Synthesis and characterization of a coplanar-shaped hexa-CuII sandwiched arsenotungstate

An organic–inorganic coplanar-shaped hexa-Cu^II sandwiched hybrid, (H₂en){[Cu(en)₂]₂[Cu₂(en)₂Cu₄(H₂O)₂](B-α-AsW₉O₃₄)₂}?·?5H₂O (en?=?ethylenediamine) (1), has been synthesized via hydrothermal method and further characterized by IR spectroscopy, thermogravimetric analysis, and X-ray single-crystal diffraction. Single-crystal X-ray diffraction analysis shows that 1 contains an organic–inorganic hybrid polyoxoanion {Cu₂(en)₂Cu₄(H₂O)₂(B-α-AsW₉O₃₄)₂}^6?, which can be described as a coplanar-shaped hexa-Cu^II cluster sandwiched by two trivacant [B-α-AsW₉O₃₄]^9? fragments. Complex 1 represents a rare organic–inorganic coplanar-shaped hexa-Cu^II cluster sandwiched arsenotungstate. Magnetic susceptibility measurements indicate that 1 demonstrates ferromagnetic coupling interactions within the Cu^II centers.     

Synthesis,structure, and spectroscopic characterization of a 2-D organic–inorganic hybrid CuII–ErIII heterometallic arsenotungstate

An organic–inorganic hybrid Cu^II–Er^III heterometallic arsenotungstate Na₃[Cu(en)₂(H₂O)][Cu(en)₂]_1.5[H₃Er(α-AsW₁₁O₃₉)₂]·4H₂O (1) (en = ethylenediamine) has been hydrothermally synthesized and structurally characterized by elemental analyses, IR and UV spectra, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry and single-crystal X-ray diffraction. 1 displays an organic–inorganic 2-D sheet structure constructed by sandwich-type [H₃Er(α-AsW₁₁O₃₉)₂]⁸⁻ fragments and [Cu(en)₂]²⁺ connectors. From the topological viewpoint, if the [H₃Er(α-AsW₁₁O₃₉)₂]⁸⁻ fragments are viewed as 3-connected nodes and [Cu(en)₂]²⁺ connectors are considered as linkers, the 2-D sheet can be simplified into a 2-D (6,3)-network topology.     

Tungstoarsenate(III) polyoxoanions as inorganic ligands for polynuclear copper complexes

A trinuclear copper(II) complex and a tetranuclear copper(II) complex that each incorporate a 9-tungstoarsenate(III) polyoxoanion ligand and several 2,2′-bipyridine (2,2′-bpy) ligands co-crystallize as the acid form: H₄[{Cu(2,2′-bpy)}₃(α-AsW₉O₃₃)] · [{Cu(2,2′-bpy)₂}{Cu(2,2′-bpy)}₃(α-AsW₉O₃₃)] · 38H₂O (1). Compound 1 was obtained from a hydrothermal reaction employing the trivacant lacunary polyoxometalate [α-AsW₉O₃₃]^9? as a precursor. The α-isomeric form of the parent ion is retained in both product anions. Four different coordination modes are observed for the seven copper centers, with unusual structural distortions imposed by the steric bulk of the polyanion. Intra- and intermolecular π-stacking of the 2,2′-bpy ligands are both evident. Variable temperature magnetic susceptibility, magnetization and EPR data are consistent with very weak antiferromagnetic interactions between the copper centers that are likely mediated by the π-stacking of the 2,2′-bpy ligands.     

