Untersuchungen an Natriumtrifluormethylsulfonat – Kristallstruktur und Phasenumwandlung des Monohydrats und Natriumionenleitfähigkeit des wasserfreien Salzes

Studies on Sodium Trifluormethanesulfonate – Crystal Structure and Phase Transition of Sodium Trifluormethanesulfonate Monohydrate and Sodium Ion Conductivity of Anhydrous Sodium Trifluormethanesulfonate According to the results of temperature dependent powder diffractometry (Guinier-Simon-technique) sodium trifluormethanesulfonate monohydrate is dimorphous. The phase transition occurs at ?35°C. The room-temperature modification crystallizes monoclinic in space group P2₁/c with the lattice parameters a = 941.6(5) pm, b = 654.3(2) pm, c = 1062.4(5) pm and β = 107.73(2)°. The crystal structure consists of double layers of trifluormethanesulfonate anions, the lipophilic CF₃-groups pointing at each other. Sodium is coordinated by four oxygen atoms from four different anions and by two molecules of crystal water. The resulting polyhedron may be addressed as a distorted octahedron. The low-temperature modification crystallizes orthorhombic in space group Pnma with the lattice parameters a = 645.31(9) pm, b = 538.03(9) pm, c = 1745.3(3) pm. The loss of crystal water occurs at 136°C. Anhydrous sodium trifluormethanesulfonate shows a phase transition at 252°C. The high-temperature modification is a good sodium ionic conductor (σ = 4.1 · 10^?1 Ω^?1 cm^?1 at 250°C).     

Über Münzmetall‐Quecksilber‐Chalkogenidhalogenide. II Hydrothermalsynthese,Kristallstruktur und Phasenumwandlung von CuHgSCl und CuHgSBr

On Coinage Metal Mercury Chalcogenide Halides II: Hydrothermal Synthesis, Crystal Structure, and Solid State Phase Transition of CuHgSCl and CuHgSBr The hydrothermal reaction of CuCl and CuBr with HgS in concentrated aqueous HX (X = Cl, Br) as solvent at 670 K in sealed glass ampoules yields yellow‐orange crystals of CuHgSCl and CuHgSBr. Both compounds crystallize isotypically (orthorhombic, Pbam, a = 984.01(8), b = 1775.1(2), c = 409.59(3) pm for CuHgSCl and a = 1003.7(4), b = 1833.6(5), c = 412.4(2) pm for CuHgSBr, Z = 8). The structures consist of plane folded HgS chains connected by pairs of distorted CuS₂X₂ tetrahedra sharing the X—X‐edge (X = Cl, Br) in which the copper atoms occupy off‐centered positions. The large displacement factors of the Cu atoms represent thermal vibrations as shown by additional X‐ray investigations at different temperatures. The single‐crystal structure determination shows that the earlier structure model, based on powder diffraction data, is incorrect. The structure type of CuHgSCl und CuHgSBr shows distinct similarities to the structure type of the already known compounds CuHgSeBr, AgHgSBr and AgHgSI (MHgYX). At 323 K CuHgSBr undergoes a second order phase transition into a higher symmetric structure of the MHgYX type (orthorhombic, Pmam, a = 1009.2(3), b = 918.40(4), c = 413.81(2) pm) with halved b‐axis.     

Kristallstruktur und Phasenumwandlung von Betain-Borat, (CH3)3NCH2COO·B(OH)3

Summary Betaine borate undergoes a phase transition of strongly second order at 142.5 K. Crystals below this temperature belong to the ferroelastic Aizu species mmmF2/m. The crystal structures of both phases have been determined. Paraelastic phase: Pmcn,a=7.769(1),b=9.873(2),c=11.974(2)Å,Z=4,T=293K,R=0.041 for 519 unique observed reflections. Ferroelastic phase: P2₁/c,a=7.615(5),b=9.872(3),c=11.947(5)Å, =92.98(8)°,Z=4,T=130K,R=0.083 for 507 unique observed reflections. In both structures the betaine molecules are connected to B(OH)₃-groups via hydrogen bonds to form chains running parallel[001]. These chains are associated to each other by van der Waals forces.

