Synthesis, structures and properties of new hybrid solids containing ruthenium complexes and polyoxometalates

Two new organic-inorganic hybrid solids containing Keggin ions and ruthenium complexes have been synthesized and characterized by FT-IR, UV-vis, luminescence, X-ray, and TG analysis. In KNa[Ru(bpy)₃]₂[H₂W₁₂O₄₀]·8H₂O (1), the [Ru(bpy)₃]²⁺ (bpy=2,2′-bipyridine) complex ions are located in between the infinite one-dimensional double-chains formed by adjacent Keggin anions [H₂W₁₂O₄₀]⁶⁻ linked through {KO₇} and {NaO₆} polyhedra, while in K₆[Ru(pzc)₃]₂[SiW₁₂O₄₀]•12H₂O (2), the [Ru(pzc)₃]⁻ (pzc=pyrazine-2-carboxylate) complex anions are confined by layered networks of the [SiW₁₂O₄₀]⁴⁻ clusters connected by potassium ions. Both compounds exhibit three-dimensional frameworks through noncovalent interactions such as hydrogen bonds and anion?π interactions. Additionally, compound 1 shows strong luminescence at 604 nm in solid state at room temperature.     

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.     

Channel Structure Formed by Hydrogen Bonds and Filled by Water Molecules and Dodecatungstosilicate Anions

A new compound consisting of Keggin-type polyoxometalate and transition metal complex, [Cr(apca)₂(H₂O)₂]₄[SiW₁₂O₄₀]·12H₂O(1), (apca^??=?3-aminopyrazine-2-carboxylate anion), was synthesized with conventional method and characterized by single crystal X-ray diffraction, elemental analysis, IR spectroscopy, TG analyses, PXRD. Fluorescent property was explored. The [SiW₁₂O₄₀]^4? anions and complex cations [Cr(apca)₂(H₂O)₂]⁺ in compound 1 are connected by hydrogen bonds and π–π interaction, forming the 3D structure. Especially, [Cr(apca)₂(H₂O)₂]⁺ cations are linked into left-hand helical chain extending along c-axis through hydrogen bonds, forming a channel A. The chains connect other four chains from four directions also through hydrogen bonds, then the four chains enclose a channel B whose inside dimension is a little bigger than that of A, polyoxoanions fill in the channel B, and free waters in the channel A. Compound 1 shows an asymmetric wide emission band at λ_max?=?435 nm, which may belongs to the intraligand π*?→?π transition.     

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.     

Synthesis, structure, and characterization of a silicotungstate anion-supported organic-inorganic hybrid complex [Zn(2,2′-Bipy)3]1.5[SiW12O40Zn(2,2′-Bipy)2(OH)] · 0.25H2O

A new Keggin-type silicotungstate anion-supported organic-inorganic hybrid transition metal complex, [Zn(Bipy)₃]_1.5[SiW₁₂O₄₀Zn(Bipy)₂(OH)] · 0.25H₂O (I) (Bipy = 2,2′-bipyridine), has been synthesized by the hydrothermal method and characterized by elemental analysis, IR, UV, and EPR spectra, TG-DTA analysis, and single crystal X-ray diffraction. The structural analysis indicates that each structural unit of I consists of one [SiW₁₂O₄₀Zn(Bipy)₂(OH)]³⁻ heteropolyanion, one and a half isolated [Zn(Bipy)₃]²⁺ cations, and a quarter of crystal water molecule. The [Zn(Bipy)₂(OH)]⁺ unit is covalently bonded to one Keggin polyoxoanion [SiW₁₂O₄₀]⁴⁻ in the [SiW₁₂O₄₀Zn(Bipy)₂(OH)]³⁻ cluster. The EPR spectrum indicates the existence of Zn²⁺ with the high-spin state, and TG-DTA analysis exhibits that I has two steps of weight loss and the polyoxoanion framework is collapsed at 618°C.     

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.     

Assembly of a Supramolecular Architecture Based on Keggin POMs and Lanthanide Coordination Cations

Two new compounds based on Keggin polyoxometalates (POMs) [SiW₁₂O₄₀]⁴⁻ (SiW₁₂), [Na(H₂O)₃(H₂L)SiW₁₂O₄₀](H₂L)₂   6H₂O (1), and [Ce(H₂O)₃(HL)₂(H₂L)]₂[SiW₁₂O₄₀]₂ 10H₂O (2) (HL = C₆H₅NO₂ = isonicotinic acid), have been conventionally synthesized and characterized by routine methods. Compound 1 possesses a 1D right-handed helical structure constructed by SiW₁₂O₄₀ ⁴⁻ {SiW₁₂} and [Na(H₂O)₃(HL)] complexes. Interestingly, these right-handed helical chains are linked together via H-bonds forming a novel chiral layer. By using the similar synthesis method to that for compound 1, except for employing Ce³⁺ cations in instead of La³⁺ cations, a 3D supramolecular compound 2 based on SiW₁₂ and Ce³⁺ coordination cations has been obtained, which contains 1D channels along a axis. Additionally, the luminescence properties of 2 were studied. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The first chromate containing both Cr<Subscript>2</Subscript>O<Subscript>7</Subscript> and Cr<Subscript>3</Subscript>O<Subscript>10</Subscript> groups,bis(1,3-bis(4-piperidinium)propane) dichromate trichromate monohydrate: Synthesis and crystal structure