Two new polyoxometalate-based organic-inorganic hybrids: synthesis,crystal structure and characterization

Two new organic-inorganic hybrids, (4,4′-bipy)[Cu^I(2,2′-bipy)₂]₂[W₆O₁₉] (2,2′-bipy = 2,2′-bipyrine, 4,4′-bipy = 4,4′-bipyrine) (1) and (C₆H₅NO₂)₄{Mn^III(H₂O)}[As^IIIW₉O₃₃]₂{W(OH)}- {W(H₂O)}?～18H₂O (2), have been synthesized and characterized by elemental analysis, IR, TG, UV–Vis, XRPD, XPS, electrochemical analysis and single-crystal X-ray diffraction. Single crystal X-ray diffraction analysis shows that 1 is a new Lindqvist-type polyoxoanion bisupported by copper(I) coordination cations and 2,2′-bipy ligands and exhibits a three-dimensional (3-D) supermolecular framework by aromatic π–π stacking interactions. Compound 2 is constructed from a manganese(III)-substituted sandwich-type polyoxoanion based on [α-AsW₉O₃₃]^9? units and dissociative, protonated pyridine-4-carboxylic acid molecules, which act as the charge compensation cations. The cyclic voltammogram of 2 shows an irreversible redox process for Mn³⁺ ions.     

Two new 2-D frameworks based on tetra-copper(II)-substituted sandwich-type polyoxotungstate anions and [Cu2(dien)2(OH)]3+ cations

Two new organic–inorganic polyoxometalates [Cu(dien)(H₂O)]₂{[Cu₂(dien)₂(OH)]₂[Cu₄(B-α-XW₉O₃₃)₂]}·4H₂O (X?=?Sb, 1; X?=?As, 2) (dien?=?diethylenetriamine) were hydrothermally synthesized and characterized by elemental analysis, IR spectra, thermogravimetric (TG) analyses, and single-crystal X-ray diffraction. Both compounds are constructed from one four-coordinate [Cu(dien)(H₂O)]²⁺, one {[Cu₂(dien)₂(OH)]₂[Cu₄(B-α-XW₉O₃₃)₂]} building unit, and four water molecules of crystallization. Structural analysis shows that the sandwich-like polyoxotungstate cluster anions [Cu₄(B-α-XW₉O₃₃)₂]^10? are linked by six adjacent dimeric cations [Cu₂(dien)₂(OH)]³⁺ into a 2-D architecture with a (6,3)-connected topology. Magnetic measurements of 1 and 2 exhibit the presence of antiferromagnetic interactions within the tetranuclear-Cu^II cluster.     

A New Polynuclear Copper‐Complex‐Substituted Tungstoarsenate(V)

A new polynuclear copper‐complex‐substituted dimeric tungstoarsenate(V), H₂[{Cu(2,2′‐bpy)}₈(H₂O)₂(AsW₉O₃₄)₂] · 12H₂O ( 1 ) (2,2′‐bpy = 2,2′‐bipydine), was synthesized hydrothermally and its structure was determined by single‐crystal X‐ray diffraction. The title compound has Ci symmetry and consists of two trilacunary Keggin anions [α‐AsW₉O₃₄]^9– supported by eight copper complex cations. The compound was also characterized by IR and fluorescence spectroscopy, TG analysis, and magnetic measurements. The emission spectrum of the compound in solid‐state exhibits a redshift relative to those of Na₈[A‐HAsW₉O₃₄] · 11H₂O and the free ligand 2,2′‐bpy. Magnetic measurements of the compound indicate competing ferro‐ and antiferromagnetic intramolecular coupling among the Cu^II atoms in the cluster anion.     

A series of heterometallic 3d-4f polyoxometalates as single-molecule magnets

Three sandwich-like [Ln₂Fe₂(B-α-FeW₉O₃₄)₂]^10? clusters (Ln₂Fe₄, Ln = Dy (1), Ho (2), and Y (3)) were obtained by reacting Na₉[B-α-SbW₉O₃₃], Ln₂O₃, FeCl₃·6H₂O and KH₂PO₄. The [B-α-FeW₉O₃₄]^11? units were formed via the in situ conversion of lacunary polyoxometalates (POM) [B-α-SbW₉O₃₃]^9? and the Ln³⁺ ions were generated from the slow dissolution of Ln₂O₃, both of which play important roles in the synthesis of Ln₂Fe₄. Ln₂Fe₄ is the first 3d-4f cluster assembled from d-metal heteroatom-containing POM. The Dy₂Fe₄ cluster exhibits single-molecule magnet properties with an 80 K energy barrier in an optimal DC field. Cyclic voltammetry tests and controlled-potential coulometry experiments show that the polyoxometalate Fe heteroatom in clusters 1–3 is also electrochemically active.     

