K3TaF8 from laboratory X‐ray powder data

The crystal structure of tripotassium octafluoridotantalate, K₃TaF₈, determined from laboratory powder diffraction data by the simulated annealing method and refined by total energy minimization in the solid state, is built from discrete potassium cations, fluoride anions and monocapped trigonal–prismatic [TaF₇]²⁻ ions. All six atoms in the asymmetric unit are in special positions of the P6₃mc space group: the Ta and one F atom in the 2b (3m) sites, the K and two F atoms in the 6c (m) sites, and one F atom in the 2a (3m) site. The structure consists of face‐sharing K₆ octahedra with a fluoride anion at the center of each octahedron, forming chains of composition [FK₃]²⁺ running along [001] with isolated [TaF₇]²⁻ trigonal prisms in between. The structure of the title compound is different from the reported structure of Na₃TaF₈ and represents a new structure type.     

Two tantalum fluorides templated with tren: [H4tren](TaF7)2·H2O and [H4tren](TaF7)2

Using tris(2-aminoethyl)amine [(C₂H₄NH₂)₃N] (tren) as a template, two new tantalum fluorides are obtained by slow evaporation of solutions: [H₄tren](TaF₇)₂·H₂O (I) and [H₄tren](TaF₇)₂ (II). The structure determinations are performed by single crystal X-ray technique. Structures of I and II are built up from isolated TaF₇ distorted monocapped trigonal prisms or pentagonal bipyramids; charge balance is achieved by tetraprotonated [H₄tren]⁴⁺ cations which possess a “scorpion” configuration. In I and II, TaF₇ polyhedra, connected by hydrogen bonds with water molecules in I, lie in corrugated layers; hydrogen bond networks ensure the cohesion between these layers and [H₄tren]⁴⁺cations.     

The three‐dimensional intermolecular network formed via water molecules in trans‐bis(nitrito‐κN)tetrakis(pyridine‐κN)ruthenium(II) dihydrate

The molecular geometry of the tetragonal crystal structure of the title compound, [Ru(NO₂)₂(C₅H₅N)₄]·2H₂O, differs from that previously determined by powder diffraction [Schaniel et al. (2010). Phys. Chem. Chem. Phys. 12 , 6171–6178]. In the [Ru(NO₂)(C₅H₅N)₄] molecule, the Ru atom lies at the intersection of three twofold axes (Wyckoff position 8b). It is coordinated by four N atoms of the pyridine rings, as well as by two N atoms of N‐nitrite groups. The last two N atoms are located on a twofold axis (Wyckoff position 16f). The O atoms of the water molecules are situated on a twofold axis (Wyckoff position 16e). Short intermolecular contacts are observed in the crystal structure, viz. N—O...OW and N—O...H—OW contacts between nitrite and water, and weak C—H...OW hydrogen bonds between pyridine and water. Thus, the intercalated water molecules act as bridges connecting the trans‐[Ru(NO₂)₂(py)₄] molecules into a three‐dimensional network.     

Reaktionen am metallischen Substrat: Einkristalle von Ni(NH3)2V2F8

Reactions at the Metallic Substrate: Single Crystals of Ni(NH₃)₂V₂F₈ Except for the main product (NH₄)₂[TaF₇] and some [Ni(NH₃)₆][TaF₆]₂, the new light green Ni(NH₃)₂V₂F₈ is obtained by the reaction of (NH₄)F with tantalum and vanadium (molar ratio of (NH₄)F : Ta : V = 36 : 6 : 1) at 400 °C in a sealed Monel ampoule (Cu32Ni68). The crystal structure (orthorhombic, Fmmm, Z = 4, a = 752.9(1), b = 762.9(1), c = 1307.6(2) pm) is related to that of (NH₄)[VF₄]. According to {Ni(NH₃)₂}_0,5[VF₄], corrugated layers of vertex-connected octahedra [VF_4/2F_2/1] are stacked in the [001] direction. Between these layers trans-{Ni(NH₃)₂} units are inserted so that Ni²⁺ enhances its coordination number to 6 by two times two F^– from the layers above and below.     

Bildung des „superoktaedrischen”︁ Heteropolyanions [Ni(TaF6)6]4− bei der Oxidation von Tantal mit Ammoniumfluorid an der Monel-Wand

Formation of the “Superoctahedral” Heteropolyanion [Ni(TaF₆)₆]^4? through Oxidation of Tantalum with Ammonium Fluoride at the Monel-Container Wall A few single crystals of (NH₄)₄[Ni(TaF₆)₆] are obtained besides (NH₄)[TaF₆] as the main product of the reaction of (NH₄)F with tantalum powder in an He-are-welded Monel metal container at 400°C. The crystal structure (trigonal, R-3c (Nr. 167), Z = 6, a = 1723,0(2); c = 2166,6(2) pm; R1 = 0,0303, _WR2 = 0,0609) contains the superoctahedral heteropolyanion [Ni(TaF₆)₆]^4? and (NH₄)⁺ ions; it may be recognized as a derivative structure of the K₄CdCl₆ type according to (NH₄)₄[Ni(TaF₆)₆]?K₄[Cd(Cl)₆].     

