On crystal chemistry of mercury chromates. Details of fragmentation and packing in crystal structures

In the crystal structures of the minerals edoylerite, deanesmithite, and wattersite and in the structures of the compounds HgCrO₄, Hg₃O₂CrO₄ (analog of the mineral schuetteite), and Pb₂HgO₂CrO₄, there are atomic groups or fragments linked by relatively strong (covalent) bonds. The anion fragments represented by CrO₄ tetrahedra are condensed into pairs and chains, in which adjacent tetrahedra are related by symmetry centers. The cation fragments form various patterns from zigzag ribbons of [Hg₄S₄] rings to ribbons and frameworks with [Hg₆O₂] r-octahedra, [Hg₂CrO] and [Pb₂HgO] triangles, and [Hg₆Cr₂O₄] (stella quadrangula) groups. The symmetry of the fragments and their assemblies is analyzed. Analysis of the reference crystal-forming planes has revealed cation sublattices (close to the F-cubic sublattice in two cases), determining the typical features of the structures.Original Russian Text Copyright © 2004 by S. V. Borisov, S. A. Magarill, and N. V. PervukhinaTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 471–479, May–June, 2004.     

[Hg3]4+ Cation in Inorganic Crystal Structures

The crystal-chemical structure of the minerals and inorganic compounds kuznetsovite [Hg₃](AsO₄)Cl and terlinguaite [Hg₃][HgO₂]Cl₂, as well as [Hg₃]₃(AsO₄)₄ and [Hg₃]₂[HgO₂](PO₂ and their analogs, is considered from the viewpoint of the packing of large supramolecular atomic groups. The cationic layer of polyhedra around the large [Hg₃]⁴⁺ cations, alternating with the anionic layer of [HgO₂]^2-, (AsO₄)^3-, (PO₄)^3-, Cl^-, plays the major role in structure formation. Segregation of mercury cations of different valences possibly reflects the solid-state transformations occurring in nature and accompanied by mercury liberation.     

Crystal-chemical analysis of the structures of minerals with [Hg<Subscript>2</Subscript>]<Superscript>2+</Superscript> dumbbells

An analysis of the structures of minerals with [Hg₂]²⁺ dumbbells including poyarkovite [Hg₂]₃Cl₂O₂, shakhovite [Hg₂]₂Sb(OH)₃O₃, vasilyevite Hg₂₀O₆I₃Br₂Cl(CO₃), and kelyanite [Hg₂]₆[SbO₆]BrCl₂ was carried out. The determining factor in structure formation is the ordering of the centers of the cluster groups of mercury and large anions by systems of equidistant parallel planes with d _hkl ～ 2.5–4.5 Å. The different combinations of atoms and fragments in the structure are ordered by their own pseudotranslation lattices; this probably reflects the stages of crystallization. The crystal structures under study are examples of balance between the local interatomic interactions and the forces that create long-range order for different stoichiometries, masses, and sizes of components.     

The mercury chromates Hg6Cr2O9 and Hg6Cr2O10—Preparation and crystal structures, and thermal behaviour of Hg6Cr2O9

