Organometallics play a vital role in catalytic and synthetic processes.Understanding the indi-vidual elementary steps of the reactions of organo metallic com-pounds is crucial for the development and ratio-nal design ...Organometallics play a vital role in catalytic and synthetic processes.Understanding the indi-vidual elementary steps of the reactions of organo metallic com-pounds is crucial for the development and ratio-nal design of new organometallic reagents and catalysts.Study of gas-phase reactions is one of the key approaches to probing the individual elementary steps under isolated and re-producible conditions.A series of investigations have been reported on the gas-phase reac-tions between organometallic ions and neutral molecules under room temperature conditions.However,studies about the reactions between organometallic ions and neutral molecules un-der heating conditions are very limited.In this work,an apparatus with an electrospray ion-ization source and an ion funnel trap,which can be coupled with a high-temperature linear ion trap reactor,was designed and built.The apparatus can be used to investigate the reac-tions between organometallic ions and neutral molecules under heating conditions.By using the apparatus,the adsorption reactions of Rh(PPh_(3))_(2)^(+)+CO→Rh(PPh_(3))_(2)CO^(+)and CuPPh_(3)^(+)+CO_(2)→CuPPh_(3)CO_(2)+under variable temperature conditions have been conducted.The experiments showed that the reaction rate constant of Rh(PPh_(3))_(2)^(+)+CO increases first and then decreases with increasing temperature.In contrast,the rate constant of CuPPh_(3)^(+)+CO_(2)decreases monotonically as the temperature increases.Density functional theory calculations indicate that the adsorption reaction of Rh(PPh_(3))_(2)^(+)+CO→Rh(PPh_(3))_(2)CO^(+)is subject to a small barrier,while CuPPh_(3)^(+)+CO_(2)→CuPPh_(3)CO_(2)+is barri-erless,which is consistent with the experimentally observed temperature-dependent rate con-stants.The newly built apparatus can thus provide new kinetic information to address reac-tion mechanisms for organometallic ions.展开更多
Reactions of gas-phase species with small molecules are being actively studied to understand the elementary steps and mechanistic details of related condensed-phase processes.Activation of the very inert N≡N triple b...Reactions of gas-phase species with small molecules are being actively studied to understand the elementary steps and mechanistic details of related condensed-phase processes.Activation of the very inert N≡N triple bond of dinitrogen molecule by isolated gas-phase species has attracted considerable interest in the past few decades.Apart from molecular adsorption and dissociative adsorption,interesting processes such as C-N coupling and degenerate ligand exchange were discovered.The present review focuses on the recent progress on adsorption,activation,and functionalization of N2 by gas-phase species(particularly metal cluster ions)using mass spectrometry,infrared photo-dissociation spectroscopy,anion photoelectron spectroscopy,and quantum chemical calculations including density functional theory and high-level ab initio calculations.Recent advances including characterization of adsorption products,dependence of clusters’reactivity on their sizes and structures,and mechanisms of N≡N weakening and splitting have been emphasized and prospects have been discussed.展开更多
The reactions of cationic zirconium oxide clusters （ZrxOy^＋） with ethylene （C2H4） were investigated by using a time-of-flight mass spectrometer coupled with a laser ablation/supersonic expansion cluster source. S...The reactions of cationic zirconium oxide clusters （ZrxOy^＋） with ethylene （C2H4） were investigated by using a time-of-flight mass spectrometer coupled with a laser ablation/supersonic expansion cluster source. Some hydrogen containing products （ZrO2）xH^＋（x=-1-4） were observed after the reaction. The density functional theory calculations indicate that apart from the common oxygen transfer reaction channel, the hydrogen abstraction channel can also occur in （ZrO2）x^＋＋C2H4, which supports that the observed （ZrO2）xH^＋ may be due to （ZrO2）x^＋＋C2H4→（ZrO2）xH^＋＋C2H3. The rate constants of different reaction channels were also calculated by Rice-Rarnsberger-Kassel-Marcus theory.展开更多
