The carbides RE2MnC4 (RE = Y,Er, Tm) with Er2FeC4-type structure

The title compounds were prepared from coldpressed pellets of the elemental components by arcmelting. They crystallize with the orthorhombic Er₂FeC₄-type structure, which was refined from X-ray data of an Er₂MnC₄ single crystal: Ibam, a = 760.4(1)pm, b = 937.1(1)pm, c = 504.0(1)pm, R = 0.021 for 524 structure factors and 17 variable parameters. Y₂MnC₄ does not become superconducting down to 1.7 K. Chemical bonding in these compounds is briefly discussed.     

Zwei neue Alkylimido-methylgallane mit Käfigstruktur

Two New Alkylimido-Methylgallanes with Cage Structure The tetrameric alkylimido-methylgallanes (MeGa? NR)₄ (R = CH(CH₃)₂ ( ⁱPr), C(CH₃)₃ ( ^tBu) and Me = CH₃) have been prepared by pyrolyses of the dimeric amido compounds (Me₂Ga? N(H)R)₂ at 250–260°C. The mass, NMR and vibrational spectra are discussed, they prove almost identical structures of the skeletons. The X-Ray structure determination of (MeGa? N^tBu)₄ shows four heterocubane molecules in the trigonal unit cell (space group P3 c1, a = b = 1061.7(1), c = 3191.8(5) pm) and two disordered benzene solvate molecules. The Ga? N bonds range between 198.4 to 199.9 pm, the Ga? N? Ga and N? Ga? N bond angles lie between 90.6 to 91.4 and 88.6 to 89.2°, respectively. The structure was refined to an R₁(R₂)-value of 0.049 (0.057).     

Die Kristall- und Molekülstrukturen von Chlorotrispyridinium-bis-(tetrachloroaluminat(III)) und einer weiteren Modifikation von Pyridiniumchlorid

Crystal- and Molecular Structures of Chlorotrispyridinium-bis-(tetrachloroaluminate(III)) and a New Modification of Pyridinium Chloride The compounds PyHCl and ((PyH)₃Cl)(AlCl₄)₂ are formed by hydrolysis during the synthesis of adducts in the system AlCl₃/pyridine. The second room temperature modification of PyHCl crystallizes in the space group P2₁/c with the lattice constants a = 847.9(3), b = 1770.2(3), c = 801.9(3) pm, β = 95.23(3)°, Z = 8. The atomic parameters were refined from 4471 measured intensities to R(F) = 6,9%. The N? Cl distances are 306.8(7) and 311.0(8) pm. The unit cell of ((PyH)₃Cl)(AlCl₄)₂ is orthorhombic (space group Pbca) and has the lattice constants a = 1306.3(4), b = 1589.4(4), c = 2708.6(7) pm, Z = 8. The crystal structure was refined from 7226 measured intensities to R(F) = 6.7%. The cation shows three pyridinium ions to have NH…?Cl hydrogen bonds to a central positioned chloride ion with N? Cl distances of 301.4(7), 305(1) and 306(1) pm.     

Nitrido-silicate. III. Hochtemperatur-Synthese,Kristallstruktur und magnetische Eigenschaften von Ce3[Si6N11]

Nitrido-silicates. III [1] High-Temperature Synthesis, Crystal Structure, and Magnetic Properties of Ce₃[Si₆N₁₁] Pure Ce₃[Si₆N₁₁] was obtained as transparent yellow crystals by reaction of metallic cerium with silicon diimide (Ce:Si = 1:2) under nitrogen atmosphere in a specially developed high-frequency furnace at 1660°C. Ce₃[Si₆N₁₁] (P4bm, a = 1013.7(3), c = 483.9(5) pm, Z = 2, R = 0.034, wR = 0.024) contains Ce³⁺ ions as well as a three-dimensional covalent anionic network structure of corner-sharing SiN₄ tetrahedra. Measurements of the magnetic susceptibility gave no indications for magnetic ordering phenomena in the temperature range between 2 and 300 K. Above 100 K pure Curie-Weiss behaviour (μ_eff = 2,10 μ_B, determined at room temperature) was observed.     