The basic mercury(I) chromate(VI), Hg₆Cr₂O₉ (=2Hg₂CrO₄·Hg₂O), has been obtained under hydrothermal conditions (200 °C, 5 days) in the form of orange needles as a by-product from reacting elemental mercury and K₂Cr₂O₇. Hydrothermal treatment of microcrystalline Hg₆Cr₂O₉ in demineralised water at 200 °C for 3 days led to crystal growth of red crystals of the basic mercury(I, II) chromate(VI), Hg₆Cr₂O₁₀ (=2Hg₂CrO₄·2HgO). The crystal structures were solved and refined from single crystal X-ray data sets. Hg₆Cr₂O₉: space group P2₁2₁2₁, Z=4, a=7.3573(12), b=8.0336(13), , 3492 structure factors, 109 parameters, R[F²>2σ(F²)]=0.0371, wR(F² all)=0.0517; Hg₆Cr₂O₁₀: space group Pca2₁, Z=4, a=11.4745(15), b=9.4359(12), , 3249 structure factors, 114 parameters, R[F²>2σ(F²)]=0.0398, wR(F² all)=0.0625. Both crystal structures are made up of an intricate mercury-oxygen network, subdivided into single building blocks [O-Hg-Hg-O] for the mercurous compound, and [O-Hg-Hg-O] and [O-Hg-O] for the mixed-valent compound. Hg₆Cr₂O₉ contains three different Hg₂²⁺ dumbbells, whereas Hg₆Cr₂O₁₀ contains two different Hg₂²⁺ dumbbells and two Hg²⁺ cations. The Hg^I-Hg^I distances are characteristic and range between 2.5031(15) and 2.5286(9) Å. All Hg₂²⁺ groups exhibit an unsymmetrical oxygen environment. The oxygen coordination of the Hg²⁺ cations is nearly linear with two tightly bonded O atoms at distances around 2.07 Å. For both structures, the chromate(VI) anions reside in the vacancies of the Hg-O network and deviate only slightly from the ideal tetrahedral geometry with average Cr-O distances of ca. 1.66 Å. Upon heating at temperatures above 385 °C, Hg₆Cr₂O₉ decomposes in a four-step mechanism with Cr₂O₃ as the end-product at temperatures above 620 °C.     

Syntheses, structures, and magnetic and optical properties of the compounds [Hg3Te2][UCl6] and [Hg4As2][UCl6]

Two new quaternary salts, [Hg₃Te₂][UCl₆] and [Hg₄As₂][UCl₆], have been synthesized and their structures determined by single-crystal X-ray diffraction analysis. [Hg₃Te₂][UCl₆] is the product of a reaction involving UCl₄, HgCl₂, and HgTe at 873 K. The compound crystallizes in space group P2₁/c of the monoclinic system. [Hg₄As₂][UCl₆] results from the reaction of U, Hg₂Cl₂, and As at 788 K. It crystallizes in space group Pbca of the orthorhombic system. [Hg₃Te₂][UCl₆] has a two-dimensional framework of layers, whereas [Hg₄As₂][UCl₆] has a three-dimensional framework of layers interconnected by Hg atoms linearly bonded to As atoms. Both framework structures contain discrete [UCl₆]²⁻ anions between the layers. [Hg₃Te₂][UCl₆] exhibits temperature-independent paramagnetism. The optical absorption spectra of these compounds display f-f transitions.     

[Cl3Cu(I)-As(III)O3]: Ein kristallchemisch neues Bauelement in der Struktur des Pb6Cu(AsO3)2Cl7

The synthetic compound Pb₆Cu(AsO₃)₂Cl₇ crystallizes in space group R witha ₀=9.8614(4),c ₀=17.089(2)Å,Z=3. The crystal structure, determined by single crystal X-ray work, is a typical layer structure. Complex Pb₆(AsO₃)₂Cl₆ layers are combined via monovalent Cu and Cl atoms. A novel element within the structure is a [Cl₃Cu(I)-As(III)O₃] group with the interatomic distances (Å): Cu-Cl=2.44 (3×), As-O=1.76 (3×), Cu-As=2.34 (1×).

     

Thermal analysis in the synthesis and crystal formation of oxides

Vapour phase treatment at elevated temperatures with an activating agent is an effective method of synthesis and purposeful modification of amorphous and fine-grained crystalline substances. In the systems amorphous silica-quartz and amorphous Al(OH)₃ -crystalline-Al₂O₃ different forms of bound water are of prime importance. DTA, TG, DSC, NMR¹H,²⁹Si,²⁷Al, IR spectroscopy, electron- and optical microscopy methods have been used. The interaction of water molecules with the base skeleton and with hydroxide groups on the surface and in the bulk of the silica is of primary significance for modification of the silica structure. The proportion of different forms of the bound water determines the integral evaporation enthalpy of water. Various properties of silica are determined by weak bound water in the surface layer of the material. In the sequence Al(OH)₃ —-Al₂O₃ the structure transformation is observed according to the following scheme:-Al(OH)₃ —-AlOOH- -Al₂O₃, which takes place during the vapour phase treatment with activator.

