Synthesis and characterization of one- to three-dimensional compounds composed of paradodecatungstate-B cluster and transition metals as linkers

Three new extended frameworks built from paratungstate and transition metals have been synthesized and characterized. In the compound Na₈[{Cd (H₂O)₂}(H₂W₁₂O₄₂)]·32H₂O (1), two neighboring paratungstate-B ions [H₂W₁₂O₄₂]¹⁰⁻ are linked by [Cd(H₂O)₂]²⁺ units, leading to the formation of infinite one-dimensional (1D) anion chain [{Cd(H₂O)₂}(H₂W₁₂O₄₂)]_n⁸ⁿ⁻. The anion [{Co(H₂O)₃}{Co(H₂O)₄}(H₂W₁₂O₄₂)]_n⁶ⁿ⁻ of the compound Na₆[{Co(H₂O)₃}{Co(H₂O)₄}(H₂W₁₂O₄₂)]·29H₂O (2) shows a layer-like (2D) structure in which paratungstate-B units are linked by CoO₆ octahedra, while the anion [{Co(H₂O)₃}₃(H₂W₁₂O₄₂)]_n⁴ⁿ⁻ of the compound (H₃O⁺)₃[{Na(H₂O)₄}{Co(H₂O)₄}₃(H₂W₁₂O₄₂)]·24.5H₂O (3) is a three-dimensional (3D) anionic polymer that consists of paratungstate-B units linked by CoO₆ octahedra. Compound 3 can reversibly adsorb and desorb water molecules leading to the color reversibly change from pink to violet. The preliminary magnetic measurement and electrochemical properties of compounds are performed. The crystal structure of unexpected product Na₄[NiW₆O₂₄H₆]·13H₂O (4) is described here for the rare report of crystal structure information on the Anderson-type polyoxotungstate which has nickel as a heteroatom.     

Synthesis and characterization of homo- and heterobimetallic niobium and tantalum peroxo-polyaminocarboxylato complexes and their use as single or multiple molecular precursors for Nb-Ta mixed oxides

New water-soluble bimetallic peroxo complexes of niobium^V and/or tantalum^V with high-denticity polyaminocarboxylate ligands have been prepared, characterized from the spectroscopic point of view, and used as molecular precursors for Nb-Ta mixed oxides. Four new homobimetallic complexes, (gu)₃[Nb₂(O₂)₄(dtpaO₃)]·3H₂O 1, (gu)₃[Ta₂(O₂)₄(dtpaO₃)]·5H₂O 2, (gu)₃[Nb₂(O₂)₄(HtthaO₄)]·2H₂O 4 and (gu)₃[Ta₂(O₂)₄(HtthaO₄)]·3H₂O 5 and the corresponding heterometallic complexes, (gu)₃[NbTa(O₂)₄(dtpaO₃)]·2.5H₂O 3 and (gu)₃[NbTa(O₂)₄(HtthaO₄₎]·2H₂O 6 have been obtained. In these compounds, the in situ oxidation of the nitrogen atoms of the PAC ligands into N-oxide groups has been evidenced by IR spectroscopy and mass spectrometry. The thermal treatment of the homonuclear complexes in air at 700 or 800 °C, depending on the Ta content, provided Nb₂O₅ or Ta₂O₅ while the heteronuclear compounds led to the solid solution TaNbO₅. BET and SEM measurements have been carried out and comparison of the morphology of the samples prepared from homo- and heterometallic precursors is discussed.     

Structure and characterization of zero- to two-dimensional compounds built up of the sandwich-type clusters and transition-metal linkers

Five new heteropolyoxotungstates K₂Na₂Mn₂(H₂O)₁₂[Mn₂(H₂O)₁₀Mn₄(H₂O)₂(XW₉O₃₄)₂]·18H₂O (X=Ge, 1; X=Si, 2), Na₄[Mn₄(H₂O)₁₈Mn₄(H₂O)₂(XW₉O₃₄)₂]·22H₂O (X=Ge, 3; X=Si, 4) and K₃Na₅[Mn₂(H₂O)₆Mn₄(H₂O)₂(SiW₉O₃₄)₂]·23.5H₂O (5) have been obtained by the routine synthetic reactions in aqueous solution. In 1 and 2, two isolated Mn²⁺ ions are covalently linked to the sandwich-type polyoxoanions [Mn₄(H₂O)₂(B-α-XW₉O₃₄)₂]¹²⁻ (X=Ge or Si) by two μ₂-oxygen atoms resulting in the disupporting sandwich-type polyoxometalates (POMs). Compounds 3 and 4 are built from the disupporting sandwich-type polyoxoanions 1 and 2, linked by additional four Mn²⁺ ions to construct a 1D ladder-like chain-like structure, which is rarely observed in the POM chemistry. Compound 5 represents the first example of the 2D structure consisting of the sandwich-type polyoxoanion [Mn₄(H₂O)₂(SiW₉O₃₄)₂]¹²⁻ and the binuclear {Mn₂(H₂O)₆}⁴⁺ group. The magnetic studies of compounds 1, 4 and 5 indicate that the antiferromagnetic interactions are predominant in the three compounds between Mn(II) metal ions.     

