Two types of small iron clusters supported on γ-Al2O3-RT（dehydroxylated at room temperature） and γ-Al2O3-800 （dehydroxylated at 800 ℃） were prepared by solvated metal atom impregnation （SMAI） techniques. The ...Two types of small iron clusters supported on γ-Al2O3-RT（dehydroxylated at room temperature） and γ-Al2O3-800 （dehydroxylated at 800 ℃） were prepared by solvated metal atom impregnation （SMAI） techniques. The iron atom precursor complex, bis（toluene）iron（0） formed in the metal atom reactor, was impregnated into γ-Al2O3 having different concentrations of surface hydroxyl groups to study the effect of surface hydroxylation on the crucial stage of iron cluster formation. Catalysts prepared in this way were characterized by TEM, Mǒssbauer, and chemisorption measurements, and the results show that higher concentration of surface hydroxyl groups of γ-Al2O3-RT favors the formation of more positively charged supported iron cluster Fen/γ-Al2O3-RT, and the lower concentration of surface hydroxyl groups of γ-Al2O3-800 favors the formation of basically neutral supported iron cluster Fen/γ-Al2O3-800. The measured results also indicate that the higher concentration of surface hydroxyl groups causes the rapid decomposition of precursor complex, bis（toluene）iron（0）, and favors the formation of relatively large iron cluster. Consequently, these two types of catalysts show different catalytic properties in Fischer-Tropsch reaction. The catalytic pattern of Fen/γ-Al2O3-RT in F-T reaction is similar to that of the unreduced γ-Fe2O3 and that of Fen/γ-Al2O3-800 is similar to that of the reduced α-Fe2O3.展开更多
Two kinds of small iron clusters supported on SiO2-200 (dehydroxylated at 200℃ and SiO2-600 (de-hydroxylated at 600℃) were prepared by Solvated Metal Atom Impregnation (SMAI) techniques. The iron atom precursor comp...Two kinds of small iron clusters supported on SiO2-200 (dehydroxylated at 200℃ and SiO2-600 (de-hydroxylated at 600℃) were prepared by Solvated Metal Atom Impregnation (SMAI) techniques. The iron atom precursor complex, bis (toluene) iron(0) formed in the metal atom reactor, was impregnated into SiO2 having different concentrations of surface hydroxyl groups to study the effect of surface hydroxylation on the crucial stage of iron cluster formation. Catalysts prepared in this way were characterized by THM, Mosbauer and chemisorption measurements, and the resules show that higher concentration of surface hydroxyl groups of SiO2-200 favours the formation of more positively charged support iron cluster Fen/SiO2-200 and the lower concentration of surface hydroxyl groups of SiO2-600 favours the formation of basically neutral supported iron cluster Fe2/SiO2-600. The measured results also indicate that the higher concentration of surface hydroxyl groups causes the precursor complex,bis(toluene) fron(0), to decompose more rapidly, and favours the formation of relatively large iron cluster. As a consequence, these two kinds of catalysts show different catalytic properties in Fischer-Tropsch reaction. The catalytic pattern of Fe/SiO2-200 in F-T reaction is similar to that of the unreduced a-Fe2O2, while Fe2/SiO2 -600 is similar to that of reduced α-Fe2O2.展开更多
A novel (Me 3PhCH 2N) 2[MoFe 4S 4(SC 6H 11 ) 7] cubane like cluster was obtained from a reaction system including (NH 4) 2MoS 4, FeCl 2 and NaSC 6H 11 in methanol, and characterized by X ray crystallography. The title...A novel (Me 3PhCH 2N) 2[MoFe 4S 4(SC 6H 11 ) 7] cubane like cluster was obtained from a reaction system including (NH 4) 2MoS 4, FeCl 2 and NaSC 6H 11 in methanol, and characterized by X ray crystallography. The title compound crystallizes in triclinic space group P 1 with a =1.523 1(3), b =1.610 5(3), c =1.838 3(4) nm, α =77.18 (3)°, β =75.17(3)°, γ =64.60 (3)°, and Z =2. Also included in this paper are the discussions on the variation of the reaction products obtained from the participation of cyclohexylthiolate and on the changes of the structural features of the products.展开更多
The vinylidene-bridged cluster μ_3-FcCHCFeCo_2(CO)_9 2 was prepared by the expansionreaction of ferrocenyl-acetylene dicobalt complex μ-FcCCHCo_2(CO)_6 1. Benzylideneacetone-tricarbonyliron [(BDA)Fe(CO)_3] was used ...The vinylidene-bridged cluster μ_3-FcCHCFeCo_2(CO)_9 2 was prepared by the expansionreaction of ferrocenyl-acetylene dicobalt complex μ-FcCCHCo_2(CO)_6 1. Benzylideneacetone-tricarbonyliron [(BDA)Fe(CO)_3] was used as the source of Fe(CO)_3. The molecular structure of thecluster 2 was detendned by x-ray structural analysis.展开更多
