Determination of kinetic parameters of inorganic metalporphyrins

The thermal properties of four heteropoly complexes α-K₃H₃[SiW₁₁Ni(H₂O)O₃₉]·11.5H₂O (I), α-K₃H₂[SiW₁₁Fe(H₂O)O₃₉]·9H₂O (II), α-[(C₄H₉)₄N]_3.5H_1.5[SiW₁₁Fe(H₂O)O₃₉]·4.5H₂O (III) and α-[(C₄H₉)₄N]_3.5H_2.5[SiW₁₁Cu(H₂O)O₃₉]·6H₂O (IV) were studied by means of TG, DTA and DSC. The activation energy and reaction order of the thermal decomposition reaction of these complexes have been calculated.

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Zusammenfassung Mittels TG, DTA und DSC wurden die thermischen Eigenschaften der vier heteropolaren Komplexe α-K₃H₃[SiW₁₁Ni(H₂O)O₃₉]·11.5H₂O (I), α-K₃H₂[SiW₁₁Fe(H₂O)O₃₉]·9H₂O (II), α-[(C₄H₉)₄N]_3.5H_1,5[SiW₁₁Fe(H₂O)O₃₉]·4.5H₂O (III) und α-[(C₄H₉)₄N]_3.5H_2,5 [SiW₁₁Cu(H₂O)O₃₉]·6H₂O (IV) untersucht. Die Aktivierungsenergie und Reaktionsordnung der thermischen Zersetzungsreaktion dieser Komplexe wurde berechnet.

     

Investigation of the state of palladium in the potassium palladium-11-tungstosilicate/alumina system by diffuse-reflectance IR spectroscopy

The influence of redox treatments on the state of palladium in the K₆[SiW₁₁PdO₃₉]·11H₂O/γ-Al₂O₃ system was investigated by diffuse-reflectance IR (DRIFT) spectroscopy using CO as a probe molecule. The K₆[SiW₁₁PdO₃₉]·11H₂O heteropoly-compound (HPC) and starting γ-Al₂O₃ support were studied for comparison. It was shown that palladium is present in HPC mainly in the form of Pd²⁺ ions. Treatment of HPC in an H₂ flow results in complete reduction of palladium to Pd⁰. The HPC is unstable in redox cycles at temperatures above 373 K. When the HPC was supported on alumina, the Keggin units were stabilized on the support surface and Pd⁺ formed in the oxidized sample. The supported K₆[SiW₁₁PdO₃₉]·11H₂O/γ-Al₂O₃ catalyst displays higher thermal stability and does not decompose during redox treatments at temperatures up to 723 K. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 7, pp. 1271–1275. July, 1999.     

New Series of Porous Ionic Crystals Constructed from Various Polyoxometalate Anions and Macrocations: Syntheses,Crystal Structures,and Comparison with Diverse Spatial Arrangement

A new series of ionic crystals, KH₂[Cr₃O(OOCCH₃)₆(H₂O)₃][α‐SiMo₁₂O₄₀] · 11 H₂O ( 1 ), KH₂[Cr₃O(OOCCH₃)₆(H₂O)₃][α‐SiW₁₂O₄₀]μ·μ11H₂O ( 2 ), K₂[Cr₃O(OOCCH₃)₆ (H₂O)₃][α‐PW₁₂O₄₀]μ· 17H₂O ( 3 ), Na[Cr₃O(OOCCH₃)₆(H₂O)₃]₂[α‐PMo₁₂O₄₀] · 11H₂O ( 4 ), H₅[Cr₃O(OOCCH₃)₆(H₂O)₃] [α‐P₂Mo₁₈O₆₂] · 10H₂O ( 5 ) based on a polyoxometalate building block with a macrocation, have been synthesized in aqueous solution and structurally characterized by single‐crystal X‐ray diffraction, IR spectra, elemental analysis, thermogravimetric analysis (TGA). The polyanions and macrocations stacked alternately through hydrogen bonds as well as electrostatic interactions to constitute a novel porous microstructure. In the crystal structures of 1 , 2 , and 3 , oppositely charged cluster ions stacked alternately to form one‐dimensional channels. Compound 4 exhibits an unique structure that six macrocation pillars packed along the a‐axis to form a straight 1D channel, in which accommodates a polyoxometalate pillar. In compound 5 , six α‐Dawson‐type polyoxometalate pillars stacked on top of each other along the a‐axis to form a straight 1D channel, which houses a macrocation pillar. The magnetic investigation on compounds 1 and 5 shows a typical antiferromagnetic interaction of the macrocation [Cr₃O(OOCCH₃)₆(H₂O)₃]⁺, almost independent from the presence of polyoxometalate anions.     

