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We bootstrap the 4-point amplitude of N = 2 hypermultiplets in AdS2 × S2 at tree-level and for arbitrary external weights. We hereby explicitly demonstrate the existence of a hidden four-dimensional conformal symmetry that was used as an assumption in previous studies to derive this result. [ABSTRACT FROM AUTHOR]

Soybean is one of the most versatile crops for oil production, human diets, and feedstocks. The vegetative biomass of soybean is an important determinant of seed yield and is crucial for the forage usages. However, the genetic control of soybean biomass is not well explained. In this work, we used a soybean germplasm population, including 231 improved cultivars, 207 landraces, and 121 wild soybeans, to investigate the genetic basis of biomass accumulation of soybean plants at the V6 stage. We found that biomass-related traits, including NDW (nodule dry weight), RDW (root dry weight), SDW (shoot dry weight), and TDW (total dry weight), were domesticated during soybean evolution. In total, 10 loci, encompassing 47 putative candidate genes, were detected for all biomass-related traits by a genome-wide association study. Among these loci, seven domestication sweeps and six improvement sweeps were identified. Glyma.05G047900, a purple acid phosphatase, was a strong candidate gene to improve biomass for future soybean breeding. This study provided new insights into the genetic basis of biomass accumulation during soybean evolution. [ABSTRACT FROM AUTHOR]

Amines play an important role in synthesizing drugs, pesticides, dyes, etc. Herein, we report on an efficient catalyst for the general construction of amine mediated by nickel boride nanoclusters supported by a TS-1 molecular sieve. Efficient production of amines was achieved via catalytic hydrogenation of N=X (X = C, O, H) bonds. In addition, the catalyst maintains excellent performance upon recycling. Compared with the previous reports, the high activity, simple preparation and reusability of the Ni-B catalyst in this work make it promising for industrial application in the production of amines. [ABSTRACT FROM AUTHOR]

Die durch das Übergangsmetallnitrid‐Ion [NbN]+ vermittelte, katalytische Reduktion von N2O durch CO wurde unter thermischen Bedingungen in der Gasphase mittels FT‐ICR‐Massenspektrometrie und quantenchemischen Rechnungen untersucht. Während das [NbN]+/[ONbN]+‐System die Oxidation von CO durch N2O katalysiert, ermöglichen die Systeme [Nb]+/[NbO]+ und [NbO]+/[Nb(O)2]+ zwar die Oxidation von [Nb]+ und [NbO]+ durch N2O, jedoch reagieren weder [NbO]+ noch [Nb(O)2]+ bei Zimmertemperatur mit CO. Die Ursachen dieser durch den Stickstoffliganden hervorgerufenen, deutlich unterschiedlichen Reaktivitäten wurden mit quantenchemischen Rechnungen ermittelt. Eine Spin‐Frage: Das [NbN]+/[ONbN]+‐System katalysiert die Oxidation von CO durch N2O. Die Systeme [Nb]+/[NbO]+ und [NbO]+/[Nb(O)2]+ ermöglichen die Oxidation von [Nb]+ und [NbO]+ durch N2O, jedoch reagieren bei Zimmertemperatur weder [NbO]+ noch [Nb(O)2]+ mit CO. Die Ursachen dieser durch den Stickstoffliganden hervorgerufenen, deutlich unterschiedlichen Reaktivitäten wurden mit quantenchemischen Rechnungen ermittelt. [ABSTRACT FROM AUTHOR]

The thermal gas‐phase catalytic reduction of N2O by CO, mediated by the transition‐metal nitride cluster ion [NbN]+, has been explored by using FT‐ICR mass spectrometry and complemented by high‐level quantum chemical calculations. In contrast to the [Nb]+/[NbO]+ and [NbO]+/[Nb(O)2]+ systems, in which the oxidation of [Nb]+ and [NbO]+ with N2O is facile, but in which neither [NbO]+ nor [Nb(O)2]+ react with CO at room temperature, the [NbN]+/[ONbN]+ system at ambient temperature mediates the catalytic oxidation of CO. The origins of the distinctly different reactivities upon nitrogen ligation are addressed by quantum chemical calculations. A matter of spin: The [NbN]+/[ONbN]+ system catalyzes the oxidation of CO through N2O. In contrast, in the [Nb]+/[NbO]+ and [NbO]+/[Nb(O)2]+ systems, [Nb]+ and [NbO]+ are oxidized by N2O, even though neither [NbO]+ nor [Nb(O)2]+ react with CO at room temperature. The origins of the distinctly different reactivities are addressed by quantum chemical calculations. [ABSTRACT FROM AUTHOR]

Thermal gas‐phase reactions of the ruthenium‐oxide clusters [RuOx]+ (x=1–3) with methane and dihydrogen have been explored by using FT‐ICR mass spectrometry complemented by high‐level quantum chemical calculations. For methane activation, as compared to the previously studied [RuO]+/CH4 couple, the higher oxidized Ru systems give rise to completely different product distributions. [RuO2]+ brings about the generations of [Ru,O,C,H2]+/H2O, [Ru,O,C]+/H2/H2O, and [Ru,O,H2]+/CH2O, whereas [RuO3]+ exhibits a higher selectivity and efficiency in producing formaldehyde and syngas (CO+H2). Regarding the reactions with H2, as compared to CH4, both [RuO]+ and [RuO2]+ react similarly inefficiently with oxygen‐atom transfer being the main reaction channel; in contrast, [RuO3]+ is inert toward dihydrogen. Theoretical analysis reveals that the reduction of the metal center drives the overall oxidation of methane, whereas the back‐bonding orbital interactions between the cluster ions and dihydrogen control the H−H bond activation. Furthermore, the reactivity patterns of [RuOx]+ (x=1–3) with CH4 and H2 have been compared with the previously reported results of Group 8 analogues [OsOx]+/CH4/H2 (x=1–3) and the [FeO]+/H2 system. The electronic origins for their distinctly different reaction behaviors have been addressed. The influences of oxidation states of the ruthenium‐oxide clusters [RuOx]+ (x=1–3) on the thermal activation of CH4 and H2 have been revealed (see figure). Theoretical analysis indicates that the reduction of metal center drives the overall oxidation of CH4, and the back‐bonding orbital interactions between the cluster ions and H2 control the H−H bond activation. [ABSTRACT FROM AUTHOR]

