A Novel Polyoxovanadium Cluster Shell: β‐As8V14O42

The hydrothermal reaction of VOSO₄, As₂O₅, piperazine and H₂O produces [H₂N(CH₂)₄NH₂]₄[β‐As₈V₁₄O₄₂(SO₄)]·2HSO₄ ( 1 ), which is the first arsenic‐vanadium cluster containing a spherical β‐As₈V₁₄O₄₂ shell. The structure of this compound was characterized by single crystal X‐ray diffraction, elemental analysis, TG, and IR spectrum. Crystal data for 1 : Orthorhombic, Cmcm, a = 15.369(1) Å, b = 16.404(1) Å, c = 25.772(1) Å, V = 6497.4(9) ų, Z = 4.     

Two New Polyoxovanadate‐supported Transition Metal Complexes: [Zn(en)2][Zn(en)2(H2O)2][{Zn(en)(enMe)}As6V15O42(H2O)]·4H2O and [Zn2(enMe)2(en)3][{Zn(enMe)2}As6V15O42(H2O)]·4H2O

Two novel As‐V‐O cluster supported transition metal complexes, [Zn(en)₂][Zn(en)₂(H₂O)₂][{Zn(en)(enMe)}As₆V₁₅O₄₂(H₂O)]·4H₂O ( 1 ) and [Zn₂(enMe)₂(en)₃][{Zn(enMe)₂}As₆V₁₅O₄₂(H₂O)]·4H₂O ( 2 ), have been hydrothermally synthesized. The single X‐ray diffraction studies reveal that both compounds consist of discrete noncentral polyoxoanions [{Zn(en)(enMe)}As₆V₁₅O₄₂(H₂O)]^4? or [{Zn(enMe)₂}As₆V₁₅O₄₂(H₂O)]^4? cocrystallized with respective zinc coordination complexes. Interestingly, compounds 1 and 2 exhibit the first two polyoxovanadates containing As₈V₁₅O₄₂‐(H₂O)]^6? cluster decorated by only one transition metal complex. Crystal data: 1 , monoclinic, P2₁/n, a = 14.9037(4) Å, b = 18.1243(5) Å, c = 27.6103(7) Å, β = 105.376(6)°, Z = 4; 2 monoclinic, P2₁/n, a = 14.9786(7) Å, b = 33.0534(16) Å, c = 14.9811(5) Å, Z = 4.     

Darstellung,Ramanspektren und Kristallstrukturen von V2O3(SO4)2, K[VO(SO4)2] und NH4[VO(SO4)2]

Preparation, Raman Spectra, and Crystal Structures of V₂O₃(SO₄)₂, K[VO(SO₄)₂], and NH₄[VO(SO₄)₂] The oxo-sulfato-vanadates(V) V₂O₃(SO₄)₂, K[VO(SO₄)₂], and NH₄[VO(SO₄)₂] have been prepared as crystals suitable for X-ray structure determination. In all structures sulfate acts as an unidentate ligand only toward a single vanadium atom. The structure of V₂O₃(SO₄)₂ consists of a threedimensional network of pairs of cornershared VO₆ octahedra with one terminal oxygen atom each, and SO₄ tetrahedra. All oxygen atoms of the sulfate ions are coordinated. NH₄[VO(SO₄)₂] and K[VO(SO₄)₂] are isostructural. VO₆ octahedra with one terminal oxygen atom and pairs of sulfate tetrahedra form infinite chains by corner sharing. The chains are weakly interlinked to layers. The sulfate ions are distorted towards planar SO₃ molecules and single oxygen atoms attached to vanadium. This structural detail gives an explanation for the mechanism of the reversible reaction K[VO(SO₄)₂] ? K[VO₂(SO₄)] + SO₃ at 400°C. Raman spectra of the compounds have been recorded and interpreted with respect to their structures. Crystal data: V₂O₃(SO₄)₂, monoclinic, space group P2₁/a, a = 947.2(4), b = 891.3(3), c? 989.1(4) pm, β = 104.56(3)°, Z = 4, 878 unique data, R(R_w) = 0.039(0,033); K[VO(SO₄)₂], orthorhombic, space group P2₁2₁2₁, a = 495.3(2), b = 869.6(9), c = 1 627(1)pm, Z = 4, 642 unique data, R(R_w) = 0,11(0,10); NH₄[VO(SO₄)₂], orthorhombic, space group P2₁2₁2₁, a = 495.3(1), b = 870.0(2), c = 1 676.7(4)pm, Z = 4, 768 unique data, R(R_w) = 0.088(0.083).     