Three inorganic–organic hybrid compounds based on Keggin polyoxometalate and transition metal complexes: crystal structures and electrochemical properties

Polyoxometalate (POM)-based coordination polymers, [Cu(L)₂][SiW₁₂O₄₀]·4py·H₂O (1), [Ag(py)₂]₄[SiW₁₂O₄₀] (2) and [Co(L)₃]₂[SiW₁₂O₄₀]·py·7H₂O (3) (L?=?pyridine-2-carboxylic acid, py?=?pyridine), have been obtained hydrothermally and characterized by elemental analyses, IR and single-crystal X-ray diffraction analyses. Electrochemical properties are also investigated.     

Visible‐Light‐Induced Water Oxidation Mediated by a Mononuclear‐Cobalt(II)‐Substituted Silicotungstate

A mononuclear‐cobalt(II)‐substituted silicotungstate, K₁₀[Co(H₂O)₂(γ‐SiW₁₀O₃₅)₂] ? 23 H₂O (POM‐ 1 ), has been evaluated as a light‐driven water‐oxidation catalyst. With in situ photogenerated [Ru(bpy)₃]³⁺ (bpy=2,2′‐bipyridine) as the oxidant, quite high catalytic turnover number (TON; 313), turnover frequency (TOF; 3.2 s^?1), and quantum yield (Φ_QY; 27 %) for oxygen evolution at pH 9.0 were acquired. Comparison experiments with its structural analogues, namely [Ni(H₂O)₂(γ‐SiW₁₀O₃₅)₂]^10? (POM‐ 2 ) and [Mn(H₂O)₂(γ‐SiW₁₀O₃₅)₂]^10? (POM‐ 3 ), gave the conclusion that the cobalt center in POM‐ 1 is the active site. The hydrolytic stability of the title polyoxometalate (POM) was confirmed by extensive experiments, including UV/Vis spectroscopy, linear sweep voltammetry (LSV), and cathodic adsorption stripping analysis (CASA). As the [Ru(bpy)₃]²⁺/visible light/sodium persulfate system was introduced, a POM–photosensitizer complex formed within minutes before visible‐light irradiation. It was demonstrated that this complex functioned as the active species, which remained intact after the oxygen‐evolution reaction. Multiple experimental parameters were investigated and the catalytic activity was also compared with the well‐studied POM‐based water‐oxidation catalysts (i.e., [Co₄(H₂O)₂(α‐PW₉O₃₄)₂]^10? (Co₄‐POM) and [Co^IIICo^II(H₂O)W₁₁O₃₉]^7? (Co₂‐POM)) under optimum conditions.     

Synthesis, structural characterization and properties of a 3D infinitely extended structural rare earth coordination compound of K3{[Sm(H2O)7]2Na[α-SiW11O39Sm(H2O)4]2} · 14 H2O· 14 H2O