The thermal gas‐phase reactions of [Al2VO5]+ and [AlV2O6]+ with methane have been explored by using Fourier transform ion cyclotron resonance (FT‐ICR) mass spectrometry complemented by high‐level quantum chemical calculations. Both cluster ions chemisorbed methane as the major reaction channels at room temperature. [Al2VO5]+ could break only one C−H bond to liberate CH3, whereas [AlV2O6]+ exhibited higher oxidizing ability such that it brings about the selective generation of formaldehyde. Mechanistic aspects are revealed and the crucial roles of the metal centers are discussed. The reactivity of cluster oxides [AlnV3−nO7−n]+ (n=1, 2) towards methane was tuned by varying the composition of the metal centers. The thermal gas‐phase reactions of [Al2VO5]+ and [AlV2O6]+ with methane have been explored by using Fourier transform ion cyclotron resonance (FT‐ICR) mass spectrometry complemented by high‐level quantum chemical calculations. Mechanistic aspects are revealed and the crucial roles of the metal centers are discussed. [ABSTRACT FROM AUTHOR]

Die thermischen Reaktionen von [CeON]+ mit Methan wurden mithilfe von FT‐ICR‐Massenspektrometrie und quantenchemischen Rechnungen untersucht. Als einziger Reaktionspfad wurde die Übertragung eines Stickstoffatoms vom Cluster‐Ion auf Methan beobachtet. Laut Rechnungen handelt es sich bei dem gebildeten Neutralmolekül entweder um CH2NH2 oder um CH3NH. Außer durch die relativ schwache OCe+‐N‐Bindung wird diese Reaktion auch von einem hocheffizienten Intersystem Crossing angetrieben. Mechanistische Aspekte und die damit verbundenen elektronischen Ursachen werden diskutiert, und ein detaillierter Vergleich von [CeON]+, [CeO]+, [CeN]+, [CeO2]+ und atomarem Stickstoff in deren Reaktionen mit CH4 wird geliefert. Es kann nur einen geben: Bei der thermischen Reaktion von [CeON]+ mit Methan wurde als einziger Reaktionspfad die Übertragung eines N‐Atoms vom Cluster‐Ion auf Methan beobachtet. Rechnungen zufolge handelt es sich beim gebildeten Neutralmolekül um CH2NH2 oder CH3NH. Abgesehen von der relativ schwachen OCe+‐N‐Bindung wird diese Reaktion von einem hocheffizienten Intersystem Crossing angetrieben. [ABSTRACT FROM AUTHOR]

The thermal gas‐phase reactions of [CeON]+ with methane have been explored by FT‐ICR mass spectrometry and high‐level quantum‐chemical calculations. Nitrogen‐atom transfer from the cluster ion to methane was observed as the only reaction channel. Based on computational work, the neutral molecule formed corresponds to either CH2NH2 or CH3NH. In addition to a rather weak OCe+−N bond, this reaction benefits from a highly efficient intersystem crossing. Mechanistic aspects and the associated electronic origins are discussed, and a detailed comparison of [CeON]+, [CeO]+, [CeN]+, [CeO2]+, and atomic N in their reactions with CH4 is given. The one and only: Nitrogen‐atom transfer from the cluster ion to methane was observed as the only reaction channel for thermal gas‐phase reactions of [CeON]+ with methane. Based on computational work, the neutral molecule formed corresponds to either CH2NH2 or CH3NH. This reaction benefits from a rather weak OCe+−N bond and a highly efficient intersystem crossing. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The thermal gas-phase reactions of [MO 3 ]+ (M = Mn, Re) with methane have been explored by using FT-ICR mass spectrometry complemented by high-level quantum chemical calculations. • Two product ions, [Re,O 3 ,C,H 2 ]+ and [Re,O 2 ,H 4 ]+, are generated in the reaction of [ReO 3 ]+ with CH 4 , and theory revealed that in both rather complex reaction channels methane is converted to CO. • Methane absorption upon releasing molecular dioxygen dominates the reaction of [MnO 3 ]+ with methane. • The rather different reactivities of [MO 3 ]+ (M = Mn, Re) towards methane result from their different structures, which originates from the higher ionization energies of Mn compared to Re. Abstract The thermal gas-phase reactions of [MO 3 ]+ (M = Mn, Re) with methane have been explored by using FT-ICR mass spectrometry complemented by high-level quantum chemical calculations. Upon reaction with methane, [ReO 3 ]+ brings about the generation of the product pairs [Re,O 3 ,C,H 2 ]+/H 2 and [Re,O 2 ,H 4 ]+/CO, while [MnO 3 ]+ only absorbs CH 4 upon releasing O 2. Combining experiment and computation it can be concluded that methane is selectively oxidized to CO by [ReO 3 ]+; for [MnO 3 ]+/CH 4 , however, simple ligand exchange prevails. The associated reaction mechanisms are revealed, and the origins for the rather different behaviors of [MO 3 ]+ (M = Mn, Re) are discussed. [ABSTRACT FROM AUTHOR]

