Synthesis, crystal structure and magnetic property of a new nickel selenite chloride: Ni5(SeO3)4Cl2

The new nickel selenite chloride, Ni₅(SeO₃)₄Cl₂, was obtained by high-temperature solid state reaction of NiCl₂, Ni₂O₃ and SeO₂ in a 1:2:4 molar ratio at 700 °C in an evacuated quartz tube. Its structure was established by single-crystal X-ray diffraction. Ni₅(SeO₃)₄Cl₂ crystallizes in the triclinic system, space group P-1 (No. 2) with cell parameters of a=8.076(2), b=9.288(2), c=9.376(2) Å, α=101.97(3), β=105.60(3), γ=91.83(3)° and Z=2. All nickel(II) ions in Ni₅(SeO₃)₄Cl₂ are octahedrally coordinated by selenite oxygens or/and chloride anions (([Ni(1)O₅Cl], [Ni(2)O₄Cl₂], [Ni(3)O₅Cl], [Ni(4)O₆] and [Ni(5)O₄Cl]). The structure of the title compound features a condensed three-dimensional (3D) network built by Ni(II) ions interconnected by SeO₃²⁻ anions as well as Cl⁻ anions. Magnetic property measurements show strong antiferromagnetic interaction between nickel(II) ions.     

The crystal structure of hydrogen cerium(III) sulfate hydrate, [H3O][Ce(SO4)2] · H2O

[H₃O][Ce(SO₄)₂] · H₂O crystallizes in the monoclinic system with unit-cell dimensions (from single-crystal data) a = 9.359(4), b = 9.926(4), c = 8.444(3) Å, β = 96.53(9)° and space group P2₁/n, z = 4. The structure was solved by conventional heavy-atom methods using 1787 counter-measured reflections (MoKα radiation), and refined using full-matrix least-squares techniques to an R of 0.0465 (ωR = 0.0413). The structure consists of cerium(III) ions in irregular nine-coordination to oxygen atoms from two bidentate sulfate ions, four monodentate sulfate oxygen atoms, and one water molecule. The oxonium ions are present as isolated ions in the structure and take par in the hydrogen bonding network. The Ce-O bond lengths range from 2.454(7) to 2.626(6) Å.     

Thermodynamic parameters of vaporization of EuBr2

The vaporization process of europium dibromide was studied using high-temperature mass spectrometry. It was ascertained that saturated vapor in temperature range of 1049–1261 K was represented mainly by EuBr₂ molecules; the fraction of dimer molecules Eu₂Br₄ was less than 1%. Heat capacities of solid and liquid europium dibromide, as well as the melting enthalpy were measured by means of differential scanning calorimetry in temperature range 300–1100 K; using these data thermodynamic functions for EuBr₂ in condensed state were calculated. For all experimental data, including the literature data, thermodynamic characteristics of the vaporization of europium dibromide were determined using a unified set of thermodynamic functions according to the methods of the second and third laws of thermodynamics. The value of Δ_s H ^o(298.15 K) = 354 ± 5 kJ/mol was recommended for the reaction of sublimation of EuBr₂(cr.) = EuBr₂.     

Substitution in barium-fluoride apatite: The crystal structures of Ba10(PO4)6F2, Ba6La2Na2(PO4)6F2 and Ba4Nd3Na3(PO4)6F2

The crystal structures of the apatites Ba₁₀(PO₄)₆F₂(I), Ba₆La₂Na₂(PO₄)₆F₂(II) and Ba₄Nd₃Na₃(PO₄)₆F₂ (III) have been determined by single-crystal X-ray diffraction. All three compounds crystallize in a hexagonal apatite-like structure. The unit cells and space groups are: I, a = 10.153(2), c = 7.733(1)Å, $\text{P6}{}_3\text{m}\text{; a = 9.9392(4), c = 7.4419(5)}$Å, $\text{P}\text{6}$; III, a = 9.786(2), c = 7.281(1)Å, $\text{P}\text{3}$. The structures were refined by normal full-matrix crystallographic least squares techniques. The final values of the refinement indicators R_w and R are: I, R_w = 0.026, R = 0.027, 613 observed reflections; II, R_w = 0.081, R = 0.074, 579 observed reflections; III, R_w = 0.062, R = 0.044, 1262 observed reflections.In I, the Ba(1) atoms located in columns on threefold axes, are coordinated to nine oxygen atoms; the Ba(2) sites form triangles about the F site and are coordinated to six oxygen atoms and one fluoride ion. The fluoride ions are statistically displaced ～0.25 Å from the Ba(2) triangles. This displacement of the F ions is analogous to the displacement of OH ion in Ca₁₀(PO₄)₆(OH)₂.The structures of II and III contain disordered cations. In II there is disorder between La and Na in the column cation sites as well as triangle sites. In III, Nd and Na ions are ordered in the column sites, but there is disorder among Ba and the remaining Nd and Na ions in the triangle sites to give an average site population of $\text{2}\text{3}\text{Ba}\text{,}\text{1}\text{6}\text{Nd}\text{,}\text{1}\text{6}\text{Na}$. The coordination of the rare earth ions and Na ions in the ordered column sites are nine and six oxygens, respectively, in accord with the greater charge of the rare earth ions as compared with Na. The F ions in both II and III suffer from considerable disorder in position, and their locations are not precisely known.     