Two Hexa-Ni-Substituted AsW9O34 Clusters Functionalized by Organic Ligands

Hydrothermal reactions of trilacunary precursor A-α-AsW₉O₃₄ ^9? polyoxoanions and nickel ions in the presence of ethylenediamine (en = ethylenediamine) led to two new hexa-Ni-substituted Keggin-type tungstoarsenates [Ni₆(μ ₃-OH)₃(en)₃(H₂O)₆(B-α-AsW₉O₃₄)]·6H₂O (1) and [Ni₆(μ ₃-OH)₃(en)₃(H₂O)₆(B-α-AsW₉O₃₄)]·10H₂O (2), which have been characterized by elemental analyses, IR spectra, powder X-ray diffraction, thermogravimetric analyses and single-crystal X-ray diffraction. Crystal data for 1: hexagonal, R3c, a = b = 20.4379(5) Å, c = 21.5062(6) Å, β = 120º, V = 7779.8 (3) Å³ and Z = 6; for 2: momoclinic, P2₁/c, a = 13.4200(3) Å, b = 19.1428(5) Å, c = 22.8845(9) Å, β = 112.403(3)º, V = 5435.2(3) Å³ and Z = 4. Structural analyses reveal that the [Ni₆(μ ₃-OH)₃(B-α-AsW₉O₃₄)] clusters in 1 and 2 are covalently functionalized by neutral en ligands, in which two similar {Ni₆(μ ₃-OH)₃(en)₃(H₂O)₆}⁹⁺ cores have been observed by our lab. Notably, 1 and 2 represent the highest number of substituted transition metal ions in all known lacunary Keggin-type polyoxotungstoarsenate monomers.     

A 3D Polyoxometalate Network Based on the Tetra-CoII Sandwiched Phosphotungstate Units Linked by Cs+ Cations

A tetra-Co^II substituted sandwich-type polyoxotungstate (H₂TED)₂Cs₄[Co₄(H₂O)₂(B-α-HPW₉O₃₄)₂]·28H₂O (TED = triethylenediamine) has been hydrothermally synthesized and characterized by IR spectrum, elemental analysis, thermogravimetric analysis, powder X-ray diffraction and single-crystal X-ray diffraction, respectively. Single-crystal structure analysis reveals that the tetra-Co^II substituted sandwich-type phosphotungstate units [Co₄(H₂O)₂(B-α-PW₉O₃₄)₂]^10? are combined together by Cs⁺ cations giving rise to the 3D framework with the “sqc876” 3D net.     

Synthesis and characterization of hybrid organic-inorganic, dimeric tungstoantimonate, {[Cu(En)2(H2O)]2[Cu4Na2(H2O)2(OH)2](α-SbW9O33)2}6?1

The copper-substituted tungstoantimonate(III) [Cu(En)₂(H₂O)₂]₂[Cu(En)₂(H₂O)]{[Cu(En)₂ (H₂O)]₂[Cu₄Na₂(H₂O)₂(OH)₂][(??-SbW₉O₃₃)₂]} · 3H₂O (I) (En = ethylenediamine) has been synthesized and characterized by IR spectrum, elemental analysis, and XPS. X-ray single-crystal analyses were carried out on I, which crystallizes in the triclinic system, space group P-1, with a = 13.071(2) ?, b = 14.434(2) ?, c = 15.729(2) ?, ?? = 83.004(3)°, ?? = 71.237(2)°, ?? = 74.787(2)°, and Z = 1. The title polyanion consists of two [??-SbW₉O₃₃]^9? trivacant moieties joined together by an annular [Cu₄Na₂(H₂O)₂(OH)₂]^8? unit leading to a sandwich-type structural framework. The central belt of I contains two crystallography unique Cu²⁺ and four disordered Cu²⁺/Na⁺ ions which reduce the symmetry of the polyanion to C _2??.     