Zur Kenntnis von CsLiCl2

On CsLiCl₂ CsLiCl₂ crystallizes with a = 492.35(9), c = 950.0(3) pm (Guinier data), tetragonal, P4/nmm, Z = 2. The crystal structure was determined and refined from single crystal data (R = 5.2, R_w = 4.0%). It is essentially that proposed earlier for KCoO₂ which is isotypic with CsLuO₂. In CsLiCl₂ Cs⁺ has C.N. = 9 (d? = 363 pm), Li⁺ C.N. = 5 (tetragonal pyramid) with d(Li? Cl) = 231 and 4 × 260 pm, respectively.     

Copper Weberites: Crystal Structure and Magnetic Investigation of Na2CuGaF7 and Na2CuInF7

The crystal structures of two new copper weberites Na₂CuGaF₇ and Na₂CuInF₇ have been determined. Na₂CuGaF₇ has the monoclinic space group C2/c: a = 1232.5(5) pm, b = 731.8(1) pm, c = 1278.0(5) pm, β = 109.29(2)° and Z = 8. Na₂CuInF₇ crystallizes in the orthorhombic space group Pmnb: a = 731.8(1) pm, b = 1060.2(2) pm, c = 771.2(1) pm and Z = 4. The structures have been refined from 1175 reflections to R = 0.043 (wR = 0.035) for Na₂CuGaF₇, and from 1917 reflections to R = 0.034 (wR = 0.025) for Na₂CuInF₇. The structures consist of [CuF₅]_n^3n? chains which are parallel the a-axis in Na₂CuInF₇ and oriented in two alternating directions in Na₂CuGaF₇. Sodium atoms exhibit either seven-fold or eight-fold coordination. Although strong antiferromagnetic interactions are observed inside the chains, there is no evidence for three-dimensional ordering.     

Strukturverfeinerung und magnetische Messungen an Mn2SnS4

Structure Redetermination and Magnetic Studies on Mn₂SnS₄ The crystal structure of Mn₂SnS₄ was redetermined by single crystal and powder X-ray studies. It has a deficient NaCl superstructure crystallizing in the orthorhombic space group Cmmm proposed by Wintenberger and Jumas in 1980 (Z = 2, a = 740.7(1), b = 1047.5(1) and c = 366.7(2) pm, R_f = 1.4% for 266 unique reflections with I > 0σ₁). Some additional reflections, which are not compatible with this cell, can be refined assuming formation of twinned trilling crystals. Mn₂SnS₄ undergoes antiferromagnetic ordering below 160 K. The effective magnetic moment μ_eff of Mn²⁺ is 5.92 B.M. The IR and Raman spectra display 5 and 3 bands in the range 150–320 cm^?1, respectively.     

Die Kristallstruktur von Ga5Pd13 – eine niedersymmetrische Ordnungsvariante der kubisch dichtesten Kugelpackung

The Crystal Structure of Ga₅Pd₁₃ – a Low‐Symmetrical Ordering Variant of the Cubic Close Sphere Packing Ga₅Pd₁₃ is accessible from the elements in the presence of catalytically active amounts of iodine at 520 °C. The phase decomposes at 897 °C in a peritectoid reaction. The monoclinic crystal structure was determined from the intensities of an X‐ray powder diffractogram and refined by a Rietveld profile fit: C 2/m, Z = 2, a = 2425.99(5) pm, b = 405.060(7) pm, c = 544.37(1) pm, β = 102.690(1)°, R_p = 0.069. The new structure type is described as an ordering variant of the cubic close sphere packing. The ordering pattern and the distortions in the primary coordination of the atoms reflect the definite impact of the intermetallic bonding interactions on the differentiation of the structure.     

