Selective oxidation of methanol on V2O5 and V2O5?MoO3 supported on montrmorillonite

Methanol oxidation on V₂O₅ and V₂O₅–MoO₃ catalysts supported on montmorillonite has been studied in the temperature range of 250–500°C. The V₂O₅–MoO₃ containing sample shows higher selectivity towards formaldehyde formation than the V₂O₅ catalyst.     

Unsaturation in binuclear cyclopentadienylchromium carbonyl thiocarbonyls: Viability of (η-C5H5)2Cr2(CS)2(CO)3 in contrast to (η-C5H5)2Cr2(CO)5

The cyclopentadienylchromium carbonyl thiocarbonyls Cp₂Cr₂(CS)₂(CO)_n (n = 4, 3, 2, 1) have been studied by density functional theory using the B3LYP and BP86 functionals. The lowest energy Cp₂Cr₂(CS)₂(CO)₄ structure can be derived from the experimentally characterized unbridged Cp₂Cr₂(CO)₆ structure by replacing the two terminal carbonyl groups furthest from the Cr-Cr bond with two terminal CS groups. The two lowest energy Cp₂Cr₂(CS)₂(CO)₃ structures have a single four-electron donor η²-μ-CS group and a formal Cr-Cr single bond of length ∼3.1 Å. In contrast to the carbonyl analogue Cp₂Cr₂(CO)₅ these Cp₂Cr₂(CS)₂(CO)₃ structures are viable with respect to disproportionation into Cp₂Cr₂(CS)₂(CO)₄ and Cp₂Cr₂(CS)₂(CO)₂ and thus are promising synthetic targets. The lowest energy Cp₂Cr₂(CS)₂(CO)₂ structures have all two-electron donor CO and CS groups and short CrCr distances around ∼2.3 Å suggesting the formal triple bonds required to give the chromium atoms the favored 18-electron configurations. These Cp₂Cr₂(CS)₂(CO)₂ structures are closely related to the known structure for Cp₂Cr₂(CO)₄. In addition, several doubly bridged structures with four-electron donor η²-μ-CS bridges are found for Cp₂Cr₂(CS)₂(CO)₂ at higher energies. The global minimum Cp₂Cr₂(CS)₂(CO) structure is a triply bridged triplet with a CrCr triple bond (2.299 Å by BP86). A higher energy singlet Cp₂Cr₂(CS)₂(CO) structure has a shorter Cr-Cr distance of 2.197 Å (BP86) suggesting the formal quadruple bond required to give each chromium atom the favored 18-electron configuration.     

Dehydrogenation of Isobutane Over V2O5/γ-Al2O3 Catalyst

The effect of the type of the support and the amount of V₂O₅ loading on the activity of V₂O₅/γ-Al₂O₃ catalyst for the dehydrogenation of isobutane have been investigated. Based on the experimental results of TPR, XRD and ESR spectroscopy, it is suggested that there are strong interactions between vanadia and carrier and that the V⁴⁺ species on the surface is the active site of V₂O₅/γ-Al₂O₃ for this reaction. This revised version was published online in June 2006 with corrections to the Cover Date.     

夹心化合物Ni(C5H5)2的Xα研究

用Xα方法计算了Ni(C5H5)2的电子能级与归一化电荷,讨论了夹心化合物成键的特点,并用过渡态方法分析Ni(C5H5)2的光电子能谱及紫外可见吸收光谱,结果与实验相符。     

The preparation and crystal structure of (η-C5H5)(OC)3Mo(CH2)3C6H5

The reaction of with p-CH₃C₆H₄S(O)₂O(CH₂)₃C₆H₅ produces (η⁵-C₅H₅)(OC)₃Mo(CH₂)₃C₆H₅. This is only the second structurally characterized organometallic species in which an aromatic moiety is separated by three or more methylene groups. The alkyl chain adopts a staggered conformation, the Mo-C(1)-C(2)-C(3)-C(4) unit is nearly coplanar, and the alkyl chain eclipses the trans-carbonyl group on Mo. NMR evidence indicates that this conformation is preserved in solution.     

Crystal structure of Cs8[α-BW12O40][RhCl6]·5·5H2O double salt

By heating in the air [HBW₁₁O₃₉]⁸⁻ with [Rh₂(CH₃COO)₄(H₂O)₂] in the excess of tungstate followed by crystallization in the presence of CsCl, a double salt of Cs₈[6h-BW₁₂O₄₀][RhCl₆]·5.5H₂O is obtained and structurally characterized. Its crystal structure is determined by single crystal X-ray diffraction. The structure is ionic with Cs⁺ cations, [BW₁₂O₄₀]⁵ anions with the Keggin structure, and [RhCl₆]³ octahedral anions.     

