Die ersten Hydrogencarbonate mit einer trimeren [H2(CO3)3]4−-Baugruppe: Zur Darstellung und Kristallstruktur von Rb4H2(CO3)3 · H2O und K4H2(CO3)3 · 1,5 H2O

The First Hydrogencarbonates with a Trimeric [H₂(CO₃)₃]^4? Group: Preparation and Crystal Structure of Rb₄H₂(CO₃)₃ · H₂O and K₄H₂(CO₃)₃ · 1.5 H₂O Rb₄H₂(CO₃)₃ · H₂O and K₄H₂(CO₃)₃ · 1,5 H₂O were prepared by means of the reaction of (CH₃)₂CO₃ with RbOH resp. KOH in aqueous methanole. Trimer [H₂(CO₃)₃]^4?-anions were found in the crystal structure of Rb₄H₂(CO₃)₃ · H₂O (orthorhombic, Pnma (no. 62), a = 1 218.0(1) pm, b = 1 572.3(6) pm, c = 615.9(1) pm, V_EZ = 1 179.5(5) · 10⁶ pm³, Z = 4, R1(I ≥ 2σ(I)) = 0.027, wR2(I ≥ 2σ(I)) = 0.055). K₄H₂(CO₃)₃ · 1,5 H₂O crystallizes in an OD-structure. The determined superposition structure (orthorhombic, Pbam (no. 55), a = 1 161.8(1) pm, b = 597.0(1) pm, c = 383.85(3) pm, V_EZ = 266.3(1) · 10⁶ pm³, Z = 1, R1(I ≥ 2σ(I)) = 0.035, wR2(I ≥ 2σ(I)) = 0.074) can be derived from the structure of the rubidium compound. The thermal decomposition of the substances is discussed.     

Potassium hydrogen trans‐glutaconate monohydrate at 295, 245 and 40 K,and its rubidium analogue at 298 K

A centrosymmetric and short O—H?O hydrogen bond was found in isomorphic crystals of potassium hydrogen trans‐glutaconate monohydrate (potassium hydrogen trans‐pent‐2‐ene‐1,5‐dioate, K⁺·C₅H₅O₄^?·H₂O), (I), and rubidium hydrogen trans‐glutaconate monohydrate (rubidium hydrogen trans‐pent‐2‐ene‐1,5‐dioate, Rb⁺·C₅H₅O₄^?·H₂O), (II). The O?O distance at room temperature is 2.444 (3) Å in (I), and 2.417 (4) Å in (II). The O?O distance for (I) showed no significant decrease at low temperatures.     

Alkalimolybdotellurate: Darstellung und Kristallstruktur von Rb6[TeMo6O24] · 10H2O und Rb6[TeMo6O24] · Te(OH)6 · 6H2O

Alkaline Molybdotellurates: Preparation and Crystal Structures of Rb₆[TeMo₆O₂₄] · 10H₂O and Rb₆[TeMo₆O₂₄] · Te(OH)₆ · 6H₂O Single crystals of Rb₆[TeMo₆O₂₄] · 10 H₂O and Rb₆[TeMo₆O₂₄] · Te(OH)₆ · 6 H₂O, respectively, were grown from aqueous solution. Rb₆[TeMo₆O₂₄] · 10 H₂O possesses the space group P1 . The lattice dimensions are a = 963.40(13), b = 972.56(12), c = 1 056.18(13) pm, α = 97.556(10), β = 113.445(9), γ = 102.075(10)°; Z = 1, 2 860 reflections, 215 parameters refined, R_g = 0.0257. The centrosymmetrical [TeMo₆O₂₄]^6? anions are stacked parallel to [010]. Rb(2) is coordinated with one exception by water molecules only. Folded chains consisting of [TeMo₆O₂₄]^6? anions and Rb(2) coordination polyhedra which are linked to pairs represent the prominent structural feature. Rb₆[TeMo₆O₂₄] · Te(OH)₆ · 6 H₂O crystallizes monoclinically in the space group C2/c with a = 1 886.4(3), b = 1 000.9(1), c = 2 126.5(3) pm, and β = 115.90(1)°; Z = 4, 3 206 reflections, 240 parameters refined, R_g = 0.0333. It is isostructural in high extent with (NH₄)₆[TeMo₆O₂₄] · Te(OH)₆ · 7 H₂O. Hydrogen bonds between Te(OH)₆ molecules and [TeMo₆O₂₄]^6? anions establish infinite strands. The [TeMo₆O₂₄]^6? anions gather around Te(OH)₆ providing channel-like voids extending parallel to [001].     

