Phase Transfer Research for Heteropolyanions Containing Cr（Ⅲ），Mn（Ⅳ），Co（Ⅱ），Zn（Ⅱ）

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Charge Transport Processes of Immobilized Heteropolyanions at Self-assembled Monolayer Modified Gold Electrode by Electrochemical Quartz Crystal Microbalance Measurement

The in situ electrochemical quartz crystal microbalance（EQCM） technique was used to investigate the ion transport of immobilized heteropolyanions at a self-assembled monolayer（SAM） modified gold electrode during electrochemical redox process.A mixed transfer method was presented to analyse the abnormal change of resonant frequency based on the simultaneous insertion/extraction of different ions.The results indicate that the migration of HSO4-anions was indispensable in the redox process of the heteropolyanions in a 1 mol/L H2SO4 solution and played a key role in the abnormal change of the resonant frequency.Such a change was attributed to different packing densities derived by means of differently immobilized methods.

Studies on Redox Properties of Heteropoly Compounds Containing Rare Earth Elements

The redox properties of four series of more than one handred acids and salts of rare earth heteropoly compounds, such as LnHSiMoi2O40, In (PMo11 O39)211-, Ln (PW11 O39)211-, Ln (AsW11 O39)211-, Ln(GeW11O39)213-, Ln(BW11O39)215-, Ln(GaW11O39)216-, Ln(P2Mo17O61)217-, Ln (As2W17O61)217-, Ln2P2Mo18O62and Ln2HP2Mo17VO62(Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, etc. ) which have Keggin, Daw-son and their derivative structures, were studied by means of potentiometric titration, polarography and cy-clovoltammetry. The mechanisms of the redox reactions were supposed-and the orders of redox ability of the heteropoly compounds were concluded. The periodic changes in reduction potentials of Ln(PMo11O39)211-and Ln(P2Mo17O61)2217- with Ln atomic numbers, and the correlation between E1/2 of Ln(XMo11O39)2(?)-(X =P, Ge, Si) and nq2(n is the main quantum number of the central atoms and q is their charges) were found.

Comparative study between gas phase and liquid phase for the production of DMC from methanol and CO_2

Direct synthesis of dimethyl carbonate （DMC） from methanol and carbon dioxide over Co1.5PW12O40 in liquid and in gas phase is investigated. The synthesized catalyst has been characterized by means of FTIR and XRD. Liquid phase experiment results showed that high pressures are favorable for the synthesis of DMC. However, DMC formation is limited by the reaction with co-produced water. DMC selectivity is more strongly dependent on the temperature than on the pressure of CO2. As for the reactions in gas phase, it has been found that both CH3OH conversion and DMC selectivity decreased with increasing temperature, owing to the decomposition of DMC at high temperatures. High temperatures and more amount of Co1.5PW12O40 catalyst favor the formation of dimethoxymethane （DMM） and methyl formate （MF）.

Synthesis, Character and Crystal Structure of the Complex {Er(DMSO)_7}PW_(12)O_(40)

The synthesis, X-ray crystal structure, thermal properties and electrochemistry of the new complex formulated as {Er（DMSO）7}PW12O40 are reported. The single-crystal X-ray analysis reveals that the crystal crystallizes in the monoclinic system, space group P21/c with a=11.767（2）, b=14.909（3）, c=34.905（7）A, β=98.97（3）°, Mr=3591.33, V=6049（2）A^3, Dc=3.944g/cm^3, Z=4, GOOF=1.098, F（000）=6340, R=0.0490 and wR=0.1202. Crystal structure analysis indicates that the Er（Ⅲ） is seven-coordinate with a distorted pentagonal bipyramid and combines to the anion [PW12O40]3- via static electric force.

A New Sandwich Type Transition Metal Substituted Polyoxotungstate under Hydrothermal Conditions: [NH_3(CH_2)_4NH_3]_6[Co_4(H_2O)_2(B-α-GeW_9O_(34))_2]}·7H_2O

A new sandwich transition metal substituted polyoxotungstate, [NH3（CH2）4NH3]6[Co4（H2O）2（B-α-GeW9O34）2]}·7H2O 1, was hydrothermaUy synthesized and characterized by IR spectra and single-crystal X-ray diffraction. The single-crystal X-ray analysis reveals that the crystal crystallizes in monoclinic system, space group P21/c with a = 16.6073（6）, b = 15.3333（5）, c = 19.9869（7） A, β = 103.41（1）°, Mr = 5481.38, V = 4950.8（3） A3, Z = 2, Dc = 3.677 g/cm^3, F（000） = 4900, μ（MoKa） = 22.165 mm^-1, GOOF = 1.005, the final R = 0.0228 and wR = 0.0527. The crystal structure indicates that the [Co4（H2O）2（B-α-GeW9O34）2]^12- polyoxoanion contains two trivacant Keggin [B-α-GeW9O34]^10- fragments in a staggered fashion linked via a rhomb-like Co4O16 group in a centrosymmetric arrangement （C2h symmetry） leading to a sandwich-type structure.

