Spectroscopic characterization of CO activation on multiple metal-containing catalysts remains an important and challenging goal for identifying the structure and nature of active site in many industrial processes suc...Spectroscopic characterization of CO activation on multiple metal-containing catalysts remains an important and challenging goal for identifying the structure and nature of active site in many industrial processes such as Fischer-Tropsch chemistry and alcohol synthesis.Here,we use mass-selected photoelectron velocity-map imaging spectroscopy and quantum chemical calculations to study the reactions of CO molecules with several heterobinuclear transition metal-iron clusters M-Fe(M=Ti,V,Cr).The mass spectra reveal the favorable formation of MFe(CO)_(4)^(-)with relatively high thermodynamic stability.The MFe(CO)_(4)^(-)(M=Ti,V,Cr) complexes are established to have a metal-Fe bonded M-Fe(CO)_(4) structure with C_(3 v) geometry.While the positive charge and unpaired electrons are mainly located on the M atom,the natural charge of Fe(CO)_(4) is about-2 e.The MFe(CO)_(4)^(-)(M=Ti,V,Cr) can be seen as being formed via the interactions between the M^(+)fragment and the [Fe(CO)_(4)]^(2-)core,which satisfies the 18-electron rule.The CO molecules are remarkably activated in these MFe(CO)_(4)^(-).These results shed insight into the structure-reactivity relationship of heterobinuclear transition metal carbonyls and would have important implications for understanding of CO activation on alloy surfaces.展开更多
Thermal treatment of the pyridyl side chain functionalized tetramethyl cyclopen- tadiene C5Me4CH2(C5H4N) with Fe(CO)5, Ru3(CO)12 and Mo(CO)6 in refluxing xylene respectively gave the corresponding dinuclear me...Thermal treatment of the pyridyl side chain functionalized tetramethyl cyclopen- tadiene C5Me4CH2(C5H4N) with Fe(CO)5, Ru3(CO)12 and Mo(CO)6 in refluxing xylene respectively gave the corresponding dinuclear metal carbonyl complexes 1~3. These complexes have been characterized by elemental analysis, IR and IH NMR spectra. The molecular structures of 1~3 were determined by X-ray diffraction analysis.展开更多
A series of heterotrinuclear Ti_(2)Ni(CO)_(n)^(-)(n=6-9)carbonyls have been generated via a laser vaporization supersonic cluster source and characterized by mass-selected photoelectron velocity-map imaging spectrosco...A series of heterotrinuclear Ti_(2)Ni(CO)_(n)^(-)(n=6-9)carbonyls have been generated via a laser vaporization supersonic cluster source and characterized by mass-selected photoelectron velocity-map imaging spectroscopy.Quantum chemical calculations have been carried out to identify the structures and understand the experimental spectral features.The results indicate that a building block of Ti-Ti-Ni-C four-membered ring with the C atom bonded to Ti,Ti,and Ni is dominated in the n=6-8 complexes,whereas a structural motif of Ti-Ti-Ni triangle core is preferred in n=9.These complexes are found to be capable of simultaneously accommodating all the main modes of metal-CO coordination(i.e.,terminal,bridging,and side-on modes),where the corresponding mode points to the weak,moderate,high C-O bond activation,respectively.The number of CO ligands for a specific bonding mode varies with the cluster size.These findings have important implications for molecular-level understanding of the interaction of CO with alloy surfaces/interfaces and tuning the appropriate CO activation via the selection of different metals.展开更多
Infrared spectra of mass-selected homoleptic dinuclear palladium carbonyl cluster cations Pd2(CO)n (n=5 8) are measured via infrared photodissociation spectroscopy in the carbonyl stretching frequency region. The ...Infrared spectra of mass-selected homoleptic dinuclear palladium carbonyl cluster cations Pd2(CO)n (n=5 8) are measured via infrared photodissociation spectroscopy in the carbonyl stretching frequency region. The structures are established by comparison of the experimental spectra with simulated spectra derived from density functional calculations. The Pd2(CO)+ cation is characterized to have two weakly semibridging CO groups with C2 symmetry. The Pd2(CO)6+ and Pd2(CO)7+ cations are determined to involve one weakly semibridging CO group. The Pd2(CO)8+ cation is a CO coordination saturated cluster, which is determined to have a D2d structure with all of the carbonyl groups terminally bonded. Bonding analysis indicates that these cluster cations each has a Pd--Pd half bond. The Pd--Pd distance increases with the number of CO ligands.展开更多
