Synthesis and characterization of sandwiched heteropolycompound

New complex K5O4Na4H5 [Sn-3(PW9O34)(2)]. 16N(2)O was prepared and its structure was determined by elemental analysis, IR, P-31, W-183 NMR, polarography, XPS and X-ray crystallography. The anion has A-alpha-Keggin structure. The new complex crystallize is the monoclinic, P2(1)/n with a = 1.3625 (3) nm, b = 2.3625 (5) nm, c = 2.9306 (6) nm, alpha = 90 degrees, beta = 99.67 (3)degrees, gamma = 90 degrees, V = 9.299 nm(3), Z = 4.

(NH4)(3)[PMo12O40]center dot 21H(2)O

The determination of the crystal structure of the title compound, triammonium hexatriacontaoxo(tetraoxophosphato)dodecamolybdate(3-) henicosahydrate, shows that the polyanion has a pseudo-Keggin structure with m (3) over bar m symmetry. The central PO4 group is disordered with P-O distances of 1.55 (3) Angstrom. The Mo-O distances range from 1.617 (14) to 2.414 (14) Angstrom.

Immobilization of the heteropoly acid (HPA) H4SiW12O40 (SiW12) on mesoporous molecular sieves (HMS and MCM-41) and their catalytic behavior

Supported catalysts, consisting of SiW12 immobilized on hexagonal mesoporous silica (HMS) and its aluminum-substituted derivative (MCM-41) with different loadings and calcination temperatures, have been prepared and characterized by X-ray diffraction, FT-IR and NH3-temperature programmed desorption. It is shown that SiW12 retains the Keggin structure on the mesoporous molecular sieves and no HPA crystal phase is developed, even at SiW12 loadings as high as 50 wt%. In the esterification of acetic acid by n-butanol, supported catalysts exhibit a higher catalytic activity and stability and held some promise of practical application. In addition, experimental results indicate that the loaded amount of SiW12 and the calcination temperatures have a significant influence on the catalytic activity, and the existence of aluminum has also an effect on the properties of supported catalysts.

SYNTHESIS AND CHARACTERIZATION OF ALPHA,BETA-TRIINDIUM SUBSTITUTED HETEROPOLYTUNGSTATES

The complexes of alpha,beta-K(a)H(b)XW(9)O(37)(InH2O)(3) . xH(2)O (X = Si, Ge; a+b = 7) were synthesized from their lacunary precursors alpha,beta-XW(9)O(34)(10-) (X = Si, Ge) and characterized by elemental analysis, W-183 NMR, IR and UV spectroscopy and polarography. W-183 NMR spectra of the title complexes consist of two lines with intensity ratio 2:1, as expected for the C-3 nu structure of trisubstituted A alpha- and A beta-Keggin anions.

THE CATALYTIC ACTIVITY OF HETEROPOLY ACIDS (SALTS) AND MONO-LACUNARY HETEROPOLY TUNGSTOPHOSPHORIC COMPOUND IN THE OXIDATION OF ALCOHOLS

The catalytic activity of heteropoly compounds in the oxidation of benzyl alcohol and cyclohexa nol under phase transfer conditions has been studied. The catalytic activity of six kinds of heteropoly acids with Keggin structure will drop by the order of GeMo12 (H4GeMo12O40). PW12, PMo12, SiMo12, GeW12 and SiW12. When the three protons of H3PW12O40 Were replaced by Na+ step by step, the catalytic activity will raise gradually with the drop of acidity. The addition of base and trace amount of sulfuric acid to the reaction system resulted in an increase of catalytic activity. It was found that catalytic activity of mono-lacunary heteropoly compounds is higher than that of the primary heteropoly acids (or salts). The catalytic oxidation system of HPA-H2O2-PTC is very active in the oxidation of benzyl alcohol ana cyclohexanol, but it has little activity in the oxidation of inactive compounds such as n(or iso)-proplalcohol. n-butyl alcohol and n-hexanol. Solvent has great effect on reaction, when polar compounds such as water were used as solvent, the catalytic activity is better than that when non-polar compounds were used as solvent.

XPS study of basic aluminum sulphate and basic aluminium nitrate

Basic aluminium sulphate and nitrate crystals were prepared by forced hydrolysis of aluminium salt solution followed by precipitation with a sulphate solution or by evaporation for the basic aluminium nitrate. X-ray Photoelectron Spectroscopy (XPS) confirms the chemical composition determined by ICP-AES in earlier work. High resolution XPS scans of the individual elements allow the identification of both the central (AlO4)-Al-IV group and the 12 aluminium octahedra in the [IVAlO4AlVI(OH)(24)(H2O)(12)] building unit by two Al 2p transitions with binding energies of 73.7 and 74.2 eV in both the basic aluminium sulphate and nitrate. Four different types of oxygen atoms were identified in the basic aluminium sulphate associated with the central AlO4, OH, H2O and SO4 groups in the crystal structure with transitions at 529.4, 530.1, 530.7 and 531.8 eV, respectively. (c) 2005 Elsevier B.V. All rights reserved.

Preparação, caracterização e aplicação de derivados do ácido 12- tungstofosfórico suportado em SBA-15

Dissertação (mestrado)—Universidade de Brasília, Instituto de Química, Programa de Pós-Graduação em Química, 2016.

Hydrothermal synthesis and structure of [{Mo8V4O36(VO4)(VO)(2)}(n)](7n-) bi-capped alpha-Keggin fragments linked to a chain

The title compound, (H(2)en)(3)H3O {MO8V4O36 (VO4) (VO)(2)} . 4H(2)O, was hydrothermally synthesized and structurally characterized by means of IR, ESR spectrum and single crystal X-ray diffraction. It crystallized in a monoclinic system with space group P2(1)/c, a=1. 980 4(4) nm, b=2. 063 4(4) nm, c=1. 192 0(2) nm, (beta =94. 76(3)degrees and deep black colour. The compound contains V-centered bi-capped alpha -Keggin fragments {Mo8V7O42} that are linked together by edge-shared units (VO5)-O-N via V-O-V bonds, forming a chain.

