The Single Crystal Structures of the Copper Usovites Ba2CaCuV2F14 and Ba2CaCuCr2F14

The results of single crystal X‐ray structure determinations are reported for Ba₂CaCuV₂F₁₄ (a = 1383.6(3), b = 540.89(8), c = 1493.1(3) pm, β = 91.65(3)°) and Ba₂CaCuCr₂F₁₄ (a = 1381.1(5), b = 535.5(1), c = 1481.4(6) pm, β = 91,50(4)°), both isotypic with usovite (space group C2/c, Z = 4). The resulting average distances are V‐F: 193.8 pm, Cr‐F: 190.7 pm, and Cu‐F: 209.2 resp. 207.1 pm for the Jahn‐Teller elongated [CuF₆] octahedra. Within the cross‐linked double chains of octahedra F‐bridged trimers M‐Cu‐M, magnetically studied earlier, are confirmed and discussed.     

Li4Sr2[Cr2N6]: Ein Hexanitridodichromat(V)

Li₄Sr₂[Cr₂N₆]: A Hexanitridodichromate(V) The quaternary hexanitridodichromate(V) Li₄Sr₂[Cr₂N₆] was obtained by reaction of the metals with flowing nitrogen at 900 °C as black‐shining crystals with a platy habit. The crystal structure was determined by X‐ray single crystal methods (orthorhombic, Pbca; a = 914.0 pm, b = 735.4 pm, c = 1053.6 pm; Z = 4). The compound contains isolated complex anions [Cr₂N₆]^8— consisting of two tetrahedra CrN₄ sharing a common edge. The distance Cr—Cr in the complex anion is 249.7 pm. The analysis of the Electron Localization Function (ELF) indicates bonding interactions Cr—Cr. Strontium is in a sixfold (distorted octahedral), Lithium in a distorted tetrahedral ([3+1]) coordination by nitrogen. According to measurements of the magnetic susceptibility the compound is diamagnetic.     

The Crystal Structure of Solvent‐Free Silver Dodecachloro‐closo‐dodecaborate Ag2[B12Cl12] from Aqueous Solution

Colourless octahedral single crystals of solvent‐free Ag₂[B₁₂Cl₁₂] (cubic, Pa3¯; a = 1238.32(7) pm, Z = 4) are obtained by the metathesis reaction of Cs₂[B₁₂Cl₁₂] with an aqueous solution of silver nitrate (AgNO₃) and recrystallization of the crude product from water. The crystal structure is best described as a distorted anti‐CaF₂‐type arrangement in which the quasi‐icosahedral [B₁₂Cl₁₂]^2— anions (d(B—B) = d(B—Cl) = 177—180 pm) are arranged in a cubic closest‐packed fashion. The tetrahedral interstices are filled with Ag⁺ cations which are strongly displaced from their ideal positions. Thereby each silver atom gets coordinated by six chlorine atoms from the edges of three [B₁₂Cl₁₂]^2— anions providing a distorted octahedral coordination sphere to the Ag⁺ cations (d(Ag—Cl) = 283—285 pm, CN = 6).     

Potassium gallium hydrogenphosphate fluoride,K2Ga[H(HPO4)2]F2

Hydrothermally synthesized dipotassium gallium {hydrogen bis[hydrogenphosphate(V)]} difluoride, K₂Ga[H(HPO₄)₂]F₂, is isotypic with K₂Fe[H(HPO₄)₂]F₂. The main features of the structure are ([Ga{H(HPO₄)₂}F₂]²⁻)_n columns consisting of centrosymmetric Ga(F₂O₄) octahedra [average Ga—O = 1.966 (3) Å and Ga—F = 1.9076 (6) Å] stacked above two HPO₄ tetrahedra [average P—O = 1.54 (2) Å] sharing two O‐atom vertices. The charge‐balancing seven‐coordinate K⁺ cations [average K—O,F = 2.76 (2) Å] lie in the intercolumn space, stabilizing a three‐dimensional structure. Strong [O...O = 2.4184 (11) Å] and medium [O...F = 2.6151 (10) Å] hydrogen bonds further reinforce the connections between adjacent columns.     