A new organic-inorganic hybrid material (C₁₃H₂₈N₂)₂[Cr₂O₇][Cr₃O₁₀]·H₂O (1) was synthesized by slow solvent evaporation at room temperature, and its crystal structure was determined by single crystal X-ray diffraction. This compound crystallizes in the monoclinic space group P2₁/c. The asymmetric unit contains two crystallographically independent 1,3-bis(4-piperidinium)propane, (H₂bppp)²⁺ cations (A and B), one trichromate Cr₃O ₁₀ ^2? anion, one dichromate Cr₂O ₇ ^2? anion, and one water molecule. All these entities are interconnected into a complicated two-dimensional hydrogen bonded network via N–H?O and O–H?O hydrogen bonds. Furthermore, this structure is stabilized by a large number of C–H?O interactions, thus establishing a three-dimensional network structure. This compound appears to be the first example of chromates containing both Cr₂O₇ and Cr₃O₁₀ groups.     

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.     

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.     

Investigation of inorganic–organic hybrid materials containing polyoxometalate cluster anions and organic dye cations

Two new ionic-pair salts containing an organic dye cation, i.e. New Fuchsin or Pararosaniline cation, with Keggin-type POMs, [SiW₁₂O₄₀]^4? and [BW₁₂O₄₀]^6?, have been isolated under hydrothermal conditions. [(C₂₂H₂₄N₃)₄][SiW₁₂O₄₀] (1) and [(C₁₉H₁₈N₃)₆][BW₁₂O₄₀] (2) have been characterized by elemental analyses, FT-IR and single crystal X-ray crystallography. Both of these complexes have strong absorption in the visible-light range due to the involvement of the organic dye and both show weak fluorescence emission.     

Synthesis and Structure of Two Keggin-Type Heteropolyanions: [VMo12O40]3n− n (1) and [H3PMoVMoVI 11O40]1− (2)

Two Keggin-type heteropolyanions were synthesized and characterized by X-ray crystal structure and elemental analysis as well as infrared spectroscopy. Both K₃[VMo₁₂O₄₀]19H₂O (1) and [N _i (H₂O)₆][H₃PMo^VMo^VI ₁₁O₄₀]₂30 H₂O (2) were prepared in aqueous solution. Compound 1 crystallized in the space group Pm-3m, a=10.6513(1) Å, V=1208.4(3) ų, Z=1. Compound 2 crystallized in the space group R-3 with a=b=13.9669(2) Å, c=42.0075(5) Å, V=7096.71(2) ų, Z=3. The compound 1 contains a {K₆VMo₁₂O₄₀} group in which six potassium ions form a regular {K₆} octahedron. The heteropolyanion [VMo₁₂O₄₀]^3– was capped by six potassium ions and enclosed by {K₆} octahedron. A three-dimensional structure was formed by the buildup of {K₃[VMo₁₂O₄₀]} _n . Compound 2 contains a one-electron reduced heteropolyanion [H₃PMo^VMo^VI ₁₁O₄₀]^1–. Ni²⁺ coordinated by six water molecules as the counter cation balances the negative charge of the molecule.     

Ionothermal synthesis and characterization of two new heteropolytungstates with 1-ethyl-3-methylimidazolium bromide ionic liquid as solvent

In this article, we have synthesized two new heteropolytungstate-based compounds [EMIM]₄[SiW₁₂O₄₀] (1) and [EMIM]₆[P₂W₁₈O₆₂] · 4H₂O (2) using the ionic liquid (IL) [EMIM]Br (EMIM = 1-ethyl-3-methylimidazolium) as a solvent and characterized them by infrared (IR) and ultraviolet (UV) spectra, thermogravimetric (TG) and elemental analyses, electrochemistry, and single-crystal X-ray analyses. Compound 1 is constructed from one [SiW₁₂O₄₀]^4? and four [EMIM]⁺. In the structure, [SiW₁₂O₄₀]^4? and [EMIM]⁺ are connected by hydrogen bonds with the surface oxygens of the polyoxoanion to form a 3-D supramolecular framework. The heteropolyanion of 2 is a classical Dawson-type structure [P₂W₁₈O₆₂]^6? and connected with six cations through hydrogen bonds. The structures of these two heteropolyanions are consistent with those synthesized by traditional methods, indicating that ionothermal synthesis is an effective method for the preparation of heteropolyoxometalates. The photocatalytic properties of these compounds have also been investigated.     