Kristallstrukturen von Verbindungen A2[MnF3(SO4)] (A = Rb,NH4, Cs): Jahn‐Teller‐Ordnung in Mangan(III)‐fluoridsulfaten. I.

Jahn‐Teller Ordering in Manganese(III) Fluoride Sulphates. I. Crystal Structures of A₂[MnF₃(SO₄)] (A = Rb, NH4, Cs) The three isostructural fluorosulphatomanganates(III) A₂[MnF₃(SO₄)] (A = Rb, NH₄, Cs) crystallize in space group P2₁/c, Z = 4. Rb₂[MnF₃(SO₄)]: a = 7.271, b = 11.091, c = 8.776Å, β = 92.26°, R = 0.033; (NH₄)₂[MnF₃(SO₄)]: a = 7.299, b = 10.157, c = 8.813Å, β = 91.51°, R = 0.025; Cs₂[MnF₃(SO₄)]: a = 7.365, b = 11.611, c = 9.211, β = 92.30°, R = 0.029. In the chain anions [MnF₃(SO₄)]^2— manganese(III) is coordinated by two trans‐terminal and two trans‐bridging fluorine ligands, and by the O‐atoms of two briding sulphate ligands in trans position. The Jahn‐Teller effect induces a variety of antiferrodistortive ordering resulting in distorted [MnF₄O₂] octahedra with alternating elongation of F—Mn—F — and O—Mn—O — axes, respectively. Thus, only asymmetrical bridges are formed.     

New Perspectives in Polyoxometalate Chemistry by isolation of compounds containing very large moieties as transferable building blocks: (NMe4)5[As2Mo8V4AsO40] · 3H2O, (NH4)21[H3Mo57V6(NO)6O183(H2O)18] · 65 H2O, (NH2Me2)18(NH4)6[Mo57V6(NO)6O183(H2O)18] · 14 H2O,and (NH4)12[Mo36(NO)4O108(H2O)16] · 33 H2O

The compounds (NMe₄)₅[As₂Mo₈V₄AsO₄₀] · 3 H₂O 2a , (NH₄)₂₁[H₃Mo₅₇V₆(NO)₆O₁₈₃(H₂O)₁₈] · 65 H₂O 3a , (NH₂Me₂)₁₈(NH₄)₆[Mo₅₇V₆(NO)₆O₁₈₃(H₂O)₁₈] · 14 H₂O 3b and (NH₄)₁₂[Mo₃₆(NO)₄O₁₀₈(H₂O)₁₆] · 33 H₂O 4a ( 3a and 4a were not correctly reported in the literature regarding to their composition, structures and the oxidation states of the metal centres) which contain large isolated anionic species, have been prepared (among them 3a, 3b , and 4a in rather high yield) and characterized by complete crystal structure analysis as well as IR/Raman, UV/VIS/NIR, ESR spectroscopy and magnetic susceptibility measurements, redox titrations, bond valence sum calculations, elemental analyses and thermogravimetric studies. Perspectives for polyoxometalate chemistry referring to the synthesis of “extremely” large nanoscaled species are discussed, together with the occurrence of a large transferable {Mo₁₇} building block in the compounds 3a, 3b and 4a which also exists in the corresponding iron compound Na₃(NH₄)₁₂[H₁₅Mo₅₇Fe₆(NO)₆O₁₈₃(H₂O)₁₈] · 76 H₂O 7a .     