Structure and Properties of EuZnGa

New ternary gallide EuZnGa was synthesized by reaction of the elements in a sealed tantalum tube at 1320 K and subsequent annealing at 970 K for seven days. EuZnGa was investigated by X‐ray diffraction on both powders and single crystals. Its structure was refined from single crystal diffractometer data: KHg₂ type, space group Imma, a = 461.7(2), b = 761.4(3), c = 777.0(3) pm, R = 0.041 for 486 structure factors and 13 variables. The zinc and gallium atoms statistically occupy the mercury position of the KHg₂ type of structure. No long‐range ordering between the zinc and gallium atoms could be detected from the X‐ray data. Magnetic susceptibility measurements show Curie‐Weiss behavior above 50 K with a magnetic moment of μ_exp = 7.86(5) μ_B/Eu and θ = 17(2) K, suggesting divalent europium. Low‐field, low‐temperature susceptibility measurements indicate cluster glass behavior (mictomagnetism) with a freezing temperature of 24(2) K. Magnetization measurements show a magnetic moment of 4.9(1) μ_B/Eu at 2 K and a magnetic flux density of 5.5 T. Electrical resistivity data indicate metallic behavior. ¹⁵¹Eu Mössbauer spectroscopic measurements show onset of magnetic hyperfine splitting at ≤ 17.0 K. Down to the temperature of 4.2 K the spectra reflect magnetic relaxation effects suggesting the presence of a substantial extent of disordering. This observation is consistent with the cluster glass behavior as evident from the magnetic susceptibility data and may be a consequence of the presence of multiple local Eu sites as expected from the statistical Zn and Ga distribution over the corresponding sites in the KHg₂ structure.     

Electronic Conditions of Diatomic (BN) Anions in the Structure of CaNiBN

CaNiBN was synthesized from Ca, Ni and BN in sealed tantalum containers at 1000 °C. The structure was determined by single‐crystal X‐ray diffraction (P4/nmm, Z = 2, a = 353.24(3) pm, c = 763.59(9) pm, R₁ = 0.019, wR₂ = 0.045 for all collected independent reflections). CaPdBN was synthesized after the same method, and a powder pattern was indexed isotypically (P4/nmm, a = 377.38(1) pm, c = 760.95(4) pm). The CaNiBN structure contains (BN) units with B—N bond lengths of 138.1(4) pm. If the (BN) unit in CaMBN (M = Ni, Pd) is replaced by (C₂), the structure can be considered as being isotypic with the structure of UCoC₂. Crystals of CaNiBN exhibit metallic lustre. According to the calculated band structure an extremely narrow band gap is present. The covalency between Ni and BN is marked by two important σ type interactions. A third type of interaction between (BN) π* and Ni orbitals represents the slightly occupied conduction bands. CaNiBN exhibits temperature independent paramagnetism and no superconducting transition down to 4 K.     

Struktur‐ und magnetochemische Untersuchungen an KCuGaF6

Structural and Magnetochemical Studies on KCuGaF₆ The crystal structure of KCuGaF₆ was determined on the base of X‐ray single crystal data (wR₂ = 0.084 for 2476 independent reflections). The compound crystallizes with a = 728.56(4), b = 989.51(6), c = 676.27(3) pm, β = 93.120(5)°, Z = 4 in space group P2₁/c of the pyrochlore related KCuCrF₆ type. The octahedral coordinations [GaF₆] and [CuF₆] are slightly resp. strongly distorted (mean values Ga‐F: 188.2 pm resp. Cu‐F: 188.2/200.1/227.6 pm). The longest distances Ga‐F and the shortest ones Cu‐F are found within octahedral chains of these two kinds of atoms, running along [100] and [001], resp., and being mutually bridged as well (M‐F‐M in between 114 and 145°). The magnetic mole susceptibilities measured at powders and at a single crystal follow the isotropic Heisenberg model for S = ¹/₂, if effects of chain disrupture are considered in the form of some paramagnetic portion. No indication of threedimensional magnetic order is observed down to T = 2 K and low magnetic fields H < 100 G. KCuGaF₆ (J/k = —71 K for the powder) is distinguished this way from the chain structure compounds KCuAlF₆ und Na₂CuScF₇ (J/k = —76 resp. —59 K) which were also magnetically studied and yield similar antiferromagnetic exchange constants J/k.     