Oxidation of CO by gas-phase atomic clusters is being actively studied to understand the molecular-level mechanisms of heterogeneous CO oxidation over related catalytic surfaces. However, it is experimentally challeng...Oxidation of CO by gas-phase atomic clusters is being actively studied to understand the molecular-level mechanisms of heterogeneous CO oxidation over related catalytic surfaces. However, it is experimentally challenging to study CO oxidation by neutral heteronuclear metal oxide clusters because of the difficulty of cluster ionization and detection without fragmentation. Herein, the neutral AuVO2-4 clusters were experimentally generated and their reactions with CO and O2 were studied. The experimental results showed that CO adsorption is the dominant channel on the interactions of AuVO4 and AuVO3 with CO, and AuVO2 can pick up an O2 molecule to generate AuVO4. Theoretical studies indicated that the oxidation of the trapped CO in AuVO3,4CO into CO2 is exothermic while the reaction barriers have to be overcome at the elevated temperatures. A catalytic cycle for CO oxidation by AuVO2-4 is proposed.展开更多
Manganese oxide cluster cations Mnm180n＋ were prepared by laser ablation and reacted with hydrogen sulfide （H2S） in a fast flow reactor under thermal collision conditions. A time-of-flight mass spectrometer was use...Manganese oxide cluster cations Mnm180n＋ were prepared by laser ablation and reacted with hydrogen sulfide （H2S） in a fast flow reactor under thermal collision conditions. A time-of-flight mass spectrometer was used to detect the cluster distributions before and after the interactions with H2S. The experiments suggest that oxygen-for-sulfur （O/S） ex- change reaction to release water took place in the reactor for most of the manganese oxide cluster cations： MnmlSOn＋＋H2S→Mnm18On-1S＋＋H218O. Density functional theory cal- culations were performed for reaction mechanisms of Mn202＋＋H2S, Mn203＋＋H2S, and Mn204＋＋H2S. The computational results indicate these O/S exchange reactions are both thermodynamically and kinetically favorable, thus in good agreement with the experimental observations. The O/S exchange reactions identified in this gas-phase cluster study parallel similar behavior of related condensed phase reaction systems.展开更多
Adsorption and activation of dinitrogen(N_(2)) is an indispensable process in nitrogen fixation.Metal nitride species continue to attract attention as a promsing catalyst for ammonia synthesis.However,the detailed mec...Adsorption and activation of dinitrogen(N_(2)) is an indispensable process in nitrogen fixation.Metal nitride species continue to attract attention as a promsing catalyst for ammonia synthesis.However,the detailed mechanisms at a molecular level between reactive nitride species and N_(2) remain unclear at elevated temperature,which is important to understand the temperature effect and narrow the gap between the gas phase system and condensed phase system.Herein,the ^(15)N/^(14)N isotopic exchange in the reaction between tantalum nitride cluster anions Ta_(3)^(14)N_(3)^(-) and ^(15)N_(2) leading to the regeneration of ^(14)N_(2)/^(14)N^(15)N was observed at elevated temperature(393-593 K)using mass spectrometry.With the aid of theoretical calculations,the exchange mechanism and the effect of temperature to promote the dissociation of N_(2) on Ta_(3)N_(3)^(-) were elucidated.A comparison experiment for Ta_(3)^(14)N_(4)^(-)/^(15)N_(2) couple indicated that only desorption of ^(15)N_(2) from Ta_(3)^(14)N_(4)^(15)N_(2)^(-) took place at elevated temperature.The different exchange behavior can be well understood by the fact that nitrogen vacancy is a requisite for the dinitrogen activation over metal nitride species.This study may shed light on understanding the role of nitrogen vacancy in nitride species for ammonia synthesis and provide clues in designing effective catalysts for nitrogen fixation.展开更多
Dissociation of molecular hydrogen （H2） is extensively studied to understand the mechanism of hydrogenation reactions. In this study, H2 dissociation by Aul-doped closed-shell titanium oxide cluster anions AuTi3O7 a...Dissociation of molecular hydrogen （H2） is extensively studied to understand the mechanism of hydrogenation reactions. In this study, H2 dissociation by Aul-doped closed-shell titanium oxide cluster anions AuTi3O7 and AuTi3O8 has been identified by mass spectrometry and quantum chemistry calculations. The clusters were generated by laser ablation and mass- selected to react with H2 in art ion trap reactor. In the reaction of AuTi3O8 with H2, the ion pair Au＋-O22 rather than Au＋-O2 is the active site to promote H2 dissociation. This finding is in contrast with the previous result that the lattice oxygen is usually the reactive oxygen species in H2 dissociation. The higher reactivity of the peroxide species is further supported by frontier molecular orbital analysis. This study provides new insights into gold catalysis involving H2 activation and dissociation.展开更多