Two highly connected POM-based hybrids varying from 2D to 3D: The use of the isomeric ligands

Through employing two isomeric ligands, isonicotinic acid (HINA) and nicotinic acid (HNA), with different electron delocalization nature, two high-dimensional hybrids based on highly connected α-metatungstate clusters, [Na₂(H₂O)₈Ag₂(HINA)₃(INA)][Na(H₂O)₂Ag₂(HINA)₄(H₂W₁₂O₄₀)]·2H₂O (1) and [Na₂(H₂O)₄Ag₆(HNA)₂(NA)₂(H₂W₁₂O₄₀)]·8H₂O (2), have been conventionally synthesized and structurally characterized. 1 exhibits an unusual 1D-in-2D pseudo-polyrotaxane entangled structure, namely, the 2D sheets [Na(H₂O)₂Ag₂(HINA)₄(H₂W₁₂O₄₀)]_n³ⁿ⁻ are penetrated by enantiomorphous meso-helical chains [Na₂(H₂O)₈Ag₂(HINA)₃(INA)]_n³ⁿ⁺. In the 2D sheets, each [H₂W₁₂O₄₀]⁶⁻ cluster is surrounded by six Ag and two Na atoms. 2 exhibits a 3D (4, 6)-net structure with (3²6²7²)(3²4⁴5⁴6⁴7)(3²4⁴6⁸7) topology, in which each [H₂W₁₂O₄₀]⁶⁻ cluster is connected with ten Ag atoms. These facts indicate that the isomeric ligands play a key role in the formation of final structures. From 1 to 2, the connection number of the [H₂W₁₂O₄₀]⁶⁻ cluster changes from 8 to 10 and the dimensionality increases from 2 to 3. Moreover, 1 and 2 display photoluminescent properties in the blue range at room temperature.     

Ionothermal syntheses of three transition-metal-containing polyoxotungstate hybrids exhibiting the photocatalytic and electrocatalytic properties

Employing the ionothermal synthesis approach, three new transition-metal-containing polyoxotungstate hybrids: [Dmim]₂Na₃[SiW₁₁O₃₉Fe(H₂O)]·H₂O (Dmim=1,3-Dimethylimidazole) (1), [Emim]₉Na₈[(SiW₉O₃₄)₃{Fe₃(μ₂-OH)₂(μ₃-O)}₃(WO₄)]·0.5H₂O(Emim=1-Ethyl-3-meth-ylimidazole) (2) and [Dmim]2[HMim]Na₆[(AsW₉O₃₃)₂{Mn^III(H₂O)}₃]·3H₂O (Dmim=1,3-Dimethylimidazole; Mim=1-Methylimidazole) (3) have been synthesized in 1-ethyl-3-methyl imidazolium bromide ([Emim]Br) ionic liquids (ILs). Compound 1 possesses a 3-D open framework constructed from the mono-iron^III-substituted α-Keggin-type anion and the organic cations [Dmim]+ through the hydrogen bond interactions. Compound 2 contains a [{Fe^III₃(μ₂-OH)₂(μ₃-O)}₃(μ₄-WO₄)] cluster surrounded by three [SiW₉O₃₄]¹⁰⁻ ligands, eight sodium cations and nine dissociative [Emim]⁺ cations around the polyoxoanion. The polyoxoanion of 3 consists of a high-valent trinuclear-manganese (III)-substituted sandwiching polyoxoanion based on the [α-AsW₉O₃₃]⁹⁻ units. All the compounds are characterized by elemental analyses, IR, UV-vis spectra, TG-DTA and XRD analyses. The XPS and EPR spectra of Mn^III in 3 were studied. The photocatalytic and electrocatalytic properties, as well as the stabilities of 1-3 were also investigated.     