The characteristics of the flow and heat transfer in transitional flow are not clear and especially the lack of some reliable experimental data hinders the numerical study of the heat exchanger. Based on this, a two-dimensional time-resolved digital particle image velocimetry from the American-TSI-corporation was adopted. Experiments were carried out in an open-loop, recirculating water tunnel that operated at steady-state conditions. The experimental object is a three-cylinder with an equilateral triangle configuration having center-to-center distance ratio of 3. Reynolds number based on the tube diameter and the velocity of inlet is set at 70, 90, 120, 150, 200, 250 and 300. The flow parameters were quantified to research the effect of Reynolds number on flow field for supporting some facts to analyze the heat transfer. Time-mean flow field, turbulence statistics and velocity processed by proper orthogonal decomposition were investigated at different Reynolds numbers. The wake closure length, oscillation and Karman vortex in the wake of the three-cylinder model were discussed in detail. [ABSTRACT FROM AUTHOR]

Abstract: The thermal gas‐phase reaction of [Al2CuO5]+ with methane has been explored by using FT‐ICR mass spectrometry complemented by high‐level quantum chemical calculations. The generation of atomic [Cu]+ from the [Al2CuO5]+/CH4 couple corresponds to the only reaction channel. Labeling experiments and computational studies strongly suggest that methane activation is indeed involved in the production of [Cu]+, and generation of CH2O prevails. Mechanistic aspects and the associated doping effects are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Die thermischen Gasphasenreaktionen von [RuO]+ mit Methan wurden mittels FT‐ICR‐Massenspektrometrie und quantenchemischen Rechnungen untersucht. Im Gegensatz zu den bereits beschriebenen Reaktionspaaren [FeO]+/CH4 und [OsO]+/CH4, die unter Sauerstoff‐ und Wasserstoffatomübertragungen bzw. unter Dehydrierung reagieren, bildet [RuO]+ in der Reaktion mit CH4 selektiv [Ru(CH)2]+ und H2O, allerdings mit einer viel geringeren Effizienz. Unterschiedliche mechanistische Szenarien wurden untersucht und die entsprechenden elektronischen Ursachen durch quantenchemische Rechnungen identifiziert. Es ist das Zusammenspiel der Effizienz von Spin‐Bahn‐Kopplung, Orbitalüberlappung und relativistischer Effekte, auf dem die beobachteten unterschiedlichen Reaktivitäten der Reaktionspaare [MO]+/CH4 (M=Fe, Ru, Os) beruhen. [ABSTRACT FROM AUTHOR]

Abstract: The thermal gas‐phase reactions of [RuO]+ with methane have been explored by FT‐ICR mass spectrometry and high‐level quantum‐chemical calculations. In contrast to the previously studied [FeO]+/CH4 and [OsO]+/CH4 couples, which undergo oxygen/hydrogen atom transfers and dehydrogenation, respectively, the [RuO]+/CH4 system produces selectively [Ru(CH)2]+ and H2O, albeit with much lower efficiency. Various mechanistic scenarios were uncovered, and the associated electronic origins were revealed by high‐level quantum‐chemical calculations. The reactivity differences observed for the [MO]+/CH4 couples (M=Fe, Ru, Os) are due to the subtle interplay of the spin–orbit coupling efficiency, orbital overlap, and relativistic effects. [ABSTRACT FROM AUTHOR]

Abstract: In den thermischen Reaktionen der zweiatomigen Metalloxide [MO].+ der Zinktriade (M=Zn, Cd, Hg) entsteht protonierter Formaldehyd, und zwar als Hauptprodukt, ausschließlich für das [HgO].+/CH4‐Paar. Durch quantenchemische Rechnungen konnten mechanistische Einblicke in diese Reaktion erhalten werden; die unerwartete Bildung von [CH2OH]+ aus [HgO].+/CH4 beruht vermutlich auf relativistischen Effekten. [ABSTRACT FROM AUTHOR]

Abstract: In thermal reactions of methane with diatomic metal oxides [MO].+ of the zinc triad (M=Zn, Cd, Hg), protonated formaldehyde [CH2OH]+ is generated as the major product only for the [HgO].+/CH4 couple. Mechanistic insight is provided by high‐level quantum‐chemical calculations, and relativistic effects are suggested to be the root cause for the unexpected thermal production of [CH2OH]+ from [HgO].+/CH4. [ABSTRACT FROM AUTHOR]

The thermal gas-phase reactions of [ReO4]+ with methane have been explored by using Fourier Transform Ion Cyclotron Resonance (FT-ICR) mass spectrometry complemented by high-level quantum chemical calculations. Upon reacting with methane, this cluster oxide, having an even-number of valence electrons, brings about both hydrogen-atom abstraction (HAT) to generate [ReO4H].+ and the formation of formaldehyde. Mechanistically, HAT occurs on the ground-state triplet surface, while for the generation of formaldehyde a two-state reactivity scenario prevails. The branching ratio of these competing processes is affected by the rather inefficient spin-orbit coupling to bring about the required triplet-singlet intersystem crossing. [ABSTRACT FROM AUTHOR]