Ein neuer Zugang zu Alkalivanadaten(IV,V) Die Kristallstruktur von Rb2V3O8

A New Access to Alkali Vanadates(IV,V) Crystal Structure of Rb₂V₃O₈ By heating vanadium(V) oxide with rubidium iodide to 500°C, the vanadium experiences partial reduction and Rb₂V₃O₈ is obtained. It has the fresnoite structure. Crystal data: a = 892.29(7), c = 554.49(9) pm at 20°C, tetragonal, space group P4bm, Z = 2. X-ray crystal structure determination with 620 observed reflexions, R = 0.027. V₂O₇ units share vertices with VO₅ square pyramids, forming layers; a layer can be regarded as association product of VO²⁺ and V₂O₇^4? ions. The Rb⁺ ions between the layers have pentagonal-antiprismatic coordination.     

Synthesis and Study of Rubidium Hexauranate Rb2[(UO2)6O3(OH)8]·6H2O and Products of Its Heat Decomposition

The interaction of hydrated uranium(VI) oxide UO₃·2.25H₂O (schoepite) with an aqueous solution of rubidium hydroxide in an autoclave at 100°C has yielded rubidium uranate Rb₂(UO₂)₆O₃(OH)₈·6H₂O. Composition and structure of the obtained compound have been determined by chemical analysis, IR spectroscopy, X-ray diffraction, and differential thermal analysis. The processes of its dehydration and thermal decomposition have been studied.

     

Carbonat‐Hydrate der schweren Alkalimetalle: Darstellung und Struktur von Rb2CO3 · 1,5 H2O und Cs2CO3 · 3 H2O

Carbonate Hydrates of the Heavy Alkali Metals: Preparation and Structure of Rb₂CO₃ · 1.5 H₂O und Cs₂CO₃ · 3 H₂O Rb₂CO₃ · 1.5 H₂O and Cs₂CO₃ · 3 H₂O were prepared from aqueous solution and by means of the reaction of dialkylcarbonates with RbOH and CsOH resp. in hydrous alcoholes. Based on four‐circle diffractometer data, the crystal structures were determined (Rb₂CO₃ · 1.5 H₂O: C2/c (no. 15), Z = 8, a = 1237.7(2) pm, b = 1385.94(7) pm, c = 747.7(4) pm, β = 120.133(8)°, V_EZ = 1109.3(6) · 10⁶ pm³; Cs₂CO₃ · 3 H₂O: P2/c (no. 13), Z = 2, a = 654.5(2) pm, b = 679.06(6) pm, c = 886.4(2) pm, β = 90.708(14)°, V_EZ = 393.9(2) · 10⁶ pm³). Rb₂CO₃ · 1.5 H₂O is isostructural with K₂CO₃ · 1.5 H₂O. In case of Cs₂CO₃ · 3 H₂O no comparable structure is known. Both structures show [(CO₃^2–)(H₂O)]‐chains, being connected via additional H₂O forming columns (Rb₂CO₃ · 1.5 H₂O) and layers (Cs₂CO₃ · 3 H₂O), respectively.     

Nanocomposites with the layered structure of V2O5 · nH2O xerogel

New layered nanocomposites of V₂O₅ · nH₂O xerogels with poly(vinyl alcohol) (PVA), pyrocatechol (PC), and hydroquinone (HQ) were synthesized with the compositions (C₂H₃)_0.32V₂O_4.90 · nH₂O, (C₆H₄)_xV₂O_4.60 · nH₂O, and (C₆H₄)_0.17V₂O_4.94 · nH₂O and the interlayer distances d ₀₀₁ = 11.73, 12.85, and 15.28 ± 0.05 Å, respectively. IR and Raman spectroscopy was used to analyze which structural changes occur in the V-O layers of the xerogel upon composite formation. X-ray photoelectron spectroscopy showed V⁴⁺ and V⁵⁺ ions in the layers with binding energies lower than in V₂O₅ · nH₂O. The electrical conductivity of the nanofilms and the thermal properties of the nanopowders were studied.     