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Zusammenfassung Eine Dampfphasenbehandlung bei höheren Temperaturen mit einem Aktivierungsmittel ist eine effektive Methode zur Synthese und zielgerichteten Modifizierung von amorphen und feinkörnigen kristallinen Substanzen. In den Systemen amorphes Siliziumdioxid-Quarz sowie amorphes Al(OH)₃-kristallines-Al₂O₃ hat verschiedenartig gebundenes Wasser eine primäre Bedeutung. Bei den Untersuchungen kamen DTA, TG, DSC,¹H-,²⁹Si-,²⁷Al-NMR, IR-Spektroskopie sowie Elektronen- und optische Mikroskopie zur Anwendung. Die Wechselwirkung von Wassermolekülen mit dem Grundgerüst und mit Hydroxidgruppen an der Oberfläche und im Innern von Silika ist für die Modifizierung der Silikastruktur von primärer Bedeutung. Der Anteil der verschiedenartig gebundenen Wasserformen bestimmt die vollständige Verdampfungsenthalpie des Wassers. Die verschiedenen Eigenschaften von Silika werden durch schwach gebundenes Wasser in der Oberflächenschicht der Substanz bestimmt. Die Umwandlung Al(OH)₃ —-Al₂O₃ durchläuft folgendes Schema:-Al(OH)₃--AlOOH--Al₂O₃, nach dem der Vorgang bei der Gasphasenbehandlung mit Aktivator abläuft.

     

Crystal structure of Li2Cu3(SeO3)2(SeO4)2

Summary Single crystal X-ray data of the hydrothermally grown new phase Li₂Cu₃(SeO₃)₂(SeO₄)₂ were measured with a four-circle diffractometer up to sin /=0.81 Å^–1 [I2/a,Z=4,V=1175.5 ų,a=16.293(6),b=5.007(2),c=14.448(6) Å, = 94.21(1)°]. The structure was determined by direct and Fourier methods and refined toR=0.034,R _w =0.027 for 2 086 independent reflections.Cu(1)^[4+1]O₅ forms a tetragonal pyramid, Cu(2)^{[4 + 2]}O₆ is a strongly elongated octahedron. The Li atom is surrounded by four O atoms forming a distorted tetrahedron. Se(IV)O₃ and Se(VI)O₄ groups are in accordance to literature, mean Se-O bond lengths are 1.714 and 1.644 Å.

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Die Kristallstruktur von Li₂Cu₃(SeO₃)₂(SeO₄)₂

Zusammenfassung Einkristall-Röntgendaten der hydrothermal gezüchteten neuen Phase Li₂Cu₃(SeO₃)₂(SeO₄)₂ wurden mit einem Vierkreisdiffraktometer im Bereich bis zu sin /=0.81 Å^–1 gemessen [I2/a,Z=4,V=1175.5 ų,a=16.293(6),b=5.007(2),c=14.448(6) Å, =94.21(1)°]. Die Kristallstruktur wurde mittels direkter und Fourier-Methoden bestimmt und für 2 086 unabhängige Reflexe zuR=0.034,R _w =0.027 verfeinert.Cu(1)^[4+1]O₅ bildet eine tetragonale Pyramide, Cu(2)^[4+2]O₆ ist ein stark verlängertes Oktaeder. Das Li-Atom ist von vier O-Atomen in Gestalt eines verzerrten Tetraeders umgeben. Die Se(IV)O₃-und Se(VI)O₄-Gruppen entsprechen der Literatur, die mittleren Se-O-Abstände betragen 1.714 und 1.644 Å.

     

Crystal growth of a novel oxygen-deficient layered perovskite: Ba7Li3Ru4O20

Single crystals of both Ba₇Li₃Ru₄O₂₀ and Ba₄NaRu₃O₁₂ were grown from reactive molten hydroxide fluxes. Ba₇Li₃Ru₄O₂₀ is a 7L-layer perovskite-related phase resulting from the stacking of six [AO₃] layers and one oxygen deficient [AO₂] layer, thereby creating LiO₄ tetrahedra in addition to the LiO₆ octahedra and face-sharing Ru₂O₉ bi-octahedra formed from the [AO₃] layers. The compound crystallizes in the space group with a=5.7927(1) Å and c=50.336(2) Å, Z=3. Ba₄NaRu₃O₁₂ crystallizes in the space group P6₃mc with lattice parameters of a=5.8014(2) Å and c=19.2050(9) Å, Z=2. Ba₄NaRu₃O₁₂ is identical to a previously reported neutron refinement structure. The magnetic properties of Ba₇Li₃Ru₄O₂₀ are also reported.     