Reactions of trivacant lone-pair-containing tungstobismutate and electrochemical behaviors of its sandwich-type products

We report the crystal structure of dimeric precursor Na₁₂[(Na(H₂O)₂)₆(α-BiW₉O₃₃)₂] (1), and the interaction of this precursor with transition metal ions. Interaction of 1 with Cu²⁺ in neutral medium leads to the formation of a Hervé-type sandwich polyoxoanion [(Cu(H₂O))₃(α-BiW₉O₃₃)₂]^12? (2) in high yield. Interaction of 1 with M²⁺ (M?=?Zn, Ni, Co, Mn) in acidic aqueous medium leads to formation of Krebs-type sandwich polyoxoanions [(M(H₂O)₃)₂(WO)₂(β-BiW₉O₃₃)₂]^10? (3–6). Coordination geometry of the M²⁺ ions, counterions and precursors can affect the structure of products. In our experiments, only the interaction of 1 with Cu²⁺ forms a trisubstituted sandwich-type product. The method using [α-Bi^IIIW₉O₃₃]^9? as starting material is a convenient and effective route for the synthesis of sandwich-type tungstobismutates in high purity and yield. The electrochemical properties of these sandwich-type tungstobismutates in aqueous solution are described.     

Synthesis,crystal structure and magnetic properties of the cyano-bridged heteropolynuclear complex [{(Cu(dien))2Co(CN)6}n][Cu(dien)(H2O)Co(CN)6]n·5nH2O

The reaction of [Cu(dien)(H₂O)](NO₃)₂ with K₃[Co(CN)₆] leads to the cyano-bridged heteropolynuclear complex, [{(Cu(dien))₂Co(CN)₆}_n][Cu(dien)(H₂O)Co(CN)₆]_n·5nH₂O, {Cu₃Co₂}, whose crystal structure has been solved. The structure consists of two distinct ionic units, namely one-dimensional cationic chains [{(Cu(dien))₂Co(CN)₆}_n]ⁿ⁺, and discrete binuclear anionic entities [(H₂O)(dien)Cu–NC–Co(CN)₅]⁻. The cryomagnetic investigation of the title compound reveals a very weak antiferromagnetic coupling between the Cu(II) ions within the cationic chain (J=−1.02 cm⁻¹, g=2.14). The complete elimination of the water molecules from the isomorphous {Cu₃Co₂}, {Cu₃Fe₂} and {Cu₃Cr₂} complexes causes the modification of the magnetic properties. The most dramatic one is observed with the Cu(II)–Fe(III) system, where the magnetic behavior changes from ferro- to antiferromagnetic. The dehydrated chromium derivative preserves the ferromagnetic coupling, which is observed at lower temperatures (below 30 K) in comparison with the parent compound (below 150 K).     

Synthesis,crystal structure and properties of tungstoantimonates with CuII or NiII sandwiched by two [ α -SbW9O33]9− or [ β -SbW9O33]9− subunits

Two sandwich-type tungstoantimonates K₄Na₂H₃[Na₂K(H₂O)₂{Cu(H₂O)}₃(α-SbW₉O₃₃)₂]?·?15H₂O (1) and Na₄H₄[{Ni(H₂O)₃}₂{W(OH)₂}₂{β-SbW₉O₃₃}₂]?·?23H₂O (2) were prepared from aqueous solution by different strategies. They were characterized by X-ray structure analysis, electrochemical analysis, EPR and IR spectroscopy. Both compounds are sandwich-like tungstoantimonates built from two B-[SbW₉O₃₃]^9? building blocks. The polyoxoanion of 1 consists of two trivacant B-α-[SbW₉O₃₃]^9? moieties linked by three Cu²⁺ ions leading to a Hervé-type sandwich framework. The polyoxoanion in 2 is composed of two isomeric B-β-[SbW₉O₃₃]^9? subunits joined together by two Ni²⁺ and two W⁶⁺ ions resulting in a Krebs-type sandwich structure.     

