a rigid calix[4]pyrrole germanein its bis(thf) adduct. While the macrocyclic ligand assures square-planar coordination in the uncomplexed form, the labile thf donors provide robustness for isolation on a multigram scale. Unique properties of a low-lying acceptor orbital imparted to germanium(IV) can be verified, e.g., by isolating an elusive anionic hydrido germanate and exploiting it for challenging bond activations. Aldehydes, water, alcohol, and a CN triple bond are activated for the first time by germanium-ligand cooperativity. Unexpected behaviors against fluoride ion donors disclose critical interferences of a putative redox-coupled fluoride ion transfer during the experimental determination of Lewis acidity. Overall, we showcase how ligand lability grants access to the uncharted chemistry of anti-van't Hoff-Le Bel germanium(IV) and line up this element as a member in the emerging class of structurally constrained p-block elements.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Daniel Roth, Alexander T. Radosevich, Lutz Greb
Summary: A series of structurally constrained phosphenium ions based on pyridinylmethylamidophenolate scaffolds are capable of undergoing P(III)/P(V) oxidative addition reactions with C-H bonds in alkynes, alkenes, and arenes. The reactions are reversible and involve isomerizations and phosphorus-ligand cooperative effects.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Organic
Lutz Greb
Summary: In recent decades, numerous strategies have been developed to enhance the reactivity and properties of p-block elements. This Account focuses on our approaches to controlling p-block elements in their normal oxidation states using distinct ligands. Catecholato ligands on silicon, germanium, or phosphorus offer a range of rewarding properties, such as Lewis superacidity. The synthesized species can be utilized for catalysis and bond activation, enriching the chemistry of main-group elements.
Article
Chemistry, Multidisciplinary
Thaddaeus Thorwart, Lutz Greb
Summary: The silicon-carbon bond is crucial for synthetic transformations, but reversible C-H silylations have been elusive. This study demonstrates the successful CH-bond silylation of heterocycles and terminal alkynes using specific silane reagents. The reaction can be reversed by adding a silicon donor, providing a new approach to C-H silylation. This research has important implications for the development of reversible silicon-carbon bond formations.
Article
Chemistry, Multidisciplinary
Lukas M. Sigmund, Eliane Engels, Nick Richert, Lutz Greb
Summary: In this study, the synthesis, characterization, and reactivity of calix[4]pyrrolato gallates, which consist of square planar-coordinated gallium(iii) atoms, were reported. Unusual structural constraint-induced Lewis acidity and fully reversible metal-ligand cooperative capture of CO2 were revealed by both experimental and computational methods.