Synthetic aenigmatite analog Na2(Mn5.26Na0.74)Ge6O20: structure and crystal chemical considerations

Disodium hexamanganese(II,III) germanate is the first aenigmatite‐type compound with significant amounts of manganese. Na₂(Mn_5.26Na_0.74)Ge₆O₂₀ is triclinic and contains two different Na positions, six Ge positions and 20 O positions (all with site symmetry 1 on general position 2i of space group P). Five out of the seven M positions are also on general position 2i, while the remaining two have site symmetry (Wyckoff positions 1f and 1c). The structure can be described in terms of two different layers, A and B, stacked along the [011] direction. Layer A contains pyroxene‐like chains and isolated octahedra, while layer B is built up by slabs of edge‐sharing octahedra connected to one another by bands of Na polyhedra. The GeO₄ tetrahedra show slight polyhedral distortion and are among the most regular found so far in germanate compounds. The M sites of layer A are occupied by highly charged (trivalent) cations, while in layer B a central pyroxene‐like zigzag chain can be identified, which contains divalent (or low‐charged) cations. This applies to the aenigmatite‐type compounds in general and to the title compound in particular.     

catena‐Poly[tris(μ3‐acetylacetonato)nickelate(II)sodium(I)]

The title complex, [NaNi(C₅H₇O₂)₃]_n, contains an anionic tris(acetylacetonato)nickelate(II) unit, [Ni(acac)₃]⁻ (acac is acetylacetonate), with a highly regular octahedral coordination geometry. The Ni^II cation lies on a Wyckoff a site, resulting in D₃ symmetry of the anion. Charge balance is provided by sodium cations, which occupy Wyckoff type b sites. Each sodium cation is surrounded by two [Ni(acac)₃]⁻ anions, each of which is connected to the alkali metal through three O atoms, in a fac configuration. This arrangement leads to the formation of linear [Na{Ni(acac)₃}]_n chains along the c axis. The Ni...Na distance is 2.9211 (10) Å. The title complex is one of the few examples of heterometallic systems based on alkali and transition metal cations bridged by acetylacetonate ligands.     

Derivate des Flußspat-Typs: [Fe(NH3)6][TaF6]2 und [Ni(NH3)6][TaF6]2

Derivatives of the Fluorite Type: [Fe(NH₃)₆][TaF₆]₂ and [Ni(NH₃)₆][TaF₆]₂ Light blue single crystals of [Fe(NH₃)₆][TaF₆]₂ and [Ni(NH₃)₆][TaF₆]₂ are obtained from 36 : 1 : 6 molar mixtures of (NH₄)F, iron/nickel and tantalum powders, respectively, in sealed Monel metal ampoules at 400 °C. They both crystallize isotypic with [Co(NH₃)₆][PF₆]₂ (cubic, Fm-3m, Z = 4, a = 1259.0(2)/1260.4(2) pm) in a structure that can be derived from the basic fluorite-type of structure according to [Ca][F]₂≡[Fe(NH₃)₆][TaF₆]₂, for example.     

Structural Investigations and Thermal Behavior of (NH4)[Cr(C2O4)2]·2H2O

Single crystals of ammonium chromium(III) dioxalate dihydrate (or ammonium diaquo bis(μ‐oxalato)chromate(III)) have been obtained from aqueous solution of oxalic acid and ammonium dichromate. A pale violet crystal of good optical quality was used for the structure determination at ?100(2) and 25(2) °C, respectively. The basic crystallographic data for the low temperature data set are as follows: monoclinic, space group C2/m, a = 6.597(2) Å, b = 7.301(2) Å, c = 9.983(3) Å, β = 92.32(2)°, V = 480.5(2) ų. The structure was solved by direct methods and refined (using anisotropic displacement parameters for all non‐hydrogen atoms) to a final residual of R1 = 0.032 for 503 independent observed reflections (I>2σ(I)). The compound is isotypic with the corresponding rubidium salt. The structure is built up from alternating layers parallel to (001) containing (NH₄)⁺ ions or Cr(C₂O₄)₂(H₂O)₂ octahedra, respectively. The corners of the octahedra consist of four O atoms from two oxalate groups and two additional water molecules. The ammonium cations (occupying Wyckoff‐site 2a) are disordered among two possible orientations. They provide linkage between different octahedral layers by hydrogen bridging. The water molecules in turn form hydrogen bridges with adjacent octahedra within the same layer. Further structural characterization included infrared spectroscopy. According to DTA/TG experiments the present compound shows several thermal processes in the range between room temperature and 900 °C.     