A 2D organic-inorganic hybrid [Cu(En)2(H2O)]2[Cu(En)2]4[Si2Cu2W22O78]·7H2O assembled from monocopper(II)-substituted Keggin silicotungstate dimers

The reaction of Na₁₀[A-α-SiW₉O₃₄] · 18H₂O with CuCl₂ · 2H₂O in the participation of ethylenediamine (En) under hydrothermal conditions resulted in a 2D organic-inorganic hybrid monocopper(II)-substituted Keggin silicotungstate [Cu(En)₂(H₂O)]₂[Cu(En)₂]₄[Si₂Cu₂W₂₂O₇₈] · 7H₂O (I), which was structurally characterized by elemental analyses, IR spectrum, UV spectrum, powder X-ray diffraction (PXRD), and single-crystal X-ray diffraction. Single crystal structural analysis shows that adjacent monocopper(II)-substituted Keggin silicotungstate [Si₂Cu₂W₂₂O₇₈]^12? dimeric subunits are interconnected by sharing terminal oxygen atoms to make the 1D polymeric linear chain and neighboring chains are combined with each other through [Cu(En)₂]²⁺ connectors giving rise to an interesting 2D organic-inorganic hybrid sheet architecture with a 4-connected topology. To our knowledge, I is the rare organic-inorganic hybrid 2D polyoxometate constructed by mono-transition-metal substituted Keggin silicotungstate dimeric subunits. The photocatalytic measurement illustrates that I can to some extent inhibit the photodegradation of rhodamine-B.     

[Cu(mim)4]2[α-Mo8O26] – A layer-type octamolybdate framework

By reaction of (NH₄)₆Mo₇O₂₄·4H₂O, Cu(NO₃)₂·2.5H₂O and 1-methylimidazole (mim) under hydrothermal conditions the novel copper molybdate [Cu(mim)₄]₂[α-Mo₈O₂₆] is obtained in the form of blue, rectangular-shaped crystals. The title compound crystallizes with monoclinic lattice symmetry in the space group P2₁/n. The predominant structural feature of the title compound is a two-dimensional framework that is constituted by [α-Mo₈O₂₆]^4?octamolybdate units as framework nods and the copper complex [Cu(mim)₄]²⁺ as a linker. In addition to single-crystal structure analysis [Cu(mim)₄]₂[α-Mo₈O₂₆] is characterized by powder diffraction as well as by FT-IR and UV–vis spectroscopy.     

Two extended organic–inorganic hybrids based on sandwich tungstogermanates

Two inorganic–organic composite polyoxotungstates, [Cu(en)₂(H₂O)]₂[Cu(en)₂(H₂O)₂]-{[Cu(en)₂]₃[Cu₄(GeW₉O₃₄)₂]} · 10H₂O (1, en = ethylenediamine) and (H₂en){[Zn(en)₂]₄-[Zn₄(Hen)₂(GeW₉O₃₄)₂]} · 10H₂O (2), were hydrothermally synthesized and their structures determined by single-crystal X-ray diffraction. Compounds 1 and 2 consist of sandwich polyanions [Cu₄(B-α-GeW₉O₃₄)₂]^12? or [Zn₄(Hen)₂(GeW₉O₃₄)₂]^10? linked by [M(en)₂]²⁺ bridges to form 2-D networks, which are further packed into a 3-D supramolecular porous framework via extensive hydrogen bonding interactions. Their IR and UV spectra, thermal stabilities, and cyclic voltammograms were also investigated.     