Die thermischen Gasphasenreaktionen von [Al2ZnO4].+ mit Methan wurden mit FT‐ICR‐Massenspektrometrie und quantenchemischen Rechnungen untersucht. Zwei konkurrierende Mechanismen wurden identifiziert: eine Wasserstoffatomübertragung (hydrogen‐atom transfer, HAT) und ein protonengekoppelter Elektronentransfer (proton‐coupled electron transfer, PCET). Während die PCET‐Reaktion durch den ionischen Charakter der Metall‐Sauerstoff‐Bindung und durch die geometrische Flexibilität des Clusters beeinflusst wird, hängt der HAT‐Prozess interessanterweise von der Polarität der Übergangsstruktur ab. Im Vergleich zu den früher beschriebenen homonuklearen Oxiden [Al2O3].+ und [ZnO].+ reagiert das heteronukleare Oxid [Al2ZnO4].+ mit einer deutlich höheren Chemoselektivität mit Methan. Die elektronischen Ursachen dieses Dotierungseffekts wurden untersucht. Wähle deinen Weg: Für die thermische Reaktion von [Al2ZnO4].+ mit Methan werden zwei mechanistische Varianten ermittelt: eine Wasserstoffatomübertragung (HAT) und ein protonengekoppelter Elektronentransfer (PCET). Während die PCET‐Reaktion durch den ionischen Charakter der Metall‐Sauerstoff‐Bindung beeinflusst wird, hängt der HAT‐Prozess interessanterweise von der Polarität der Übergangsstruktur ab. [ABSTRACT FROM AUTHOR]

The thermal gas-phase reactions of [Al2ZnO4].+ with methane have been explored by using FT-ICR mass spectrometry complemented by high-level quantum chemical calculations. Two competitive mechanisms, that is, hydrogen-atom transfer (HAT) and proton-coupled electron transfer (PCET) are operative. Interestingly, while the HAT process is influenced by the polarity of the transition structure, both the ionic nature of the metal-oxygen bond and the structural rigidity of the cluster oxide affect the PCET pathway. As compared to the previously reported homonuclear [Al2O3].+ and [ZnO].+, the heteronuclear oxide [Al2ZnO4].+ exhibits a much higher chemoselectivity towards methane. The electronic origins of the doping effect have been explored. [ABSTRACT FROM AUTHOR]

The gas-phase reactions of [NiL]+ (L=C6H5, C5H4N, CN) with methane have been explored by using electrospray-ionization mass spectrometry (ESI-MS) complemented by quantum chemical calculations. Though the phenyl Ni complex [Ni(C6H5)]+ exclusively abstracts one hydrogen atom from methane at ambient conditions, the cyano Ni complex [Ni(CN)]+ brings about both H-atom abstraction and ligand exchange to generate [Ni(CH3)]+. In contrast, the complex 2-pyridinyl Ni [Ni(C5H4N)]+ is inert towards this substrate. The presence of the empty 4s(Ni) orbital dominates the proton-coupled electron transfer (PCET) processes for the investigated systems. [ABSTRACT FROM AUTHOR]

The thermal gas-phase reactions of methane with [OMoH]+ and [MoH]+ were investigated by using electrospray-ionization mass spectrometry (ESI-MS) complemented by quantum-chemical calculations. In contrast to the inertness of [MoH]+ towards methane, [OMoH]+ activates the C−H bond to form the ionic product [OMo(CH3)]+ concomitantly with the liberation of H2. The origin of the varying reactivities is traced back to a different influence of the oxo ligand on the Mo−C and Mo−H bonds. While the presence of this ligand weakens both the Ti−H and the Ti−CH3 bonds, both the Mo−H and Mo−CH3 bonds are strengthened. The more pronounced strengthening of the Mo−CH3 bond compared to the Mo−H bond favors the exothermicity of the reaction of [OMoH]+ with CH4. [ABSTRACT FROM AUTHOR]

Die durch die metallfreien, kationischen Cluster [Si2Ox].+ (x=2 – 5) vermittelte Reduktion von N2O durch CO wurde unter thermischen Bedingungen in der Gasphase mit Fouriertransformations ‐ Ionencyclotronresonanz(FT ‐ ICR) ‐ Massenspektrometrie und quantenchemischen Rechnungen untersucht. Ausgehend von [Si2O2].+ und N2O entsteht in drei Oxidations ‐ /Reduktionsschritten [Si2O5].+. Dieser und die intermediären Oxidcluster reagieren der Reihe nach mit CO unter Rückbildung von [Si2O2].+, d. h. es finden unter thermischen Bedingungen in der Gasphase vollständige Katalysezyklen statt. Mechanistische Aspekte dieser konsekutiven Redoxprozesse wurden untersucht, um die elektronischen Ursachen dieser beispiellosen Reaktionen aufzuklären. Der Weg von [Si2O2].+ zu [Si2O5].+ und zurück ermöglicht die katalytische Reduktion von N2O durch CO in der Gasphase. Die Reaktionsschritte im Bild wurden mithilfe der FT ‐ ICR ‐ Massenspektrometrie und quantenchemischer Rechnungen untersucht, was zur Aufklärung der elektronischen Ursachen dieser beispiellosen Reaktionen führte. Die Befunde könnten für die Entwicklung effizienterer Heterogenkatalysatoren hilfreich sein. [ABSTRACT FROM AUTHOR]