A 3D infinitely extended structural rare earth coordination compound with a formula of K₃{[Sm(H₂O)₇]₂Na[α-SiW₁₁O₃₉Sm(H₂O)₄]₂}·14H₂O has been synthesized by reaction of Sm₂O₃, HClO₄, NaOH with α-K₈SiW₁₁O39·nH₂O, and characterized by IR, UV spectra, ICP, TG-DTA, cyclic voltammetry, variable-temperature magnetic susceptibility and X-ray single-crystal diffraction. X-ray single-crystal diffraction indicates that the title compound crystallizes in a triclinic lattice, Pī space group, with a = 1.2462(3) nm, b = 1.2652(3) nm, c = 1.8420(4) nm, α = 87.45(3)°, β = 79.91(3)°, γ= 82.57(3)°, Z = 1, R₁ = 0.0778, wR₂ = 0.1610. Structural analysis reveals that Sm³⁺(1) coordination cation has incorporated into the vacant site of [α-SiW11O₃₉]⁸⁻ entity, forming the [α- SiW₁₁O₃₉Sm(H₂O)₄]⁵⁻ subunit. The two adjacent [α-SiW₁₁O₃9Sm(H₂O)4]⁵⁻ subunits are combined with each other through two Sm(1)-O-W bridges accompanying the formation of dimmer structural unit [α-SiW₁₁O₃₉Sm(H₂O)₄]₂ ¹⁰⁻ of the title compound. The neighboring dimmer structural units [α-SiW₁₁O₃₉Sm(H₂O)₄]₂ ¹⁰⁻ are linked to form the 1D chainlike structure by means of two Sm³⁺(2) and a Na⁺(1) coordination cations. The K⁺(1) cations connect the 1D packing chains constructing the 2D netlike structure, and adjacent netlike layers are also grafted by K⁺(2) cations to build the novel 3D infinitely extended structure. The result of TG-DTA curves manifests that the decomposition temperature of the title polyanionic framework is 554°C. The cyclic voltammetry measurements show that the title polyanion has the two-step redox processes in aqueous solution with pH = 3.1. Variable temperature magnetic susceptibility indicates the title compound obeys the Cruie-Weiss Law in the higher temperature range from 110 to 300 K, while in the lower temperature range from 2 to 110 K the comparatively strong antiferromagnetism interactions can be observed.     

Structural stability index of heteropoly- and isopolyanions—IV. Application to site-vacant Keggin polyanions,mixed-type Keggin polyanions,some molybdo- and tungsto-vanadates and Jeannin-type polyanion

The theory of structural stability, being based on the number of closed loops per MO₆ octahedral unit in the polyanion-cage, has been applied to a variety of heteropoly- and isopoly-compounds with previously unreported structures. The discussion includes the prediction of the structure of lacunary Keggin heteropoly-compound, Cs₇Na₂[PW₁₀O₃₇]·8H₂O, recently obtained by Knoth and Harlow, the reinvestigation of mixed-type Keggin polyanions, [SiW₉Co₃(H₂O)₃O₃₇]^10? and [SiW₁₁CoO₃₉]^6?, recently prepared by Pope's group, the interpretation of chemical behaviours of some molybdo- and tungsto-vanadates, the structural stabilities of Jeannin-type [As₂W₂₁O₆₉(H₂O)]^6? polyanion and its related compounds, and some remarks on Weakley-type [X(W₅O₁₈)₂]^n? polyanions and Flynn-Stucky-type [X(Nb₆O₁₉)₂]^n? complexes belonging to the hybrid-complex of polyanion.     

Solvent-tuned polyoxometalate-based supramolecular hybrids constructed from different metal-organic motifs: Various structures and adsorption properties for dyes

Three polyoxometalate-based supramolecular hybrids with different metal-organic motifs have been synthesized by tuning the solvents, which show various adsorption activities for different organic dyes.     

A Ag-La heterometallic 2D layer based on mono-lacunary Keggin polyoxometalate: Synthesis,structure, and photocatalytic property

A new two-dimensional (2D) purely inorganic 4d-4f heterometallic compound [La(H₂O)₈][Ag{La(H₂O)₆}₂{SiW₁₁La(H₂O)₄O₃₉}₂]·13H₂O (1), based on mono-lacunary Keggin-type {α-SiW₁₁O₃₉} cluster (abbreviated to SiW₁₁), was conventional synthesized and characterized by elemental analysis, IR, TG, and single crystal X-ray diffraction. In compound 1, two mono-substituted {SiW₁₁La(H₂O)₄O₃₉}₂ clusters (abbreviated to SiW₁₁La) polymerize together to form a dimer. And the dimers are linked by Ag⁺ and La³⁺ heterometallic cations displaying a 2D network. Furthermore, the photocatalytic experiment indicates that the title compound presents excellent photocatalytic activity towards degradation of rhodamine B (RhB) dye.     