Preparation,Crystal Structure,Vibrational Spectra,and Thermal Behavior of Rb2H2P2O6·2H2O

Single crystals of Rb₂H₂P₂O₆ · 2H₂O could be obtained from aqueous solutions of hypodiphosphoric acid and rubidium carbonate. Its crystal structure was determined by X‐ray diffraction and it crystallizes in the monoclinic space group P2₁/c with Z = 4. The salt‐like title compound consists of [H₂P₂O₆]^2– units in staggered P₂O₆‐skeleton conformation, Rb⁺ cations, and H₂O molecules, held together by intermolecular hydrogen bonds of the type O ··· O. The vibrational spectra (IR/FIR and Raman) of the rubidium salt were recorded and an assignment of the vibrational modes is proposed based on the point group C_2h for the P₂O₆‐skeleton of the anion. The thermal behavior of Rb₂H₂P₂O₆ · 2H₂O is dominated by a complex TG decay indicating a simultaneous H₂O delivery coupled with a disproportionation of [H₂P₂O₆]^2–, what is also supported by Raman spectra of heated samples.     

Thermal stability and X-ray-luminescent properties of fluorozirconates and fluorosulfatozirconates

The thermolysis of fluorozirconates (M₂ZrF₆, M₅Zr₄F₂₁ · 3H₂O, MZrF₅ · H₂O, Rb₂Zr₃OF₁₂, and Cs₂Zr₃F₁₄ · 1.5H₂O) and fluorosulfatozirconates (M₂ZrF₄SO₄, Rb₃Zr₂F₉SO₄ · 2H₂O, and Cs₈Zr₄F₂(SO₄)₁₁ · 16H₂O) with M = K, Rb, or Cs in undried air was studied by thermal analysis in tandem with X-ray powder diffraction. The X-ray luminescence (XRL) intensity was determined for these compounds and their thermolysis products. A mixture of Rb₂Zr₃OF₁₂ and Rb₂ZrF₆ luminescent phases was detected in the thermolysis products of Rb₅Zr₄F₂₁ · 3H₂O and RbZrF₅ · H₂O for the first time. After heat treatment, a considerable quantum yield was observed for ZnZrF₆ · 5H₂O, ZnZrF₆ · 6H₂O, and ZnZr₂F₁₀ · 7H₂O. The XRL luminescence was affected by the composition of the phase and the density of excited states (F* and O*).     

Synthesis,crystal structure,and vibrational spectra of M<Subscript>4</Subscript>V<Subscript>2</Subscript>O<Subscript>3</Subscript>(SO<Subscript>4</Subscript>)<Subscript>4</Subscript> (M = K,Rb, Cs)

Synthesis was performed and physicochemical properties were studied for the M₄V₂O₃(SO₄)₄ complexes, where M = K, Rb, or Cs. Their crystal structures were determined using the set of data from X-ray diffraction and neutron diffraction studies. All compounds crystallize in a triclinic lattice (space group \(P\bar 1\), Z = 2) with the parameters: a = 7.7688(2), 7.8487(1), 8.1234(1) Å; b = 10.4918(3), 10.8750(2), 11.1065(1) Å; c = 11.9783(4), 12.1336(2), and 11.8039(1) Å; α = 76.600(2)°, 77.910(1)°, 79.589(1)°; β = 75.133(2)°, 75.718(1)°, 87.939(1)°; γ = 71.285(2)°, 72.189(1)°, 75.567(1)°; V = 881.78(5), 945.42(3), 1014.34(2) ų for K, Rb, Cs, respectively. The structure of M₄V₂O₃(SO₄)₄ was found to be formed by discrete complex anions V₂O₃(SO₄) ₄ ^4? incorporating two oxygen-bridged vanadium atoms in a distorted octahedral oxygen environment. The sulfate groups are coordinated by the vanadium atoms in the chelating mode with a large scatter of S-O interatomic distances and OSO angles. Every VO₆ octahedron has a short terminal vanadium-oxygen bond with a length of about 1.6Å. The V₂O₃(SO₄) ₄ ^4? complex anions in potassium and rubidium compounds differ from that in Cs₄V₂O₃(SO₄)₄ in the type of symmetry and mutual spatial orientation. The vibrational spectra were presented and interpreted in line with the structural analysis data.     