Methane is a vital feedstock while the intrinsic inertness of CH_(4)molecule hinders the conversion of methane under mild conditions.Investigating and understanding the mechanism of methane activation is of great impo...Methane is a vital feedstock while the intrinsic inertness of CH_(4)molecule hinders the conversion of methane under mild conditions.Investigating and understanding the mechanism of methane activation is of great importance in chemistry.In this study,tantalum sulfide anions TaS_(3)^(-)were generated by laser ablation method and mass-selected by a quadrupole mass filter to react with methane,ethane,and propane in an ion funnel trap reactor under thermal collision conditions.The reactant and product ions were detected by a time-of-flight mass spectrometer.Experimental results demonstrate that TaS_(3)^(-)is able to adsorb all of the alkane molecules and break the robust C-H bonds.Further density functional theory calculations reveal that TaS_(3)^(-)is a closed-shell species and effectively activates methane via the Ta^(δ+)-S^(δ-)Lewis acid-base pair(LABP,CH_(4)+Ta^(δ+)-S^(δ-)→CH_(3)-Ta-S-H).With a comparative study with NbS_(3)^(-)that contains the Nbδ+-S^(δ-)LABP,the higher reactivity of TaS_(3)^(-)than that of NbS_(3)^(-)can be attributed to the more acidity of Ta^(δ+)than that of Nbδ+.To the best of our knowledge,this study reports the first example of gas phase species TaS_(3)^(-)to activate methane through the metal-sulfur LABP under thermal collision conditions.展开更多
Oxidation of CO into CO2 is a major solution to reduce CO emission into the atmosphere and to remove CO in fuel gas cleanup.Furthermore,CO oxidation serves as a prototypical reaction for heterogeneous catalysis.This r...Oxidation of CO into CO2 is a major solution to reduce CO emission into the atmosphere and to remove CO in fuel gas cleanup.Furthermore,CO oxidation serves as a prototypical reaction for heterogeneous catalysis.This review provides an overview and an update on how to study catalytic CO oxidation at a strictly molecular level by performing wellcontrolled gas-phase experiments in combination with quantum chemistry calculations.The advances in the unique catalytic reactivity of single-atom cluster catalysts are emphasized.The catalytically active sites and various mechanistic aspects in the redox couples N2O/CO and O2/CO for the seemingly simple oxidation reaction are described.展开更多
Methane is an attractive C1 resource for production ofvalue-added chemicals. The current industrial utilizationof methane involves indirect route via preliminary oxi-dation to syngas （a mixture of CO and H2） that ca...Methane is an attractive C1 resource for production ofvalue-added chemicals. The current industrial utilizationof methane involves indirect route via preliminary oxi-dation to syngas （a mixture of CO and H2） that can beconverted to desired products [1]. Such two-stage processis energy-intensive. Considerable efforts have been de-voted to developing catalytic processes that can efficientlyand directly transform methane through oxidative ornon-oxidative pathways [2,3].展开更多
基金supported by the National Natural Science Foundation of China(Nos.92461313 and 22121002)the National Key R&D Program of China(No.2021YFA1500704).
文摘Organometallics play a vital role in catalytic and synthetic processes.Understanding the indi-vidual elementary steps of the reactions of organo metallic com-pounds is crucial for the development and ratio-nal design of new organometallic reagents and catalysts.Study of gas-phase reactions is one of the key approaches to probing the individual elementary steps under isolated and re-producible conditions.A series of investigations have been reported on the gas-phase reac-tions between organometallic ions and neutral molecules under room temperature conditions.However,studies about the reactions between organometallic ions and neutral molecules un-der heating conditions are very limited.In this work,an apparatus with an electrospray ion-ization source and an ion funnel trap,which can be coupled with a high-temperature linear ion trap reactor,was designed and built.The apparatus can be used to investigate the reac-tions between organometallic ions and neutral molecules under heating conditions.By using the apparatus,the adsorption reactions of Rh(PPh_(3))_(2)^(+)+CO→Rh(PPh_(3))_(2)CO^(+)and CuPPh_(3)^(+)+CO_(2)→CuPPh_(3)CO_(2)+under variable temperature conditions have been conducted.The experiments showed that the reaction rate constant of Rh(PPh_(3))_(2)^(+)+CO increases first and then decreases with increasing temperature.In contrast,the rate constant of CuPPh_(3)^(+)+CO_(2)decreases monotonically as the temperature increases.Density functional theory calculations indicate that the adsorption reaction of Rh(PPh_(3))_(2)^(+)+CO→Rh(PPh_(3))_(2)CO^(+)is subject to a small barrier,while CuPPh_(3)^(+)+CO_(2)→CuPPh_(3)CO_(2)+is barri-erless,which is consistent with the experimentally observed temperature-dependent rate con-stants.The newly built apparatus can thus provide new kinetic information to address reac-tion mechanisms for organometallic ions.