EuPtSn2 – A Stannide with Sn2 Dumbbells in a Three-dimensional [PtSn2]2– Polyanion

EuPtSn₂ was obtained by melting of the elements in a sealed tantalum ampoule followed by an annealing sequence for crystal growth. The EuPtSn₂ sample was studied through its Guinier powder pattern and the structure was refined from single-crystal X-ray diffractometer data: CeRhSn₂ type, Cmcm, a = 472.05(3), b = 1724.19(12), c = 957.36(7) pm, wR₂ = 0.0388, 879 F² values and 30 variables. The platinum and tin atoms build up a three-dimensional [PtSn₂]^2– polyanionic network which consists of distorted PtSn₅ square pyramids (265–278 pm Pt–Sn) and Sn₂ dumbbells with 281 and 299 pm Sn–Sn distances. The structural relationship with DyRhGe₂ and Ce₃Pt₄Ge₆ is discussed. EuPtSn₂ shows Curie–Weiss behavior with an experimental magnetic moment of 7.78(1) μ_B / Eu, indicating stable divalent europium. This is corroborated by ¹⁵¹Eu Mössbauer spectroscopy. Antiferromagnetic ordering is detected below 3.4 K. Specific heat measurements confirm the magnetic ordering and indicate a second phase transition through a clear λ-type signal at 7.3 K which might be associated with a structural distortion.     

Untersuchungen an Polyhalogeniden. XVII. Darstellung und Kristallstruktur von Urotropiniumtriiodid,UrHI3

Studies on Polyhalides. 17. Preparation and Crystal Structure of Urotropinium Triiodide, UrHI₃ Urotropinium triiodide C₆H₁₃N₄I₃ is formed by the reaction of equimolar amounts of urotropinium iodide and iodine in ^tBuOH as red-brown cube-like crystals melting at 402 K under decomposition. The compound crystallizes monoclinically in the space group P2₁/c with a = 952.0(3) pm, b = 1 160.2(6) pm, c = 1 149.9(4) pm, β = 92.22(3)° and Z = 4. The till now not described crystal structure (R = 0.027 for 1 860 observed reflexes) contains urotropinium ions UrH⁺ and slightly distorted triiodide ions I₃^?(d(I—I) = 292.3(1), 294.1(1) pm, φ(I—I—I) = 178.27(2)°) which are linked to ion pairs by a rather short contact (d(I …? I) = 389.0(1) pm, φ(I—I …? I) = 149.12(2)°).     

CeAgAs2 — a New Derivative of the HfCuSi2 Type of Structure: Synthesis,Crystal Structure and Magnetic Properties

Single crystals of CeAgAs₂ have been obtained by chemical transport reactions starting from a pre‐reacted powder sample. The crystal structure was solved using X‐ray diffraction (space group Pmca, No. 57, a = 5.7586(4) Å, b = 5.7852(4) Å, c = 21.066(3) Å, Z = 8) and refined to a residual of R(F) = 0.029 for 46 refined parameters and 1020 reflections. The structure of CeAgAs₂ represents a new distorted and ordered variant of the HfCuSi₂ type. The characteristic feature of this structure are infinite cis‐trans chains of As atoms with As—As distances of 2.563(1) Å and 2.601(1) Å. CeAgAs₂ is paramagnetic (μ_eff = 2.37 μ_B, θ = —10.5(2) K), with antiferromagnetic ordering at 5.5(2) K and exhibits a metamagnetic transition starting at 4.6 kOe and T = 1.8 K.     