Synthesis,vibrational spectra,and structure of divalent metal peroxodisulfates

Simple strontium peroxodisulfate SrS₂O₈ · 4H₂O was synthesized by the reaction of solid Sr(OH)₂ · 8H₂O taken in 30% excess with an aqueous solution of (NH₄)₂S₂O₈; simple magnesium peroxodisulfate MgS₂O₈ · 6H₂O was synthesized by the reaction of an aqueous solution of BaS₂O₈ with a stoichiometric amount of MgSO₄ · 7H₂O. Persulfate ammine complexes [M(NH₃)₄]S₂O₈ (M = Zn, Cu) were prepared in concentrated aqueous ammonia from [Zn(NH₃)₄](OH)₂, [Cu(NH₃)₄](OH)₂, and an ammoniac solution of (NH₄)₂S₂O₈. The compounds were characterized by X-ray powder diffraction (pRSA) and vibrational (IR and Raman) spectroscopy. Their stability was studied during storage and in DTA experiments. The [Zn(NH₃)₄]S₂O₈ structure was solved. Its crystals are orthorhombic, a = 10.5512(8) Å, b = 12.8039(12) Å, c = 8.0448(5) Å, V = 1086(15) ų, Z = 4, space group Pna2₁. The compound is built of [Zn(NH₃)₄]²⁺ complex cations and S₂O ₈ ^2? persulfate anions. In a cation, Zn-N bond lengths are within 2.04(2)–2.056(14) Å. In an anion, the lengths of S(1)–O(4), S(2)–O(5), and O(4)–O(5) bridging bonds are, respectively, 1.676(14), 1.672(16), and 1.465(16) Å; the other S–O bond lengths are within 1.409(14)–1.443(12) Å; the S(1)O(4)O(5)S(2) torsion angle is 140.8(7)°.     

Contribution to the crystal chemistry of tetrametaphosphates (I)

Crystal structures of K₄P₄O₁₂ · 2H₂O and of two polymorphs of Na₂K₂P₄O₁₂ · 2H₂O are reported. K₄P₄O₁₂ · 2H₂O is triclinic P1 with a = 8.153(4), b = 8.222(4), c = 11.154(8) Å, α = 97.33(5), β = 95.46(5), γ = 88.92(5)°, and Z = 2. R = 0.021 for 2898 reflections. Na₂K₂P₄O₁₂ · 2H₂O has two crystalline forms: a triclinic one ($\text{P}\text{1}$) with a = 11.366(8), b = 7.908(5), c = 7.929(5) Å, α = 90.07(5), β = 106.85(5), γ = 95.66(5)°, and Z = 2, and a tetragonal one (P4₁) with a = 7.928(5), c = 21.66(2), and Z = 4. The crystal structures of the first and second crystalline forms have been solved with final R values of 0.022 for 2505 reflections and 0.036 for 1347 reflections, respectively. Crystal data and chemical preparations are given for Na₂(NH₄)₂P₄O₁₂ · 2H₂O and Na₂Rb₂P₄O₁₂ · 2H₂O, both isotypic with the triclinic form of Na₂K₂P₄O₁₂ · 2H₂O. Unit-cell dimensions are, respectively, a = 11.547(8), b = 8.012(5), c = 8.044(5) Å, α = 89.76(5), β = 106.22(5), and γ = 94.78(5)°, for the ammonium salt, and a = 11.577(8), b = 8.006(5), c = 8.032(5) Å, α = 89.79(5), β = 106.58(5), and γ = 95.19(5)° for the rubidium salt. In addition the crystal structures of the two crystalline forms of Na₄P₄O₁₂ · 4H₂O were reexamined in order to localize the hydrogen atoms and refine their positions.     