Kristallstrukturuntersuchungen an den Alkali- und BariumÜbergangsmetallfluoriden RbK2Mn2F7, BaNiF4 und einer 5 : 3-Phase im System BaLiF3/NaCoF3

Crystal Structural Studies of the Alkali and Barium Transition Metal Fluorides RbK₂Mn₂F₇, BaNiF₄, and a 5 : 3-Phase of the System BaLiF₃/NaCoF₃ At single crystals of the compounds RbK₂Mn₂F₇, BaNiF₄, and of a phase 0.618 BaLiF₃/0.382 NaCoF₃ the X-ray crystal structures were refined. RbK₂Mn₂F₇ is tetragonal (a = 421.1(1), c = 2188.3(2) pm, I4/mmm, Z = 2) and belongs to the Sr₃Ti₂O₇ type. The average distances are Mn–F: 210.7 pm for the [MnF₆] octahedron and A–F: 290.6 resp. 297.1 pm for the [AF₉] resp. [AF₁₂] coordination of the mixed alkali positions (A = Rb/3 + 2 K/3). BaNiF₄ (a = 413.7(1), b = 1443.1(3), c = 578.1(1) pm, Cmc2₁, Z = 4) is of the orthorhombic BaZnF₄ type; Ni–F: 200.3 pm, Ba–F: 274.3 pm for CN6 and CN9, resp.. The phase of approximate composition 5 : 3, isolated from a 1 : 1 batch BaLiF₃/NaCoF₃, is cubic (a = 801.8(1) pm, Im3, Z = 8 AMF₃) and forms a strongly disordered perovskite super-structure, the features of which are discussed.     

Röntgenstrukturuntersuchungen an den polymorphen Elpasolithen K2LiAlF6 und Rb2LiGaF6

X-Ray Structural Studies of the Polymorphic Elpasolites K₂LiAlF₆ and Rb₂LiGaF₆ At single crystals of low (LT) and high temperature (HT) modifications of K₂LiAlF₆ and of Rb₂LiGaF₆, synthesized at normal pressure (NP), the crystal structures were refined. LT-K₂LiAlF₆ is a cubic elpasolite (Fm3m, Z = 4, a = 784.2(1) pm; Al–F: 181.2(1) pm), HT-K₂LiAlF₆ and NP-Rb₂LiGaF₆ are isostructural with the hexagonal-rhombohedral type of Cs₂NaCrF₆ (R3m, Z = 6, a = 561.7(1) resp. 586.3(1), c = 2757.6(6) resp. 2856.3(5) pm; mean values Al–F: 180.5 resp. Ga–F: 189.3 pm). A cubic high pressure modification (HP) of Rb₂LiGaF₆ was obtainable as a powder only (a = 820.8(2) pm). The relations of distances between LT/HT and HP/NP polymorphs of elpasolites are compared and discussed.     

Crystal and magnetic structures of the layer Compound TlMnF4

The crystal structure and the magnetic properties of the fluoromanganate(III) TlMnF₄ have been investigated. The structure has been refined down to R/wR of 0.057/0.043 in the monoclinic I2/a space group with the unit cell constants a = 539.7(2) pm; b = 544.1(2) pm; c = 1248.4(5) pm; β = 90.19(3)° (Z = 4). TlMnF₄ is characterized by a layer structure formed of MnF₆ octahedra sharing their four equatorial corners. Within each octahedron the Mn? F distances range from 178 pm to 215 pm. The intralayer magnetic interaction (J/K) has been evaluated to be approximately ?0.45 K by fitting the experimental susceptibility in the 10–300 K range using the quadratic layer Heisenberg model. A 3 D-antiferromagnetic ordering occurs at T_n = 4.2(5) K. The magnetic cell corresponding to the nuclear one but with a primitive symmetry. The magnetic structure has been refined down to R = 0.0528 in the P2′/a′ magnetic group. The Mn^III moments are colinear to the b-axis and show antiparallel ordering within the layers.     