(Cyclopentadienyl){(N,N-dimethylaminoethyl)cyclopentadienyl} complexes of zirconium: Crystal structure of [(η-C5H5)(η-C5H4CH2CH2NHMe2)ZrCl2]2[ZrCl6]

[(η⁵-C₅H₅)ZrCl₃] reacts with [C₅H₄CH₂CH₂NMe₂]Li yielding the coordination polymer [(C₅H₅)(C₅H₄CH₂CH₂NMe₂)ZrCl₂]_n (1) as a brown solid which is very sensitive to moisture. The reaction of 1 with 1.35 equivalent of HCl (methanolic solution) yields pale yellow green crystals of [(η⁵-C₅H₅)(η⁵-C₅H₄CH₂CH₂NHMe₂)ZrCl₂]₂[ZrCl₆] (2). Compound 2 was fully characterized on the basis of NMR data and X-ray crystal structure analysis. The formation of this product indicates the elimination of C₅H₄CH₂CH₂NMe₂ as well as C₅H₅ ligands from the Zr(IV) metal centre.     

Crystal structure and spectral characteristics of {[(C6H5)NH]2C=NH(C6H5)}[B(C6H5)4]·C2H5OH

A novel compound of {[(C₆H₅)NH]₂C=NH(C₆H₅)}[B(C₆H₅)₄]·C₂H₅OH is prepared and examined by single crystal X-ray diffraction. Crystal data: C₄₅H₄₄BN₃O, M = 653.64, monoclinic, space group P2₁/c, unit cell parameters: a = 24.375(2) Å, b = 17.5829(15) Å, c = 18.090(1) Å, β = 105.277(2)°, V = 7479.0(11) ų, Z = 8, d _calc = 1.161 g/cm³, T = 293 K, R ₁ = 0.064. The structure contains two crystallographically independent cations, two anions, and two solvate ethanol molecules. Three types of interactions occur between them: interionic N-H(N)⋯π and N(H)⋯π⋯H(C), π-delocalized system of Ph rings of the anions, and interaction of ions with ethanol molecules N-H⋯O-H(O)⋯π. The compound is characterized by IR and luminescence spectra. At room temperature, the emission intensity grows with time of exposure to UV irradiation. Original Russian Text Copyright ? 2008 by T. M. Polyanskaya, E. A. Il’inchik, V. V. Volkov, M. K. Drozdova, O. P. Yur’eva, and G. V. Romanenko __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 49, No. 3, pp. 512–521, May–June, 2008.     

Synthesis and crystal structure of [Fe4O2(H2O)10(C5H5NCOO)4](NO3)8 · 2H2O

Crystals of the tetranuclear complex [Fe₄O₂(H₂O)₁₀(C₅H₅NCOO)₄](NO₃)₈ · 2H₂O are obtained by the slow evaporation of an aqueous solution of iron(III) nitrate and isonicotinic acid. According to the X-ray diffraction data, four metal atoms lie in the same plane and together with two μ₃-O oxygen atoms form the fragment [Fe₄(μ₃-O)₂]¹⁰⁺. The [Fe₄O₂(H₂O)₁₀(C₅H₅NCOO)₄]⁸⁺ cation has been obtained and structurally characterized for the first time.     

X-ray and conformation analysis of the new trinuclear cluster of osmium Os3(μ,η2-OCC6H5)(η3-C3H5)(CO)9

The crystal structure of the Os₃(μ,η²-O=CC₆H₅)(η³-C₃H₅)(CO)₉ cluster synthesized by the reaction of the (μ-H)Os₃(μ-O=CC₆H₅)(CO)₁₀ complex with allylamine in chloroform was determined by X-ray analysis. Prolonged storage of the reaction mixture led to N-C bond cleavage in allylamine and η³-addition of the allyl fragment at one of the Os atoms (Os-C 2.246 ?, 2.248 ?, and 2.273 ?). The unit cell parameters of the complex are a = 9.494(1) ?, b = 10.479(1) ?, c = 12.474(2) ?, α = 84.55(1)°, β = 70.08(1)°, γ = 70.72(1)°, V = 1255.8(4), ?³, space group P , Z = 2; C₁₉H₁₀O₁₀Os₃; d _calc = 2.922 g/cm³, 3085 I _hkl > 2σ _I of 3611 collected reflections; R = 0.0252. The structure of Os₃(μ,η²-O=CC₆H₅)(η³-C₃H₅)(CO)₉ is molecular. The plane of the Os₃ triangle and the OsCOOs plane are connected according to the “butterfly” principle with an angle of 103.4° between them. The Os-Os distances in the cluster core vary from 2.836(1) ? to 2.844(1) ?; the Os-C_carb distances are 1.88(1)–1.97(1) ?; the distances to the atoms of the bridging ligands are Os-C 2.11(1) ?, Os-O 2.14(1) ?; the O-C bridging bond is 1.24(1) ?. of the Os₃(μ,η²-O=CC₆H₅)(η³-C₃H₅)(CO)₉ triosmium cluster were studied theoretically. The potential curve of the internal rotation of the allyl ligand relative to the Os(1)-C(9) bond was determined. The rotation barrier of the allyl ligand in crystal relative to the Os(1)-C(9) bond is 8.38 kJ/mol, and the rotation of the ligand is not hindered. The effects of the intra-and intermolecular interactions on the conformation state of the cluster complex are considered. Original Russian Text Copyright ? 2008 by V. A. Maksakov, N. V. Pervukhina, N. V. Podberezskaya, M. Yu. Afonin, V. A. Potemkin, and V. P. Kirin __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 49, No. 5, pp. 926–932, September–October, 2008.     