Complex (Et4N) [VFe3S4Cl3 (CH3CN)(3)] (1) has been obtained from (NH4)(3) VS4/FeCl2/NaHS/Et-4 NCl reaction system in CH3CN solvent and structurally characterized by X-ray diffraction analysis. It crystallizes in ortho...Complex (Et4N) [VFe3S4Cl3 (CH3CN)(3)] (1) has been obtained from (NH4)(3) VS4/FeCl2/NaHS/Et-4 NCl reaction system in CH3CN solvent and structurally characterized by X-ray diffraction analysis. It crystallizes in orthorhombic space group Pnma (No. 62) with a = 8.851(2), b =16.447(3), c = 19.448(4) Angstrom, V = 2865.6(10) Angstrom (3), Z = 4, M-r = 706.49, D-c =1.638g/cm(3), F(000)=1428, mu (MoK alpha)=2.385 cm(-1) and T = 293(2)K. With use of 1467 observed reflections (I >2 sigma (I)) the structure was refined to R = 0.0874 and wR = 0.2065. Complex 1 contains a VFe3S4 cuboidal core with average V - Fe distance of 2.759(4) Angstrom, which is a little longer than Fe - Fe of 2.716(3) Angstrom,. Around the core, each Fe atom is coordinated by one Cl atom and V atom by three N atoms of CH3CN ligands.展开更多
Here a direct calculation of the dipolar interaction in a single crystal Mn12, with all of Mn ions summed, shows that a transition between ferromagnetic and antiferromagnetic ground states takes place where the dimens...Here a direct calculation of the dipolar interaction in a single crystal Mn12, with all of Mn ions summed, shows that a transition between ferromagnetic and antiferromagnetic ground states takes place where the dimension along the α（b） axis versus the dimension along the c axis reaches a certain critical value. It is shown that the w ~ ~ ground state is dependent upon the shape of the specimen. The reason of the shape dependence of ordering is that dipolar interaction is of long-range nature and the sign of dipolar interaction is dependent on the direction.展开更多
Tris)(η 5-cyclopentadienyl-μ-carbonyl-iron)-μ3-nitrosyl cluster was obtained from the reaction of cyclopentadienyl dicarbonyliron dimer with nitrogen monoxide in xylene. The cluster was characterized by elemental a...Tris)(η 5-cyclopentadienyl-μ-carbonyl-iron)-μ3-nitrosyl cluster was obtained from the reaction of cyclopentadienyl dicarbonyliron dimer with nitrogen monoxide in xylene. The cluster was characterized by elemental analyses, IR, MS and 1H NMR. The crystal structure of [(η5-C5H5)(μ-CO)Fe]3(μ3-NO).C4H8O was determined by X-ray diffraction analysis. It crystallizes in the orthorhombic space group Pnma, a=9.053(2), 6=10.545(2), c=22.525(4) A, V=2150.3(7) A3, Z=4,Dc=1.68 g.cm-3; structure solution and refinement based on 1141 reflections with I > 3.0 (I) (MoKa, A=0.71073 A) converged at R=0.0540. The infrared absorption band at 1325 cm-1 of the μ3-NO in the cluster, which is red shifted, shows that μ3-NO is activated.展开更多
文摘Two types of small iron clusters supported on γ-Al2O3-RT（dehydroxylated at room temperature） and γ-Al2O3-800 （dehydroxylated at 800 ℃） were prepared by solvated metal atom impregnation （SMAI） techniques. The iron atom precursor complex, bis（toluene）iron（0） formed in the metal atom reactor, was impregnated into γ-Al2O3 having different concentrations of surface hydroxyl groups to study the effect of surface hydroxylation on the crucial stage of iron cluster formation. Catalysts prepared in this way were characterized by TEM, Mǒssbauer, and chemisorption measurements, and the results show that higher concentration of surface hydroxyl groups of γ-Al2O3-RT favors the formation of more positively charged supported iron cluster Fen/γ-Al2O3-RT, and the lower concentration of surface hydroxyl groups of γ-Al2O3-800 favors the formation of basically neutral supported iron cluster Fen/γ-Al2O3-800. The measured results also indicate that the higher concentration of surface hydroxyl groups causes the rapid decomposition of precursor complex, bis（toluene）iron（0）, and favors the formation of relatively large iron cluster. Consequently, these two types of catalysts show different catalytic properties in Fischer-Tropsch reaction. The catalytic pattern of Fen/γ-Al2O3-RT in F-T reaction is similar to that of the unreduced γ-Fe2O3 and that of Fen/γ-Al2O3-800 is similar to that of the reduced α-Fe2O3.