Einkristallstrukturbestimmungen der kubischen Hochdruckelpasolithe Rb2LiFeF6 und Cs2NaFeF6: Druck-Abstands-Paradoxon ohne Änderung der Koordinationszahl

Single Crystal Structure Determinations of the Cubic High Pressure Elpasolites Rb₂LiFeF₆ and Cs₂NaFeF₆: Pressure-Distance Paradox without Change of Coordination Number At single crystals of metastable high pressure phases of Rb₂LiFeF₆ (a = 824.4 pm) and Cs₂NaFeF₆ (a = 873,9 pm) the parameters of the cubic elpasolite structure (Fm3 m, Z = 4) were determined by X-ray methods. Compared to the 12L-structures of the normal pressure phases (R3 m, hex. Z = 6) only the distances within the 12-coordination, Rb? F = 291.7 resp. Cs? F = 309.9 pm, are compressed by 2–3%. However, the octahedral distances Fe? F = 194.6 pm and Li? F = 217.6 pm resp. Fe? F = 194.9 pm and Na? F = 242.0 pm, are enlarged by 1–4%, though there was no increase in coordination number. This paradoxical behaviour is discussed. Difference Fourier syntheses reveal disorder only for the lithium positions in Rb₂LiFeF₆, which are 30 pm off-center, corresponding to a splitting of distances Li? F into 188, 247 and 4 × 220 pm.     

Die Kristallstruktur von Na2NiAlF7—ein Beitrag zum Problem der wahren Raumgruppe orthorhombischer Weberite

The Crystal Structure of Na₂NiAlF₇ — a Contribution to the Problem of the True Space Group of Orthorhombic Weberites The X-ray single crystal structure determination of the orthorhombic weberite Na₂NiAlF₇ (a = 707.4(2), b = 1003.8(2), c = 731.5(1) pm; Z = 4) was performed in space group Imma, after all reflections hk0 with h(k) = 2n + 1 could be eliminated, as they proved simulated by Renninger effect and/or λ/2 reflections. The alternative space groups Imm2 resp. I2₁2₁2₁ of former weberite structure determinations thus became obsolete. The refinement using 880 independent reflections ended at wR = 0.0232. The resulting average distances within the framework of octahedra are Ni? F = 197.3, Al? F = 180.4 pm.     

Synthese,Kristallstruktur und magnetisches Verhalten von (2,4,6‐Trimethylpyridinium)10[ErCl6][ErCl5(H2O)]2Cl3

Preparation, Crystal Structure, and Magnetic Behaviour of (2,4,6‐Trimethylpyridinium)₁₀[ErCl₆][ErCl₅(H₂O)]₂Cl₃ Crystals of the complex chloride (2,4,6‐Trimethylpyridinium)₁₀[ErCl₆][ErCl₅(H₂O)]₂Cl₃ have been prepared by reaction of ErCl₃·6H₂O with 2,4,6‐Trimethylpyridiniumchloride in ethanol solution for the first time. The crystal structure has been determined from single crystal X‐ray diffraction data. The compound crystallizes monoclinically in the space group P2₁/a (Z = 2) with a = 1704.5(3) pm, b = 1696.7(2) pm, c = 1798.5(4) pm and β = 90.76(3)°. The structure contains octahedral building units [ErCl₆]^3— and [ErCl₅(H₂O)]^2—. The octahedra, the organic cations and isolated chloride anions are interconnected via hydrogen bonds forming layers parallel to the ac‐plane (0 1 0). The magnetic behaviour of (2,4,6‐Trimethylpyridinium)₁₀[ErCl₆][ErCl₅(H₂O)]₂Cl₃ has been studied. The magnetic data are interpreted by ligand field calculations applying the angular overlap model.     