Syntheses, structures and properties of 3D inorganic-organic hybrid frameworks constructed from lanthanide polymer and Keggin-type tungstosilicate

Inorganic-organic hybrid frameworks, namely [Ce(H₂O)₃(pdc)]₄[SiW₁₂O₄₀]·6H₂O 1, [M(H₂O)₄(pdc)]₄[SiW₁₂O₄₀]·2H₂O (M=Ce for 2a, La for 2b, Nd for 2c; H₂pdc=pyridine-2,6-dicarboxylic acid) were assembled through incorporation of Keggin-type heteropolyanion [SiW₁₂O₄₀]⁴⁻ within the voids of lanthanides-pdc network as pillars or guests under hydrothermal condition. Single-crystal X-ray analyses of these crystals reveal that compound 1 presents 3D pillar-layered framework with the [SiW₁₂O₄₀]⁴⁻ anions located on the square voids of the two-dimensional Ce-pdc bilayer. Compounds 2a-c are isostructural and constructed from 3D Ln-pdc-based metal-organic framework (MOF) incorporating noncoordinating guests Keggin structure [SiW₁₂O₄₀]⁴⁻. Solid-state properties of compounds 1 and 2a-c such as thermal stability and photoluminescence have been further investigated.     

Assemblies based on the directing effect of non-classical W18 anionic clusters and the rod-like trans-1,2-di-(4-pyridyl)-ethylen (bpe)

Two polyoxometalate (POM) supramolecular assemblies based on W₁₈ clusters and the rigid organic trans-1,2-di-(4-pyridyl)-ethylen (bpe) have been synthesized and fully characterized, namely (H₂bpe)3.5H₂[SbW₁₈O₆₀]·5H₂O (1), and (H₂bpe)5[Ni₄(AsW₉O₃₄)₂(H₂O)₂]·3H2O (2). Compounds 1-2 are formed from organic bpe cations and different polytungstate anions: pseudo-Dawson-type [SbW₁₈O₆₀]⁹⁻ in 1 and sandwich-type [Ni₄(H₂O)₂(AsW₉O₃₄)₂]¹⁰⁻ in 2. Both of compounds 1-2 crystallize in a low-symmetrical space group of P-1 and consist of a complicated supramolecular network based on non-covalent intermolecular weak interactions, including hydrogen bonding and π···π stacking. The multipoint hydrogen bonding interactions constitute the structural feature in two supramolecular frameworks. The UV-vis, fluorescence and electrochemistry properties are also studied.     

Polyoxometalate immobilization in Cu/Ag-pz porous coordination polymers: The influences of them on the structural properties of frameworks

Three new high dimensional Cu^I/Ag-pz porous coordination polymers (PCPs) with different Keggin polyoxometalate templates have been hydrothermally synthesized: [Cu^I₅(pz)₆Cl][HPMo^VI₁₀Mo^V₂O₄₀] (1) [Ag₅(pz)₇(BW₁₂O₄₀)] (2) and [Cu^I₅(pz)₆H(H₂W₁₂O₄₀)]·4H₂O (3) (pz=pyrazine). The choice of the particular Keggin POM templates is shown to influence the structural properties of the Cu/Ag PCPs. Compound 1 shows a Cl-bridged Cu-pz-Cl double layer, between which two kinds of [HPMo^VI₁₀Mo^V₂O₄₀]⁴⁻(PMo₁₂) polyanions are located. Compound 2 presents a 3D Ag-pz framework with parallelogram-like voids, into which BW₁₂O₄₀⁵⁻ (BW₁₂) Keggin ions are incorporated. Compound 3 contains a Cu-pz cationic layer framework, between which are located [H(H₂W₁₂O₄₀)]⁵⁻ (W₁₂) Keggin ions. Primary photocatalytic experiment indicates that compound 1 presents excellent photocatalytic activity. The photoluminescence properties and electrochemistry properties of the compounds are also discussed.     