     

(NH4)3[M2NCl10] (M = Nb,Ta): Synthese,Kristallstruktur und Phasenumwandlung

(NH₄)₃[M₂NCl₁₀] (M = Nb, Ta): Synthesis, Crystal Structure, and Phase Transition The nitrido complexes (NH₄)₃[Nb₂NCl₁₀], and (NH₄)₃[Ta₂NCl₁₀] are obtained in form of moisture-sensitive, tetragonal crystals by the reaction of the corresponding pentachlorides with NH₄Cl at 400 °C in sealed glass ampoules. Both compounds crystallize isotypically in two modifications, a low temperature form with the space group P4/mnc and a high temperature form with space group I4/mmm. In case of (NH₄)₃[Ta₂NCl₁₀] a continuous phase transition occurs between –70 °C and +60 °C. For the niobium compound this phase transition is not yet fully completed at 90 °C. The structure of (NH₄)₃[Nb₂NCl₁₀] was determined at several temperatures between –65 °C und +90 °C to carefully follow the continuous phase transition. For (NH₄)₃[Ta₂NCl₁₀] the structure of the low temperature form was determined at –70 °C, and of the high temperature form at +60 °C. The closely related crystal structures of the two modifications contain NH₄⁺ cations and [M₂NCl₁₀]^3– anions. The anions with the symmetry D_4h are characterized by a symmetrical nitrido bridge M=N=M with distances Nb–N = 184.5(1) pm at –65 °C or 183.8(2) pm at 90 °C, and Ta–N = 184.86(5) pm at –70 °C or 184.57(5) pm at 60 °C.     

Natriumtrithiophosphat(V): Kristallstruktur und Natriumionenleitfähigkeit

Sodium Trithiophosphate(V): Crystal Structure and Sodium Ionic Conductivity Na₃POS₃ was synthesized from the corresponding hydrate by freeze‐drying. The crystal structure of Na₃POS₃ was determined using X‐ray and neutron powder data, and refined applying simultaneous Rietveld refinements of the neutron and X‐ray data (Cmc2₁, a = 9.5105(1), b = 11.5463(1), c = 5.9323(1)Å, R_p = 5.37 %, R_wp = 4.47 %). The barycenters of the POS₃ tetrahedra are arranged in the sense of a hexagonal close packing. The P—O bonds are oriented in a polar manner parallel to the c‐axis, and with the PS₃‐groups in an eclipsed mutual orientation. The structure of Na₃POS₃ is closely related (maximal subgroup) to the one of Ca₃CrN₃. Above 250 °C, Na₃POS₃ can be considered as a fast ionic conductor due to its throughout high conductivity.     

Strukturbeziehungen zwischen Tetraselen(2+)‐hexachlorometallaten: Synthese und Kristallstruktur von Se4[ReCl6] und Phasenumwandlung von Se4[MCl6] (M = Zr,Hf)

Structure Relationships between Tetraselenium(2+) Hexachlorometalates: Synthesis and Crystal Structure of Se₄[ReCl₆] and the Solid State Phase Transition of Se₄[MCl₆](M = Zr, Hf). The reaction of Se, SeCl₄, and ReCl₄ in a closed, evacuated glass ampoule at 485 K yields dark‐red moisture sensitive crystals of Se₄[ReCl₆] (orthorhombic, Pccn, a = 1091.5(1), b = 1057.2(1), c = 1015.0(1) pm). The crystal structure consists of almost square‐planar Se₄²⁺ cations and slightly distorted octahedral [ReCl₆]^2— anions. Se₄[ReCl₆] is paramagnetic with a moment of 3.54 μ_B/Re according to a d³ configuration and Re(IV). The magnetic moment obeys the Curie‐Weiss law with a Weiss constant of —33 K. The already known compounds Se₄[ZrCl₆] and Se₄[HfCl₆] crystallize in a closely related structure with tetragonal symmetry (space group P4₂/ncm). Both undergo a phase transition in the solid state into an orthorhombic low temperature form, which is isotypic to Se₄[ReCl₆]. The phase transition was monitored by single crystal and powder diffraction, the transition temperature was determined to 193(1) K for Se₄[ZrCl₆]. The changes of the lattice constants with temperature imply a displacive transition of mainly second order which is allowed by the translationsgleiche supergroup‐subgroup relation of index 2 between the space groups. No phase transition into a tetragonal high‐temperature form could be observed for the orthorhombic Se₄[ReCl₆].     