Tantalum Clusters in Oxidic Matrices — Synthesis,Crystal Structure and Magnetic Properties of Eu1.83Ta15O32

The mixed‐valent oxotantalate Eu_1.83Ta₁₅O₃₂ was prepared from a compressed mixture of Ta₂O₅ and the metals in a sealed Ta ampoule at 1400 °C. The crystal structure was determined by means of single crystal X‐ray diffraction: space group R3¯, a = 777.2(6) pm and c = 3523.5(3) pm, Z = 3, 984 symmetrically independent reflections, 83 variables, R_F = 0.027 for I > 2σ (I). The structure is isotypic to Ba₂Nb₁₅O₃₂. The salient feature is a [Ta(+8/3)₆O₁₂ⁱO₆^a] cluster consisting of an octahedral Ta₆ core bonded to 12 edge‐bridging inner and six outer oxygen atoms. The clusters are arranged to slabs which are sandwiched by layers of [Ta(+5)₃O₁₃] triple octahedra. Additional Ta(+5) and Eu(+2) atoms provide the cohesion of these structural units. Twelve‐fold coordinated Eu(+2) atoms are situated on a triply degenerate position 33 pm displaced from the threefold axis of symmetry. A depletion of the Eu(+2) site from 6 to 5.5 atoms per unit cell reduces the number of electrons available for Ta‐Ta bonding from 15 to 14.67 electrons per cluster. Between 125 and 320 K Eu_1.83Ta₁₅O₃₂ is semi‐conducting with a band gap of 0.23 eV. The course of the magnetization is consistently described with the Brillouin function in terms of a M_mol/(N_Aμ_B) versus B/T plot in the temperature range 5 K — 320 K and at magnetic flux densities 0.1 T — 5 T. At moderate flux densities (< 1 T) the magnetic moment agrees fairly well with the expected value of 7.94 μ_B for free Eu (2+) ions with 4f⁷ configuration in ⁸S_7/2 ground state. Below 5 K, anisotropic magnetization measurements at flux densities B < 1 T point to an onset of an antiferromagnetic ordering of Eu spins within the layers and an incipient ferromagnetic ordering perpendicular to the layers.     

Struktur und Magnetismus von Fluoriden Cs2MCu3F10 (M = Mg,Mn, Co,Ni), Varianten des CsCu2F5‐Typs

Structure and Magnetism of Fluorides Cs₂MCu₃F₁₀ (M = Mg, Mn, Co, Ni), Variants of the CsCu₂F₅ Type X‐ray structure determinations of single crystals showed that compounds Cs₂MCu₃F₁₀ crystallize with Z = 2 in space group P2₁/n (No.14) (M = Mn) of the CsCu₂F₅ type resp. in its supergroup I2/m (No.12) (M = Mg, Co, Ni). Cs₂MgCu₃F₁₀: a = 714.9(1), b = 736.8(1), c = 940.4(1) pm, b = 96.29(1)°, (Mg‐F: 199.2 pm); Cs₂MnCu₃F₁₀: a = 725.1(1), b = 742.7(1), c = 951.0(2) pm, b = 97.28(3)°, (Mn‐F: 209.1 pm); Cs₂CoCu₃F₁₀: a = 717.8(3), b = 739.1(2), c = 939.4(4) pm, b = 97.49(2)°, (Co‐F: 203.1 pm); Cs₂NiCu₃F₁₀: a = 716.3(1), b = 737.7(1), c = 938.2(2) pm, b = 97.09(1)°, (Ni‐F: 201.0 pm). As determined directly for the Mg compound and generally concluded from the average distances M‐F noted, M substitution concerns mainly the octahedrally coordinated position of the CsCu₂F₅ structure, the distortion of which is very much reduced thereby. Within the remaining [CuF₄] and [CuF₅] coordinations, in contrast to CsCu₂F₅, one F ligand is disordered, in case of the Mn compound the pyramidally coordinated Cu atom, too. The magnetic properties are complex and point to frustration and spin glass effects. Only at the diamagnetically substituted variants with M = Mg, Zn no Néel point appears, which is reached at 27, 23, 36 and 55 K for M = Mn, Co, Ni and Cu, resp. At lower temperatures ferri‐ resp. weak ferromagnetism and hysteresis is observed.     