The thermal gas-phase reactions of rhenium carbonyl complexes [Re(CO) x]+ ( x=0-3) with methane have been explored by using FT-ICR mass spectrometry complemented by high-level quantum chemical calculation. While it had been concluded in previous studies that addition of closed-shell ligands in general decreases the reactivity of metal ions, the current work provides an exception: the previously demonstrated inertness of atomic Re+ towards methane is completely changed upon ligation with CO. Both [Re(CO)]+ and [Re(CO)2]+ bring about efficient dehydrogenation of the hydrocarbon under ambient conditions. However, addition of a third ligand to form [Re(CO)3]+ completely quenches the reactivity. [ABSTRACT FROM AUTHOR]

The thermal gas-phase reactions of rhenium carbonyl complexes [Re(CO) x]+ ( x=0-3) with methane have been explored by using FT-ICR mass spectrometry complemented by high-level quantum chemical calculation. While it had been concluded in previous studies that addition of closed-shell ligands in general decreases the reactivity of metal ions, the current work provides an exception: the previously demonstrated inertness of atomic Re+ towards methane is completely changed upon ligation with CO. Both [Re(CO)]+ and [Re(CO)2]+ bring about efficient dehydrogenation of the hydrocarbon under ambient conditions. However, addition of a third ligand to form [Re(CO)3]+ completely quenches the reactivity. [ABSTRACT FROM AUTHOR]

A computational model using a compound grid system for the in-line double column cylinders was developed to investigate the mechanisms of heat transfer enhancement in transitional flow. The results show that flow instability of wake flow causes two different effects, time-mean effect and statistical fluctuation effect (i.e. obtained from the time-mean effect and the statistical fluctuation parameters, respectively), to enhance the heat transfer of the downstream cylinders. According to the clue, time-mean velocity and temperature in the wake of the upstream cylinders as the time-mean effect were investigated. It was found that fast recovery of velocity and temperature improves the effective Reynolds number and temperature difference. Then velocity cross-correction and velocity–temperature cross-correction in the wake of the upstream cylinders as statistical fluctuation effect were investigated. It was found that the fluid mixing enhances the motion in a certain direction near the front face of cylinders. [ABSTRACT FROM AUTHOR]

The thermal reaction of methane with the metal-free cluster cation [Si2O4].+ has been examined by using Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometry. In addition to generating a methyl radical via hydrogen-atom abstraction, [Si2O4].+ can selectively oxidize methane to formaldehyde. The mechanisms of these rather efficient reactions have been elucidated by high-level quantum-chemical calculations. [ABSTRACT FROM AUTHOR]

Die thermischen Gasphasenreaktionen der geschlossenschaligen heteronuklearen Metalloxidcluster [AlCeOx]+ (x=2-4) mit Methan wurden mittels FT-ICR-Massenspektrometrie und quantenchemischer Rechnungen untersucht. Während [AlCeO2]+ und [AlCeO4]+ unter thermischen Bedingungen gegenüber Methan inert sind, reagiert [AlCeO3]+ spontan unter Wasserstoffatomabstraktion. Unter Berücksichtigung mechanistischer Aspekte konnten die Ursachen dieser deutlich unterschiedlichen Eigenschaften der [AlCeOx]+/CH4-Paare aufgedeckt werden; die elektronische Grundlage der beispiellosen, einfachen Wasserstoffatomabstraktion von Methan durch den geschlossenschaligen Cluster [AlCeO3]+ wird diskutiert. [ABSTRACT FROM AUTHOR]

The thermal gas-phase reactions of the closed-shell heteronuclear metal-oxide clusters [AlCeOx]+ ( x=2-4) with methane have been explored by FT-ICR mass spectrometry and high-level quantum-chemical calculation. Whereas [AlCeO2]+ and [AlCeO4]+ are inert towards methane under ambient conditions, [AlCeO3]+ spontaneously abstracts one hydrogen atom from methane. Mechanistic aspects have been addressed to reveal the reasons for the rather distinct reactivities of the [AlCeOx]+/CH4 couples, and the electronic origins of the unprecedented single hydrogen-atom abstraction from methane by closed-shell [AlCeO3]+ are discussed. [ABSTRACT FROM AUTHOR]

Die thermische Reaktion des zweiatomigen Rheniumnitridkations [ReN]+ mit Methan wurde mit FT ‐ ICR ‐ Massenspektrometrie und quantenchemischen Rechnungen untersucht. Unter besonderer Berücksichtigung mechanistischer Aspekte der Reaktion konnten Szenarien für die kompetitive Erzeugung eines an das Metallzentrum gebundenen Methylen ‐ bzw. Cyanwasserstoffliganden entworfen werden. Die Rolle des Stickstoffatoms des reaktiven [ReN]+/CH4 ‐ Paares wurde aufgeklärt und die Ursache der ziemlich unterschiedlichen Reaktivitäten von [ReN]+ und [MnN]+ ermittelt. Nimm mir meinen Wasserstoff: Die thermische Aktivierung von Methan durch [ReN]+ und mechanistische Details der kompetitiven Bildung der Produkt ‐ Ionen [NRe(CH2)]+ (Methylenligand) und [HRe(NCH)]+ (Cyanwasserstoffligand) werden diskutiert. Außerdem wird eine Erklärung dafür angeboten, warum die Reaktivität von [ReN]+ gegenüber Methan hoch ist, das leichtere [MnN]+ dagegen in dieser Reaktion inert ist. [ABSTRACT FROM AUTHOR]