The crystal structure of Mg51Zn20

The crystal structure of Mg₅₁Zn₂₀, a phase designated conventionally as “Mg₇Zn₃,” has been determined by the single-crystal X-ray diffraction method. It was solved by the examination of a Patterson synthesis, and refined by the ordinary Fourier and least-squares method; the R value obtained was 4.8% for 1167 observed reflections. The crystal is orthorhombic, space group Immm, with a = 14.083(3), b = 14.486(3), c = 14.025(3) Å, and Z = 2. There are 18 independent atomic sites, Zn1Zn6, Mg1Mg10, A, and B, and the last two sites are statistically occupied by Zn and Mg atoms with the occupancies; 0.46(2)Zn7 + 0.52(2)Mg11 and 0.24(2)Zn8 + 0.74(2)Mg12, for A and B, respectively. The structure of the crystal is described as an arrangement of icosahedral coordination polyhedra, to which all the atomic sites but Zn3 site belong. In this arrangement the Zn atoms other than the Zn3 and Zn8(B) center the icosahedral coordination polyhedra with coordination number 12. The Zn3, Zn8 atoms, and all the Mg atoms except Mg11(A) are located at the centers of various coordination polyhedra with the coordination numbers from 11 to 15. The distances between neighboring atoms are 2.71–3.07, 2.82–3.65, and 2.60–3.20 Å for ZnZn, MgMg, and ZnMg, respectively.     

Neutron and X-ray diffraction study on polymorphism in lithium orthotantalate,Li3TaO4

The structures of the low-and high-temperature modifications of lithium orthotantalate, Li₃TaO₄, have been determined by neutron and X-ray diffraction methods. The low-temperature, or β, phase has symmetry $\text{C2}\text{c}$ and lattice parameters a₁ = 8.500(3), b₁ = 8.500(3), c₁ = 9.344(3)Å, and β = 117.05(2)°. The high-temperature, or α, phase has symmetry P2 and lattice parameters a_h = 6.018(1), b_h = 5.995(1), c_h = 12.865(2)Å, and β_h = 103.53(2)°. Both structures are ordered. The β-phase has a rock salt-type structure with a 3 : 1 ordering of the Li⁺ and Ta⁵⁺ ions. Its structure can be generated from the low-temperature modification by means of a complex pattern of shifts of the Ta⁵⁺ ions.     

Preparation,crystal structure,and properties of the mixed-valence compound Nb3Se5Cl7

The new compound Nb₃Se₅Cl₇ was prepared by heating 2NbSe₂Cl₂ + 1NbCl₄ at 530°C for 2–3 weeks. The compound is monoclinic with a = 7.599, b = 12.675, c = 8.051Å; β = 106.27°; space group $\text{P2}{}_1\text{m}$. The corresponding bromide, Nb₃Se₅Br₇ (obtained by decomposition of NbSe₂Br₂ under NbSeBr₃), is isotypic with a = 7.621, b = 12.833, c = 8.069Å; β = 106.21°. from the crystal structure and XPS spectra it follows that Nb₃Se₅Cl₇ can be formulated as: [Nb⁴⁺₂Nb⁵⁺₁(Se₂)^2?₂Se^2?₁Cl^?₇]. The structure consists of chains of composition [Nb⁴⁺₂(Se₂)^2?₂Cl^?₅], to which side chains [Nb⁵⁺Se^2?Cl^?₂] are attached. The Nb⁴⁺ atoms form pairs (NbNb = 2.94 Å) which explains that Nb₃Se₅Cl₇ is a diamagnetic semiconductor with a band gap (1.59 eV at 5°K, 1.49 eV at 300°K) very similar to that of NbSe₂Cl₂.     