Synthesis,Characterization and Catalysis of New Pillared Anionic Clays by[GaW_(11)O_(39)M(H_(2)O)]^(7-)(M=Mn^(2+),Co^(2+)or Ni^(2+))

Pillared anionic clays or layered double hydroxides were prepared by means of hydrothermal ion exchange reaction of [Zn 2Al(OH) 6]NO 3· x H 2O (ZnAl NO 3) with [GaW 11 O 39 M(H 2O)] 7- (abbreviated as GaW 11 M, M=Mn 2+ , Co +2 or Ni 2+ ). The layered compounds were characterized by means of XRD, IR, elemental analysis and DTA. The X ray diffraction and IR spectra show that the new anionic clays synthesized are layered compounds with the gallery heights of 0.99-1.00 nm and the Keggin structure tungstogallic heteropolyanions almost completely replace the interlayer NO - 3, entering the layer and retain their Keggin structure. The DTA gives a thermostability order of ZnAl GaW 11 Ni >ZnAl GaW 11 Co>ZnAl GaW 11 Mn>ZnAl NO 3. The ctalytic tests showed that the new pillared compounds have higher catalytic activities in the cyclooxidation reaction of maleic acid.

SYNTHESIS AND ^（183）W，^（51）V NMR CHARACTERIZATION OF a－［GaW9V8O（40）］（5－） HETEROPOLYANION

The trivanadium-subatituted heteropolytungstates have been synthesized from their lacunary precusor a-Na9GaW9O(34)H2.(183)W NMR spectrum of the title anion consists of two lines as expected for the C3v structure of the trisubetituted A-type Keggin anion.

Synthesis, Crystal Structure and Electrochemistry of Two Complexes (YLn)^(3+)[PW_(12)O_(40)]^(3-)(L=Me_2SO, Me_2NCHO)

The reaction of α-H3[PW12O40] with Y（NO3）3 in the presence of DMF or DMSO leads to two complexes with the formulae {Y（DMSO）7}·PW12O40（1） and {[Y（DMF）7]2PW12O40}·PW12O40（2）. The crystal structures indicate that complex 1 consists of discrete [YLn]3＋ cations and α-Keggin heteropolyanions [PW12O40]3-, whereas, in complex 2, donor-acceptor interaction results in a cation-anion-cation triplet. In addition, the electrochemical behavior of the two complexes indicates the usual successive reduction processes of the W atoms in the anions.

Heteropolytungstates Containing Organotin and Cobalt or Zinc Atom

Organotin substituted heteropolytungstates with cobalt or zinc atom as the central atom, \{K 6H[XW 11 O 39 (RSn)]\}· n H 2O(X=Zn, Co; R=CH 3OOCCH 2CH 2, CH 2OOCCH(CH 3)CH 2, NCCH 2CH 2) were prepared and characterized by elemental analysis, IR, UV Vis spectroscopy, ESR, NMR spectroscopy and electrochemical study. The results show that these anions possess Keggin like structures.

Synthesis,Characterization and Catalytic Activity of ZnAl Anionic Clay Pillared by α-Na_(6)[GaW_(11)O_(39)Fe(H_(2)O)]·18H_(2)O

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Studies on the Redox Properties of Rare Earth Heteropoly Tungstoarsenate K_17[Ln(As_2W_17O_61)_2]·xH_2O

The redox properties of K17[Ln(As2W17O61)2](Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Tm or Yb) in solution were investigated using polarographic and cyclic voltammographic methods. Experimental results indicate that the heteropolyanions underwent three-step-two-electron-tungsten-reduction processes, and each reduction process was accompanied by adding two protons.

Synthesis and Properties of Nonatungstotricobaltosilicate Isomers

Introduction Recently substituted-type of heteropolyanions has received much attention from the point of view of their catalysis. Hill, Finke, Neumann reported respectively that transition metal mono-substituted heteropolyanions PW;M, P;W;M and SiW;Ru have an ability to catalyze the epoxidation of olefin. We discovered that trisubstituted Keggin heteropolyanions have this property too. This paper describes the synthesis, properties of α- and β-[SiW;O;Co;（H;O）;];and its catalysis for the epoxidation of olefin by PhIO.