Aluminum‐ and Gallium‐Containing Open‐Dawson Polyoxometalates

Al‐ and Ga‐containing open‐Dawson polyoxometalates (POMs), K₁₀[{Al₄(μ‐OH)₆}{α,α‐Si₂W₁₈O₆₆}] · 28.5H₂O ( Al₄ ‐ open ) and K₁₀[{Ga₄(μ‐OH)₆}(α,α‐Si₂W₁₈O₆₆)] · 25H₂O ( Ga₄ ‐ open ) were synthesized by the reaction of trilacunary Keggin POM, [A‐α‐SiW₉O₃₄]^10–, with Al(NO₃)₃ · 9H₂O or Ga(NO₃)₃ · nH₂O, and unequivocally characterized by single‐crystal X‐ray analysis, ²⁹Si and ¹⁸³W NMR, and FT‐IR spectroscopy as well as elemental analysis and TG/DTA. Single‐crystal X‐ray analysis revealed that the {M₄(μ‐OH)₆}⁶⁺ (M = Al, Ga) clusters were included in an open pocket of the open‐Dawson polyanion, [α,α‐Si₂W₁₈O₆₆]^16–, which was constituted by the fusion of two trilacunary Keggin POMs via two W–O–W bonds. These two open‐Dawson structural POMs showed clear difference of the bite angles depending on the size of ionic radii. In cases of both compounds, the solution ²⁹Si and ¹⁸³W NMR spectra in D₂O showed only one signal and five signals, respectively. These spectra were consistent with the molecular structures of Al₄ ‐ and Ga₄ ‐ open , suggesting that these polyoxoanions were obtained as single species and maintained their molecular structures in solution.     

Tripotassium tris­(oxalato‐κ2O,O′)­aluminate bis(hydrogen peroxide) hydrate,the first example of a cyclic hydrogen‐bonded H2O2 dimer

In addition to associating into cyclic hydrogen‐bonded dimers [O⋯O = 2.663 (1) and 2.914 (1) Å], each hydrogen peroxide mol­ecule in the title structure, K₃[Al(C₂O₄)₃]·1.75H₂O₂·0.25H₂O, hydrogen bonds to a neighbouring oxalate ligand [O⋯O = 2.700 (1) and 2.730 (1) Å] and coordinates to two K⁺ ions [K⋯O = 2.6620 (9)–2.8380 (7) Å].     

Some properties of potassium hexaniobates

The effects of KOH and K₂CO₃ concentrations in the solution and temperature on the solubilities of K₇[HNb₆O₁₉] · 10H₂O and K₈ [Nb₆O₁₉] · 16H₂O are studied. The structure of K₇[HNb₆O₁₉] · 13H₂O is established.     

Peroxide derivatives of heteropoly compounds with Keggin anions [PW<Subscript>12</Subscript>O<Subscript>40</Subscript>]<Superscript>3−</Superscript> and [SiW<Subscript>12</Subscript>O<Subscript>40</Subscript>]<Superscript>4−</Superscript>: Synthesis and structure

Peroxide derivatives of heteropoly compounds with Keggin anions [PW₁₂O₄₀]^3? and [SiW₁₂O₄₀]^4? are isolated in an individual state from concentrated hydrogen peroxide solutions and characterized by physicochemical methods. The structure of Ba₂[SiW₁₂O₄₀] · 4H₂O₂ · 11H₂O (I) is solved by X-ray crystallography. Crystals of compound I (H₃₀Ba₂O₅₉Si₁W₁₂, FW = 3483.21) are monoclinic, space group C2/c, a = 24.981(2) Å, b = 12.2103(11) Å, c = 18.7142(17) Å, β = 122.620(2)^o, V = 4808.0(8) ų, Z = 4. The structure contains Keggin anions [SiW₁₂O₄₀]^4?; all hydrogen peroxide molecules are coordinated to Ba²⁺ cations.     