The series of heterodinuclear metal oxide carbonyls in the form of TaNiO(CO)_(n)(n=5-8) are generated in the pulsed-laser vaporization source and characterized by mass-selected photoelectron velocity-map spectroscopy....The series of heterodinuclear metal oxide carbonyls in the form of TaNiO(CO)_(n)(n=5-8) are generated in the pulsed-laser vaporization source and characterized by mass-selected photoelectron velocity-map spectroscopy.During the consecutive CO adsorption,the μ^(2)-O-bent structure initially is the most favorable for TaNiO(CO)_(5),and subsequently both μ^(2)-O-bent and μ^(2)-O-linear structures are degenerate for TaNiO(CO)_(6),then the μ^(2)-O-linear structure is most preferential for TaNiO(CO)_(7),and finally the η^(2)-CO_(2)-tagged structure is the most ene rgetically competitive one for TaNiO(CO)_(8),i.e., the CO oxidation occurs at n=8.ln contrast to the literature reported CO oxidation on heteronuclear metal oxide complexes generally proceeding via Langmuir-Hinshelwood-like mechanism,complementary theo retical calculations suggest that both Langmuir-Hinshelwood-like and Eley-Rideal-like mechanisms prevail for the CO oxidation reaction on TaNiO(CO)_(8) complex.Our findings provide new insight into the composition-selective mechanism of CO oxidation on heteronuclear metal complexes,of which the composition be tailored to fulfill the desired chemical behaviors.展开更多
基金supported by the National Natural Science Foundation of China (21688102, 21873097, and 92061203)the Youth Innovation Promotion Association of the Chinese Academy of Sciences (CAS)(2020187)+3 种基金the Strategic Priority Research Program of CAS (XDB17000000)CAS (GJJSTD20190002)the International Partnership Program of CAS (121421KYSB20170012)the K.C.Wong Education Foundation (GJTD-2018-06)。
文摘Spectroscopic characterization of CO activation on multiple metal-containing catalysts remains an important and challenging goal for identifying the structure and nature of active site in many industrial processes such as Fischer-Tropsch chemistry and alcohol synthesis.Here,we use mass-selected photoelectron velocity-map imaging spectroscopy and quantum chemical calculations to study the reactions of CO molecules with several heterobinuclear transition metal-iron clusters M-Fe(M=Ti,V,Cr).The mass spectra reveal the favorable formation of MFe(CO)_(4)^(-)with relatively high thermodynamic stability.The MFe(CO)_(4)^(-)(M=Ti,V,Cr) complexes are established to have a metal-Fe bonded M-Fe(CO)_(4) structure with C_(3 v) geometry.While the positive charge and unpaired electrons are mainly located on the M atom,the natural charge of Fe(CO)_(4) is about-2 e.The MFe(CO)_(4)^(-)(M=Ti,V,Cr) can be seen as being formed via the interactions between the M^(+)fragment and the [Fe(CO)_(4)]^(2-)core,which satisfies the 18-electron rule.The CO molecules are remarkably activated in these MFe(CO)_(4)^(-).These results shed insight into the structure-reactivity relationship of heterobinuclear transition metal carbonyls and would have important implications for understanding of CO activation on alloy surfaces.
基金financially supported by the National Natural Science Foundation of China(No.21372061)Natural Science Foundation of Hebei Province(Nos.B2013205025 and B2014205018)the Key Research Fund of Hebei Normal University(No.L2012Z02)
文摘Thermal treatment of the pyridyl side chain functionalized tetramethyl cyclopen- tadiene C5Me4CH2(C5H4N) with Fe(CO)5, Ru3(CO)12 and Mo(CO)6 in refluxing xylene respectively gave the corresponding dinuclear metal carbonyl complexes 1~3. These complexes have been characterized by elemental analysis, IR and IH NMR spectra. The molecular structures of 1~3 were determined by X-ray diffraction analysis.