Crystal structure and luminescence of Sr0.99Eu0.01AlSiN3

Strontium europium aluminum silicon nitride, Sr_0.99Eu_0.01AlSiN₃, was synthesized by heating a mixture of binary nitrides at 2173 K and a N₂ gas pressure of 190 MPa. Single crystals of Sr_0.99Eu_0.01AlSiN₃ approximately 30 μm were obtained. The structure was confirmed to be an isotypic structure of CaAlSiN₃ in the orthorhombic space group Cmc2₁, analyzed by single-crystal X-ray diffraction. The lattice parameters are a=9.843(3), b=5.7603(16), c=5.177(2) Å, cell volume=293.53(17) Å³. It shows an orange-red photoluminescence by 5d→4f transition of Eu²⁺ at around 610 nm under excitation ranging from ultraviolet to 525 nm. The photoluminescence intensity, temperature characteristics, and oxidative stability were comparable or superior to those of CaAlSiN₃:Eu²⁺ phosphor.     

On basic thallium sulfates: Structure of Tl2Tl OH(SO4)2

The Tl₂TlOH(SO₄)₂ compound is monoclinic, a = 7.758 (3), b = 17.587 (9), c = 7.356 (3) Å, β = 119.91 (3)°, S. G. Cc, Z = 4. The structure was solved by full-matrix least square refinement to R = 0.033 from 1242 single-crystal reflections collected on an automated diffractometer. Tl⁺ ions ensure bonding between [Tl^IIIOH(SO₄)₂]_∞ sheets. These sheets may be viewed as criss-crossing TlSO₄ chains. In the [101] direction, the linking of Tl^III is reinforced by bidentate OH groups, so the usual hexacoordination of trivalent thallium is preserved. A transition occurring at 104°C is under investigation.     

Crystal structure and magnetic properties of Co2TeO3Cl2 and Co2TeO3Br2

The crystal structures of the two new synthetic compounds Co₂TeO₃Cl₂ and Co₂TeO₃Br₂ are described together with their magnetic properties. Co₂TeO₃Cl₂ crystallize in the monoclinic space group P2₁/m with unit cell parameters a=5.0472(6) Å, b=6.6325(9) Å, c=8.3452(10) Å, β=105.43(1)°, Z=2. Co₂TeO₃Br₂ crystallize in the orthorhombic space group Pccn with unit cell parameters a=10.5180(7) Å, b=15.8629(9) Å, c=7.7732(5) Å, Z=8. The crystal structures were solved from single crystal data, R=0.0328 and 0.0412, respectively. Both compounds are layered with only weak interactions in between the layers. The compound Co₂TeO₃Cl₂ has [CoO₄Cl₂] and [CoO₃Cl₃] octahedra while Co₂TeO₃Br₂ has [CoO₂Br₂] tetrahedra and [CoO₄Br₂] octahedra. The Te(IV) atoms are tetrahedrally [TeO₃E] coordinated in both compounds taking the 5s² lone electron pair E into account. The magnetic properties of the compounds are characterized predominantly by long-range antiferromagnetic ordering below 30 K.     

A new structural type in ternary chalcogenide chemistry: Structure and properties of Nb2Pd3Se8

A study of the NbPdSe system has afforded a new phase, Nb₂Pd₃Se₈. The structure of this phase has been established through single-crystal X-ray measurements. The compound crystallizes in space group D⁹_2h-Pbam with two formula units in a cell of dimensions a = 15.074(6), b = 10.573(4), c = 3.547(2)Å. In this unusual structure there are two chains of edge-sharing selenium trigonal prisms centered by niobium atoms. These chains conjoin through two types of palladium atoms—square planar and square pyramidal—each coordinated by selenium atoms. As a consequence of this conjunction tunnels extending along c result. Electrical conductivity measurements indicate that this material is a metallic-semiconductor.     

Crystal and molecular structure of [{Rh(C5Me5)}3Cl5np3]PF6 · 0.5 C3H8O

The crystal and molecular structure of the monoligand trimetallic complex [{Rh(C₅Me₅)}₃Cl₅np₃]PF₆ · 0.5 C₃H₈O (np₃  tris(2-diphenylphosphinoethyl)-amine) have been established by a single-crystal X-ray diffraction study. The cation of the complex contains two Rh(C₅Me₅)Cl₂ units each bound through the metal to one phosphorus atom of the ligand and a Rh(C₅Me₅)Cl group in which the rhodium is bound to the third phosphorus atom and to the nitrogen of the tetradentate ligand.The crystals are triclinic, space group P$\text{1}$, with cell dimensions a 28.598(8), b 13.757(4), c 10.748(3) Å, α 90.69(4), β 96.67(4), γ 99.71(4)°, D_c 1.38 g cm^?3 for Z  2. The structure was solved by three dimensional Patterson and Fourier syntheses and refined by least-squares techniques to a final conventional R value of 0.098.     