基金supported by the National Natural Science Foundation of China(No.21833011 and No.21973101)the Youth Innovation Promotion Association CAS(No.2020034)the K.C.Wong Education Foundation。
文摘Reactions of gas-phase species with small molecules are being actively studied to understand the elementary steps and mechanistic details of related condensed-phase processes.Activation of the very inert N≡N triple bond of dinitrogen molecule by isolated gas-phase species has attracted considerable interest in the past few decades.Apart from molecular adsorption and dissociative adsorption,interesting processes such as C-N coupling and degenerate ligand exchange were discovered.The present review focuses on the recent progress on adsorption,activation,and functionalization of N2 by gas-phase species(particularly metal cluster ions)using mass spectrometry,infrared photo-dissociation spectroscopy,anion photoelectron spectroscopy,and quantum chemical calculations including density functional theory and high-level ab initio calculations.Recent advances including characterization of adsorption products,dependence of clusters’reactivity on their sizes and structures,and mechanisms of N≡N weakening and splitting have been emphasized and prospects have been discussed.
基金VI. ACKNOWLEDGEMENTS This work was supported by the Hundred Talents fund of The Chinese Academy of Sciences, the National Natural Science Foundation of China （No.20703048, No.20803083, and No.20933008）, the Center for Molecular Science Foundation of Institute of Chemistry, Chinese Academy of Sciences （No.CMS-CX200803）, and the National Basic Research Programs of China （No.2006CB932100 and No.2006CB806200）.
文摘The reactions of cationic zirconium oxide clusters （ZrxOy^＋） with ethylene （C2H4） were investigated by using a time-of-flight mass spectrometer coupled with a laser ablation/supersonic expansion cluster source. Some hydrogen containing products （ZrO2）xH^＋（x=-1-4） were observed after the reaction. The density functional theory calculations indicate that apart from the common oxygen transfer reaction channel, the hydrogen abstraction channel can also occur in （ZrO2）x^＋＋C2H4, which supports that the observed （ZrO2）xH^＋ may be due to （ZrO2）x^＋＋C2H4→（ZrO2）xH^＋＋C2H3. The rate constants of different reaction channels were also calculated by Rice-Rarnsberger-Kassel-Marcus theory.
基金supported by the National Natural Science Foundation of China(No.21773254,No.21773253,and No.21773073)the Youth Innovation Promotion Association,Chinese Academy of Sciences(No.2016030)the Beijing Natural Science Foundation(No.2172059)
文摘Oxidation of CO by gas-phase atomic clusters is being actively studied to understand the molecular-level mechanisms of heterogeneous CO oxidation over related catalytic surfaces. However, it is experimentally challenging to study CO oxidation by neutral heteronuclear metal oxide clusters because of the difficulty of cluster ionization and detection without fragmentation. Herein, the neutral AuVO2-4 clusters were experimentally generated and their reactions with CO and O2 were studied. The experimental results showed that CO adsorption is the dominant channel on the interactions of AuVO4 and AuVO3 with CO, and AuVO2 can pick up an O2 molecule to generate AuVO4. Theoretical studies indicated that the oxidation of the trapped CO in AuVO3,4CO into CO2 is exothermic while the reaction barriers have to be overcome at the elevated temperatures. A catalytic cycle for CO oxidation by AuVO2-4 is proposed.
文摘Manganese oxide cluster cations Mnm180n＋ were prepared by laser ablation and reacted with hydrogen sulfide （H2S） in a fast flow reactor under thermal collision conditions. A time-of-flight mass spectrometer was used to detect the cluster distributions before and after the interactions with H2S. The experiments suggest that oxygen-for-sulfur （O/S） ex- change reaction to release water took place in the reactor for most of the manganese oxide cluster cations： MnmlSOn＋＋H2S→Mnm18On-1S＋＋H218O. Density functional theory cal- culations were performed for reaction mechanisms of Mn202＋＋H2S, Mn203＋＋H2S, and Mn204＋＋H2S. The computational results indicate these O/S exchange reactions are both thermodynamically and kinetically favorable, thus in good agreement with the experimental observations. The O/S exchange reactions identified in this gas-phase cluster study parallel similar behavior of related condensed phase reaction systems.
