Strukturen caesiumhaltiger Fluoride. VIII. Cs7Ni4F15 und Cs7Co4F15: Die Kristallstrukturbestimmung an den bisher caesiumreichsten Verbindungen in den zugehörigen Systemen CsF/MF2

Structures of Cesium-containing Fluorides. VIII. Cs₇Ni₄F₁₅ and Cs₇Co₄F₁₅: Crystal Structure Determination of the Hitherto Cesium-richest Compounds in the Corresponding Systems CsF/MF₂ . The only nickel-containing phase we could identify after solid state reaction 2 CsF + NiF₂ was the compound Cs₇Ni₄F₁₅. The single crystal structure determination of this monoclinic fluoride (and its cobalt analog Cs₇Co₄F₁₅) yielded a = 787.2 (788.3), b = 1089.7 (1096.6), c = 1149.5 (1164.9) pm, β = 92.74 (92.59)°, space group P2₁/c, Z = 2, R_g = 0.045 (0.058) for 2543 (2716) independent reflections. The resulting strongly puckered layer structure rather than of single octahedra consists of face-sharing M₂F₉ units, which are connected via the half of their remaining corners. The M? F distances vary from 195.1 to 212.0 (196.7 to 217.0) pm and show unusual high mean values of 203.7 (206.5) pm. Data for comparison and further details are discussed.     

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.     

Zur Kenntnis des Systems Cs/Cu/F: Über CsCuIICuIIIF6

The System Cs/Cu/F: On CsCu^IICu^IIIF₆ ?CsCuF_3,6’? is described in literature as a darkbrown powder which is supposed to crystallize in a cubic lattice (a = 882 pm, Debyeogramms). However Guinier photographs show that ?CsCuF_3,6’? is a mixture of CsCu^IICu^IIIF₆ (black, isotypic to CsNi^IINi^IIIF₆, a = 706.7 b = 727.7, c = 1032.2 pm, Z = 4) and Cs₂CuCu^IIIF₆ (auburn, pseudocubic, a = 623.4 c = 886.4 pm, Z = 2).     

Strukturen caesiumhaltiger Fluoride. V. Die pseudohexagonale Wolframbronzestruktur der monoklinen Phase Cs0,4Zn0,4Fe1,6F6 und verwandter Cäsium-Übergangsmetallfluoride

Structures of Cesium-containing Fluorides. V. Pseudohexagonal Tungsten Bronze Structure of the Monoclinic Phase Cs_0.4Zn_0.4Fe_1.6F₆ and Related Cesium Transition Metal Fluorides The crystal structure of the pseudohexagonale phase Cs_0.4Zn_0.4Fe_1.6F₆ was refined in the monoclinic space group P2₁ (a = 747.4, b = 763.6, c = 746.1 pm, β = 120.0°, z = 3). Using 1067 single crystal reflections R = 6.3% was reached. Compared to the hexagonal tungsten bronze structure the corner-sharing of octahedra shows pronounced angles also along the unique axis (M? F? M = 159.0°). The average bridge angle in the framework of tilted octahedra is 149.6°. Structural relations are discussed.     

Bi12,86Ni4Br6 und Bi12,86Ni4I6: Subhalogenide mit intermetallischen und salzartigen Schichtpaketen in alternierender Abfolge

Bi_12.86Ni₄Br₆ and Bi_12.86Ni₄I₆: Subhalides with Alternating Intermetallic and Salt‐like Layers The reaction of bismuth and nickel with bromine or iodine at 730 K yields black, air insensitive, needle shaped crystals of the ternary subhalides Bi_12.86Ni₄X₆ (X = Br, I). The isotypic compounds crystallize in the orthorhombic space groups Immm with a = 405.69(6) pm, b = 874.00(8) pm, c = 3744.7(4) pm for X = Br, and a = 410.05(5) pm, b = 912.84(7) pm, c = 3826.7(3) pm for X = I. The crystal structures contain characteristic fragments of the intermetallic phase Bi₃Ni: chains consisting of face‐sharing mono‐capped trigonal prisms of bismuth atoms with a nickel atom in the center of each prism. The chains form corrugated layers which are separated by halogen atoms and oligomeric [Bi_nX_4n+2] units of varying length. The halogenobismutate(III) units consist of trans‐edge‐sharing [BiX₆] octahedra. They are disordered within the crystal structures. The non‐integer stoichiometric coefficients of Bi_12.86Ni₄X₆ are due to the metric adjustment between the ionic and intermetallic parts of the structure. Extended Hückel calculations indicate, that the partial oxidation of the intermetallic phase causes a strengthening of the chemical bonding within the Bi₃Ni chains. The subiodide Bi_12.86Ni₄I₆ is paramagnetic and shows ferromagnetic ordering below 25 K.     