Jahn‐Teller‐Ordnung in Mangan(III)‐fluoridsulfaten. II. Phasenübergang und Verzwillingung bei K2[MnF3(SO4)] und 1D Magnetismus in Verbindungen A2[MnF3(SO4)] (A = K,NH4, Rb,Cs)

Jahn‐Teller Ordering in Manganese(III) Fluoride Sulfates. II. Phase Transition and Twinning of K₂[MnF₃(SO₄)] and 1D Magnetism in Compounds A₂[MnF₃(SO₄)] (A = K, NH₄, Rb, Cs) According to single‐crystal X‐ray investigations, K₂[MnF₃(SO₄)] crystallizes at low temperature, like the isostructural Rb, NH₄, and Cs analogues in space group P2₁/c, Z = 4, e.g. at 100 K with a = 7.197, b = 10.704, c = 8.427Å, β = 91.84°. Below about 300 K, the crystals are found to be [001] axis twins. Using a new integration method for area detector records, nearly complete intensity data could be gained allowing for structure refinements of similar quality as for untwinned crystals (e.g. at 100 K: wR₂ = 0.050, R = 0.020 for all reflections). With rising temperature, the monoclinic angle approaches continuously 90°. For an ordering parameter Δβ = β?90° a 2^nd‐order phase transition is observed with an exponent λ = 0.17. At the transition temperature of 280 K resulting from the fit, the monoclinic structure changes – with delay – to orthorhombic with the minimum super‐group Pnca, a = 7.243, b = 10.763, c = 8.457Å, R = 0.024, as found in an early structure determination at room temperature by Edwards 1971. In the chain‐like [MnF₃(SO₄)]^2? anions, manganese(III) is octahedrally coordinated by two trans‐terminal and two trans‐bridging fluorine ligands as well as by the O atoms of two trans‐bridging sulfate ligands. At low temperature, the octahedral elongation by the Jahn‐Teller effect alternates between a F–Mn–F and an O–Mn–O axis (antiferrodistortive ordering). All bridges are asymmetric. From about 320 K on they become symmetric. Due to 2D dynamical Jahn‐Teller effect all octahedra appear compressed. All compounds A₂[MnF₃(SO₄)] show 1D antiferromagnetism. The antiferrodistortive Jahn‐Teller order at low temperatures and the small bridge angles explain the much lower magnetic exchange energies and their inverse relation to the bridge angles as compared with other fluoromanganate(III) chain compounds with the usual ferrodistortive ordering.     

High Nuclearity Antimonato‐Polyoxovanadate Cluster {V15Sb6O42} as a Synthon for the Solvothermal in situ Generation of α‐ and β‐{V14Sb8O42} Isomers

New heteroatom polyoxovanadates (POVs) were synthesized by applying a water‐soluble high‐nuclearity cluster as new synthon. The [V₁₅Sb₆O₄₂]^6? cluster shell exhibiting D₃ symmetry was in situ transformed into completely different cluster shells, namely, the α‐[V₁₄Sb₈O₄₂]^4? isomer with D_2d and the β‐[V₁₄Sb₈O₄₂]^4? isomer with D_2h symmetry. The solvothermal reaction of {Ni(en)₃}₃[V₁₅Sb₆O₄₂(H₂O)_x] ? 15 H₂O (x=0 or 1; en=ethylenediamine) in water led to the crystallization of [{Ni(en)₂}₂V₁₄Sb₈O₄₂] ? 5.5 H₂O containing the β‐isomer. The addition of [Ni(phen)₃](ClO₄)₂ ? 0.5 H₂O (phen=1,10‐phenanthroline) to the reaction slurry gave the new compound {Ni(phen)₃}₂[V₁₄Sb₈O₄₂] ? phen ? 12 H₂O with the α‐isomer. Both transformation reactions are complex due the change of symmetry, the chemical composition, and rearrangement of the VO₅ square pyramids and Sb₂O₅ handle‐like moieties.     