Synthese,Struktur und Phasenumwandlung von Te4[AsF6]2·SO2

Synthesis, Crystal Structure, and Solid State Phase Transition of Te₄[AsF₆]₂·SO₂ The oxidation of tellurium with AsF₅ in liquid SO₂ yields Te₄²⁺[AsF₆^—]₂ which can be crystallized from the solution in form of dark red crystals as the SO₂ solvate. The crystals are very sensitive against air and easily lose SO₂, so handling under SO₂ atmosphere or cooling is required. The crystal structure was determined at ambient temperature, at 153 K, and at 98 K. Above 127 K Te₄[AsF₆]₂·SO₂ crystallizes orthorhombic (Pnma, a = 899.2(1), b = 978.79(6), c = 1871.61(1) pm, V = 1647.13(2)·10⁶pm³ at 297 K, Z = 4). The structure consists of square‐planar Te₄²⁺ ions (Te‐Te 266 pm), octahedral [AsF₆]^— ions and of SO₂ molecules which coordinate the Te₄ rings with their O atoms in bridging positions over the edges of the square. At room temperature one of the two crystallographically independent [AsF₆]^— ions shows rotational disorder which on cooling to 153 K is not completely resolved. At 127 K Te₄[AsF₆]₂·SO₂ undergoes a solid state phase transition into a monoclinic structure (P112₁/a, a = 866.17(8), b = 983.93(5), c = 1869.10(6) pm, γ = 96.36(2)°, V = 1554, 2(2)·10⁶ pm³ at 98 K, Z = 4). All [AsF₆]^— ions are ordered in the low temperature form. Despite a direct supergroup‐subgroup relationship exists between the space groups, the phase transition is of first order with discontinuous changes in the lattice parameters. The phase transition is accompanied by crystal twinning. The main difference between the two structures lies in the different coordination of the Te₄²⁺ ion by O and F atoms of neighbored SO₂ and [AsF₆]^— molecules.     

Synthese und Kristallstrukturen von α‐ und β‐Ba3(PS4)2 sowie von Ba3(PSe4)2

Synthesis and Crystal Structures of α‐, β‐Ba₃(PS₄)₂ and Ba₃(PSe₄)₂ Ba₃(PS₄)₂ and Ba₃(PSe₄)₂ were prepared by heating mixtures of the elements at 800 °C for 25 h. Both compounds were investigated by single crystal X‐ray methods. The thiophosphate is dimorphic and undergoes a displacive phase transition at about 75 °C. Both modifications crystallize in new structure types. In the room temperature phase (α‐Ba₃(PS₄)₂: P2₁/a; a = 11.649(3), b = 6.610(1), c = 17.299(2) Å, β = 90.26(3)°; Z = 4) three crystallographically independent Ba atoms are surrounded by ten sulfur atoms forming distorted polyhedra. The arrangement of the PS₄ tetrahedra, isolated from each other, is comparable with the formation of the SO₄^2? ions of β‐K₂SO₄. In β‐Ba₃(PS₄)₂ (C2/m; a = 11.597(2), b = 6.727(1), c = 8.704(2) Å; β = 90.00(3)°; Z = 2) the PS₄ tetrahedra are no more tilted along [001], but oriented parallel to each other inducing less distorted tetrahedra and polyhedra around the Ba atoms, respectively. Ba₃(PSe₄)₂ (P2₁/a; a = 12.282(2), b = 6.906(1), c = 18.061(4) Å; β = 90.23(3)°; Z = 4) is isotypic to α‐Ba₃(PS₄)₂ and no phase transition could be detected up to about 550 °C.     

Natriummonothiophosphat(V): Kristallstruktur und Natriumionenleitfähigkeit

Sodium Monothiophosphate(V): Crystal Structure and Sodium Ionic Conductivity Anhydrous sodium monothiophosphate Na₃PO₃S was synthesized along a novel route by freezedrying of the hydrate and subsequent annealing in an argon atmosphere. The crystal structure was determined using X‐ray and neutron powder data. The structural model was found by means of a combined optimization of the difference between the calculated and the measured powder intensities, and of the potential energy of the system. Simultaneous Rietveld refinements of the neutron and X‐ray data (R3c, a = 8.4442(1) Å, c = 11.7412(1) AÅ) resulted in a profile R‐value R_p = 4.86 % and weighted profile R‐value R_wp = 5.86 %. The baricenters of the PO₃S tetrahedra are arranged in the sense of a cubic close packing whith the P—S‐bonds oriented in a polar manner parallel to the c axis, and with the PO₃‐groups in an eclipsed mutual orientation. The Na‐P‐S‐framework of Na₃PO₃S is — according to the formulation SPNa₃ — related to the LiNbO₃‐structure type. The title compound was investigated using solid state NMR spectroscopy. The isotropic chemical shift δ_iso is 33.4 ppm for the phosphorus nuclei, and 7.7 ppm for the sodium nuclei. For the latter ones, a quadrupole coupling constant Q_CC = 3.0 MHz and an asymmetry parameter η_Q = 0.40 were determined. The chemical shift tensor of the phosphorus nuclei is characterized by an asymmetry parameter η = 0.43 and an anisotropy Δσ = ‐48.5 ppm. Consequently, phosphorus as well as sodium, is not surrounded axial symmetrically.     