Dioxochromium(V) complexes with 1,10-phenanthroline and 2,2′-bipyridine ligands

cis-[Cr^III(phen)₂(H₂O)₂]³⁺ and cis-[Cr^III(bipy)₂(H₂O)₂]³⁺ (phen = 1,10-phenanthroline and bipy = 2,2-bipyridine) were readily oxidized by either PbO₂ or PhIO to form the chromium(V) complexes [Cr^V(phen)₂(O)₂]⁺ and [Cr^V(bipy)₂(O)₂]⁺ respectively, which were characterized by elemental analysis, i.r. and e.s.r. spectroscopy.     

Supramolecular Networks Extended by N–H···O Interactions between Cu‐Benzimidazole Subunits and Keggin Anions

Three new 2D/3D supramolecular architectures derived from Cu‐organic subunits and Keggin anions, [Cu^II₂(biz)₈(HPMo^VI₁₀Mo^V₂O₄₀)(H₂O)₂] · 2H₂O ( 1 ), [Cu^I₄(biz)₈(SiW₁₂O₄₀)] · 2H₂O ( 2 ) and [Cu^I₂(dmbiz)₄(Hdmbiz)₂(SiW₁₂O₄₀)] ( 3 ) (biz = benzimidazole, dmbiz = 5, 6‐dimethyl benzimidazole), were obtained under hydrothermal conditions. Single crystal X‐ray diffraction analysis reveals that compound 1 has two kinds of [Cu^II(biz)₂]²⁺ cations, which are further extended by Keggin anions into a 2D (4, 8)‐connected supramolecular network by hydrogen bonding interactions. In compound 2 , four types of [Cu^I(biz)₂]⁺ subunits link the [SiW₁₂O₄₀]^4– anions to form a 3D (2, 6)‐connected supramolecular structure. Compound 3 shows a 3D supramolecular network with a NaCl‐type topology constructed by [Cu^I(dmbiz)₂]⁺ subunits, anions, and discrete [Hdmbiz]⁺ cations. Moreover, the electrochemical and photocatalytic properties of compounds 1 and 2 were investigated.     

Two new hybrid compounds assembled from Keggin-type polyoxometalates and transition metal coordination complexes

Two new hybrid compounds based on Keggin-type polyoxometalates: {[PMo₁₂O₄₀][Ni(Phen)₂(H₂O)]₂}·K·2OH⁻ (1) and [Cd₂(Phen)₄Cl₂][HPW₁₂O₄₀]·H₂O (2) (Phen=1,10-phenanthroline), have been prepared and characterized by IR, UV-vis, XPS, XRD and single crystal X-ray diffraction analyses. Compound 1 exhibits a 1-D chain structure constructed from Pseudo-Keggin polyoxometalate bi-supported transition metal coordination complexes linked by K⁺ ions. Compound 2 contains Pseudo-Keggin polyoxoanions [HPW₁₂O₄₀]²⁻ and novel metal-chloride-ligand coordination complexes [Cd₂(Phen)₄Cl₂]²⁺.     

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 bis[(18-crown-6)oxonium]tetrabromomanganese(II)

A new complex compound, bis[(18-crown-6)oxonium]tetrabromomanganese(II), 2[(H₃O)⁺(18-crown-6)]·[MnBr₄]^2–, was prepared and studied by X-ray diffraction to reveal its unusual cubic crystal structure, space group Fd $ \bar 3 A new complex compound, bis[(18-crown-6)oxonium]tetrabromomanganese(II), 2[(H₃O)⁺(18-crown-6)]·[MnBr₄]^2–, was prepared and studied by X-ray diffraction to reveal its unusual cubic crystal structure, space group Fd, a 20.424 ?, and Z 8. In this crystal structure, the complex cation [(H₃O)⁺(18-crown-6)] the point symmetry position and the anion [MnBr₄]²⁻ with the point symmetry 23. The complex cation [(H₃O)⁺(18-crown-6)] has a guest-host structure, and, unlike metal complexes by hydrogen bonds between H₃O⁺ hydrogens and 18-crown-6 oxygens, rather than by coordination bonds. The pyramidal cation H₃O⁺ in this crystal structure is statistically disordered, and the tetrahedral anion [MnBr₄]²⁻ is reorientationally disordered. Original Russian Text ? A.N. Chekhlov, 2008, published in Zhurnal Obshchei Khimii, 2008, vol. 78, No. 10, pp. 1622–1626.     

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.