Crystal Structures of Alkali Metal Peroxodiphosphates

Peroxodiphosphates of alkali metals can be prepared from K₄P₂O₈, which is synthesized by electrolysis, in metathesis reactions with the corresponding perchlorates. Single crystals have been obtained by diffusion of methanol into aqueous solutions of the peroxodiphosphates. The crystal structures of Li₄P₂O₈·4H₂O (P2₁/n; a = 8.057(2) Å, b = 5.074(1) Å, c = 12.288(3) Å, β = 100.53(2)°; V = 493.9(2) ų; Z = 2), Na₄P₂O₈·18H₂O (at 130 K: P6₁; a = 9.0984(14) Å, c = 49.926(13) Å; V = 3579.2(12) ų; Z = 6) and K₄P₂O₈ (P2₁/c; a = 5.9041(15) Å, b = 10.254(2) Å, c = 7.356(2) Å, β = 99.05(3)°; V = 439.79(18) ų; Z = 2) have been determined by X‐ray diffraction. In the Li salt the cations are tetrahedrally coordinated by one water molecule and three oxygen atoms of the anions, whereas the Na salt is characterized by binuclear [Na₂(H₂O)₉]²⁺ complexes. At low temperatures, the latter undergoes a phase transition from a structure with disordered anions to a completely ordered phase. K₄P₂O₈ is solvent‐free and exhibits irregular cation coordination. The structure of the peroxodiphosphate anion is very similar in all compounds; the mean O–O distance is 1.49(1) Å. In addition, the structure determination of K₄(HPO₄)₂·3H₂O₂ (P2₁/n; a = 6.076(1) Å, b = 6.579(1) Å, c = 17.215(2) Å, β = 99.73(1)°; V = 678.26(17) ų; Z = 2), which can be mistaken for K₄P₂O₈, is presented.     

Phase formation in the ZrO(NO3)2-H3PO4-RbF-H2O system: the PO 43? /Zr = 0.5 section

We studied phase formation in the ZrO(NO₃)₂-H₃PO₄-RbF-H₂O system along PO₄³⁻/Zr = 0.5 (mol/mol) and RbF/Zr = 1–5 (mol/mol) sections with 2–10 wt % ZrO₂ in the starting solution. We recovered amorphous rubidium oxofluorophosphatozirconate Rb₂Zr₃OF₆(PO₄)₂ · 2H₂O and the following fluorophosphatonitratozirconates: Rb₂ZrF₄(PO₄)_0.33NO₃, which forms large cubic system crystals; weakly crystallized RbZr₃OF₃(PO₄)₂(NO₃)₂ · 5H₂O; and amorphous Zr₃OF₃(PO₄)₂NO₃ · (7–8) H₂O. A shown by its IR spectrum, Rb₂ZrF₄(PO₄)_0.33NO₃ contains NO₃- and PO₄ groups that are not coordinated to zirconium, meaning that this is a triple salt ZrF₄ · Rb(PO₄)_0.33 · RbNO₃. The formula units of the RbZr₃OF₃(PO₄)₂(NO₃)₂ · 5H₂O and Zr₃OF₃(PO₄)₂NO₃ · (7–8)H₂O phases are only conventional. All compounds have been recovered for the first time.     

Die Vanadin-Koordination in den Phasen 4 PbO · V2O5 und 8 PbO · V2O5

Coordination of Vanadium in the Phases 4 PbO · V₂O₅ and 8 PbO · V₂O₅ It is demonstrated, using infrared spectroscopy, that the coordination of vanadium in the two binary phases 4 PbO · V₂O₅ and 8 PbO · V₂O₅ is tetrahedral. The spectra in the V? O stretching region closely resembles that of the lead(II) orthovanadate, Pb₃(VO₄)₂.     