X-ray and mössbauer studies of tricyclohexyltin(IV) halides. The crystal structures of (cyclo-C6H11)3SnX (X = F,Br and I)

The structures of tricyclohexyltin fluoride (I), bromide (II) and iodide (III) have been determined by X-ray analysis. Compound I crystallizes in the space group P2₁/m with a = 10.422(6), b = 17.238(9), c = 5.769(3) Å, β = 104.6(1)° and Z = 2. Compounds II and III crystallize in the space group Pcmn with a = 10.427(6), b = 16.914(9), c = 11.366(6) Å, Z = 4; and a = 10.400(6), b = 16.900(10), c = 11.400(4) Å, Z = 4, respectively. All three structures consist of discrete tetrahedral (cyclo-C₆H₁₁)₃SnX units.The temperature dependence of the Mössbauer resonance areas has been examined in order to obtain information about the relationship between chemical structure and lattice dynamics.     

Formation energies of molecules and anions of europium bromides

The content of saturated vapors above europium dibromide and Eu-EuBr₂, Eu-Ba-BaBr₂, EuBr₂-LaBr₃ systems is investigated by means of high-temperature mass-spectrometry in the electron ionization and thermoionic emission regimes. On the basis of the measured equilibrium constants for reactions with participation of molecules and negative ions, the enthalpies of formation ??_fH₂₉₈° (kJ/mol) are determined using the method of the third law of thermodynamics: ?59 ± 13 (EuBr), ?349 ± 19 (EuBr₂), and ?861 ± 24 (EuBr ₃ ^? ).     

Low-alkali metal content in β-vanadium mixed bronzes: The crystal structures of β-Kx(V,Mo)6O15 (x=0.23 and 0.32) by single-crystal X-ray diffraction

The vanadium-molybdenum mixed oxide bronzes of composition K_0.23(V_5.35Mo_0.65)O₁₅ and K_0.32(V_5.48Mo_0.52)O₁₅ have a monoclinic structure with s.g. C2/m, Z=2, and unit-cell dimensions a=15.436(2), b=3.6527(5), c=10.150(1) Å, β=108.604(3)° and a=15.452(2), b=3.6502(5), c=10.142(1) Å, β=109.168(3)°, respectively, as determined by single-crystal X-ray diffraction. These compounds show the β-Na_xV₆O₁₅ tunnel structure, which is isostructural with bannermanite, natural sodium-potassium vanadate. Structure refinements from diffracted intensities collected in the 2-38°θ range converged to final R=5.58% and 7.48% for the two crystals, respectively. The V atoms are distributed on three different crystallographic sites. Partial substitution of V with Mo occurs in only one of these positions. Oxygen atoms involved in vanadyl groups point toward the tunnels. The K ions in the tunnels are coordinated by seven oxygen atoms. The alkali metal content in these crystals is much lower than the solubility limit found for the analogous Na containing compound.     

Synthesis, structure and properties of SrAu3In3 and EuAu3In3—New indides with gold zig-zag chains

New indides SrAu₃In₃ and EuAu₃In₃ were synthesized by induction melting of the elements in sealed tantalum tubes. Both indides were characterized by X-ray diffraction on powders and single crystals. They crystallize with a new orthorhombic structure type: Pmmn, Z=2, a=455.26(9), b=775.9(2), c=904.9(2) pm, wR2=0.0425, 485 F² values for SrAu₃In₃ and a=454.2(2), b=768.1(6), c=907.3(6) pm, wR2=0.0495, 551 F² values for EuAu₃In₃ with 26 variables for each refinement. The gold and indium atoms build up three-dimensional [Au₃In₃] polyanionic networks, which leave distorted hexagonal channels for the strontium and europium atoms. Within the networks one observes Au2 atoms without Au-Au contacts and gold zig-zag chains (279 pm Au1-Au1 in EuAu₃In₃). The Au-In and In-In distances in EuAu₃In₃ range from 270 to 290 and from 305 to 355 pm. The europium atoms within the distorted hexagonal channels have coordination number 14 (8 Au+6 In). EuAu₃In₃ shows Curie-Weiss behavior above 50 K with an experimental magnetic moment of 8.1(1) μB/Eu atom. ¹⁵¹Eu Mössbauer spectra show a single signal at δ=−11.31(1) mm/s, compatible with divalent europium. No magnetic ordering was detected down to 3 K.     