基金supported by the National Natural Science Foundation of China(No.21973101 and No.21833011)the Youth Innovation Promotion Association CAS(No.2020034)the K.C.Wong Education Foundation。
文摘Adsorption and activation of dinitrogen(N_(2)) is an indispensable process in nitrogen fixation.Metal nitride species continue to attract attention as a promsing catalyst for ammonia synthesis.However,the detailed mechanisms at a molecular level between reactive nitride species and N_(2) remain unclear at elevated temperature,which is important to understand the temperature effect and narrow the gap between the gas phase system and condensed phase system.Herein,the ^(15)N/^(14)N isotopic exchange in the reaction between tantalum nitride cluster anions Ta_(3)^(14)N_(3)^(-) and ^(15)N_(2) leading to the regeneration of ^(14)N_(2)/^(14)N^(15)N was observed at elevated temperature(393-593 K)using mass spectrometry.With the aid of theoretical calculations,the exchange mechanism and the effect of temperature to promote the dissociation of N_(2) on Ta_(3)N_(3)^(-) were elucidated.A comparison experiment for Ta_(3)^(14)N_(4)^(-)/^(15)N_(2) couple indicated that only desorption of ^(15)N_(2) from Ta_(3)^(14)N_(4)^(15)N_(2)^(-) took place at elevated temperature.The different exchange behavior can be well understood by the fact that nitrogen vacancy is a requisite for the dinitrogen activation over metal nitride species.This study may shed light on understanding the role of nitrogen vacancy in nitride species for ammonia synthesis and provide clues in designing effective catalysts for nitrogen fixation.
基金supported by the National Natural Science Foundation of China(No.21573246,No.21773253,and No.21773254)the Beijing Natural Science Foundation(2172059)the Youth Innovation Promotion Association,Chinese Academy of Sciences(2016030)
文摘Dissociation of molecular hydrogen （H2） is extensively studied to understand the mechanism of hydrogenation reactions. In this study, H2 dissociation by Aul-doped closed-shell titanium oxide cluster anions AuTi3O7 and AuTi3O8 has been identified by mass spectrometry and quantum chemistry calculations. The clusters were generated by laser ablation and mass- selected to react with H2 in art ion trap reactor. In the reaction of AuTi3O8 with H2, the ion pair Au＋-O22 rather than Au＋-O2 is the active site to promote H2 dissociation. This finding is in contrast with the previous result that the lattice oxygen is usually the reactive oxygen species in H2 dissociation. The higher reactivity of the peroxide species is further supported by frontier molecular orbital analysis. This study provides new insights into gold catalysis involving H2 activation and dissociation.
基金supported by the National Natural Science Foundation of China(No.92161205 and No.22121002)the Youth Innovation Promotion Association of CAS(No.2022033).
文摘Methane is a vital feedstock while the intrinsic inertness of CH_(4)molecule hinders the conversion of methane under mild conditions.Investigating and understanding the mechanism of methane activation is of great importance in chemistry.In this study,tantalum sulfide anions TaS_(3)^(-)were generated by laser ablation method and mass-selected by a quadrupole mass filter to react with methane,ethane,and propane in an ion funnel trap reactor under thermal collision conditions.The reactant and product ions were detected by a time-of-flight mass spectrometer.Experimental results demonstrate that TaS_(3)^(-)is able to adsorb all of the alkane molecules and break the robust C-H bonds.Further density functional theory calculations reveal that TaS_(3)^(-)is a closed-shell species and effectively activates methane via the Ta^(δ+)-S^(δ-)Lewis acid-base pair(LABP,CH_(4)+Ta^(δ+)-S^(δ-)→CH_(3)-Ta-S-H).With a comparative study with NbS_(3)^(-)that contains the Nbδ+-S^(δ-)LABP,the higher reactivity of TaS_(3)^(-)than that of NbS_(3)^(-)can be attributed to the more acidity of Ta^(δ+)than that of Nbδ+.To the best of our knowledge,this study reports the first example of gas phase species TaS_(3)^(-)to activate methane through the metal-sulfur LABP under thermal collision conditions.
基金This work was financially supported by the National Natural Science Foundation of China(21773253).
文摘Oxidation of CO into CO2 is a major solution to reduce CO emission into the atmosphere and to remove CO in fuel gas cleanup.Furthermore,CO oxidation serves as a prototypical reaction for heterogeneous catalysis.This review provides an overview and an update on how to study catalytic CO oxidation at a strictly molecular level by performing wellcontrolled gas-phase experiments in combination with quantum chemistry calculations.The advances in the unique catalytic reactivity of single-atom cluster catalysts are emphasized.The catalytically active sites and various mechanistic aspects in the redox couples N2O/CO and O2/CO for the seemingly simple oxidation reaction are described.
文摘Methane is an attractive C1 resource for production ofvalue-added chemicals. The current industrial utilizationof methane involves indirect route via preliminary oxi-dation to syngas （a mixture of CO and H2） that can beconverted to desired products [1]. Such two-stage processis energy-intensive. Considerable efforts have been de-voted to developing catalytic processes that can efficientlyand directly transform methane through oxidative ornon-oxidative pathways [2,3].