A Bicapped α‐Keggin Unit‐Supported Transition Metal Complex: Hydrothermal Synthesis and Characterization of [Cu(en)2(H2O)]2[Cu(en)2]0.5[Mo8V7O42{Cu(en)2}]

A new metal‐oxo cluster supported transition metal complex, [Cu(en)₂(H₂O)]₂[Cu(en)₂]_0.5[Mo^VI₈V^IV₆V^VO₄₂{Cu(en)₂}], has been synthesized under hydrothermal conditions. Its structure was determined by single‐crystal X‐ray diffraction. The compound crystallizes in the triclinic system, space group (No. 2), a = 12.245(5), b = 12.669(5), c = 20.949(8) Å, α = 77.120(13), β = 78.107(17), γ = 65.560(14)°, V = 2860(2) ų, Z = 2. The metal‐oxo cluster contains a novel bicapped a‐Keggin structure unit and a [Cu(en)₂]²⁺ unit covalently bonded to the [Mo₈V₇O₄₂]^7? cluster.     

Synthese und Charakterisierung von Aquapentachloroplatinaten(IV) – Struktur von [K(18-Krone-6)][PtCl5(H2O)]

Synthesis and Characterization of Aquapentachloroplatinates(IV) – Structure of [K(18-crown-6)][PtCl₅(H₂O)] The crown ether complex of the aquapentachloroplatinic acid of the composition [H₁₃O₆][PtCl₅(H₄O₂)] · 2(18-cr-6) ( 2 ) reacts with K₂CO₃ and [NⁿBu₄]OH in aqueous solution to give [K(18-cr-6)][PtCl₅(H₂O)] ( 5 a ) and [NⁿBu₄][PtCl₅(H₂O)] · ¹/₂ (18-cr-6) · H₂O ( 5 b ), respectively. Both compounds were characterized by microanalysis, vibrational (IR, Raman) and NMR (¹H, ¹³C, ¹⁹⁵Pt) spectroscopy. The X-ray structure analysis of 5 a (orthorhombic, pnma; a = 16,550(4), b = 18,044(3), c = 7,415(1) Å; Z = 4; R1 = 0,0183; wR2 = 0,0414) reveals that the crystal is threaded by chains built up of [PtCl₅(H₂O)]^? and [K(18-cr-6)]⁺ units. There are tight K …? Cl contacts (d(K? Cl1)) = 3,0881(9) Å and O_W? H? O_cr hydrogen bridges (d(O1 …? O2) = 2,806(3) Å) between these units. The coordination polyhedron [PtCl₅O] has approximately C_4v symmetry.     

Das erste Vanadium(III)‐Borophosphat: Darstellung und Kristallstruktur von CsV3(H2O)2[B2P4O16(OH)4]

The First Vanadium(III) Borophosphate: Synthesis and Crystal Structure of CsV₃(H₂O)₂[B₂P₄O₁₆(OH)₄] CsV₃(H₂O)₂[B₂P₄O₁₆(OH)₄] was prepared under mild hydrothermal conditions (T = 165 °C) from mixtures of CsOH_(aq), VCl₃, H₃BO₃, and H₃PO₄ (molar ratio 1 : 1 : 1 : 2). The crystal structure was determined by X‐ray single crystal methods (monoclinic; space group C2/m, No. 12): a = 958.82(15) pm, b = 1840.8(4) pm, c = 503.49(3) pm; β = 110.675(4)°; Z = 2. The anionic partial structure contains oligomeric units [BP₂O₈(OH)₂]^5–, which are built up by a central BO₂(OH)₂ tetrahedron and two PO₄ tetrahedra sharing common corners. V^III is octahedrally coordinated by oxygen of adjacent phosphate tetrahedra and OH groups of borate tetrahedra as well as oxygen of phosphate tetrahedra and H₂O molecules, respectively (coordination octahedra VO₄(OH)₂ and VO₄(H₂O)₂). The oxidation state +3 for vanadium was confirmed by measurements of the magnetic susceptibility. The trimeric borophosphate groups are connected via vanadium centres to form layers with octahedra‐tetrahedra ring systems, which are likewise linked via V^III‐coordination octahedra. Overall, a three‐dimensional framework constructed from VO₄(OH)₂ and VO₄(H₂O)₂ octahedra as well as BO₂(OH)₂ and PO₄ tetrahedra results. The structure contains channels running along [001], which are occupied by Cs⁺ in a distorted octahedral coordination (CsO₄(H₂O)₂).     