Die thermische Gasphasenreaktion des geschlossenschaligen Metalloxidclusters [Al2TaO5]+ mit Methan ist mittels FT ‐ ICR ‐ Massenspektrometrie und quantenchemischen Rechnungen untersucht worden. Mechanistische Aspekte der C ‐ H ‐ Bindungsaktivierung von Methan werden beleuchtet, um die Ursachen dieser effizienten Chemisorption aufzudecken, und die elektronischen Ursachen des recht ausgeprägten Unterschieds zwischen den Eigenschaften von [Al2TaO5]+/CH4 und denen anderer Systeme werden diskutiert. Die thermische Gasphasenreaktion des geschlossenschaligen Metalloxidclusters [Al2TaO5]+ mit Methan unter C ‐ H ‐ Bindungsaktivierung wurde FT ‐ ICR ‐ massenspektrometrisch und mithilfe quantenchemischer Rechnungen untersucht. Das Bild zeigt die thermische Aktivierung von Methan durch [Al2TaO5]+ (das mit „×” markierte Signal ist auf Reaktionen mit Hintergrundwasser zurückzuführen). [ABSTRACT FROM AUTHOR]

The thermal reaction of the diatomic rhenium nitride cation [ReN]+ with methane has been explored using FT-ICR mass spectrometry complemented by high-level quantum chemical calculations. Mechanistic aspects of the reaction have been addressed to uncover scenarios for the competitive generation of a methylene and a hydrogen cyanide ligand attached to the rhenium center. The role the nitrogen atom plays in the reactive [ReN]+/CH4 couple is elucidated, and the cause of the rather different reactivities of [ReN]+ and its lighter congener [MnN]+ is revealed. [ABSTRACT FROM AUTHOR]

The thermal gas-phase reactions of the closed-shell metal-oxide cluster [Al2TaO5]+ with methane have been explored by using FT-ICR mass spectrometry complemented by high-level quantum chemical calculations. Mechanistic aspects have been addressed to reveal the origins of the efficient addition process which results in activating the C−H bond of methane. The [Al2TaO5]+/CH4 couple has been compared with several other systems reported previously, and the electronic origins of their rather distinct performances are discussed. [ABSTRACT FROM AUTHOR]

The reactivity of the cationic gold carbide [AuC]+ (bearing an electrophilic carbon atom) towards methane has been studied using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). The product pairs generated, that is, Au+/C2H4, [Au(C2H2)]+/H2, and [C2H3]+/AuH, point to the breaking and making of C−H, C−C, and H−H bonds under single-collision conditions. The mechanisms of these rather efficient reactions have been elucidated by high-level quantum-chemical calculations. As a major result, based on molecular orbital and NBO-based charge analysis, an unprecedented hydride transfer from methane to the carbon atom of [AuC]+ has been identified as a key step. Also, the origin of this novel mechanistic scenario has been addressed. The mechanistic insights derived from this study may provide guidance for the rational design of carbon-based catalysts. [ABSTRACT FROM AUTHOR]

Die thermischen Reaktionen von Methan mit den sauerstoffreichen Cluster ‐ Kationen [Si2O5].+ und [Si2O5H2].+ wurden mit Fourier ‐ Transformations ‐ Ionencyclotronresonanz(FT ‐ ICR) ‐ Massenspektrometrie und modernen quantenchemischen Rechnungen untersucht. Während [Si2O5].+ gegenüber Methan inert ist, vermittelt das hydrierte Kation [Si2O5H2].+ die H ‐ Abstraktion von Methan mit einer Effizienz von 28 % bezogen auf die Stoßrate. Der Mechanismus dieses Prozesses wurde eingehend untersucht, und die Ursachen der enorm unterschiedlichen Reaktivitäten beider Cluster konnten aufgeklärt werden. Zwei Wasserstoffatome machen den Unterschied: Während das Radikalkation [Si2O5].+ die H ‐ Abspaltung aus Methan in der Gasphase nicht katalysiert, ist das hydrierte Analogon [Si2O5H2].+ dabei hoch aktiv. Als Gründe wurden eine Umverteilung der Spindichte und damit die Erzeugung eines aktiven Zentrums in Form einer terminalen Oxogruppe ermittelt. Letztere ermöglicht dann eine effiziente homolytische C ‐ H ‐ Spaltung. [ABSTRACT FROM AUTHOR]

The reactivity of the cationic gold carbide [AuC]+ (bearing an electrophilic carbon atom) towards methane has been studied using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). The product pairs generated, that is, Au+/C2H4, [Au(C2H2)]+/H2, and [C2H3]+/AuH, point to the breaking and making of C−H, C−C, and H−H bonds under single-collision conditions. The mechanisms of these rather efficient reactions have been elucidated by high-level quantum-chemical calculations. As a major result, based on molecular orbital and NBO-based charge analysis, an unprecedented hydride transfer from methane to the carbon atom of [AuC]+ has been identified as a key step. Also, the origin of this novel mechanistic scenario has been addressed. The mechanistic insights derived from this study may provide guidance for the rational design of carbon-based catalysts. [ABSTRACT FROM AUTHOR]

The thermal reactions of methane with the oxygen-rich cluster cations [Si2O5]⋅+ and [Si2O5H2]⋅+ have been examined using Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometry in conjunction with state-of-the-art quantum chemical calculations. In contrast to the inertness of [Si2O5].+ towards methane, the hydrogenated cluster [Si2O5H2].+ brings about hydrogen-atom transfer (HAT) from methane with an efficiency of 28 % relative to the collision rate. The mechanisms of this process have been investigated in detail and the reasons for the striking reactivity difference of the two cluster ions have been revealed. [ABSTRACT FROM AUTHOR]

