A5049067941- Boron Compounds in Chemistry
- Inorganic Fluorides and Related Compounds
- Radioactive element chemistry and processing
- Organoboron and organosilicon chemistry
- Spectroscopy and Quantum Chemical Studies
- Metal-Catalyzed Oxygenation Mechanisms
- Microfluidic and Capillary Electrophoresis Applications
- Innovative Microfluidic and Catalytic Techniques Innovation
- Inorganic Chemistry and Materials
- Ammonia Synthesis and Nitrogen Reduction
- Pickering emulsions and particle stabilization
- Metabolism and Genetic Disorders
- Photochemistry and Electron Transfer Studies
- Neonatal Health and Biochemistry
- X-ray Diffraction in Crystallography
- Carbohydrate Chemistry and Synthesis
- Advanced ceramic materials synthesis
- Synthesis of Indole Derivatives
- Glass properties and applications
- Molecular Spectroscopy and Structure
- Mass Spectrometry Techniques and Applications
- Radiopharmaceutical Chemistry and Applications
- Chemical Analysis and Environmental Impact
- Covalent Organic Framework Applications
- Bioactive natural compounds
Leipzig University
2017-2022
Institut de Chimie Séparative de Marcoule
2017
University of Leeds
1978
Significance Strong electrophilicity usually goes hand in with positive charge. In contrast, most negative ions behave like nucleophiles. Here we challenge this conventional wisdom by introducing an apparently counterintuitive idea that anions can, under well-defined circumstances, as superelectrophiles and even show superior binding strength kinetic product stabilization comparison typical superelectrophilic cations. Emanating from the stable gas-phase dianion [B 12 (CN) ] 2− , synthesized...
Abstract It is common and chemically intuitive to assign cations electrophilic anions nucleophilic reactivity, respectively. Herein, we demonstrate a striking violation of this concept: The anion [B 12 Cl 11 ] − spontaneously binds the noble gases (Ngs) xenon krypton at room temperature in reaction that typical “superelectrophilic” dications. Ng] adducts, with Ng binding energies 80 100 kJ mol −1 , contain B−Ng bonds substantial degree covalent interaction. nature confirmed spectroscopically...
Noble gas (Ng) containing molecular anions are much scarcer than Ng cations. No neon anion has been reported so far. Here, the experimental observation of [B12(CN)11Ne]- and a theoretical analysis boron-neon bond is reported.
Alkanes and [B12X12]2- (X = Cl, Br) are both stable compounds which difficult to functionalize. Here we demonstrate the formation of a boron-carbon bond between these substances in two-step process. Fragmentation gas phase generates highly reactive [B12X11]- ions spontaneously react with alkanes. The reaction mechanism was investigated using tandem mass spectrometry gas-phase vibrational spectroscopy combined electronic structure calculations. reacts by an electrophilic substitution proton...
Abstract Electrophilic anions of type [B 12 X 11 ] − posses a vacant positive boron binding site within the anion. In comparatitve experimental and theoretical study, reactivity with X=F, Cl, Br, I, CN is characterized towards different nucleophiles: (i) noble gases (NGs) as σ‐donors (ii) CO/N 2 σ‐donor‐π‐acceptors. Temperature‐dependent formation NG] indicates enthalpy order (X=CN)>(X=Cl)≈(X=Br)>(X=I)≈(X=F) almost independent NG in good agreement calculated trends. The observed...
A cryogenic ion trap vibrational spectrometer is combined with a microfluidic chip reactor in proof-of-principle experiment on the Hantzsch cyclization reaction forming 2-amino-4-phenyl thiazole from phenacyl bromide and thiourea. First, composition of solution characterized using electrospray-ionization mass spectrometry two-color infrared photodissociation (IRPD) spectroscopy. The latter yields isomer-specific spectra intermediates products. comparison to results electronic structure...