文摘Two kinds of small iron clusters supported on SiO2-200 (dehydroxylated at 200℃ and SiO2-600 (de-hydroxylated at 600℃) were prepared by Solvated Metal Atom Impregnation (SMAI) techniques. The iron atom precursor complex, bis (toluene) iron(0) formed in the metal atom reactor, was impregnated into SiO2 having different concentrations of surface hydroxyl groups to study the effect of surface hydroxylation on the crucial stage of iron cluster formation. Catalysts prepared in this way were characterized by THM, Mosbauer and chemisorption measurements, and the resules show that higher concentration of surface hydroxyl groups of SiO2-200 favours the formation of more positively charged support iron cluster Fen/SiO2-200 and the lower concentration of surface hydroxyl groups of SiO2-600 favours the formation of basically neutral supported iron cluster Fe2/SiO2-600. The measured results also indicate that the higher concentration of surface hydroxyl groups causes the precursor complex,bis(toluene) fron(0), to decompose more rapidly, and favours the formation of relatively large iron cluster. As a consequence, these two kinds of catalysts show different catalytic properties in Fischer-Tropsch reaction. The catalytic pattern of Fe/SiO2-200 in F-T reaction is similar to that of the unreduced a-Fe2O2, while Fe2/SiO2 -600 is similar to that of reduced α-Fe2O2.
文摘A novel (Me 3PhCH 2N) 2[MoFe 4S 4(SC 6H 11 ) 7] cubane like cluster was obtained from a reaction system including (NH 4) 2MoS 4, FeCl 2 and NaSC 6H 11 in methanol, and characterized by X ray crystallography. The title compound crystallizes in triclinic space group P 1 with a =1.523 1(3), b =1.610 5(3), c =1.838 3(4) nm, α =77.18 (3)°, β =75.17(3)°, γ =64.60 (3)°, and Z =2. Also included in this paper are the discussions on the variation of the reaction products obtained from the participation of cyclohexylthiolate and on the changes of the structural features of the products.
文摘The vinylidene-bridged cluster μ_3-FcCHCFeCo_2(CO)_9 2 was prepared by the expansionreaction of ferrocenyl-acetylene dicobalt complex μ-FcCCHCo_2(CO)_6 1. Benzylideneacetone-tricarbonyliron [(BDA)Fe(CO)_3] was used as the source of Fe(CO)_3. The molecular structure of thecluster 2 was detendned by x-ray structural analysis.
基金granted by NNSFC(No.29733090,39970177 and 29973047).
文摘Complex (Et4N) [VFe3S4Cl3 (CH3CN)(3)] (1) has been obtained from (NH4)(3) VS4/FeCl2/NaHS/Et-4 NCl reaction system in CH3CN solvent and structurally characterized by X-ray diffraction analysis. It crystallizes in orthorhombic space group Pnma (No. 62) with a = 8.851(2), b =16.447(3), c = 19.448(4) Angstrom, V = 2865.6(10) Angstrom (3), Z = 4, M-r = 706.49, D-c =1.638g/cm(3), F(000)=1428, mu (MoK alpha)=2.385 cm(-1) and T = 293(2)K. With use of 1467 observed reflections (I >2 sigma (I)) the structure was refined to R = 0.0874 and wR = 0.2065. Complex 1 contains a VFe3S4 cuboidal core with average V - Fe distance of 2.759(4) Angstrom, which is a little longer than Fe - Fe of 2.716(3) Angstrom,. Around the core, each Fe atom is coordinated by one Cl atom and V atom by three N atoms of CH3CN ligands.
基金Supported partially by the National Natural Science Foundation of China under Grant No 10334080.
文摘Here a direct calculation of the dipolar interaction in a single crystal Mn12, with all of Mn ions summed, shows that a transition between ferromagnetic and antiferromagnetic ground states takes place where the dimension along the α（b） axis versus the dimension along the c axis reaches a certain critical value. It is shown that the w ~ ~ ground state is dependent upon the shape of the specimen. The reason of the shape dependence of ordering is that dipolar interaction is of long-range nature and the sign of dipolar interaction is dependent on the direction.
文摘Tris)(η 5-cyclopentadienyl-μ-carbonyl-iron)-μ3-nitrosyl cluster was obtained from the reaction of cyclopentadienyl dicarbonyliron dimer with nitrogen monoxide in xylene. The cluster was characterized by elemental analyses, IR, MS and 1H NMR. The crystal structure of [(η5-C5H5)(μ-CO)Fe]3(μ3-NO).C4H8O was determined by X-ray diffraction analysis. It crystallizes in the orthorhombic space group Pnma, a=9.053(2), 6=10.545(2), c=22.525(4) A, V=2150.3(7) A3, Z=4,Dc=1.68 g.cm-3; structure solution and refinement based on 1141 reflections with I > 3.0 (I) (MoKa, A=0.71073 A) converged at R=0.0540. The infrared absorption band at 1325 cm-1 of the μ3-NO in the cluster, which is red shifted, shows that μ3-NO is activated.