The closed-shell cluster ion [OSiOH]+ is generated in the gas phase and its reactivity towards the thermal activation of CH4 has been examined using Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometry in conjunction with state-of-the-art quantum chemical calculations. Quite unexpectedly at room temperature, [OSiOH]+ efficiently mediates C−H bond activation, giving rise to [SiOH]+ and [SiOCH3]+ with the concomitant formation of methanol and water, respectively. Mechanistic aspects for this unprecedented reactivity pattern are presented, and the properties of the [OSiOH]+/CH4 couple are compared with those of the closed-shell systems [OCOH]+/CH4 and [MgOH]+/CH4; the last two couples exhibit an entirely different reactivity scenario. [ABSTRACT FROM AUTHOR]

Die thermische Reaktion des zweiatomigen Tantalnitridkations [TaN]+ mit Methan ist mittels FT ‐ ICR ‐ Massenspektrometrie und genauen quantenchemischen Rechnungen untersucht worden. Durch diesen experimentell ‐ theoretischen Ansatz konnten mechanistische Details einer hocheffizienten C ‐ N ‐ Kupplung aufgeklärt werden. Im Unterschied zu [TaN]+ sind die leichteren Nitride [VN]+ und [NbN]+ unter thermischen Bedingungen gegenüber Methan inert. Die Ursachen dieser deutlich unterschiedlichen Effizienzen der drei Nitride konnten durch CCSD(T) ‐ Rechnungen aufgeklärt werden. Die thermische Aktivierung von Methan durch [TaN]+ unter C ‐ N ‐ Kupplung wurde mithilfe von Massenspektrometrie und quantenchemischen Rechnungen untersucht (siehe Ausschnitt des Massenspektrums; das mit „×” markierte Signal ist auf Reaktionen mit Hintergrundgasen zurückzuführen). [ABSTRACT FROM AUTHOR]

The thermal reaction of diatomic tantalum nitride cation [TaN]+ with methane has been explored using FT-ICR mass spectrometry complemented by high-level quantum chemical calculation; based on this combined experimental/computational approach, mechanistic aspects of this novel, highly efficient C−N coupling process have been uncovered. In distinct contrast to [TaN]+, its lighter congeners [VN]+ and [NbN]+ are inert towards methane under ambient conditions, and the origins of the remarkably variable efficiencies of the three metal nitrides are uncovered by CCSD(T) calculations. [ABSTRACT FROM AUTHOR]

Die thermischen Reaktionen von [AuO]+ mit Methan wurden mittels FT ‐ ICR ‐ Massenspektrometrie und quantenchemischen Rechnungen untersucht. Im Gegensatz zu den bereits untersuchten Oxiden der 11. Gruppe, [CuO]+ und [AgO]+, reagiert [AuO]+ mit CH4 ausschließlich unter Bildung von CH3OH durch Sauerstoffatomübertragung. Der neuartige Mechanismus dieser spezifischen Oxidation wird vorgestellt und die Ursachen der Trägheit des [AgO]+/CH4 ‐ Reaktionspaares mittels theoretischer Untersuchungen aufgedeckt. Massenspektrometrische Studien und quantenchemische Rechnungen belegen, dass die selektive Oxidation von Methan zu Methanol vermittelt durch [AuO]+ unter Sauerstoffatomübertragung verläuft. Das mit „x” markierte Signal stammt von Reaktionen mit Hintergrundgasen (siehe Ausschnitt des Massenspektrums). [ABSTRACT FROM AUTHOR]

The thermal reaction of [AuO]+ with methane has been explored using FT-ICR mass spectrometry complemented by high-level quantum chemical calculations. In contrast to the previously studied congener [CuO]+, and to [AgO]+, [AuO]+ reacts with CH4 exclusively via oxygen-atom transfer to form CH3OH, and a novel mechanistic scenario for this selective oxidation process has been revealed. Also, the origin of the inertness of the [AgO]+/CH4 couple has been addressed computationally. [ABSTRACT FROM AUTHOR]

Die thermischen Reaktionen von Methan mit [HfO].+ und [XHfO]+ (X=F, Cl, Br, I) wurden mittels FT‐ICR‐Massenspektrometrie und modernen quantenchemischen Rechnungen untersucht. Während [HfO].+ gegenüber Methan inert ist, ermöglichen die geschlossenschaligen Ionen [XHfO]+ (X=F, Cl, Br) überraschenderweise die Aktivierung der H3C‐H‐Bindung unter Bildung des Insertionsproduktes [Hf(X)(OH)(CH3)]+. Mögliche Ursachen dieses außergewöhnlichen Ligandeneffekts werden diskutiert. Die thermischen Reaktionen von Methan mit [HfO].+ und [XHfO]+ (X=F, Cl, Br, I) wurden mit Massenspektrometrie (siehe Spektrum) und quantenchemischen Rechnungen untersucht. Während [HfO].+ inert gegen Methan ist (links im Bild; C grau, H dunkelblau, Hf hellblau, O rot), ermöglichen die geschlossenschaligen Ionen [XHfO]+ (X=F, Cl, Br) die Aktivierung der H3C‐H‐Bindung unter Bildung des Insertionsproduktes [Hf(X)(OH)(CH3)]+ (rechts; X grün). [ABSTRACT FROM AUTHOR]

The thermal reactions of methane with [HfO].+ and [XHfO]+ (X=F, Cl, Br, I) were investigated by using FT-ICR mass spectrometry complemented by high-level quantum chemical calculations. Surprisingly, in contrast to the inertness of [HfO].+ towards methane, the closed-shell oxide ions [XHfO]+ (X=F, Cl, Br) activate the H3C−H bond to form the insertion products [Hf(X)(OH)(CH3)]+. The possible origin of this remarkable ligand effect is discussed. [ABSTRACT FROM AUTHOR]