Ternäre Halogenide vom Typ A3MX6. III [1, 2]. Synthese,Strukturen und Ionenleitfähigkeit der Halogenide Na3MX6 (X = Cl,Br)

Ternary Halides of the A₃MX₆ Type. III [1, 2]. Synthesis, Structures, and Ionic Conductivity of the Halides Na₃MX₆ (X = Cl, Br) The bromides Na₃MBr₆ crystallize with the stuffed LiSbF₆-type structure (type I; M = Sm? Gd) or with the structure of the mineral cryolite (type II; M = Gd? Lu). The structure types were refined from single crystal X-ray data (Na₃SmBr₆: trigonal, space group R3 , a = 740.8(2) pm, c = 1 998.9(8) pm, Z = 3; Na₃YBr₆: monoclinic, space group P2₁/n, a = 721.3(4) pm, b = 769.9(2) pm, c = 1 074.8(4) pm, β = 90.60(4)°, Z = 2). Reversible phase transitions from one structure to the other occur. The phase transition temperatures were determined for the bromides as well as for the chlorides Na₃MCl₆ (M = Eu? Lu). The refinement of both structures for one compound was possible for Na₃GdBr₆ (I: trigonal, space group R3 , a = 737.1(5) pm, c = 1 887(2) pm, Z = 3; II: monoclinic, space group P2₁/n, a = 725.2(1) pm, b = 774.1(3) pm, c = 1 080.1(3) pm, β = 90.76(3)°, Z = 2). All compounds exhibit ionic conductivity of the sodium ions which decreases with the change from type I to type II. The conductivity of the bromides is always higher when compared with the respective chlorides.     

Preparation and crystal structure of the Isotypic Carbides Ln4Ni2C5 (Ln = Er,Tm, Yb and Lu)

The title compounds were prepared from the elemental components in a lithium flux. Their crystal structure was determined for the ytterbium compound from single-crystal X-ray data. It is orthorhombic, Pmm2, a = 352.88(6) pm, b = 1 143.0(3) pm, c = 366.16(6) pm, Z = 1, R = 0.020 for 1 261 structure factors and 29 variable parameters. The structure may be viewed as an intergrowth of slabs consisting of the CeNiC₂ and the ScC (NaCl type) structures. It thus contains C₂ pairs with a C? C distance of 138(1) pm and isolated carbon atoms. Together with the nickel atoms the C₂ pairs form one-dimensionally infinite building elements [Ni₂C₄]_n. The fifth carbon atom is octahedrally coordinated by ytterbium atoms. Accordingly the compound may be rationalized to a first approximation with the formula (Yb³⁺)₄[Ni₂C₄^8?]C^4?. Yb₄Ni₂C₅ shows Curie-Weiss behaviour with a magnetic moment of μ_exp = 4.44 μ_B per ytterbium atom in good agreement with the theoretical moment of μ_eff = 4.53 μ_B for Yb³⁺.     

Zur kenntnis ‚Kationen-reicher’︁ Tantalate und Niobate Über Na5TaO5 und Na5NbO5

On Tantalates and Niobates ‘rich in Cations’. On Na₅TaO₅ and Na₅NbO₅ Colourless, transparent single crystals of Na₅TaO₅ [annealed mixtures of Na₂O, Li₂O, and Ta₂O₅, Na : Li : Ta = 6.6 : 1.1 : 1, Ni-cylinder, 1000°C, 75 d] as well as Na₅NbO₅ [annealed mixtures of Na₂O, Li₂O, and Nb₂O₅, Na : Li : Nb = 6.6 : 1.1 : 1, Ni-cylinder, 1000°C, 75 d] have been prepared. Single crystal data show that both isotypic oxides represent a deformed variant of the NaCl-type of structure [Na₅TaO₅: 1154 from 1250 I₀ (hkl), four-cycle diffractometer Philips PW 1100, ω2-θ scan, Ag? Kα , R = 4.88%, space group c2/c with a = 629.3(1) pm, b = 1025.4(2) pm, c = 1004.6(2) pm, b? 106.80(2)°, z = 4 and Na₅NbO₅: 998 from 1247 I₀(hkl), four-cycle diffractometer Philips PW 1100, ω-2θ scan, Ag? Kα , R = 8.58% and R_w = 7.67%, space group C2/2 with a = 629.1(1) pm, b = 1024.4(2) pm, c = 1004.2(2) pm, b? = 106.80(2)°, Z = 4]. The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, the latter derived from Mean Effective Fictive Ionic Radii, MEFIR, as well as Charge Distribution, CHARDI, are calculated.     