Syntheses,crystal structures and properties of tetrahydrofuran-2,3,4,5-tetracarboxylato bridged copper(II) coordination polymers with alkali metals

Four tetrahydrofuran-2,3,4,5-tetracarboxylato bridged copper(II) coordination polymers with alkali metals, Na₂[Cu(H₂O)(THFTC)]·5H₂O 1, K₂[Cu₃(H₂O)₂(THFTC)₂]·9H₂O 2, Rb₂[Cu₃(H₂O)₂(THFTC)₂]·6H₂O 3 and Cs₂[Cu₃(H₂O)₂(THFTC)₂]·6H₂O 4 (H₄THFTC = tetrahydrofuran-2,3,4,5-tetracarboxylic acid) were prepared from reactions of Cu(NO₃)₂·3H₂O, tetrahydrofuran-2,3,4,5-tetracarboxylic acid and alkali hydroxide or carbonate at pH 5.0–6.0 under ambient conditions. Compound 1 features 2D (3³·4³·5⁴) topological layers generated from six-coordinated Cu²⁺ cations interlinked by (THFTC)⁴⁻ anions, and the resulting layers are ecliptically stacked along [1 0 0] direction to form lozenge-shaped and octagonal channels filled with Na⁺ ions and lattice H₂O molecules. In 2–4, both penta- and hexa-coordinated copper(II) ions are bridged by tetracarboxylate anions to form negatively charged 2D layers formulated as ²_∞[Cu(H₂O)₂L_3/2]²⁻ with the corresponding alkali metal cations (K⁺, Rb⁺ or Cs⁺ ions) and hydrogen bonded lattice H₂O molecules sandwiched between them. Additionally, the results about i.r. spectroscopic, thermal characterizations and magnetic properties are presented.     

Syntheses, structures and photoelectronic properties of a series of tri- and tetra-nuclear metal complexes based on a 36-membered tetraphenol macrocyclic ligand

In this article, tetranuclear Zn^II coordination complexes [Zn₄L(μ₂-OH)₂]·2(NO₃)·6(CH₃OH)·H₂O (1) and [Zn₄L(μ₂-OH)₂(H₂O)₂]·(p-bdc)·2(CH₃OH)·3H₂O (2), dinuclear Zn^II complex [Zn₄L(NH₂-bdc)₂]·2(CH₃OH)·3H₂O (3), and trinuclear Cd^II complexes [Cd₃L(m-bdc)]·6.5H₂O (4) and [Cd₃L(NH₂-bdc)]·5.5H₂O (5), based on a tetraphenol 36-membered macrocycle (L) having four ethylenediamine and four 2,6-diformyl-4-methylphenol functionalities, have been synthesized at room temperature (p-bdc = 1,4-benzenedicarboxylate, NH₂-bdc = 5-aminoisophthalate and m-bdc = 1,3-benzenedicarboxylate). In 1 and 2, four Zn^II centers are bridged by phenoxide and hydroxy atoms of the L ligands to form tetranuclear Zn^II complexes. The inorganic and organic anions in 1 and 2 do not coordinate to Zn^II centers, but act as counter anions. In 3, two Zn^II centers are bridged by two phenoxide O atoms to form a Zn^II cluster (Zn₂O₂N₄). Moreover, two (Zn₂O₂N₄) clusters within the ring of the L ligand are further bridged by two NH₂-bdc anions in a monodentate fashion. Compound 4 possesses the trinuclear Cd^II clusters (Cd₃N₈O₈), which has a similar structure to compound 5. The trinuclear Cd^II clusters are bridged by the dicarboxylate anions to yield an infinite coordination polymers chain. The photoelectric transfer properties of complexes 1, 2 and 4 were investigated by surface photovoltage spectroscopy (SPS) and the field-induced surface photovoltage spectra (FISPS) techniques. The results reveal that the complexes exhibit positive surface photovoltage (SPV) responses in the range of 300-600 nm, possessing the p-type semiconductor characteristics. So far, the surface photovoltage properties of the macrocycle complexes based on tetraphenol macrocyclic ligands were investigated for the first time. Moreover, elemental analyses, IR spectra, and luminescent properties of these compounds were also studied.     