Die thermischen Reaktionen des geschlossenschaligen Metalloxidclusters [TaO3]+ mit Methan wurden mittels FT ‐ ICR ‐ Massenspektrometrie sowie modernen quantenchemischen Methoden untersucht. Während die Bildung von Methanol und Formaldehyd zu erwarten war, ist die Fähigkeit von [TaO3]+ zur Abstraktion von zwei Wasserstoffatomen unter Eliminierung von CH2 sehr ungewöhnlich. Mechanistisch entstehen CH2O und CH3OH auf der Potentialfläche des Singulett ‐ Grundzustandes, während die Eliminierung von 3CH2 über eine Zweizustandsreaktivität verläuft. Fähigkeit zur Abstraktion: Die thermischen Reaktionen des geschlossenschaligen Clusters [TaO3]+ mit Methan wurden massenspektrometrisch und quantenchemisch untersucht. Erwartungsgemäß bilden sich Methanol und Formaldehyd, ungewöhnlich ist jedoch die Fähigkeit von [TaO3]+ zur Abstraktion zweier H ‐ Atome unter CH2 ‐ Eliminierung. CH2O und CH3OH entstehen auf der Potentialfläche des Singulett ‐ Grundzustandes; die Eliminierung von 3CH2 verläuft über eine Zweizustandsreaktivität. [ABSTRACT FROM AUTHOR]

Thermal reactions of the closed-shell metal-oxide cluster [TaO3]+ with methane were investigated by using FTICR mass spectrometry complemented by high-level quantum chemical calculations. While the generation of methanol and formaldehyde is somewhat expected, [TaO3]+ remarkably also has the ability to abstract two hydrogen atoms from methane with the elimination of CH2. Mechanistically, the generation of CH2O and CH3OH occurs on the singlet-ground-state surface, while for the liberation of 3CH2, a two-state reactivity scenario prevails. [ABSTRACT FROM AUTHOR]

High-level electronic structure calculations, in combination with Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometric studies, permit the mechanism by which closed-shell, 'naked' [TaO2]+ brings about C−H bond activation of methane to be revealed. These studies also help to understand why the lighter congeners of [MO2]+ (M=V, Nb) are unreactive under ambient conditions. [ABSTRACT FROM AUTHOR]

The thermal reaction of [Ho(CH2S)]+ with toluene giving rise to [C6H5CHSHo]+ and CH4 has been investigated using Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometry complemented by density functional theory (DFT) calculations. The high reactivity of [Ho(CH2S)]+ which is in distinct contrast with the non-reactivity of 'bare' Ho+ has its origin in the presence of a carbon-centered radical; the latter initiates hydrogen-atom abstraction from the methyl group of toluene as the first step of a sequence of hydrogen and sulfur transfer mediated by cationic holmium. [ABSTRACT FROM AUTHOR]

Carbon-atom extrusion from the ipso-position of a halobenzene ring (C6H5X; X=F, Cl, Br, I) and its coupling with a methylene ligand to produce acetylene is not confined to [LaCH2]+; also, the third-row transition-metal complexes [MCH2]+, M=Hf, Ta, W, Re, and Os, bring about this unusual transformation. However, substrates with substituents X=CN, NO2, OCH3, and CF3 are either not reactive at all or give rise to different products when reacted with [LaCH2]+. In the thermal gas-phase processes of atomic Ln+ with C7H7Cl substrates, only those lanthanides with a promotion energy small enough to attain a 4fn5d16s1 configuration are reactive and form both [LnCl]+ and [LnC5H5Cl]+. Branching ratios and the reaction efficiencies of the various processes seem to correlate with molecular properties, like the bond-dissociation energies of the C−X or M+−X bonds or the promotion energies of lanthanides. [ABSTRACT FROM AUTHOR]

Die thermischen Reaktionen des geschlossenschaligen, “nackten” Gold ‐ Carben ‐ Komplexes [Au(CH2)]+ mit Methan wurden mittels FT ‐ ICR ‐ Massenspektrometrie und quantenchemischen Rechnungen (CCSD(T)//BMK) untersucht. Die effiziente Insertion des Carbenliganden in die C ‐ H ‐ Bindung von Methan wird unter mechanistischen Gesichtspunkten beleuchtet, und die Ursache der unerwartet hohen Reaktivität von [Au(CH2)]+ gegenüber dem höchst inerten Kohlenwasserstoff diskutiert. Die thermischen Reaktionen des geschlossenschaligen Gold ‐ Carben ‐ Komplexes [Au(CH2)]+ mit Methan wurden durch FT ‐ ICR ‐ Massenspektrometrie und quantenchemischen Rechnungen untersucht. Die Insertion des Carbenliganden in die C ‐ H ‐ Bindung von Methan wird unter mechanistischen Aspekten beleuchtet, und die Ursache der unerwartet hohen Reaktivität von [Au(CH2)]+ gegenüber dem höchst inerten Kohlenwasserstoff diskutiert. [ABSTRACT FROM AUTHOR]

The thermal reactions of the closed-shell, "naked" gold-carbene complex [Au(CH2)]+ with methane have been explored by using FTICR mass spectrometry complemented by quantum chemical (QC) calculations at the CCSD(T)//BMK level of theory. Mechanistic aspects for this unprecedentedly efficient carbene insertion in the CH bond of methane have been addressed and the origin of the counterintuitive high reactivity of [Au(CH2)]+ towards this most inert hydrocarbon is discussed. [ABSTRACT FROM AUTHOR]