Darstellung und Kristallstruktur von K4[SnO3]

Preparation and Crystal Structure of K₄[SnO₃] K₄[SnO₃] crystallizes with the K₄[PbO₃] structure in the orthorhombic spacegroup Pbca (No. 61) with the lattice constants a = 652.2(3) pm, b = 1 112.1(5) pm and c = 1 893.7(7) pm. In the structure isolated ψ-tetrahedral anions [Sn^IIO₃]^4? are arranged in layers perpendicular [001]. The structure of K₄[SnO₃] will be compared with those of stannates and plumbates of composition A₄[M^IIO₃] (A = Na, K, Rb, Cs) and with the known potassium stannates(II).     

Kristallstruktur,Leitfähigkeit und magnetische Suszeptibilität von Er2Te3

Crystal Structure, Conductivity, and Magnetic Susceptibility of Er₂Te₃ Via a chemical vapour transport reaction with ErCl₃ as transporting agent, single crystals of Er₂Te₃ up to a size of 1.5 mm are available. X-ray structure analysis revealed for the compound the Sc₂S₃-type with the space group Fddd and the lattice parameters a = 1212.7(2) pm, b = 858.1(2) pm and c = 2572.8(4) pm (Z = 16). According to measurements of the fundamental absorption (DRIFT) the compound is a semiconductor with a band gap of 0.77(5) eV. Magnetic susceptibility measurements revealed paramagnetic behaviour in the temperature range 5–300 K with μ_p = 9.07 B.M. and θ_p = –4.3 K.     

Darstellung,Kristallstruktur und Eigenschaften von Kaliumhydrogencyanamid

Preparation, Crystal Structure, and Properties of Potassium Hydrogen Cyanamide For the preparation of KHCN₂ melamine has been reacted with potassium amide in liquid ammonia. After evaporation of the solvent the resulting solid has been transformed at 210°C. KHCN₂ (P2₁2₁2₁, a = 708.7(2), b = 909.0(2), c = 901.4(2) pm, Z = 8, R = 0.039, wR = 0.016) is yielded as a coarse crystalline product. In the solid K⁺ and HCN ions occur. As expected two significantly differing bond-distances C? N (117.3(5) pm) and HN? C (128.7(5) pm) have been found in the anion. According to IR-spectroscopy a non linear group N? C? N (174.4(4)°) is observed.     

Synthese und Kristallstruktur von K2Mn3S4

Synthesis and Crystal Structure of K₂Mn₃S₄ Single crystals of K₂Mn₃S₄ have been prepared by a fusion reaction of potassium carbonate with manganese in a stream of hydrogen sulfide at 900 °C. K₂Mn₃S₄ crystallizes in a new monoclinic layered structure type (P2/c, a = 7.244(2) Å, b = 5.822(1) Å, c = 11.018(5) Å, β = 112.33(3)°, Z = 2) which can be described as a stacking variant of the orthorhombic Cs₂Mn₃S₄ structure type. Measurements of the magnetic susceptibilities show antiferro‐magnetic interactions.     

Synthese und Kristallstruktur von [KNPPh3]6 · 4 C7H8

Synthesis and Crystal Structure of [KNPPh₃]₆ · 4 C₇H₈ [KNPPh₃]₆ · 4 C₇H₈ ( 1 ) has been prepared from HNPPh₃ and potassium hydride in boiling toluene forming pale yellow moisture sensitive crystals, which were characterized by a crystal structure determination. Space group P1, Z = 2, lattice dimensions at –83 °C: a = 1517.9(2), b = 1894.0(2), c = 2150,4(2) pm, α = 84.39(1)°, b = 89.31(1)°, c = 89.97(1)°, R₁ = 0.0684. 1 forms a K₆N₆ skeleton of a double cube with a common face of two K and two N atoms, the latter being fivefold coordinated by four K atoms and the P atom of the PPh₃ groups.     