Synthesis and Crystal Structure of K6.5H4.5[CeK2(SiW11O39)2]·26H2O

The title compound, K_6.5H_4.5[CeK₂(SiW₁₁O₃₉)₂]·26H₂O was prepared and its structure characterized by IR and single crystal X-ray structural analysis. It belongs to triclinic, space group P1 with a = 12.719(3) Å, b = 16.658(4) Å, c = 23.075(6) Å, α = 94.41(2)°, β = 98.90(2)°, γ = 92.40(2)°; V = 4809(2) Å^?3, Z = 2, Dc = 4.344 g cm^?3, μ = 27.170 mm^?1, F (000) = 5519. The results show that the cerium and two potassium atoms link the two anionic units SiW₁₁O^8? ₃₉ through O-Ce-O and O-K-O bridges and construct the double 1 : 11 series heteropolytungstate. Furthermore, cerium is coordinated to eight oxygen atoms (four O_c and four O_b) from two tetradentate SiW₁₁O^8? ₃₉ ligands forming a square anti-prism. The coordination numbers for K1 and K2 are 8 and 7, respectively.     

ChemInform Abstract: Revisiting the Polyoxometalate‐Based Late‐Transition‐Metal‐Oxo Complexes: The “Oxo Wall” Stands.

New XRD data of the previously published K₁₄[P₂W₁₉O₆₉(H₂O)] (I), the ¹⁷O NMR spectrum of (Bu₄N)₇[PW₁₁O₃₉], a careful titration of “K₇H₂ [Au(O)(OH₂)P₂W₂₀O₇₀ (OH₂)₂]” followed by ³¹P NMR spectroscopy, and a new X‐ray crystal structure of the compound reformulated as K₁₂ [PdWO(H₂O)(PW₉O₃₄)₂] (II) are reported.     

A series of new organic–inorganic compounds templated by the [SiW12O40]4− polyanion

Two couples of new compounds templated by the polyanion [SiW₁₂O₄₀]^4?,[Hbix][Cu^I(bix)]₃[SiW₁₂O₄₀]·4H₂O (1) and [Cu^II(H₂O)(Hbix)₂(bix)]₂[Cu^II(H₂O)₂(Hbix)₂(bix)][SiW₁₂O₄₀]₃·4H₂O (2) (bix = 1,4-Bis(imidazol-1-ylmethyl)benzene), [Cu^I(bbi)]₄[SiW₁₂O₄₀]·2H₂O (3) and [Cu^II(bbi₂)]₂[SiW₁₂O₄₀] (4) (bbi = 1,1′-(1,4-butanediyl)bis(imidazole)) were hydrothermally synthesized, and characterized by elemental analyses, IR spectroscopy, thermogravimetric analyses and single X-ray diffraction. Compounds 1 and 2 were synthesized from the same reactants but exhibited distinct structures which could be ascribed to the different ratios of the reactant bix to Cu^II. In compound 1, the higher ratio of bix results in the transformation of the Cu^II to Cu^I, the [SiW₁₂O₄₀]^4? templates direct the Cu^I–bix coordination polymers to form a 3D supramolecular framework with grid-like channels along two directions. The [SiW₁₂O₄₀]^4? templates in compound 2 locate in the voids of the 3D supramolecular network constructed by Cu^II–bix coordination polymers, which exhibits the interdigitation fashion in both the formation of the 2D layer and the 3D framework. Compounds 3 and 4 were synthesized similar to 1 and 2, except for the change of bix to bbi. In compound 3, the Cu^I–bbi polymers form a supramolecular metal–organic host framework with rhombic channels in which the SiW₁₂ templates reside. Compound 4 shows a framework with hexagonal channels constructed by Cu^II–bbi coordination polymers which accommodated the SiW₁₂ templates.     

ChemInform Abstract: Crystal Structure of Potassium Sodium Heptahydrogen Hexamolybdocobaltate(III) Octahydrate: An Extra‐Protonated B‐Series Anderson‐Type Heteropolyoxidometalate.