Hydrothermal synthesis and structure of a bi-capped Keggin polyoxoanion, [(As2AsMo8V4O40)-As-III-Mo-V-O-IV](5-)

The title compound, [NH3CH2CH2CH2NH2][NH3CH2CH2CH2NH3](2)[As-2(III) As-v Mo-8 V-4(IV) O-40] (.) 5H(2)O, was hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. Crystal data: monoclinic, C2/c, a = 45.375(9) Angstrom, b = 11.774(2) Angstrom, c = 23.438(5) Angstrom, beta = 96.62(3)degrees. X-ray crystallographic study showed that the crystal structure was constructed by bi-capped alpha -Keggin fragments [(As2AsMo8V4O40)-As-III-Mo-v-O-IV](5-) polyoxoanion. (C) 2001 Elsevier Science B.V. All rights reserved.

Synthesis, electrical properties and crystal structure of a new radical-ion salt based on pi-extended bis(TTF) and a Keggin heteropolymolybdate

By electrocrystallization of 2,6-[4,5-bis(n-butylsulfanyl)-1,3-dithiol-2-ylidene]-4,8-bis(6-iodo-n-hexyloxy)-1,3,5,7-tetrathia-s-indacene (BHBDTI) and [NBu4](4)[SiMo12O40] in the mixed solvent CHCl2CH2Cl and CH3CN, the new radical-ion salt [C42H60Cl2O2S12](2)[SiMo12O40] was prepared. It was characterized by means of IR and ESR spectroscopy and X-ray diffraction. In the crystal structure, organic radical dications and silicomolybdate anions are alternatively arranged along the a axis to form a 1-D conducting layer. The organic layer consists of two isolated groups of BHBDTI divided by the (011) plane without short interatomic contacts. However, in each group, BHBDTI molecules associate with each other in a head to tail manner running along the [011] direction and face-to-face overlapping with a relative shift by approximately one TTF subunit along the long axis of the molecule and a slight shift along the short axis of the molecule with significantly short S ... S contacts. The room-temperature d.c. conductivity determined by the two-probe method is 10(-4) S cm(-1), suggesting that the compound is a semiconductor.

Hydrothermal synthesis and structural characterization of novel alpha-Keggin unit-supported Cu(II)- and Mn(II)-bipyridine complexes from a tri-lacunary precursor

Blue [{Cu(2,2'-bipy)(2)}(2){alpha-SiW12O40}] (bipy = bipyridyl) (1) and pale yellow [Mn(2,2'-bipy)(3)](2)[alpha-SiW12O40] (2) have been synthesized hydrothermally and characterized by IR spectroscopy and single crystal X-ray structure analysis. In 1, the [alpha-SiW12O40](4-) ion acts as a bridge between the two [{Cu(2,2'-bipy)(2)](2+) moieties via coordination through the terminal oxygen atoms, while in 2, the [Mn(2,2'-bipy)(3)](2+) ion balances the charge on the polyoxo anion without forming any covalent bond. To the best of our knowledge, this is the first example of transition metal-mediated transformation of [alpha-SiW9O34](10-) to [alpha-SiW12O40](4-).

A new alpha-Keggin type polyoxometalate coordinated to four silver complex moieties: {PW9V3O40[Ag(2,2 '-bipy)](2)[Ag-2(2,2 '-bipy)(3)](2)}

A new polyoxometalate derivative {PW9V3O40[Ag(2,2'-bipy)](2)[Ag-2(2,2'-bipy)(3)](2)} 1 has been hydrothermally synthesized and structurally characterized by the single crystal X-ray diffraction. X-Ray analysis showed that both [Ag(2,2'-bipy)](+) and [Ag-2(2,2'-bipy)(3)](2+) units are supported on the alpha-Keggin polyoxoanion [PW9V3O40](6-) via the surface bridging oxygen atoms. 1 represents the first alpha-Keggin type polyoxoanion coordinated with four transition metal complex moieties, which further acts as a neutral molecular units for the construction of an interesting three-dimensional supramolecular framework.

Modified polyoxometalates: Hydrothermal syntheses and crystal structures of three novel reduced and capped Keggin derivatives decorated by transition metal complexes

Three novel polyoxometalate derivatives decorated by transition metal complexes have been hydrothermally synthesized. Compound 1 consists of [(PMo6Mo2V8O44)-Mo-VI-V-V-O-IV{CO (2,2'-bipy)(2)(H2O)}(4)](3+) polyoxocations and [(PMo4Mo4V8O44)-Mo-IV-V-V-O-IV{Co(2,2'-bipy)(2)(H2O)}(2)](3-) polyoxoanions, which are both built on mixed-metal tetracapped [PMo8V8O44] subunits covalently bonded to four or two {Co(2,2'-bpy)(2)(H2O)}(2+), clusters via terminal oxo groups of the capping V atoms. Compound 2 is built on [(PMo8V6O42)-V-VI-O-IV{Cu-I(phen)}(2)](5-) clusters constructed from mixed-metal bicapped [(PMo8V6O42)-V-VI-O-IV](7-) subunits covalently bonded to two {Cu(phen)}(+) fragments in the similar way to 1. The structure of 3 is composed of [(PMo9Mo3O40)-Mo-VI-O-V](6-) units capped by two divalent Ni atoms via four bridging oxo groups.