Two new crystals of chlorovanadates,Ba_8Cs_5V_8O_（24）Cl_（13）（1） and MgCsV_2O_6Cl（2）,were grown in the molten salt media. 1 crystallizes in tetragonal,space group P4/mmm（No. 123）,with a = 14.801（2）,c = 12....Two new crystals of chlorovanadates,Ba_8Cs_5V_8O_（24）Cl_（13）（1） and MgCsV_2O_6Cl（2）,were grown in the molten salt media. 1 crystallizes in tetragonal,space group P4/mmm（No. 123）,with a = 14.801（2）,c = 12.341（3） ？,V = 2703.5（8） ？~3,Z = 2,Mr = 3015.56,F（000） = 2640,μ = 11.044 mm-1,Dc = 3.704 g/cm3,the final R = 0.0380 and wR = 0.0937 for 1654 observed reflections with I 〉 2σ（I）. 2 crystallizes in a monoclinic space group C2/c（No. 15） with a = 11.128（2）,b = 10.540（2）,c = 6.9892（14） ？,β = 118.38（3）°,V = 721.2（2） ？~3,Z = 4,M_r = 390.55,F（000） = 712,μ = 7.997 mm-1,D_c = 3.597 g/cm^3,the final R = 0.0537 and w R = 0.1363 for 740 observed reflections with I 〉 2σ（I）. 1 exhibits a novel 8-membered-ring [V_8O_（24）] consisting of 8 corner-shared VO_4 tetrahetra,but in 2,an infinite ladder-like [VO_3]_∞ chain is formed by VO_5 square pyramids through sharing the edges.展开更多
Density functional theory (DFT) study of reaction between vanadium trioxide cluster cation (VO3+) and ethylene (C2H4) to yield VO2+ + CH3CHO (acetaldehyde) and VO2CH2+ + HCHO (formaldehyde) is carried out. Structures ...Density functional theory (DFT) study of reaction between vanadium trioxide cluster cation (VO3+) and ethylene (C2H4) to yield VO2+ + CH3CHO (acetaldehyde) and VO2CH2+ + HCHO (formaldehyde) is carried out. Structures of all reactants, products, intermediates, and transition state in the reaction have been optimized and characterized. The results show unexpected barriers in the reaction due to the existence of a η2-O2 moiety in the ground state structure of VO3+. The initial reaction steps combining ethylene adsorption, C=C activation and O-O cleavage are proposed as rate limiting processes. Comparison of reactions of VO3+ + C2H4 with VO3 + C2H4 and VO2+ + C2H4 in the previous studies is made in detail. The results of this work may shed light on the understanding of C=C bond cleavage in related heterogeneous catalysis.展开更多
基金supported by the National Natural Science Foundation of China(No.21541009)
文摘Two new crystals of chlorovanadates,Ba_8Cs_5V_8O_（24）Cl_（13）（1） and MgCsV_2O_6Cl（2）,were grown in the molten salt media. 1 crystallizes in tetragonal,space group P4/mmm（No. 123）,with a = 14.801（2）,c = 12.341（3） ？,V = 2703.5（8） ？~3,Z = 2,Mr = 3015.56,F（000） = 2640,μ = 11.044 mm-1,Dc = 3.704 g/cm3,the final R = 0.0380 and wR = 0.0937 for 1654 observed reflections with I 〉 2σ（I）. 2 crystallizes in a monoclinic space group C2/c（No. 15） with a = 11.128（2）,b = 10.540（2）,c = 6.9892（14） ？,β = 118.38（3）°,V = 721.2（2） ？~3,Z = 4,M_r = 390.55,F（000） = 712,μ = 7.997 mm-1,D_c = 3.597 g/cm^3,the final R = 0.0537 and w R = 0.1363 for 740 observed reflections with I 〉 2σ（I）. 1 exhibits a novel 8-membered-ring [V_8O_（24）] consisting of 8 corner-shared VO_4 tetrahetra,but in 2,an infinite ladder-like [VO_3]_∞ chain is formed by VO_5 square pyramids through sharing the edges.
基金Supported by the Hundred Talents FundChinese Academy of Sciences and National Natural Science Foundation of China (Grant No. 20703048)
文摘Density functional theory (DFT) study of reaction between vanadium trioxide cluster cation (VO3+) and ethylene (C2H4) to yield VO2+ + CH3CHO (acetaldehyde) and VO2CH2+ + HCHO (formaldehyde) is carried out. Structures of all reactants, products, intermediates, and transition state in the reaction have been optimized and characterized. The results show unexpected barriers in the reaction due to the existence of a η2-O2 moiety in the ground state structure of VO3+. The initial reaction steps combining ethylene adsorption, C=C activation and O-O cleavage are proposed as rate limiting processes. Comparison of reactions of VO3+ + C2H4 with VO3 + C2H4 and VO2+ + C2H4 in the previous studies is made in detail. The results of this work may shed light on the understanding of C=C bond cleavage in related heterogeneous catalysis.