Diamond‐ and Graphite‐Like Octacyanometalate‐Based Polymers Induced by Metal Ions

By using cyclohexane‐1,2‐diamine (chxn), Ni(ClO₄)₂ ? 6H₂O and Na₃[Mo(CN)₈] ? 4H₂O, a 3D diamond‐like polymer {[Ni^II(chxn)₂]₂[Mo^IV(CN)₈] ? 8H₂O}_n ( 1 ) was synthesised, whereas the reaction of chxn and Cu(ClO₄)₂ ? 6H₂O with Na₃[M^V(CN)₈] ? 4H₂O (M=Mo, W) afforded two isomorphous graphite‐like complexes {[Cu^II(chxn)₂]₃[Mo^V(CN)₈]₂ ? 2H₂O}_n ( 2 ) and {[Cu^II(chxn)₂]₃[W^V(CN)₈]₂ ? 2H₂O}_n ( 3 ). When the same synthetic procedure was employed, but replacing Na₃[Mo(CN)₈] ? 4H₂O by (Bu₃NH)₃[Mo(CN)₈] ? 4H₂O (Bu₃N=tributylamine), {[Cu^II(chxn)₂Mo^IV(CN)₈][Cu^II(chxn)₂] ? 2H₂O}_n ( 4 ) was obtained. Single‐crystal X‐ray diffraction analyses showed that the framework of 4 is similar to 2 and 3 , except that a discrete [Cu(chxn)₂]²⁺ moiety in 4 possesses large channels of parallel adjacent layers. The experimental results showed that in this system, the diamond‐ or graphite‐like framework was strongly influenced by the inducement of metal ions. The magnetic properties illustrate that the diamagnetic [Mo^IV(CN)₈] bridges mediate very weak antiferromagnetic coupling between the Ni^II ions in 1 , but lead to the paramagnetic behaviour in 4 because [Mo^IV(CN)₈] weakly coordinates to the Cu^II ions. The magnetic investigations of 2 and 3 indicate the presence of ferromagnetic coupling between the Cu^II and W^V/Mo^V ions, and the more diffuse 5d orbitals lead to a stronger magnetic coupling interaction between the W^V and Cu^II ions than between the Mo^V and Cu^II ions.     

Syntheses,solid state electronic and infrared spectra of the Ni(II), Pd(II) and Cu(II) complexes of N-(2-hydroxyethyl) and N-(3-hydroxypropyl) oxamide

The new complexes K₂[Ni(Hheo)₂], K₂[Cu(Hheo)₂]·H₂O, K₂[Ni(Hhpo)₂]·H₂O, K₂[M(Hhpo)₂]·0.5H₂O (M = Cu, Pd) and K₂[Cu₂(hpo)₂·0.5H₂O, where H₃heo = N-(2-hydroxyethyl)oxamide and H₃hpo = N-(3-hydroxypropyl)oxamide, have been prepared. Several synthetic routes were investigated and the complexes were characterized by analyses, conductivity measurements, thermogravimetry, magnetic susceptibility and spectroscopy (i.r. and far i.r., diffuse reflectance u.v.). Monomeric square planar structures are found for the [M(Hheo)₂]²⁻ and [M(Hhpo)₂]²⁻ complex anions, while the hpo³⁻ Cu(II) complex appears to be a square planar dimer. The doubly deprotonated Hheo²⁻ and Hhpo²⁻ ions exhibit a bidentate N(secondary amide), N′(tertiary amide)-coordination with the OH-group remaining uncoordinated, while the triply deprotonated hpo³⁻ ion behaves as a bridging N(secondary amide), N′(tertiary amide), O(deprotonated) ligand, while two Cu(II) centres are bridged by two alkoxide-O atoms. The vibrational analysis of the dehydrated complexes is carried out, using NH/ND, OH/OD, ⁵⁸Ni/⁶²Ni and ⁶³Cu/⁶⁵Cu substitutions.     