Kaliumhydrogensulfat-Dihydrogensulfat,K(HSO4)(H2SO4) – Synthese und Kristallstruktur

Potassium Hydrogensulfate Dihydrogensulfate, K(HSO₄)(H₂SO₄) – Synthesis and Crystal Structure Single crystals with the composition KH₃(SO₄)₂ have been synthesized from the system Potassium sulfate/sulfuric acid. The hitherto crystallographically not investigated compound crystallizes in the monoclinic space group P2₁/c (14) with the unit cell parameters a = 7.654(3), b = 11.473(5) and c = 8.643(3) Å, β = 112.43(3)°, V = 701.6 ų, Z = 4 and D_x = 2.22 g · cm^?3. The structure contains two types of tetrahedra, SO₃(OH) and SO₂(OH)₂. These tetrahedra form tetramers via hydrogen bonds consisting of both, two SO₃(OH) and two SO₂(OH)₂ tetrahedra. The tetramers are linked to each other via hydrogen bonds. Potassium is coordinated by 9 oxygen atoms which belong to both kinds of tetrahedra. These potassium oxygen polyhedra are connected by common faces forming chains running parallel z.     

Kristallstruktur und elektrische Leitfähigkeit von Li2–2xMn1+xCl4-Spinelltyp-Mischkristallen

Crystal Structure and Electric Conductivity of Spinel-Type Li_2–2xMn_1+xCl₄ Solid Solutions The electric conductivity of the fast lithium ion conductors Li_2–2xMn_1+xCl₄ was measured by impedance spectroscopic methods. The conductivities obtained, e.g. ～ 4 × 10^?1 Ω^?2 cm^?1 at 570 K, depend only little on the lithium content. The crystal structure of Li_1.6Mn_1.2Cl₄ was determined by neutron powder and X-ray single crystal diffraction (space group Fd3 m, Z = 8, a = 1 049.39(6) pm, R_w = 1.4% on the basis of 170 reflections). The lithium deficient chloride crystallizes in an inverse spinel structure like the stoichiometric compound Li₂MnCl₄ according to the formula (Li_0,8)[Li_0,4Mn_0,6]₂Cl₄ with vacancies ( ) at the tetrahedral sites. The decrease of the M_oct? Cl distances with the increase of x reveals that the ionic radius of Mn²⁺ in chlorides is equal or even smaller than that of Li⁺ opposite to fluorides and oxides. The ? Cl distances of spinel type chlorides are 237 ( _tet) and 274 pm ( _oct), respectively. The mechanism of the ionic conductivity is discussed.     

Die Kristallstruktur von Kaliummonomethylcarbonat

Crystal Structure of Potassium Monomethylcarbonate Potassium monomethylcarbonate KCH₃CO₃ was obtained from reaction of dimethylcarbonate with potassium hydroxide in methanole. The crystal structure was determined (triclinic, P1 (no. 2), Z = 2, a = 380.9(2) pm, b = 558.9(3) pm, c = 985.3(3) pm, α = 100.71(2)°, β = 90.06(3)°, γ = 92.48(3)°, V = 205.9(2) · 10⁶ pm³, wR(F²) = 0.054, wR_obs(F) = 0.022). Structural relations between potassium monomethylcarbonate and potassium hydrogencarbonate are discussed.     

Hochdruck‐Synthese,Kristallstruktur und Eigenschaften von NaPN2

High‐Pressure Synthesis, Crystal Structure, and Properties of NaPN₂ Single phase NaPN₂ was synthesized by the reaction of NaN₃ and P₃N₅ in a multianvil assembly at 3 GPa and 1000 °C. The title compound crystallizes in a variant of the chalcopyrite structure type and is isotypic to LiPN₂. The crystal structure was refined by the Rietveld method (I 4 2d, a = 497.21(2), c = 697.60(3) pm, Z = 4, 36 observed reflections, R_p = 0.0502, wR_p = 0.0649, R_F = 0.0788).     

Kristallstruktur von Kaliumtriflat‐Butyrolacton, [K3(O3SCF3)3(O2C4H6)2]

Crystal Structure of Potassium Triflate‐butyrolactone, [K₃(O₃SCF₃)₃(O₂C₄H₆)₂] Single Crystals of [K₃(O₃SCF₃)₃(O₂C₄H₆)₂] ( 1 ) have been obtained as a by‐product from the reaction of KNPPh₃ with Yb(O₃SCF₃)₃ in THF with subsequent addition of butyrolactone. The structure of 1 consists of three symmetry‐independent potassium ions which are linked by the oxygen atoms of the triflate ions and the butyrolactone molecules to give a supramolecular structure with layers normal to the crystallographic b‐axis. The carbonyl oxygen atoms of both butyrolactone molecules show a μ₃‐bridging function between three K⁺ ions, one of them is, in addition, coordinated by the ring O‐atom in a chelate manner. 1 : Space group P2₁/c, Z = 4, lattice dimensions at 193 K: a = 1155.0(1), b = 1537.2(1), c = 1531.1(1) pm, β = 100.623(7)°, R = 0.0484.