基金supported by the National Natural Science Foundation of China(Nos.21873097,22103082,92061203,22125303 and 22288201)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(CAS,No.2020187)the Strategic Priority Research Program of CAS(No.XDB17000000)。
文摘A series of heterotrinuclear Ti_(2)Ni(CO)_(n)^(-)(n=6-9)carbonyls have been generated via a laser vaporization supersonic cluster source and characterized by mass-selected photoelectron velocity-map imaging spectroscopy.Quantum chemical calculations have been carried out to identify the structures and understand the experimental spectral features.The results indicate that a building block of Ti-Ti-Ni-C four-membered ring with the C atom bonded to Ti,Ti,and Ni is dominated in the n=6-8 complexes,whereas a structural motif of Ti-Ti-Ni triangle core is preferred in n=9.These complexes are found to be capable of simultaneously accommodating all the main modes of metal-CO coordination(i.e.,terminal,bridging,and side-on modes),where the corresponding mode points to the weak,moderate,high C-O bond activation,respectively.The number of CO ligands for a specific bonding mode varies with the cluster size.These findings have important implications for molecular-level understanding of the interaction of CO with alloy surfaces/interfaces and tuning the appropriate CO activation via the selection of different metals.
文摘Infrared spectra of mass-selected homoleptic dinuclear palladium carbonyl cluster cations Pd2(CO)n (n=5 8) are measured via infrared photodissociation spectroscopy in the carbonyl stretching frequency region. The structures are established by comparison of the experimental spectra with simulated spectra derived from density functional calculations. The Pd2(CO)+ cation is characterized to have two weakly semibridging CO groups with C2 symmetry. The Pd2(CO)6+ and Pd2(CO)7+ cations are determined to involve one weakly semibridging CO group. The Pd2(CO)8+ cation is a CO coordination saturated cluster, which is determined to have a D2d structure with all of the carbonyl groups terminally bonded. Bonding analysis indicates that these cluster cations each has a Pd--Pd half bond. The Pd--Pd distance increases with the number of CO ligands.
基金supported by the National Natural Science Foundation of China (Nos.21603130,21673231,21688102 and 21873097)the Key Research Program (No.KGZD-EW-T05)+2 种基金the Strategic Priority Research Program (No.XDB17000000) of the Chinese Academy of Sciencethe Shanxi Province Science Foundation for Youths (No. 201901D211395)the 1331 Engineering of Shanxi Province and the Start-up Fund from Shanxi Normal University for support。
文摘The series of heterodinuclear metal oxide carbonyls in the form of TaNiO(CO)_(n)(n=5-8) are generated in the pulsed-laser vaporization source and characterized by mass-selected photoelectron velocity-map spectroscopy.During the consecutive CO adsorption,the μ^(2)-O-bent structure initially is the most favorable for TaNiO(CO)_(5),and subsequently both μ^(2)-O-bent and μ^(2)-O-linear structures are degenerate for TaNiO(CO)_(6),then the μ^(2)-O-linear structure is most preferential for TaNiO(CO)_(7),and finally the η^(2)-CO_(2)-tagged structure is the most ene rgetically competitive one for TaNiO(CO)_(8),i.e., the CO oxidation occurs at n=8.ln contrast to the literature reported CO oxidation on heteronuclear metal oxide complexes generally proceeding via Langmuir-Hinshelwood-like mechanism,complementary theo retical calculations suggest that both Langmuir-Hinshelwood-like and Eley-Rideal-like mechanisms prevail for the CO oxidation reaction on TaNiO(CO)_(8) complex.Our findings provide new insight into the composition-selective mechanism of CO oxidation on heteronuclear metal complexes,of which the composition be tailored to fulfill the desired chemical behaviors.