Electrochemical and Spectroelectrochemical studies of Mixed-Valence Heteropolyanion VMo_(12)O_(40)^(n-)(n=4,5,6) in Aprotic Media

The mixed-valence heteropolyanion VMo12O40 n-(where n=4,5,6) in aprotic media wasinvestigated by cyclic voltammatry and in-situ FTIR and UV-visible-near-lRspectroelectrochemical methods. The results indicate that the heteropolyanion VMo12O403-undergoes three reversible one electron transfer reductions and the mixed-valenceheteropolyanion VMo12O40n-(where n=4,5,6) was formed after electroreduction. The spectraof the aforementioned mixed-valence compounds were characterized by in-situspectroelectrochemical mathods

Electrochemical Behavior and Its Electrocatalytic Activity of A P-Mo Heteropolyanion Modified ITO Electrode

s: A new method for the preparation of an organic-inorganic composite film of the heteropolyanion has been developed by modifying P(Mo2O7)6-7 to the indium tin oxide (ITO) electrode surface. The modified electrode displayed a strong catalytic activity towards the reduction of IO3-. In the range of 1.0?0-6~5?0-4mol/L, the catalytic current was linear proportional to the IO3- concentration.

Synthesis and ￣（183）W NMR Characterization of β－［（CeO）＿3（SiW＿9O＿（34））＿2］￣（14－） Heteropolyanion

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Effects of vanadium(V)-substitution on the oxidative properties of α-Keggin-type heteropolyanion clusters——progress in DFT theoretical studies

The redox properties of α-Keggin-type heteropolyanion clusters [XM12O40]n-(X = Si,P; M = Mo,W) mainly depend on their constituent outer metal-oxygen cages {M12O36}. They act as "reservoirs",through which the transfer and transition of electrons and protons may occur. At the atomic and molecular level,the redox properties of these clusters can be controlled and also tuned by modifying the metal M in the cages and the central heteroatom X of the clusters. Combined with relevant experimental results,this review summarizes our recent theoretical investigations of the effect of vanadium substitution on the redox properties of Keggin anion clusters. Theoretical modeling and calculation results showed that the oxidative ability of the modified species was increased by partial substitution of the cage M atoms of the Keggin clusters by vanadium atoms which have lower electronegativity. A linear correlation between the catalytic efficiency per vanadium atom and the microstructures of the vanadium(V)-substituted heteropolyanions [PVnMo12-nO40](3+n)-(n = 1-3) was established for the first time. This relationship may be suitable to interpret the catalytic behavior of the title compounds in the hydroxylation of benzene to phenol,and may also be used in understanding other reactions such as the oxidative dehydrogenation of isobutyric acid and the nitration of adamantine. The establishment of this nearly linear structure-property relationship may lay the foundations of understanding the behavior of the title compounds in homogeneous catalytic oxidation reactions,and may direct the design of future catalysts and the choice of other catalytic reactions.

Synthesis and characterization of trisubstituted heteropolytungstogermanates containing group 3A elements

Six new compounds, alpha,beta-KaHb[GeW(9)M(3)(H2O)(3)O-37]. xH(2)O(M = Al, Ga, In; a + b = 7) and alpha-K9H5[Ge2W18Ga6(H2O)(3)O-74]. 20H(2)O, were synthesized from the lacunary precursors a and beta-GeW9O3410- and characterized by elemental analysis, spectroscopy and electrochemistry. Tungsten-183 NMR spectra of the title complexes consist of two lines with intensity ratio 2:1 as expected for trisubstituted heteropoly anions. The intensity ratio of alpha-Ga compound is 1:2, which is different from others(a:1). With the help of FAB mass spectrum, we concluded that it is a dimer with D-3h structure in aqueous, and the others exist by monomers with C-3v structures.

Synthesis and characterization of organotitanium substituted heteropolytungstosilicates and their biological activity

Tris, di-( organotitanium) substituted tungstosilicates α,β - (CpTi)3(SiW9037)17– and γ-[(CpTi)2(SiW10O38)] 6– were prepared by the reaction of C2TiC12 (Cp= η-C5H5) with a,β-SiW9 O9/34(noted α,β Siv9,), γ-SiWO8/36 (noted γ-SiW10) The products were characterized by means of elemental analysis, IR, 1H NMR, 183W NMR and polarography. 183W NMR spectra of the complexes support the stoichiometry of the new heteropolyanions and the probable retention of the A-XW9 or γ-SiWlO units. And the organotitanium substituted compounds showed promising in vitro antitumor activity in two of human tumor cell lines.

Synthesis, characterization and oxidative activity of heteropolyanion pillared layered compound

TRANSITION element trisubstituted and Ln bi-（1:11）series heteropolyanion with Keggin struc-ture are excellent catalyst with oxidizing properties.But they have some shortcomingssuch as poor stability and impossible recycle use when they are used in homogeneous oxidation.Anions（An-）,among hydroxides（LDHS）-like layers,having a general formula[M1-x2+Mx3+-