Chains,helices, sheets and unusual 3D nets: Diverse structures of the flexible,ditopic ligand 1,2-bis(3-(4-pyridyl)pyrazolyl)ethane

The flexible ditopic ligand 1,2-bis(3-(4-pyridyl)pyrazol-1-yl)ethane (L^4Et) displays remarkable versatility in the complexes that it forms with transition metals with products ranging from 1D chains to interpenetrating 3D networks. The L^4Et ligand itself crystallises in the space group P2₁, adopting a helical twist, although it is found in a variety of other conformations in its complexes. Coordination polymers containing the L^4Et ligand vary from almost straight, parallel 1D chains of [Ag₂(L^4Et)₂(ClO₄)₂(DMF)]·DMF (1), through interdigitating helical complexes containing tetrahedral Zn(II), [Zn(NCS)₂(L^4Et)]·DMF·H₂O (2) to 2D sheets of [Cu(L^4Et)₂(H₂O)₂](PF₆)₂·xH₂O (3) and the three-fold interpenetrating 3D network of [Co(L^4Et)₂(NCS)₂] (4). The 3D network adopts an unusual 3D 4-connected dmp (6⁵.8) topology. Dimensionality can be limited by the use of chelating co-ligands, demonstrated by the formation of the dinuclear complex [{Cu(py-2,6-CO₂)(H₂O)}₂(L^4Et)] (5).     

A series of new supramolecular structures constructed from triethylenediamine and different polyoxometalates

Three new supramolecular compounds based on triethylenediamine and different polyoxometalates [W^VI₃V^V₃O₁₉H]{[Cu(HDABCO)]₂(H₂O)} (1), [P₂Mo^VI₁₈O₆₂][HDABCO]₂[H₂DABCO]₂·12 H₂O (2) and [Mo^VI_7.5W^VI_0.5O₂₇][Cu(HDABCO)]₂·2 H₃O·2 H₂O (3) (DABCO=triethylenediamine) have been synthesized hydrothermally and characterized by IR, TG, XPS and X-ray diffraction analyses. Crystal structure analyses reveal that compound 1 exhibits a face-centered cubic packing motif, compound 2 displays a supramolecular structure constructed form the “chains” arranged hexagonally, compound 3 contains [Mo_7.5W_0.5O₂₇]_∞ chain decorated by [Cu(HDABCO)]²⁺ cations, which was then packed into a layer structure. These results show that the same organonitrogen combining with the different POMs will yield different supramolecular networks.     

A series of pure inorganic eight-connected self-catenated network based on Silverton-type polyoxometalate

In this paper, three pure inorganic eight-connected self-catenated networks based on the Silverton-type polyoxometalate [CeMo₁₂O₄₂]⁸⁻ with lanthanide, transition metal and alkali metal cations as linkers: [Li(H₂O)₄]₂Co(H₂O)₄Ce(H₂O)₃[CeMo₁₂O₄₂]·3H₂O (1), H_0.5[Li(H₂O)₄]_2.5[Ni(H₂O)₄]_0.5Ce(H₂O)₃[CeMo₁₂O₄₂]·3H₂O (2) and H[Li(H₂O)₄]₃Ce(H₂O)₃[CeMo₁₂O₄₂]·3H₂O (3) have been successfully synthesized and characterized by elemental analysis, IR spectroscopy, thermal gravimetric analysis, X-ray photoelectron spectroscopy, electrochemical analyses and single crystal X-ray diffraction. The single crystal X-ray diffraction analyses reveal that compounds 1-3 are isostructural. The [Ce^IVMo₁₂O₄₂]⁸⁻ polyoxoanions are connected by Ce⁴⁺ to form the infinite 1D chains. And then the parallel stacking chains linked by transition metal cations and lithium ions construct to an eight-connected self-catenated 4²⁴56³ topology framework.     

Synthesis,crystal structures and spectroscopic studies of praseodymium(III) malonate complexes

Reactions of malonic acid (H₂mal) with PrCl₃·6H₂O afforded the known complex [Pr₂(mal)₃(H₂O)₆]_n (1), and compounds [Pr₂(mal)₃(H₂O)₆]_n·2nH₂O (2·2nH₂O), [PrCl(mal)(H₂O)₃]_n·0.5nH₂O (3·0.5nH₂O) and [Pr(mal)(Hmal)(H₂O)₃]_n·nH₂O (4·nH₂O) using various reaction ratios, reaction media (H₂O, MeOH) and pH values. Analogous reactions with CeCl₃·7H₂O afforded compounds [Ce₂(mal)₃(H₂O)₆]_n (5), [CeCl(mal)(H₂O)₃]_n·nH₂O (6·nH₂O) and [Ce(mal)(Hmal)(H₂O)₃]_n·nH₂O (7·nH₂O). Compounds 2·2nH₂O and 3·0.5nH₂O were characterized by X-ray crystallography, and 4–7 by microanalytical and spectroscopic data. The malonate(-2) ligand adopts three different coordination modes in the structures of 1–3, i.e., the μ₂-κO:κO′:κO″ and the μ₄-κ²O:κO′:κ²O″:κO? in 1 and 2 leading to a 3D network structure, and the μ₃-κ²O:κO′:κ²O″:κO? in 3 promoting an 1D structure. The thermal decomposition of 1 and 3·0.5nH₂O was monitored by TG/DTA and TG/DTG measurements. The structural features of 1–3 are discussed in terms of known malonato(-2) Ln^III and Ca^II complexes. The bioinorganic chemistry relevance of our results is discussed.     