(Et4N)4[V4O12]·2H2O

The title compound, tetrakis(tetraethylammonium) cyclo‐tetra‐μ‐oxo‐tetrakis[dioxovanadium(V)] dihydrate, (C₈H₂₀N)₄[V₄O₁₂]·2H₂O, was obtained by reacting V₂O₅ with (C₂H₅)₄NOH. It consists of a discrete centrosymmetric molecular anion, [V₄O₁₂]^4?, where four tetrahedral VO₄ units share two vertices with each other to form a ring. A water mol­ecule is attached on each side of the ring through hydrogen bonds.     

Hydrothermal Synthesis of a New Vanadium Tellurate(VI) with a Novel Chain Structure: (NH4)4{(VO2)2[Te2O8(OH)2]}·2H2O

A new ammonium vanadium tellurate, (NH₄)₄{(VO₂)₂[Te₂O₈(OH)₂]}·2H₂O ( 1 ) was hydrothermally synthesized and characterized by elemental analyses, IR spectrum, TG analysis, and single crystal X–ray diffraction. Compound 1 crystallizes in the monoclinic system, space group P2₁/n, a = 7.3843(15) Å, b = 17.111(3) Å, c = 7.3916(15) Å, β = 118.88(3)°, V = 817.9(3) ų, Z = 2, R1 (I>2σ(I)) = 0.0235, wR2 (all data) = 0.0462. The structure of 1 consists of infinite anionic chains, {(VO₂)₂[Te₂O₈(OH)₂]}^4? which contain octahedral VO₆ and TeO₅OH units. Each octahedral VO₆ and TeO₅OH unit is connected by sharing an edge to form V₂O₁₀ and Te₂O₈(OH)₂ binuclear units. The V₂O₁₀ and Te₂O₈(OH)₂ binuclear units are alternatively connected to one another, creating complete infinite {(VO₂)₂[Te₂O₈(OH)₂]}^4? chains along the c direction. The anionic chains are separated by ammonium cations and water molecules that link the chains through a network of hydrogen bonds. In addition, the structure contains an extended network of O–H·····O hydrogen bonds between the chains.     

Dinuclear Manganese(II) Complexes with Bridging Selenidodiarsenate Anions [As2Se4]4−, [As2Se5]4− and [As2Se6]2−

Solvothermal reaction of [MnCl₂(amine)] (amine = terpy and tren) with elemental As and Se at a 1:1:2 molar ratio in H₂O/tren (10:1) affords the dimanganese(II) complexes [{Mn(terpy)}₂(μ‐As₂Se₄)] ( 1 ) and [{Mn(tren)}₂(μ‐As₂Se₅)] ( 2 ) respectively. The tetradentate [As₂Se₄]^4? bridging ligands in 1 contain a central As–As bond and exhibit approximately C_2h symmetry. Pairs of gauche sited Se atoms participate in five‐membered As₂Se₂Mn chelate rings. In contrast, two AsSe₃ pyramids share a common corner in the [As₂Se₅]^4? ligands of 2 and each coordinates an [Mn(tren)]²⁺ fragment through a single terminal Se atom. Such dinuclear complexes are linked into tetranuclear moieties through weak Se···Mn interactions of length 3.026(3) Å involving one of these terminal Se atoms. At a 1:3:6 molar ratio, solvothermal reaction of [MnCl₂(tren)] with As and Se leads to formation of a second dinuclear complex [{Mn(tren)}₂(μ‐As₂Se₆)₂] ( 3 ), which contains two bridging bidentate [As₂Se₆]^2? ligands. These are cyclic with an As₂Se₄ ring and can be regarded as being derived from [As₂Se₅]^4? anions by formation of two Se‐Se bonds to an additional Se atom.     