Substitution of ligands in dichloro-2-(arylazo)heterocyclepalladium(II) by 8-quinolinol: kinetics and mechanistic studies

Nucleophilic substitutions of Pd(N,N)Cl₂[(N,N = 1-methyl-2-(arylazo)imidazole (RaaiMe), p-RC₆H₄N=NC₃H₂NN-1-Me; 2-(arylazo)pyridine (Raap), p-RC₆H₄N=NC₅H₄N; 2-(arylazo)pyrimidine (Raapm), p-RC₆H₄N=NC₄H₃N₂ where R = H (a), Me (b), Cl (c)] with 8-quinolinol (HQ) have been examined by spectrophotometry at 298 K in MeCN solution. The product, Pd(Q)₂, has also been confirmed by independent synthesis from Na₂[PdCl₄] and HQ in EtOH. The kinetics of the reaction have been studied under pseudo-first-order conditions and the analyses support a nucleophilic association path. A single phase reaction has been observed and follows the rate law, rate = a + k [Pd(N,N)Cl₂] [HQ]². Thus, the reaction is first order in [Pd(N,N)Cl₂] and second order in [HQ]. External addition of Cl^–(LiCl) suppresses the rate. The rate increases as follows: Pd(RaaiMe)Cl₂ < Pd(Raap)Cl₂ < Pd(Raapm)Cl₂.     

Synthesis, Structure, and 31P NMR of Sulfur/Oxygen-Bridged Incomplete Cubane-Type Molybdenum and Tungsten Clusters with Triphenylphosphine Ligands

Sulfur/oxygen-bridged incomplete cubane-type triphenylphosphine molybdenum and tungsten-clusters [Mo₃S₄Cl₄(H₂O)₂(PPh₃)₃]·3THF (1A), [Mo₃S₄Cl₄(H₂O)₂(PPh₃)₃]·2THF (2A), [Mo₃OS₃Cl₄(H₂O)₂(PPh₃)₃]·2THF (1B), and [W₃S₄Cl₄(H₂O)₂(PPh₃)₃]·2THF (1C) were prepared from the corresponding aqua clusters and PPh₃ in THF/MeOH. On recrystallization from THF, procedures with and without addition of hexane to the solution gave 1A and 2A, respectively, while the procedures gave no effect on the formation of 1B and 1C. Crystallographic results obtained are as follows: 1A: monoclinic, P2₁/n, a=17.141(4) Å, b=22.579(5) Å, c=19.069(4) Å, =96.18(2)°, V=7337(3) ų, Z=4, R(R _w)=0.078(0.102); 1C: monoclinic, P2 ₁/c, a=12.635(1) Å, b=20.216(4) Å, c=27.815(3) Å, =96.16(1)°, V=7062(2) ų, Z=4, R(R _w)=0.071(0.083). If the phenyl groups are ignored, the molecule [Mo₃S₄Cl₄(H₂O)₂(PPh₃)₃] in 2A has idealized CS symmetry with the mirror plane perpendicular to the plane determined by the metal atoms, while the molecule in 1A does not have the symmetry. The tungsten compound 1C is isomorphous with the molybdenum compound 2A. ³¹P NMR spectra of 1A, 2A, and 1C were obtained and compared with similar clusters with dmpe (1,2-bis(dimethylphosphino)ethane) ligands.     