Oxidative coupling of methane over Bi2O3?P2O5?K2O/Sm2O3

Oxidative coupling of methane over Bi₂O₃–P₂O₅–K₂O/Sm₂O₃ takes place giving more C₂H₄ as compared to C₂H₆. Sm₂O₃ supported Bi–P–K is a more active and selective catalyst, than TiO₂, -Al₂O₃, SiO₂ and MgO supported catalysts.

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Bi₂O₃–P₂O₅–K₂O/Sm₂O₃ , . Bi–P–K, Sm₂O₃, , TiO₂, -Al₂O₃, SiO₂, MgO.

     

Facile synthesis and X-ray structures of (η-C5Me5)Ti(OAr)3 (OAr = OC6F5, OCH2C6F5, and OCH2C6F2H3)

New half-sandwich titanocene complexes (η⁵-C₅Me₅)Ti(OC₆F₅)₃ (1), (η⁵-C₅Me₅)Ti(OCH₂C₆F₅)₃ (2), and (η⁵-C₅Me₅)Ti(OCH₂C₆F₂H₃)₃ (3) were synthesized via the displacement of methoxide ligands in (η⁵-C₅Me₅)Ti(OMe)₃ by the corresponding aryloxy or benzyloxy ligands. These compounds have been fully characterized by various spectroscopic methods including X-ray crystallography. Compound 1 has a distorted three-legged piano stool structure. However, complexes 2 and 3 have the chariot-like structure, where chariot means a two-wheeled horse-drawn vehicle. The π electron donation of oxygen atom to Ti center in complexes 1-3 is considerable.     

I2O5/NaNO2硝化富电子芳香族化合物

以富电子芳香族化合物为底物,在五氧化二碘和亚硝酸钠作用下,温和条件下直接硝化得到其相应的芳香族硝基化合物,所得硝化产物结构经¹H NMR,MS和熔点表征。并研究其可能的自由基反应历程。      

Zr 5Ir 2In 4 – A Superstructure of the Lu 5Ni 2In 4 Type

Zr₅Ir₂In₄ was synthesized by reaction of the elements in a glassy carbon crucible in a water-cooled sample chamber of an induction furnace. The sample was characterized by X-ray diffraction on both powder and single crystals. Zr₅Ir₂In₄ crystallizes with a pronounced Lu₅Ni₂In₄ type subcell, space group Pbam, a=1739.5(6), b=766.3(2), c=338.9(2) pm. Weak additional reflections force a doubling of the subcell c axis. The superstructure of Zr₅Ir₂In₄ is of a new type: Pnma, a=1739.5(6), b=677.8(2), c=766.3(2) pm, wR2=0.0529, 1592 F² values, and 60 variable parameters. The group-subgroup scheme for the klassengleiche symmetry reduction is presented. The formation of the superstructure is most likely due to a puckering effect (size of the iridium atoms). The crystal chemistry of Zr₅Ir₂In₄ is briefly discussed.     

Structure and luminescence of [Tb0.5(C6NO2H5)3(H2O)2]2n·(H3O)4n(ZnCl5)n(ZnCl4)2n

A novel bimetallic 4f-3d metal-isonicotinic acid inorganic-organic hybrid complex [Tb_0.5(C₆NO₂H₅)₃(H₂O)₂]_2n ·(H₃O)_4n (ZnCl₅) _n (ZnCl₄)_2n (1) is synthesized. It has a one-dimensional polycationic chain-like structure. Photoluminescent investigation reveals that it displays interesting emissions in the violet, blue, green, and yellow regions.     