Abstract Es entspricht der chemischen Intuition, Kationen elektrophile und Anionen nukleophile Reaktivität zuzuweisen. Wir demonstrieren hier einen bemerkenswerten Bruch mit diesem Konzept: Das Anion [B 12 Cl 11 ] − bindet die Edelgase (Ngs) Xenon Krypton spontan bei Raumtemperatur – eine Reaktion, typisch für “superelektrophile” Dikationen ist. Ng] ‐Addukte Bindungsenergien von 80–100 kJ mol −1 enthalten B‐Ng‐Bindungen erheblichen kovalenten Anteilen. Der Charakter des Anions wird...
Ephemeral intermediates often hold the key to a more detailed understanding of chemical reaction pathways. Online methods unambiguously identify structure such molecular entities, in particular presence multiple isomers, are scarce. This paper presents methodology that allows real-time monitoring isomeric solution-phase continuous-flow reactions by coupling microfluidic chip-reactor cryogenic ion trap triple mass spectrometer. The technique combines excellent control associated with chips...
We investigate the perchlorate anion, ClO4−, microhydrated with up to eight water molecules using infrared photodissociation (IRPD) spectroscopy aided by density functional theory computations. The features observed in IRPD spectra of D2-tagged ClO4−(H2O)n n = 0−8 O–H stretching (2800–3800 cm−1) and fingerprint (800–1800 spectral ranges are assigned vibrational modes solvent, i.e., free hydrogen-bonded H2O bending modes, solute, modes. splitting triply degenerate antisymmetric mode bare...
Exotic oxidation states of the first-row transition metals have recently attracted much interest. In order to investigate a series iron-oxalate complexes, an aqueous solution iron(III) nitrate and oxalic acid was studied by infrared free liquid matrix-assisted laser desorption/ionization as well ionspray mass spectrometry. Here, we show that iron is not only detected in its common +II +III, but also unusual state +I, detectable both positive-ion negative-ion modes, respectively. Vibrational...
The alkylidene double bond configuration of transient ortho-quinone methides (o-QMs) is studied by cryogenic ion trap vibrational spectroscopy. To this end, o-QMs are formed from ortho-hydroxy benzhydryl alcohols in a Brønsted acid mediated dehydration reaction on microfluidic chip reactor and the E/Z isomer ratio determined comparing measured gas phase mid-infrared fingerprints with predicted harmonic spectra density functional theory calculations. Control over stereochemistry achieved...
Abstract Exotische Oxidationszustände der Metalle ersten Übergangsreihe haben in letzter Zeit großes Interesse geweckt. Um die Oxidationsstufen einer Reihe von Eisenoxalat‐Komplexen zu untersuchen, wurde eine wässrige Lösung Eisen(III)‐nitrat und Oxalsäure mittels Flüssigstrahl‐Infrarot‐Laser‐Desorptions‐ Elektrospray‐Massenspektrometrie untersucht. Wir zeigen, dass Eisen nicht nur seinen üblichen +II +III, sondern auch ungewöhnlichen Oxidationsstufe +I nachgewiesen werden kann, sowohl im...
Das Ion [B12Cl11]− … …hat Eigenschaften, die nicht vereinbar zu sein scheinen – eine positive und negative Seite wie Göttin Helja aus der altnordischen Mythologie: Physikalisch ist ein Anion, es geht jedoch für stark elektrophile Kationen typische Reaktionen ein. In Zuschrift auf S. 8090 ff. berichten Grabowsky, J. Warneke et al., dass Elektrophilie von so hoch ist, sogar Edelgase Kr Xe spontan bei Raumtemperatur gebunden werden Reaktion Superelektrophilen. Atmosphärenchemie Photochrome...
The vibrational frequency of CO, which binds to different electrophilic anions [B12X11]- (X=F, Cl, Br, I), is determined by an interplay blue-shifting electrostatics (blue beam between boron and carbon) red shifting π-backdonation (flames). For X=Cl, I, (upper half) dominates, while for X=F (bottom) dominates CO exceptionally strongly. Measured spectra are shown on the right. band unbound would be found at position laser beam. More information can in Full Paper M. Mayer, J. Warneke, et al....