KNa[Co^III(OH)₇{Mo₆O₁₇}] ·8H₂O is obtained by ion‐exchange from a solution of K₃ [Co(μ₃‐OH)₆Mo₆O₁₈] ·7H₂O at ≈pH 1.4 using Amberlite IR120 ion exchange resin followed by concentrating the solution in a hot water bath.     

Two Bisupporting Keggin-Type POM-Based Hybrids Decorated by [Zn(phen)2]2+ Fragments

Two bisupporting Keggin-type polyoxoanion-based hybrids decorated by [Zn(phen)₂]²⁺ complexes, [Zn(phen)₂]₂(PW ₁₁ ^VI W^VO₄₀) (1) and K[Zn(phen)₂(H₂O)]₂(OH) (SiW₁₂O₄₀)·H₂O (2) (phen = 1,10′-phenanthroline), have been hydrothermally synthesized, and characterized by elemental analysis, IR spectra, UV–Vis spectrum, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis, and single-crystal X-ray diffraction. The structural analyses reveal that compound 1 consists of a 0D bisupporting Keggin-type heteropoly blue cluster obtained by using reductant glucose, which is grafted by two [Zn(phen)₂]²⁺ fragments; compound 2 presents a 1D infinite chain, which is constructed from bisupporting [SiW₁₂O₄₀]^4? polyoxoanions decorated by [Zn(phen)₂(H₂O)]²⁺ fragments and K⁺ ions. Additionally, the electrochemical behaviors of two compounds were studied.     

Synthesis and properties of two new 3D organic–inorganic hybrid compounds constructed from Keggin clusters,pyridine-2,3-dicarboxylate and Ag(I) ions

Two new three-dimensional (3D) organic–inorganic hybrid compounds [K₂Ag₈(pydc)₂(Hpydc)₂(H₂O)₄SiW₁₂O₄₀]·4H₂O (1) and (NH₄)₄[KAg₂(Hpydc) (H₂O)_4.5(H₂W₁₂O₄₀)]·4H₂O (2) [H₂pydc = pyridine-2,3-dicarboxylate], were conventionally synthesized and characterized by IR, TG, elemental analysis, and single-crystal X-ray diffraction technique. In 1, six-nucleus [Ag₆(Hpydc)₂]⁴⁺ and two-nucleus [Ag₂(pydc)₂]²⁻ are linked alternately through oxygen atoms of the carboxylic group leading to a grid-like 2D layer. These layers are supported by SiW₁₂ clusters, giving a unique 3D framework. In 2, each W₁₂ cluster connects five Ag ions and three K ions, and each Ag1 or Ag2 ion links three W₁₂ clusters, forming a double chain. Furthermore, these double chains are linked together through K⁺ ions to form a 3D framework. The solid-state luminescence properties of compounds 1, 2 and pyridine-2,3-dicarboxylate have been studied at room temperature.     

Keggin-Type Polyoxometalate Cluster Functionalized with Dinuclear M-H2biim (M = Cu, Ag) Metal–Organic Segments

Three inorganic–organic hybrid complexes, [Cu₂(H₂biim)₂(OH)₂]₂(SiW₁₂O₄₀)·2H₂O (1), [Cu₂(H₂biim)₂]₂(SiW₁₂O₄₀)·2H₂O (2) and [Ag₂(H₂biim)₂]₂(SiW₁₂O₄₀)·2H₂O (3) (H₂biim = 2, 2′-biimidazole), have been synthesized under hydrothermal conditions, and characterized by elemental analysis, IR, PXRD, TG and single-crystal X-ray diffraction. The crystallographic analysis reveals that in compounds 1–3, the Keggin polyanions [α-SiW₁₂O₄₀]^4? act as inorganic building blocks, which are linked with the dinuclear metal–organic units via Cu–O bonds in compound 1, or through supramolecular interactions in compounds 2 and 3. Compound 1 shows a 3D supramolecular structure constructed by net-like layers. Compounds 2 and 3 display 2D layer structures which were composed of wave-like chains. In addition, these compounds show electrochemical activities, and photoluminescence properties are measured in the solid state.