Alkali-metal trifluoromonosulphatomanganates (III) A2[MnF3(SO4)] (A = NH4, Li,Na or K)

Pink-brown crystalline alkali-metal trifluoromonosulphatomanganates(III), A₂[MnF₃(SO₄)] (A = NH₄, Li, Na or K), have been synthesised in high yields by reacting KMnO₄ or MnO(OH) with 40% HF and A₂SO₄ or by the reaction of MnO(OH) with 40% HF and A₂S₂O₈ (A = NH₄ or K). The chemicallly estimated oxidation state of manganese occurs between 2.9 and 3.1, and the room temperature magnetic moments lie in the range 4.0–4.2 BM. (NH₄)₂[MnF₃(SO₄)] on being pyrolysed at 340°C yields MnSO₄.     

Darstellung und spektroskopische Charakterisierung der reinen Bindungsisomeren [ReX5(NCS)]2− und [ReX5(SCN)]2−, X = Cl,Br

Preparation and Spectroscopic Characterization of the Pure Bondisomers [ReX₅(NCS)]^2? and [ReX₅(SCN)]^2?, X = Cl, Br The treatment of (TBA)₂[ReBr₆] with NaSCN in acetone or of (TBA)₂[ReCl₅I] with AgSCN in CH₂Cl₂ yields mixtures of the bondisomers [ReBr₅(NCS)]^2?/[ReBr₅(SCN)]^2? or [ReCl₅(NCS)]^2?/[ReCl₅(SCN)]^2?, which are isolated as pure compounds by ion exchange chromatography on DEAE-Cellulose. The i.r. and Raman spectra are assigned according to local symmetry C_4v. The bondisomers are significantly distinguished by the frequencies of inner ligand vibrations: ν_CN(S) > ν_CN(N), ν_CS(N) > ν_CS(S), δ_NCS > δ_SCN. The electronic absorption spectra measured at 10 K exhibit in the region 6000 to 16000 cm^?1 all intraconfigurational transitions (t) splitted into Kramers dubletts by lowered symmetry (C_4v) and spin orbit coupling. The O? O transitions are deduced from vibrational fine structure. The charge transfer spectra of the bondisomers in the UV/VIS region are similar to those of the corresponding hexahalorhenates(IV).     

Crystal Structures of [Cu2(bpy)2(H2O)(OH)2(SO4)]·4H2O and [Cu(bpy)(H2O)2]SO4 with bpy = 2, 2′‐Bipyridine

Two sulfato Cu^II complexes [Cu₂(bpy)₂(H₂O)(OH)₂(SO₄)]· 4H₂O ( 1 ) and [Cu(bpy)(H₂O)₂]SO₄ ( 2 ) were synthesized and structurally characterized by single crystal X—ray diffraction. Complex 1 consists of the asymmetric dinuclear [Cu₂(bpy)₂(H₂O)(OH)₂(SO₄)] complex molecules and hydrogen bonded H₂O molecules. Within the dinuclear molecules, the Cu atoms are in square pyramidal geometries, where the equatorial sites are occupied by two N atoms of one bpy ligand and two O atoms of different μ₂—OH groups and the apical position by one aqua ligand or one sulfato group. Through intermolecular O—H···O and C—H···O hydrogen bonds and intermolecular π—π stacking interactions, the dinuclear complex molecules are assembled into layers, between which the hydrogen bonded H₂O molecules are located. The Cu atoms in 2 are octahedrally coordinated by two N atoms of one bpy ligand and four O atoms of two H₂O molecules and two sulfato groups with the sulfato O atoms at the trans positions and are bridged by sulfato groups into ¹[Cu(bpy)(H₂O)₂(SO₄)_2/2] chains. Through the interchain π—π stacking interactions and interchain C—H···O hydrogen bonds, the resulting chains are assembled into bi—chains, which are further interlinked into layers by O—H···O hydrogen bonds between adjacent bichains.     