PbCu3(OH)(NO3)(SeO3)3·1/2H2O und Pb2Cu3O2(NO3)2(SeO3)2: Synthese und Kristallstrukturuntersuchung

Crystals of PbCu₃(OH)(NO₃)(SeO₃)₃·1/2H₂O [a=7.761(3)Å,b=9.478(4)Å,c=9.514(4)Å, =66.94(2)°, =69.83(2)°, =81.83(2)°, space group P ,Z=2] and Pb₂Cu₃O₂(NO₃)₂(SeO₃)₂ [a=5.884(2)Å,b=12.186(3)Å,c=19.371(4)Å, space group Cmc2₁,Z=4] were synthesized under hydrothermal conditions. Their crystal structures were refined with three-dimensional X-ray data toR _w=0.033 resp. 0.055. In PbCu₃(OH)(NO₃)(SeO₃)₃·1/2H₂O the Cu atoms are [4+1] and [4+2] coordinated and via SeO₃ groups a three-dimensional atomic arrangement is built up. In Pb₂Cu₃O₂(NO₃)₂(SeO₃)₂ there are sheets, which are connected only via Pb-O bonds ranging from 2.98 Å to 3.16 Å.

     

Crystal structure of synthetic Cu3SeO4(OH)4

Summary The crystal structure of synthetic Cu₃SeO₄(OH)₄ was determined by single crystal X-ray methods:a=8.382 (2) Å,b=6.087 (1) Å,c=12.285 (2) Å,V=626.8 ų,Z=4, space group Pnma,R=0.026,R _w =0.021 for 1255 independent reflections (sin / 0.8 Å^–1). The crystal structure is isotypic to that of the mineral antlerite, Cu₃SO₄(OH)₄. The copper atoms are Jahn-Teller distorted with Cu^[4+2]O₆ polyhedra forming triple chains along [010]. These chains are linked via SeO₄ tetrahedra and weak hydrogen bonds to a framework structure.

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Die Kristallstruktur von synthetischem Cu₃SeO₄(OH)₄

Zusammenfassung Die Kristallstruktur von synthetischem Cu₃SeO₄(OH)₄ wurde mittels Einkristall-Röntgenmethoden ermittelt:a=8.382 (2) Å,b=6.087 (1) Å,c=12.285 (2) Å,V=626.8 ų,Z=4, Raumgruppe Pnma,R=0.026,R _w =0.021 für 1255 unabhängige Reflexe (sin / 0.8 Å^–1). Die Kristallstruktur ist isotyp mit der des Minerals Antlerit, Cu₃SO₄(OH)₄. Die Kupferatome sind Jahn-Teller-verzerrt, die Cu^[4+2]O₆ Polyeder bilden Dreierketten entlang [010]. Diese Ketten sind über SeO₄-Tetraeder und schwache Wasserstoffbrücken zu einer Gerüststruktur verbunden.

     

Schnelle Bestimmung von Kohlenstoff und Wasserstoff in schwefelhaltigen siliciumorganischen Verbindungen

Zusammenfassung N,N,N,N-Tetrakis-(2-hydroxybutyl)-äthylendiamnioniumdiperchlorat bildet in salzsaurer Lösung in Gegenwart von Phosphat und Molybdat den schwerlöslichen Niederschlag [C₁₈H₄₀O₄N₂H₂]₃[P(Mo₃-O₁₀)₄]₂, der sich vorzüglich zur gravimetrischen Phosphorbestimmung eignet (Faktor 0,013190). Bei 93,94 bzw. 1174,2 mg Niederschlag (entspr. 0,04 mMol bzw. 0,5 mMol Phosphat) betrug die Standardabweichung ± 0,3 bzw. 0,6 mg. Fe, Mn, Cr, Co und Ni stören nicht bis zu einem 500 fachen Überschuß.

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Gravimetric determination of phosphorus with N,N,N,N-tetrakis-(2-hydroxybutyl)-ethylenediammonium-diperchlorate

This reagent forms a sparingly soluble precipitate, [C₁₈H₄₀O₄N₂H₂]₃[P(Mo₃O₁₀)₄]₂ in presence of phosphate and molybdate in hydrochloric acid solution. The precipitate is well suitable for a gravimetric determination of phosphorus (factor 0.013190). Standard deviation was ± 0.3 mg for 93.94 mg and ± 0.6 mg for 1174,2 mg of precipitate. Fe, Mn, Cr, Co and Ni do not interfere up to a 500-fold excess.