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.     

Sr5[NbN4]N ‐ A Nitridoniobate(V) Nitride Containing Isolated [NbN4]7‐ Tetrahedra and Octahedral Chains 1(Sr4Sr2/2N7+)

Sr₅[NbN₄]N (transparent, red single crystals) was synthesized by reaction of Sr2N with Nb under nitrogen at ambient pressure and 1223 K. The crystal structure was solved and refined in the space group Pbcm (no. 57), Z = 4, with lattice constants a = 646.6(3) pm, b = 1792.5(9) pm, c = 729.8(4) pm, and R = 0.019, wR² = 0.034. The crystal structure contains both isolated tetrahedra [NbN₄]^7‐ as well as chains of corner sharing octahedra 1(Sr₄Sr_2/2N⁷⁺). Strontium is irregularly coordinated by nitrogen (CN = 4 ‐ 6, Sr‐N: 252.3(4) ‐ 340.8(3) pm); nitrogen is located in a distorted octahedral environment by strontium and niobium (Nb‐N: 194.5(4) ‐ 199.2(2) pm). By formal reduction of the structural building units to their centers a close structural relationship to both the NiAs and the CaSi type structure is evident.     

Struktur und magnetische Eigenschaften von Bis{3‐amino‐1,2,4‐triazolium(1+)}pentafluoromanganat(III): (3‐atriazH)2[MnF5]

Structure and Magnetic Properties of Bis{3‐amino‐1,2,4‐triazolium(1+)}pentafluoromanganate(III): (3‐atriazH)₂[MnF₅] The crystal structure of (3‐atriazH)₂[MnF₅], space group P1, Z = 4, a = 8.007(1) Å, b = 11.390(1) Å, c = 12.788(1) Å, α = 85.19(1)°, β = 71.81(1)°, γ = 73.87(1)°, R = 0.034, is built by octahedral trans‐chain anions [MnF₅]^2–_∞ separated by the mono‐protonated organic amine cations. The [MnF₆] octahedra are strongly elongated along the chain axis (<Mn–F_ax> 2.135 Å, <Mn–F_eq> 1.842 Å), mainly due to the Jahn‐Teller effect, the chains are kinked with an average bridge angle Mn–F–Mn = 139.3°. Below 66 K the compound shows 1D‐antiferromagnetism with an exchange energy of J/k = –10.8 K. 3D ordering is observed at T_N = 9.0 K. In spite of the large inter‐chain separation of 8.2 Å a remarkable inter‐chain interaction with |J′/J| = 1.3 · 10^–5 is observed, mediated probably by H‐bonds. That as well as the less favourable D/J ratio of 0.25 excludes the existence of a Haldene phase possible for Mn³⁺ (S = 2).     

Struktur und 1D‐magnetische Eigenschaften von (pipzH2)[MnF4(H2PO4)]

Structure and 1D‐magnetic properties of (pipzH₂)[MnF₄(H₂PO₄)] From hydrofluoric and phosphoric acid solution of Manganese(III), using piperazinium(2+) counter cations (pipzH₂²⁺) the chain‐anion [MnF₄(H₂PO₄)]^2— can be stabilized providing an interesting model system for studying the magnetic exchange interaction via phosphate bridges. Depending on the HF/H₃PO₄ excess (pipzH₂)[MnF₄(H₂PO₄)] crystallizes in two polymorphs I und II , differing mainly in the orientation of the cations. Form I is monoclinic, space group P2₁/c, Z = 4, a = 6.749(1), b = 12.039(1), c = 12.501(1) Å, β = 94.420(4)°, R = 0.023, Form II crystallizes in the same space group type P2₁/c, Z = 4, a = 6.651(1), b = 12.799(1), c = 12.825(1) Å, β = 110.312(5)°, R = 0.037. The Mn³⁺ ions are octahedrally surrounded by four terminal fluoride ligands and axially by bidentate bridging dihydrogenphosphate groups. The shape of the chain anions is very close in both modifications and characteristic for ferrodistortive Jahn‐Teller ordering.The Mn—O‐bonds along the chain direction are strongly elongated (distances 2.16 to 2.21 Å) whereas all Mn—F bond (1.81—1.88Å) are ruther short. On a large single crystal of form I 1D‐antiferromagnetic properties were found. By fitting an appropriate model based on the temperature dependence of the correlation lengths using an anisotropy constant D/k = —2.9 K a remarkably high exchange energy of J/k = —1.6(1) K along the chains could be determined.     