0-D and 1-D inorganic-organic composite polyoxotungstates constructed from in-situ generated monocopper-substituted Keggin polyoxoanions and copper-organoamine complexes

Combination of in-situ generated monocopper^II-substituted Keggin polyoxoanions with copper^II-organoamine complexes under hydrothermal conditions results in seven inorganic-organic composite polyoxotungstates [Cu(en)₂(H₂O)]₂{[Cu(en)₂][α-PCuW₁₁O₃₉Cl]}·3H₂O (1), {[Cu(en)₂(H₂O)][Cu(en)₂]₂[α-PCuW₁₁O₃₉Cl]}·6H₂O (2), {[Cu(en)₂(H₂O)]₂[Cu(en)₂][α-XCuW₁₁O₃₉]}·5H₂O (3/4, X=Si^IV/Ge^IV), {[Cu(deta)(H₂O)₂]₂[Cu(deta)(H₂O)][α-XCuW₁₁O₃₉]}·5H₂O (5/6, X=Ge^IV/Si^IV) and [Cu(dap)₂]₂{[Cu(dap)₂]₂[Cu(dap)₂][α-PCuW₁₁O₃₉]₂} (7) (en=ethylenediamine, dap=1,2-diaminopropane and deta=diethylenetriamine). 1 is an isolated structure whereas 2 is a 1-D chain structure, but both contain [α-PCuW₁₁O₃₉Cl]⁶⁻ polyoxoanions. 3-6 contain the 1-D linear chains made up of [α-XCuW₁₁O₃₉]⁶⁻ polyoxoanions in the pattern of -A-A-A- (A=[α-XCuW₁₁O₃₉]⁶⁻), while 7 demonstrates the first 1-D zigzag chain constructed from [α-PCuW₁₁O₃₉]₂¹⁰⁻ polyoxoanions via [Cu(en)₂]²⁺ bridges in the pattern of -A-B-A-B- (A=[α-PCuW₁₁O₃₉]₂¹⁰⁻, B=[Cu(en)₂]²⁺). The successful syntheses of 1-7 can provide some experimental evidences that di-/tri-/hexa-vacant polyoxoanions can be transformed into mono-vacant Keggin polyoxoanions under hydrothermal conditions.     

一个新的夹心型杂多钨酸盐Na6(C5N2H7){[Na(H2O)2]3Co(H2O)5-[Co(H2O)]3(AsW9O33)2}•27H2O的晶体结构及性质

在pH＝7.5的水溶液中, Na₂WO₄•2H₂O, NaAsO₂, CoCl₂•6H₂O与对氨基吡啶反应, 得到了一种新的夹心型杂多钨酸盐Na₆(C₅H₇N₂){[Na(H₂O)₂]₃Co(H₂O)₅[Co(H₂O)]₃(AsW₉O₃₃)₂}•27H₂O单晶, 用X射线单晶衍射法及元素分析确定了其结构, 晶体属三斜晶系, P 空间群, 其晶胞参数为: a＝1.3276(8) nm, b＝1.7581(10) nm, c＝2.4381(14) nm, α＝70.954(9)°, β＝86.663(9)°, γ＝72.885(9)°, V＝5.136(5) nm³, Z＝2, R₁＝0.0608, wR₂＝0.0848 [I＞2σ(I)]. 在{[Na(H₂O)₂]₃Co(H₂O)₅[Co(H₂O)]₃(AsW₉O₃₃)₂}^7－阴离子中, 一个Co^2＋与聚阴离子{[Na(H₂O)₂]₃[Co(H₂O)]₃(AsW₉O₃₃)₂}^9－的一个端基氧共价连接, Co^2＋呈现出5和6两种配位数, 质子化的氨基吡啶正离子作为抗衡离子存在于晶体之中. 对标题化合物进行了IR, UV-Vis, TG-DSC表征. 对该化合物、Na₂WO₄•2H₂O及CoCl₂•6H₂O催化H₂O₂氧化乙醛的活性进行了比较研究, 该化合物的催化活性远优于简单化合物Na₂WO₄•2H₂O和CoCl₂•6H₂O.