     

Preparation and Crystal Structure of Re3O10

Trirheniumdecaoxide, Re₃O₁₀, was obtained by the reaction of ReO₂ and ReO₃ in an arc-melting furnace. X-ray powder diffraction revealed a tetragonal structure with space group I m2 and lattice constants a=5.171(1) and c=13.371(6) Å. The crystal structure is built up by layers of corner-sharing [ReO₅] square pyramids perpendicular to [001] with the apical oxygen pointing up and down alternatingly. These layers are interconnected by disordered [ReO₆] octahedra. Early reports on Re₂O₅ are reviewed in the light of our results.     

Hg3Se3O10, a mercury(II) compound with mixed‐valence oxoselenium(IV/VI) anions

The title compound, trimercury(II) bis­[selenite(IV)] selen­ate(VI), contains three crystallographically inequivalent Hg^II cations with coordination numbers of eight (denoted Hg1 and Hg2) and five (denoted Hg3). The corresponding coordination polyhedra around the metal atoms might be described as intermediates between a square antiprism and a triangulated dodecahedron for both Hg1 and Hg2, and a strongly distorted truncated octahedron for Hg3. [HgO_8/2] layers of edge‐sharing [HgO₈] polyhedra propagate parallel to the bc plane, and are connected via Se^VIO₄ tetrahedra and [Hg3O₅] polyhedra along the a axis, forming an arrangement with channels propagating parallel to the b axis. The two independent Se^IVO₃ pyramids bridge the Hg atoms, and the non‐bonding orbitals of the Se^IV ions protrude into the channels from opposite sides.     

Synthesis and Structure of a Neutral Trimetallic Biicosahedral Cluster, (Ph3P)10Au11Ag12Pt2Cl7. A Comparative Study of Molecular and Crystal Structures of Vertex-Sharing Biicosahedral Mixed-Metal Nanoclusters

The synthesis and structure of a new, neutral Au–Ag–Pt vertex-sharing biicosahedral cluster, [(Ph₃P)₁₀Au₁₁Ag₁₂Pt₂Cl₇] (3), is reported. The title cluster was synthesized via a new synthetic strategy based on preformed clusters. The title cluster crystallizes in a monoclinic unit cell of P2₁/m space-group symmetry with lattice parameters a=16.553(14) Å, b=25.130(7) Å, c=29.633(13) Å, =103.03(5); V=12009.3 ų and Z=2. The structure was refined to R₁=7.7% and R₂=9.2% for 3585 independent reflections (242°) with I>3. The metal core of the title structure can be described as two Pt-centered Au₆Ag₆ icosahedra sharing a common Au atom. The four metal pentagons adopt the staggered–eclipsed–staggered (ses) configuration, or, the R(0) rotamer. The ten triphenylphosphine ligands coordinate to the ten peripheral (surface) Au atoms in a radial fashion. There are five doubly-bridging chloride ligands connecting two Ag₅ pentagons and two more chloride ligands coordinating terminally to two apical Ag atoms. The title cluster completes the series of Au-shared biicosahedral clusters with 0, 1, and 2 Pt atom(s) occupying the two icosahedral centers, as exemplified by [(p-Tol₃P)₁₀Au₁₃Ag₁₂Cl₇]²⁺ (1), [(Ph₃P)₁₀Au₁₂Ag₁₂PtCl₇]⁺ (2), and the title cluster [(Ph₃P)₁₀Au₁₁Ag₁₂Pt₂Cl₇] (3), respectively. The structure of the title cluster satisfies the site preference rules established for mixed-metal vertex-sharing polyicosahedral nanoclusters. The molecular structural invariance and the ubiquity of the P2₁/m space group for the crystal structures of the biicosahedral cluster series with Ph₃P as phosphine ligands and conforming to the R(0) rotameric metal configuration are discussed. Furthermore, endo- and exo-icosahedral chemistries, and rotamerism and roulettamerism of an extensive series of vertex-sharing biicosahedral nanoclusters, as well as their bonding implications, are described via a comparative study.     