Infinite chains constructed from flexible bis(benzimidazole)-based ligands

Two neutral ligands, L¹ · 2H₂O and L² · H₂O, and seven complexes, [Cu(pmb)₂(L¹)] (1), [Cu(pmb)₂(L²)] (2), [Cu(Ac)₂(L²)] · 4H₂O (3), [Cu(4-aba)₂(L²)] (4), [Ag(4-ts)(L¹)(H₂O)] (5), [Ag₂(epes)₂(L¹)] · 2H₂O (6), [Ag(1,5-nds)_0.5(L²)] · 0.5C₂H₅OH · H₂O (7) [where L¹ = 1,1′-(1,4-butanediyl)bis(2-methylbenzimidazole); L² = 1,1′-(1,4-butanediyl)bis(2-ethylbenzimidazole), pmb = p-methoxybenzoate anion; Ac = acetate anion; 4-aba = 4-aminobenzoate anion; 4-ts = p-toluenesulfonate anion; epes = N-(2-hydroxyethyl)piperazine-N′-(2-ethanesulfonate) anion; 1,5-nds = 1,5-naphthalenedisulfonate anion], have been synthesized and characterized by elemental analysis, IR, and single-crystal X-ray diffraction. The L¹ and L² ligands in compounds 1–7 act as bridging ligands, linking metal ions into chain structures. The chains in compounds 3, 4 and 6 interlace with each other by hydrogen bonds to generate 3D supramolecular structures. In compound 5, π–π interactions between adjacent L¹ ligands hold the chains to a supramolecular layer. In compound 7, the sulfonate anions act as counterions in the framework. The thermal stabilities of 3, 6 and 7, and the luminescent properties for 5–7 in the solid states are also discussed.     

Insertion-release of guest species and ionic conduction in polyoxometalate solids with a layer-like Anderson structure

The precipitation of Na⁺ and K⁺ mixed salts of Anderson type [SbW₆O₂₄]⁷⁻ by addition of excess of NaNO₃ and NaCl yielded polycrystalline powders of Na_2.5K_5.3[SbW₆O₂₄](NO₃)_0.8·12H₂O (1) and Na₂K_5.35[SbW₆O₂₄]Cl_0.35·12H₂O (2), respectively. The two compounds are isomorphous and exhibit a layer-like Anderson (LLA) type structure, which consists of [SbW₆O₂₄]⁷⁻-containing layers and interstitial Na⁺, K⁺, NO₃⁻ or Cl⁻, and water O atoms. Recrystallization of 1 and 2 from hot water yielded Na₂K_5.4[SbW₆O₂₄](NO₃)_0.4·12H₂O (1-recry) and Na₂K_5.25[SbW₆O₂₄]Cl_0.25·12H₂O (2-recry) as a result of partial release of NO₃⁻ and Cl⁻ (and Na⁺ and K⁺ for charge compensation). Dehydration of 1 and 2 at 400 and 500 °C (1-dehyd400 and 2-dehyd500) caused a shrinkage of lattice, but their the LLA structures retained. Simulation of X-ray diffraction (XRD) patterns for the dehydrated forms allowed to presume that the each [SbW₆O₂₄]⁷⁻ anion had been 30°-rotated within its molecular plane in order to avoid intermolecular repulsion. A compressed powder of 1-dehyd400 exhibited fast alkaline-ion conduction with a bulk conductivity of 1.2×10⁻² Ω⁻¹ cm⁻¹ at 400 °C. The hosting of a sufficient amount of NO₃⁻ together with Na⁺ for charge compensation into the lattice is crucial for high conduction.     