Cr1.45Tl1.87Mo15Se19, a monoclinic variant of the hexagonal In3Mo15Se19 type

The monoclinic compound Cr_1.45Tl_1.87Mo₁₅Se₁₉ (chromium thallium pentadecamolybdenum nonadecaselenide) represents a variant of the hexagonal In₃Mo₁₅Se₁₉ structure type. Its crystal structure consists of an equal mixture of Mo₆Se₈Se₆ and Mo₉Se₁₁Se₆ cluster units. The Mo and Se atoms of the median plane of the Mo₉Se₁₁Se₆ unit, as well as three Cr ions, lie on sites with m symmetry (Wyckoff site 2e). The fourth Cr ion is in a 2b Wyckoff position with site symmetry.     

The Crystal Structure of Disodium Phosphonate,Na2HPO3

Anhydrous disodium phosphonate, Na₂HPO₃, was prepared by dehydration of its pentahydrate. The crystal structure of Na₂HPO₃ was solved from high resolution X‐ray powder diffraction data (P2₁/n; Z = 4; a = 9.6987(1), b = 6.9795(1), c = 5.0561(1) Å, β = 92.37(1)°; V = 341.97(1) ų). The crystal structure consists of two types of sodium‐oxygen polyhedra, which are connected via common edges and vertices forming layers perpendicular to [100]. These Na(1)‐ and Na(2)‐layers are interlinked via common edges, forming in a 3D‐framework. The resulting topology is providing oxygen arrangements that please the coordinative requirement of phosphorus(III).     

Magnesium diiodide,MgI2

Single crystals of magnesium diiodide have been grown and the structure solved for the first time from single‐crystal X‐ray diffraction data. This study confirms that MgI₂ is isostructural with CdI₂ (C6 or 2H structure type). The space group is with the Mg atom on a site with 3m symmetry (Wyckoff site 1a) and the I atom on a site with m symmetry (Wyckoff site 2d). Trends in the 2H structures of dihalides are discussed briefly.     

An anisaldehyde sodium bisulfite derivative: poly[[μ4‐(hydroxy)(4‐methoxyphenyl)methanesulfonato]sodium]

The title complex, [Na(C₈H₉O₅S)]_n, is polymeric and consists of broad layers parallel to (100) made up of an inner hydrophilic core of Na⁺ cations and polar SO₃C(OH)– groups, padded on both sides by two hydrophobic layers of pendant methoxyphenyl groups. The Na⁺ cations in the inner core are six‐coordinated into highly distorted NaO₆ octahedra by four symmetry‐related (hydroxy)(4‐methoxyphenyl)methanesulfonate anions, leading to a tightly woven two‐dimensional structure. While there are some hydrogen bonds providing interplanar cohesion, interactions between adjacent layers are weak hydrophobic ones. The present compound appears to be the first reported structure containing the (hydroxy)(4‐methoxyphenyl)methanesulfonate ligand.     

Rhombohedral boron subnitride,B13N2, by X‐ray powder diffraction

The structure of the title compound consists of distorted B₁₂ icosahedra linked by N—B—N chains. The compound crystallizes in the rhombohedral space group Rm (No. 166). The unit cell contains four symmetry‐independent atom sites, three of which are occupied by boron [in the 18h, 18h (site symmetry m) and 3b (site symmetry m) Wyckoff positions] and one by nitrogen (in the 6c Wyckoff position, site symmetry 3m). Two of the B atoms form the icosahedra, while N atoms link the icosahedra together. The main feature of the structure is that the 3b position is occupied by the B atom, which makes the structure different from those of B₆O, for which these atom sites are vacant, and B_4+xC_1−x, for which this position is randomly occupied by both B and C atoms.     

The Upper Limit of Luminol's Amphiprotism: The Crystal Structure of 5-Ammonium-2-hydro-1,4-phthalzinediol Sulfate(IV)

Luminol is chemically sufficiently stable to be diprotonated at high proton concentrations as provided by concentrated sulfuric acid. The luminol dication (5-ammonium-2-hydro-1,4-phthalzinediol) sulfate was isolated as macroscopic single crystals and its structure was determined and refined from single-crystal X-ray data collected at 173 K [cell parameters: a = 8.3994(17) Å, b = 6.9985(14) Å, c = 17.486(4) Å, β = 90.85(3)°, V = 1027.8(4) ų, space group P2₁/c]. The structure is comprised of layers stacked along the b axis. Intralayer interactions are accomplished by strong hydrogen bonds of three luminol dications to one central [SO₄]^2– ion. Interlayer interactions are formed by weak hydrogen bonds of one luminol dication to two [SO₄]^2– ions in the adjacent layers, respectively, and alternating sandwich and parallel-displaced π-π-stacking of the 1-hydropyridazine-3,6-diol moieties of luminol dications in adjacent layers, respectively.     