Structural chemistry of mercury chalcohalides. III. Crystal structure of Hg<Subscript>3</Subscript>S<Subscript>2</Subscript>Cl<Subscript>1.5</Subscript>Br<Subscript>0.5</Subscript> polymorphs

Single crystals of two new mercury thiohalides of the composition Hg₃S₂Cl_{2? x}Br_x(x = 0.5) have been grown from gas phase and studied by X-ray crystallography. Structure refinement for monoclinic (I) and cubic (II) phases (I: a = 16.841(2) Å, b = 9.128(2) Å, c = 9.435(4) Å; β = 90.080(10)°, V = 1450.3(7) ų, space group _C2/_{m, Z} = 8, _R = 0.0528; II: a = 18.006(2) Å, V = 5837.8(11) ų, space group \(Pm\bar 3n\), Z = 32, R = 0.0503) clearly shows that they are polymorphs of the same composition Hg₃S₂Cl_1.5Br_0.5. The monoclinic modification I is similar to the synthetic phases γ-Hg₃S₂Cl₂, β-Hg₃S₂Br₂, Hg₃Se₂Br₂ and to the analogue of radtkeite mineral, Hg₃S₂ClI. The modification II is isostructural to the synthetic β-Hg₃S₂Cl₂. In both structures, each S atom coordinates three Hg atoms with the formation of pyramidal SHg₃ units (Hg-S 2.37–2.48 Å; HgSHg 93.1–97.5 ). The SHg₃ units are linked through Hg vertices into corrugated layers [Hg₁₂S₈]_∞∞ (I) and isolated cubic groups [Hg₁₂S₈] (II). Similarly to other mercury chalcohalides, the crystal structures are basically determined by the halogen atoms which form a cubic sublattice incorporating the Hg-S moieties.     

Cu2O(SO4), dolerophanite: Refinement of the crystal structure,with a comparison of [O Cu(II)4] tetrahedra in inorganic compounds

The refinement of the crystal structure of Cu₂O(SO₄), dolerophanite, [a=9.370 (1) Å,b=6.319 (1) Å,c=7.639 (1) Å, =122.34 (1)°; space group C 2/m;Z=4;R=0.035] confirmed the trigonal dipyramidal coordination of one Cu(II) atom (mean distance Cu-O=2.025 Å). One O atom is tetrahedrally surrounded by four Cu(II) atoms; the mean Cu(II)-O distance of 1.918 Å compares well to [O Cu(II)₄] tetrahedra found in inorganic crystal structures.de|Die Verfeinerung der Kristallstruktur von Cu₂O(SO₄), Dolerophanit, [a=9.370 (1) Å,b=6.319 (1) Å,c=7.639 (1) Å, =122.34 (1)°; Raumgruppe C 2/m;Z=4;R=0.035] bestätigte die trigonal dipyramidale Koordination des einen Cu(II)-Atoms (mittlerer Cu-O-Abstand=2.025 Å). Ein O-Atom ist tetraedrisch von vier Cu(II)-Atomen umgeben; der mittlere Cu(II)-O-Abstand von 1.918 Å entspricht den in ähnlichen [O Cu(II)₄]-Tetraedern von anorganischen Kristallstrukturen gefundenen Werten.

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Cu₂O(SO₄), Dolerophanit: Verfeinerung der Kristallstruktur mit einem Vergleich von [O Cu(II)₄]-Tetraedern in anorganischen Verbindungen

     

Synthesis, crystal structure and optical properties of BiMgVO5

The new vanadate BiMgVO₅ has been prepared and its structure has been determined by single crystal X-ray diffraction: space group P2₁/n, , , , β=107.38(5)°, wR₂=0.0447, R=0.0255. The structure consists of [Mg₂O₁₀] and [Bi₂O₁₀] dimers sharing their corners with [VO₄] tetrahedra. The ranges of bond lengths are 2.129-2.814 Å for Bi-O; 2.035-2.167 Å for Mg-O and 1.684-1.745 Å for V-O. V-O bond lengths determined from Raman band wavenumbers are between 1.679 and 1.747 Å. An emission band overlapping the entire visible region with a maximum around 650 nm is observed.