Rb3LnCl6 · 2 H2O (Ln = La?Nd): Darstellung,Kristallstruktur und thermisches Verhalten

Rb₃LnCl₆ · 2 H₂O (Ln = La? Nd): Preparation, Crystal Structure, and Thermal Behaviour The compounds Rb₃LnCl₆ · 2 H₂O (Ln = La? Nd) were prepared from acetic acid as powders. The preparation from aqueous solutions does not yield the pure products because RbCl precipitates as first compound. The structure of Rb₃LaCl₆ · 2 H₂O was determined by X-ray analysis of a single crystal obtained from aqueous solution. The compounds with Ln = La? Nd are isotypic. They crystallize hexagonally in the space group P6₃/m (Rb₃LaCl₆ · 2 H₂O: a = 1 220.4(2) pm, c = 1 688.6(3) (pm) with Z = 6. Anionic trimeric units [Ln₃Cl₁₂(H₂O)₆]^3? are stacked along the c-axis over the corners of the unit cell. In the stacking frequency the units are rotated by 60° with respect to each other around the c-axis. The coordination number (C. N.) of Ln³⁺ is 8, which is satisfied by four bridging and two terminal chloride ions and two water molecules. The coordination spheres of the three rubidium ions in the different atomic positions are composed differently, their C.N. are 9, 8(+1) and 6(+6). The thermal dehydration of the compounds occurs in one step. The hydrates decompose at ca. 100°C to form the anhydrous compounds Rb₂LnCl₅ und RbCl since the anhydrous chlorides Rb₃LnCl₆ are thermodynamically stable above ca. 400°C only.     

A Novel Coordination Polymer Based on Decavanadate Units Linked by Copper(II) Ethylenediamine Complexes

Summary: A novel coordination polymer[{Cu(en)₂}(V₁₀O₂₈)]_n · 2n[Cu(en)₂(H₂O)] · 2n(H₃BO₃) · 2n(H₂O) was obtained by hydrothermal reaction. The compound crystallizes in the monoclinic crystal system, in the C2/c space group, with a = 26.490 (3) Å; b = 11.6558 (11) Å; c = 19.8426 (19) Å; β = 124.011 (1)°; V = 5078.6(8) ų. The solid structure is formed by polymeric chains, [Cu(en)₂(H₂O)]²⁺ cations, and boric acid and water solvate molecules, stabilized through a multiple hydrogen bond network.     

Standard molar enthalpy of formation of rubidium diphosphate

Rubidium carbonate (Rb₂CO₃) and ammonium dihydrogen phosphate (NH₄H₂PO₄) were used for synthesizing rubidium diphosphate (Rb₄P₂O₇). The purity of the latter compound was checked up by X-ray diffraction. Rb₄P₂O₇ was involved in an hypothetical reaction and dissolved together with the other components in a 3.85 % (m/m) phosphoric acid solution, using a C-80 SETARAM calorimeter. Mixing processes were also realized in the calorimeter in order to get the standard molar enthalpy of formation of rubidium diphosphate (Rb₄P₂O₇). For that a thermochemical cycle was investigated and the obtained value for the standard molar enthalpy of formation of rubidium diphosphate is (?3,183.7) kJ mol^?1. The result is about 1.8 % lower than literature value.     

Crystal Structure and Magnetic Properties of a Vanadium (IV) Pyrophosphate: Rb2V3P4O17

The crystal structure of Rb₂V₃P₄O₁₇ has been determined from single-crystal X-ray diffraction data. Rb₂V₃P₄O₁₇ crystallizes in the orthorhombic space group Pnma (No. 62) with a = 17.502(7), b = 7.292(2), c = 11.399(6) ų, V = 1455(1) ų, Z=4, R=0.0295, R_W = 0.0320 for 1129 unique reflections with I > 2.5 σ(I). The structure contains intersecting tunnels where the Rb⁺ cations are located. The framework can be described as consisting of V²O₁₀ units formed from one VO₅ square pyramid and one VO₆ octahedron sharing a corner, and infinite chains of corner-shared VO₆ octahedra, which are linked in three dimensions by pyrophosphate groups. The structural formula is Rb₂(VO)₃(P₂O₇)₂. A single-phase product can be obtained by heating appropriate amounts of Rb₄V₂O₇, VO₂, V, and P₂O₅ in an evacuated fused silica tube at 950°C. Powder magnetic susceptibility data confirm the presence of V⁴⁺ (d¹) ions without magnetic ordering down to 3 K.