Tetra­aqua­cobalt(II) bis­[vanadyl(IV) phosphate], [Co(H2O)4][VO(PO4)]2

The structure of [Co(H₂O)₄][VO(PO₄)]₂ is composed of [VO(PO₄)] layers and interlayer tetrahydrated Co²⁺ ions. Alternating VO₅ square pyramids and PO₄ tetrahedra share O‐atom vertices, thus forming the vanadyl phosphate layers. Two vanadyl oxo groups from neighbouring layers are coordinated to each Co atom in a trans fashion, with Co—O distances of 2.157 (4) Å, thus generating a three‐dimensional framework structure.     

Encasing of Na+ ion in dimer‐formed acetic acid clusters

Peaks with anomalous abundance found in the mass spectra are associated with ions with enhanced stability. Among the scientific community focused on mass spectrometry, these peaks are called ‘magic peaks’ and their stability is often because of suggestive symmetric structures. Here, we report findings on ionised Na‐acetic acid clusters [Na⁺‐(AcA)_n] produced by Na‐doping of (AcA)_n and UV laser ionisation. Peaks labelled n = 2, 4, 8 are clearly distinguishable in the mass spectra from their anomalous intensity. Ab initio calculations helped elucidate cluster structures and energetic. A plausible interpretation of the magic peaks is given in terms of (AcA)_n formed by dimer aggregation. The encasing of Na⁺ by twisted dimers is proposed to be the origin of the enhanced cluster stability. A conceivable dimer‐formed tube‐like closed structure is found for the Na⁺‐(AcA)₈. Copyright © 2015 John Wiley & Sons, Ltd.     

The rich crystal chemistry of the AMM′(PO4)2 morphotropic series: NaZnAl(PO4)2, the first Na representative with a new structure type

A novel phosphate, sodium zinc aluminium bis(phosphate), NaZnAl(PO₄)₂, was obtained under mild‐temperature hydrothermal conditions at 553 K. The crystal structure has been studied using single‐crystal X‐ray experimental data. The pseudo‐hexagonal phase NaZnAl(PO₄)₂ crystallizes in the monoclinic space group P2₁/c. Its unique crystal structure is based on a three‐dimensional (3D) framework built by Zn‐, Al‐ and P‐centred tetrahedra sharing vertices. Channels parallel to the [101] and [01] directions are limited by six‐ and eight‐membered windows, and incorporate Na atoms. The new compound is discussed as a member of the morphotropic series AMM′PO₄, where A = Na, K, Rb or NH₄, M = Cu, Ni, Co, Fe, Zn or Mg and M′ = Fe, Al or Ga. The title compound is the first Na representative within the series and is characterized by a 3D architecture of tetrahedra populated in an ordered manner by Zn²⁺, Al³⁺ and P⁵⁺ ions.     

A tetragonal form of dysprosium orthomolybdate at room temperature

In the present tetragonal modification of dysprosium orthomolybdate, Dy₂(MoO₄)₃, the Dy, one Mo and one O atom are located on a mirror plane with Wyckoff symbol 4e, while another Mo atom is located on a fourfold inverse axis, Wyckoff symbol 2a. A single crystal was selected from a polycrystalline mixture of the Dy₂O₃–ZrO₂–MoO₃ system and was stable at room temperature for at least three months. The structure refinement does not indicate the presence of Zr on the Dy sites (to within 1% accuracy). Thus, the stabilization of the tetragonal form is due to disordered positions for a second O atom and split positions for a third O atom that also maintain the DyO₇ coordination, which is not expected for short Dy—O distances [2.243 (6)–2.393 (5) Å].     

Die trikline Kristallstruktur von Ag2Bi2S3Cl2: Pseudosymmetrie und Zwillingsbildung

Ruby‐red crystals of Ag₂Bi₂S₃Cl₂ were synthesized from AgCl and Bi₂S₃ by cooling a melt from 770 K to room temperature. X‐ray diffraction on powders and single‐crystals revealed a triclinic crystal structure with special lattice constants (P &1macr; (No. 2), a = 1085.0(2), b = 717.2(1), c = 1137.6(1) pm, α = 89.80(1)?, β = 74.80(1)?, γ = 87.81(1)?). In the structure [Bi^IIIS₃Cl₄] polyhedra form 2[BiS_3/2Cl_4/4]^‐ double‐layers by sharing common faces and edges. The silver(I) cations between the layers are coordinated either octahedrally by sulfide ions or tetrahedrally by sulfide and chloride ions. The deviations from the monoclinic space group P 1 2₁/c 1 are small and induce twinning along [010]. Further pseudosymmetry is based on the stacking of layer packages with the symmetry of the layer group P (2/c) 2₁/c 2/b.