La3Os2O10, a new compound containing isolated clusters Os2O10 with metal-metal bonds

The formula of a new compound isolated in the LaOsO system has been established by means of crystal structure determination. There are two La₃Os₂O₁₀ units in a face-centered monoclinic unit cell (S.G. $\text{C2}\text{m}$); a = 7.911(2) Å, b = 7.963(2) Å, c = 6.966(2)Å, β = 115.76(2)°;. For 1082 intensities, collected on an automated single-crystal diffractometer, the final R value was 0.025 after absorption corrections. The structure consists of isolated Os₂O₁₀ clusters composed of two edge-shared OsO₆ octahedra. These dimeric units are connected together by two types of La³⁺ ions in eightfold coordination. In view of the OsOs distance inside the pair (2.462 Å), La₃Os₂O₁₀ provides an example of metal-metal bonding involving a transition metal in a half-integral formal oxidation state of 5.5.     

Crystal structure and phase transitions in perovskite-like C(NH2)3SnCl3

X-ray single-crystal diffraction, high-temperature powder diffraction and differential thermal analysis at ambient and high pressure have been employed to study the crystal structure and phase transitions of guanidinium trichlorostannate, C(NH₂)₃SnCl₃. At 295 K the crystal structure is orthorhombic, space group Pbca, Z=8, a=7.7506(2) Å, b=12.0958(4) Å and c=17.8049(6) Å, solved from single-crystal data. It is perovskite-like with distorted corner-linked SnCl₆ octahedra and with ordered guanidinium cations in the distorted cuboctahedral voids. At 400 K the structure shows a first-order order-disorder phase transition. The space group is changed to Pnma with Z=4, a=12.1552(2) Å, b=8.8590(2) Å and c=8.0175(1) Å, solved from powder diffraction data and showing disordering of the guanidinium cations. At 419 K, the structure shows yet another first-order order-disorder transformation with disordering of the SnCl₃⁻ part. The space group symmetry is maintained as Pnma, with a=12.1786(2) Å, b=8.8642(2) Å and c=8.0821(2) Å. The thermodynamic parameters of these transitions and the p-T phase diagram have been determined and described.     

Crystal structure and thermal study of the new hydrated cadmium-cerium(III) chloride CeCd4Cl11·13H2O

The new double-salt CeCd₄Cl₁₁·13H₂O in the ternary system CeCl₃-CdCl₂-H₂O has been prepared from aqueous solution upon evaporation at 5°C and characterized based on elemental analysis, spectroscopic data, thermal studies and X-ray powder and single-crystal diffraction. CeCd₄Cl₁₁·13H₂O crystallizes in the monoclinic space group P2₁ with a=7.667(2), b=17.351(3), c=11.970(2)Å, β=101.61(3)° and Z=2. After refinement of the structure the reliability factor R in the final cycle is 0.064. The structure can be regarded as consisting of endless double chains of CdCl₆ and CdOCl₅ octahedra and isolated tricapped triangular prisms surrounding the cerium cations. Differential scanning calorimetry showed that the title compound exhibits five endothermic anomalies interpreted from thermogravimetry. A comparison with the structure of SrCd₂Cl₆·8H₂O is proposed.     

Substitutional Effects of 3d Transition Metals on the Magnetic and Structural Properties of Quasi-Two-Dimensional La5Mo4O16

Substituted phases with the composition La₅Mo_4−xT_xO_16−δ (T=Co, Fe, Mn, and Mg and x∼0.7) were prepared by fused-salt electrolysis and/or conventional solid-state methods. The crystal structure of the parent compound, La₅Mo₄O₁₆, contains perovskite-like corner-sharing MoO₆ octahedral units in the ab plane separated by Mo₂O₁₀ bioctahedral units along the c direction. Detailed single-crystal X-ray diffraction studies on the Co-substituted phase, La₅Mo_3.31Co_0.69O_16−δ, indicated that the unit cell is triclinic (space group C-1) with Co exclusively replacing Mo atoms in the perovskite layers. X-ray absorption measurements revealed that the transition metal ions are divalent, consistent with the crystal structure analysis. The anomalous magnetic transition observed at 180 K in the parent compound shifts to lower temperatures upon substitution with transition metal ions. No long-range magnetic order was evident in the Mg²⁺-substituted compositions. The electrical resistivity of all the substituted phases was at least 3 orders of magnitude higher than that of the parent compound. Variations in the magnetic and electrical properties have been ascribed to the disruption of exchange correlations caused by substitutional disorder at the Mo sites.