Synthesis and characterization of a three-dimensional framework built up of paradodecatungstate-B clusters and transition metals as linkers

A novel paradodecatungstate compound, namely [Na₂(H₂O)₁₀][Cu₄(H₂O)₁₂(H₂W₁₂O₄₂)]·15H₂O (1) has been synthesized by convenient aqueous solution method and structurally characterized by single-crystal X-ray diffraction, IR spectra, elemental analysis, thermogravimetric analysis, and differential thermal analysis. Single-crystal X-ray diffraction reveals that in compound 1, the [H₂W₁₂O₄₂]^10? anions are connected via divalent copper cation as purely inorganic linker to form a three-dimensional structural network. In addition, compound 1 exhibits strong photoluminescent emission at room temperature.     

Molecular architecture based on manganese triangles: Monomer, dimer, and one-dimensional polymer

The reaction of salicylaldoxime (H₂salox) with MnCl₂·4H₂O and NEt₄OH in MeOH affords the trinuclear manganese complex (NEt₄)[Mn₃O(salox)₃(MeOH)₂(H₂O)₂Cl₂]·MeOH (1·MeOH). A similar reaction of 1·MeOH was carried out using MnBr₂·4H₂O to obtain the hexanuclear manganese complex (NEt₄)₃{NaBr₂[Mn₃O(salox)₃(H₂O)₄Br₂]₂} (2). The reaction of 2-hydroxy-4-methoxybenzaldehyde oxime (4-MeO-H₂salox) and Mn(ClO₄)₂·6H₂O with 1,2-di(4-pyridyl)ethylene (dpe) in MeOH/DMF mixtures yields the one-dimensional complex {[Mn₃O(4-MeOsalox)₃(dpe)_1.5(DMF)₂(H₂O)](ClO₄)}_n (3·DMF·H₂O). Complex 1·MeOH shows a typical structure of a [Mn^III₃O]⁷⁺ core, and complex 2 contains a dimer [Mn^III₃O]⁷⁺ core connected by a Na⁺ ion. Complex 3 has a one-dimensional chain structure constructed from [Mn^III₃O]⁷⁺ units linked by dpe ligands. Magnetic analysis shows that all three complexes exhibit antiferromagnetic interactions between the Mn^III ions.     

Pentacyanido(L)ferrate(III) complexes: Crystal structures, electrochemical and DFT studies (L = pyrazine, 4,4′-bipyridine, azide)

The crystal structures of two pentacyanido(L) ferrate(III) complexes, [P(C₆H₅)₄]₂[Fe(CN)₅(prz)]·4H₂O 1, [P(C₆H₅)₄]₂[Fe(CN)₅(4,4′-bipy)]·3H₂O 2, have been solved. Within the two complex anions the iron atoms are hexacoordinated by five cyanido ligands, the sixth position being occupied by the nitrogen atom arising from pyrazine and, respectively, 4,4′-bipyridine. The electrochemical properties of compounds 1, 2 and of the azido derivative, (Ph₄As)₂[Na(H₂O)₄][Fe(CN)₅(N₃)] 3, have been investigated by cyclic voltammetry. A relatively complicated redox behavior of these complexes was found, due especially to the electron transfer involving the central metallic ion that changes reversibly its oxidation state (Fe^III/Fe^II redox site) and also to the coligand (4,4′-bipyridine, pyrazine or azide) which intervenes in a distinct electron transfer. The experimental data have been rationalized through DFT calculations.     

Two new hydrogen bond-supported supramolecular compounds assembly from arsenic vanadates and [M(H2O)6] cations (MCo, Ni)

Two new supramolecular compounds based on arsenic vanadates formulated as [H₂As₆V₁₅O₄₂(H₂O)][Co(H₂O)₆]₂·2H₂O (1) and [H₂As₆V₁₅O₄₂(H₂O)][Ni(H₂O)₆]₂·2H₂O (2) have been prepared by reacting V₂O₅, H₂C₂O₄·2H₂O, As₂O₃,·H₂SO₄, CoCl₂·6H₂O (NiSO₄·6H₂O) and enMe (enMe=1,2-diaminopropane) under mild hydrothermal conditions and characterized by elemental analyses, IR, ESR, XPS and single crystal X-ray diffraction analyses. Crystal structure analyses reveal that compounds 1 and 2 are isostructural and exhibit novel 2-D supramolecular layer structures constructed from arsenic-vanadium clusters and two different types of secondary building units (SBUs), respectively, the different SBUs are formed by joint of two adjacent [Co(H₂O)₆]²⁺ cations in compounds 1 and [Ni(H₂O)₆]²⁺ cations in 2, respectively.