Caracterisation Structurale de l′Oxyfluorotungstate de Cuivre CuWO3F2

Crystal Structure of CuWO₃F₂ The crystal structure of the copper(II) oxyfluoridetungstate CuWO₃F₂ has been determined from single crystal X-ray data. The symmetry is monoclinic (space group P2₁/m) with lattice parameters a = 5.223(1) Å, b = 9.599(4) Å, c = 3.670(1) Å, β = 106.26(1)° (Z = 2). The structure has been fixed by the heavy atom method and refined by least square calculations down to a R factor of 0.019. Oxygen-fluorine ordering has been determined on the network built up by corner sharing octahedra constituting infinite chains, by several methods: Raman spectroscopy, electrostatic energy calculations, and bond valence determinations. The structural formulation of the octahedra is (WO₂F₂O_2/2)^2?.     

Ba5[CrN4]N: Das erste Nitridochromat(V)

Ba₅[CrN₄]N: The First Nitridochromate(V) Ba₅[CrN₄]N is prepared by reaction of mixtures of Li₃N, Ba₃N₂ and CrN/Cr₂N (1 : 1) (molar ratio Li : Ba : Cr = 3 : 5 : 1) in tantalum crucibles at 700°C with flowing nitrogen (1 atm) within a period of 48 h. After cooling down to room temperature (60°C/h) black-shining single crystals of the ternary phase with a platy habit are obtained (monoclinic, C2/m; a = 1054.0(2) pm, b = 1170.9(3) pm, c = 937.7(2) pm, b? = 110,79(2)°; Z = 4). The crystal structure contains isolated complex anions [Cr^VN₄]^7? which nearly satisfy the ideal tetrahedral symmetry (Cr? N [pm]: 2 × 175.3(4), 2 × 175.8(5); N? Cr? N [°]: 106.8(2), 109.5(2), 2 × 109.9(2), 2 × 110,3(2)). The coordination sphere for each of the terminal nitride functions of the complex anions is completed by five neighbouring Ba²⁺ ions (distorted CrBa₅ octahedra). The octahedra are connected via common CrBa₂ faces as well as CrBa edges thereby forming condensed tetrameric octahedral groups. The isolated nitride ions which are also present in the crystal structure of Ba₅[CrN₄]N are in an octahedral environment of Ba²⁺ ions. The presence of a d¹-System (Cr(V)) is confirmed by magnetic susceptibility data.     

Magnesiumiodatdecahydrat Mg(IO3)2 · 10 H2O – Kristallstruktur,Ramanspektren, thermischer Abbau,lone-pair-Radius von Iod(V)

Magnesium Iodate Decahydrate Mg(IO₃)₂ · 10 H₂O – Crystal Structure, Raman Spectra, Thermal Decomposition, Lone-Pair Radius of Iodine(V) Mg(IO₃)₂ · 10 H₂O crystallizes in the triclinic space group P1 (a = 654.25(9), b = 1109.8(2), c = 1176.7(2) pm; α = 105.470(8), β = 104.086(8), γ = 101.744(8)°; Z = 2). The structure has been determined by single-crystal X-ray diffraction at 273 K, and refined to a final R value of 0.0272 for 4372 observed reflections (I > 2σ(I)). The magnesium ions are coordinated to six different H₂O molecules forming a slightly distorted octahedron with Mg? O distances varying between 202.2(2) and 211.6(3) pm. The hexaaquamagnesium ions are arranged parallel to (010). The two kinds of iodate ions and the four different “free” water molecules are filled between the layers thus formed. There are twenty independent hydrogen bonds with O … O distances from 268.7(3) to 287.6(4) pm. On the basis of all intermolecular I … I distances of iodates reported in the literature, 180 pm are recommended as van-der-Waals radius resp. lonepair radius of iodine(V). DSC and Raman spectroscopic experiments as well as high-temperature Raman and X-ray measurements were performed and are discussed with respect to the energetic and geometric distortion of the IO₃^? ions and the dehydration of the decahydrate via the tetrahydrate (308 K) to Mg(IO₃)₂ (428 K).