Das erste oxidische T5‐Supertetraeder: Na26Mn39O55

The First T5‐Supertetrahedron in Oxide Chemistry: Na₂₆Mn₃₉O₅₅ Na₂₆Mn₃₉O₅₅ has been obtained from a redox reaction between manganese metal, CdO in the presence of Na₂O and Na₂SO₄ as a flux component as red single crystals with octahedral shape. The crystal structure has been determined from single crystal data (Fd3¯m, Z = 8, a = 2377.4(3) pm at 293 K and a = 2372.5(2) pm at 130 K). The rare characteristic structural feature of a T5‐Supertetrahedron, [Mn₃₅O₅₆], is observed for this new mixed‐valent sodium‐oxomanganat(II, III), Na₂₆Mn₃₉O₅₅. First investigations of the magnetic properties are reported.     

Struktur und Eigenschaften des Methylpentafluorphosphatanions, [CH3PF5]—

Structure and Properties of the Methyltetrafluorophosphate Anion, [CH₃PF₅]^— Methyltetrafluorphosphorane reacts with the fluorides NaF, KF, CsF, and (CH₃)₄NF with formation of the corresponding methylpentafluorophosphates. In case of the K and Cs salts K[CH₃PF₅] · CH₃CN and Cs[CH₃PF₅] · CH₃CN, respectively, are formed using acetonitrile as solvent. The salts are characterized by NMR, IR and Raman spectroscopy. The vibrational frequencies are compared with ab initio calculated data (RHF/6‐31+G*). The RHF/6‐31+G* calculation yields for the almost octahedral anion bond distances of d(PF_eq) = 163.7 pm, d(PF_ax) = 162.0 pm, and d(PC) = 184.8 pm.     

On the Binary Compound YbGa5

YbGa₅ was characterized in course of a re‐investigation of the Yb—Ga system in the range between 0 and 20 at. % Yb. The compound can be described as a defect variant of the Ce₂Ga₁₀Ni structure type (space group I4/mmm, a = 430.59(4) pm, c = 2587.1(4) pm). The special feature of the crystal structure is given by local disorder within the gallium network. From magnetic susceptibility, ytterbium is in the valence state 2+.     

[Ga(en)3][Ga3Se7(en)] · H2O: Ein Galliumchalkogenid mit Ketten aus [Ga3Se6Se2/2(en)]3–-Bicyclen

[Ga(en)₃][Ga₃Se₇(en)] · H₂O: A Gallium Chalcogenide with Chains of [Ga₃Se₆Se_2/2(en)]^3– Bicycles The new selenidogallate [Ga(en)₃][Ga₃Se₇(en)] · H₂O ( I ) was produced from a ethylendiamine suspension of Ga and Se at 130 °C. I crystallizes in the orthorhombic space group Pna2₁ with unit constants a = 1347.9(3) pm, b = 961.6(1) pm, c = 1967.6(4) pm and Z = 4. The crystal structure contains an anion so far not observed in gallium chalcogenides. It is built from [Ga₃Se₆Se_2/2(en)]^3– bicycles of three Ga^IIIL₄ tetrahedra (L = en, Se) connected via selenium corners to linear chains. The cations, Ga^III ions coordinated by three ethylendiamine in a distorted octahedral geometry are positioned in the holes of the hexagonal rod packing of these chains.