Two caesium vanadium hydrogenphosphates with tunnelled structures: Cs2V2O3(PO4)(HPO4) and Cs2[(VO)3(HPO4)4(H2O)]·H2O

Dicaesium divanadium trioxide phosphate hydrogenphosphate, Cs₂V₂O₃(PO₄)(HPO₄), (I), and dicaesium tris[oxidovanadate(IV)] hydrogenphosphate dihydrate, Cs₂[(VO)₃(HPO₄)₄(H₂O)]·H₂O, (II), crystallize in the monoclinic system with all atoms in general positions. The structures of the two compounds are built up from VO₆ octahedra and PO₄ tetrahedra. In (I), infinite chains of corner‐sharing VO₆ octahedra are connected to V₂O₁₀ dimers by phosphate and hydrogenphosphate groups, while in (II) three vanadium octahedra share vertices leading to V₃O₁₅(H₂O) trimers separated by hydrogenphosphate groups. Both structures show three‐dimensional frameworks with tunnels in which Cs⁺ cations are located.     

Neue Halogenochalkogen(IV)‐Säuren: [H3O(Benzo‐18‐Krone‐6)]2[Te2Br10] und [H5O2(Dibenzo‐24‐Krone‐8)]2[Te2Br10]

Novel Halogenochalcogeno(IV) Acids: [H₃O(Benzo‐18‐Crown‐6)]₂[Te₂Br₁₀] and [H₅O₂(Dibenzo‐24‐Crown‐8)]₂[Te₂Br₁₀] Systematic studies on halogenochalcogeno(IV) acids containing tellurium and bromine led to the new crystalline phases [H₃O(Benzo‐18‐Crown‐6)]₂[Te₂Br₁₀] ( 1 ) and [H₅O₂(Dibenzo‐24‐Crown‐8)]₂[Te₂Br₁₀] ( 2 ). The [Te₂Br₁₀]^2‐ anions consists of two edge‐sharing distorted TeBr₆ octahedra, the oxonium cations are stabilized by crownether. ( 1 ) crystallizes in the monoclinic space group P2₁/n with a = 14.520(5) Å, b = 22.259(6) Å, c = 16.053(5) Å, β = 97.76(3)° and Z = 4, whereas ( 2 ) crystallizes in the triclinic space group with a = 11.005(4) Å, b = 12.103(5) Å, c = 14.951(6) Å, α = 71.61(3)°, β = 69.17(3)°, γ = 68.40(3)° and Z = 1.     

[Ho5(H2O)16(OH)2As6W64O220]25−, ein großes neuartiges Polyoxoanion aus trivakanten Keggin‐Fragmenten

[Ho₅(H₂O)₁₆(OH)₂As₆W₆₄O₂₂₀]^25?, a Large Novel Polyoxoanion from Trivacant Keggin Fragments The novel polyoxotungstate Na₇K₁₈[Ho₅(H₂O)₁₆(OH)₂As₆W₆₄O₂₂₀] · 56 H₂O ( 1 ) was synthesized in aqueous solution and characterized by X‐ray structure analysis, elemental analysis and IR spectroscopy. The anion in 1 represents one of the largest polyoxoanions known yet and exhibits an unusual arrangement of six Keggin units. It consists of six trivacant lacunary α‐B‐(AsW₉O₃₃)^9? Keggin fragments which are connected by a bridging [Ho₅W₁₀(H₂O)₁₆(OH)₂O₂₂]²⁹⁺ unit. The five Ho^III atoms are coordinated by eight oxygen atoms, forming a square‐antiprism.     

[M3V18O42(H2O)12(XO4)]⋅24 H2O (M=Fe,Co; X=V,S): Metal Oxide Based Framework Materials Composed of Polyoxovanadate Clusters

New framework materials composed of well-defined vanadium oxide clusters were prepared by low-temperature reactions and characterized by X-ray crystal structure analysis. The structures of these solids contain {V₁₈O₄₂} cages linked into two interpenetrating three-dimensional networks by bridging {M(H₂O)₄} groups (M=Fe^II, Co^II; see picture).