Ammoxidation of 3- and 4-picolines over V2O5?SnO2/γ?Al2O3 catalyst

The ammoxidation of 3- and 4-picolines has been studied over V₂O₅–SnO₂/–Al₂O₃ catalysts prepared by surface impregnation technique. Best results were obtained for the generation of cyanopyridines in the temperature range 400–450°C and sub-stoichiometric value with respect to O₂. Catalysts that were calcined above 700°C showed no activity.

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3- 4- V₂O₅–SnO₂/–Al₂O₃, . 400–450°C O₂. , 700 K, .

     

EPR study of solid solutions of [Cr(NH3)5Cl]x[Rh(NH3)5Cl]1?x[PdCl4]·nH2O and [Cr(NH3)5Cl]x[Rh(NH3)5Cl]1?x[PtCl4] compounds

In order to determine the features of the structure of double complex salts (DCSs) of [Cr(NH₃)₅Cl]×[MCl₄]·nH₂O, where M = Pd, Pt, n = 0, 1, the DCS solid solutions of palladium and platinum with isostructural DCSs containing the chloropentaammine rhodium cation, [Cr(NH₃)₅Cl] _x [Rh(NH₃)₅Cl]_1−x [MCl₄]·nH₂O, where x = 0.01–0.2, are synthesized and studied by the EPR method. DCSs with the isostructural chloropentaammine rhodium cation are used as a diluter for magneto concentrated systems. It is shown that DCS of platinum and anhydrous DCS of palladium have the identical environment of chromium ions. The EPR spectra of chromium ions for these compounds are described by the following spin Hamiltonian parameters: S = 3/2, g _xx = 1.987, g _yy = 1.987, g _zz = 1.985, D = 1660 Gs, E = 235 Gs. For the palladium complex containing crystalline water, the EPR spectra of chromium ions are described by the parameters: S = 3/2, g _xx = 1.984, g _yy = 1.984, g _zz = 1.984, D = 1060 Gs, E = 350 Gs. A decrease in the crystal field parameters for the aqueous palladium complex is caused by a redistribution of the electron density to the oxygen atom in the second sphere of the chromium ion environment.     

Gas-phase measurements of the surface basicity of AlPO4?TiO2 and AlPO4?ZrO2 catalysts

The amount and strength of basic sites of AlPO₄–TiO₂ and AlPO₄–ZrO₂ catalysts over a different range of AlPO₄/metal oxide weight ratios were measured by studying the adsorption of acid molecules (acrylic acid and phenol) in the gas phase (473–673 K) by using the gas-chromatographic pulse method. The results obtained show that the basicity of AlPO₄–TiO₂ and AlPO₄–ZrO₂ catalysts is far lower than that of pure AlPO₄, and with an increase in the metal oxide (TiO₂ or ZrO₂) weight ratio, the basicity decreases. Besides, the basicity of AlPO₄–ZrO₂ is fairly low compared with that AlPO₄–TiO₂. In both cases, the total basicity (measured at 473 K vs. acrylic acid) gradually decreases with the calcination temperature while the stronger basic sites (measured at 573 K vs. phenol) remained unchanged up to calcination temperatures of 1073 K. Some weak surface basic sites remained in catalysts pretreated at 1273 K.

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- AlPO₄–TiO₂ AlPO₄–ZrO₂ AlPO₄/ , ( ) (473–673 K). , AlPO₄–TiO₂ AlPO₄–ZrO₂ AlPO₄ TiO₂ ZrO₂. , AlPO₄–ZrO₂ AlPO₄–TiO₂. — 473 K — , , 573 K , 1073 K. , 1273 K, .

     

簇合物[(η5-C5Me5)WS3{Cu(PPh3)}3Cl](PF6)的合成及晶体结构

Reaction of a preformed cluster [{(η⁵-C₅Me₅)WS₃}₃Cu₇(MeCN)₉](PF₆)₄ (1) in MeCN with LiCl and PPh₃ gave rise to a tetranuclear cationic cluster [(η⁵-C₅Me₅)WS₃{Cu(PPh₃)}₃Cl](PF₆) (2). The title compound 2 was characterized by elementary analysis, IR, UV-Vis, ¹H NMR, and its crystal structure was determined by X-ray single crystal diffraction. It belongs to monoclinic, space group P2₁/c with a=1.799 8(4) nm, b=2.083 6(4) nm, c=1.913 5(4) nm, β=113.63(3)°, V=6.574(3) nm³, Z=4. The cluster cation [(η⁵-C₅Me₅)WS₃{Cu(PPh₃)}₃Cl]⁺ of 2 contains a strongly distorted, cubane-like structure [WS₃Cu₃Cl] in which one Cl weakly fills into the void of the nido-like [WS₃Cu₃] fragment with three relatively long Cu-Cl distances. CCDC: 270415.