Zur Kenntnis von Cs4Fe3F10 [1] sowie Cs3TINi3F10 [2]

On Ca₄Fe₃F₁₀ and Cs₃TINi₃F₁₀ Single crystals of Cs₄Fe₃F₁₀ (orthorhombic, a = 629.4, b = 1450,7, c = 1410.9 pm) and Cs₃TlNi₃F₁₀ (orthorhombic, a = 610.1, b = 1442.0, c = 1366.8 pm) have been prepared. Results of X-ray investigation: Cs₄Fe₃F₁₀ is isotypic to Cs₄Mg₃F₁₀ and crystallizes in the space group Cmca (R = 3.97%, R_w = 2.75%, 1020 of 1020 I₀(hkl), fourcircle diffractometer AED 2, Fa. Siemens). A monoclinic distortion could not be observed as supposed present. Cs_4?xTl_xNi₃F₁₀ (x≈?1), R = 7.75%, R_w = 4.96%, 1079 of 1294 I₀(hkl), fourcircle diffraktometer PW 1100, Fa. Philips) confirm the possibility to substitute Cs against Tl in the Cs₄Mg₃F₁₀-type.     

Synthese und Kristallstruktur des Fluorid‐ino‐Oxosilicats Cs2YFSi4O10

Synthesis and Crystal Structure of the Fluoride ino‐Oxosilicate Cs₂YFSi₄O₁₀ The novel fluoride oxosilicate Cs₂YFSi₄O₁₀ could be synthesized by the reaction of Y₂O₃, YF₃ and SiO₂ in the stoichiometric ratio 2 : 5 : 3 with an excess of CsF as fluxing agent in gastight sealed platinum ampoules within seventeen days at 700 °C. Single crystals of Cs₂YFSi₄O₁₀ appear as colourless, transparent and water‐resistant needles. The characteristic building unit of Cs₂YFSi₄O₁₀ (orthorhombic, Pnma (no. 62), a = 2239.75(9), b = 884.52(4), c = 1198.61(5) pm; Z = 8) comprises infinite tubular chains of vertex‐condensed [SiO₄]^4? tetrahedra along [010] consisting of eight‐membered half‐open cube shaped silicate cages. The four crystallographically different Si⁴⁺ cations all reside in general sites 8d with Si–O distances from 157 to 165 pm. Because of the rigid structure of this oxosilicate chain the bridging Si–O–Si angles vary extremely between 128 and 167°. The crystallographically unique Y³⁺ cation (in general site 8d as well) is surrounded by four O^2? and two F^? anions (d(Y–O) = 221–225 pm, d(Y–F) = 222 pm). These slightly distorted trans‐[YO₄F₂]^7? octahedra are linked via both apical F^? anions by vertex‐sharing to infinite chains along [010] (?(Y–F–Y) = 169°, ?(F–Y–F) = 177°). Each of these chains connects via terminal O^2? anions to three neighbouring oxosilicate chains to build up a corner‐shared, three‐dimensional framework. The resulting hexagonal and octagonal channels along [010] are occupied by the four crystallographically different Cs⁺ cations being ten‐, twelve‐, thirteen‐ and fourteenfold coordinated by O^2? and F^? anions (viz.[(Cs1)O₁₀]^19?, [(Cs2)O₁₀F₂]^21?, [(Cs3)O₁₂F]^24?, and [(Cs4)O₁₂F₂]^25? with d(Cs–O) = 309–390 pm and d(Cs–F) = 360–371 pm, respectively).     

Die ersten oligomeren Anionen bei Fluoro-Litho-Metallaten mit Oktaeder-Sandwich-Motiv: Cs4K{[F3MIIIF3]Li[F3MIIIF3]}, MIII = Ga,Fe [1]

The First Oligomeric Anions of Fluoro-Litho Metallates with Octahedra Sandwich Motive: Cs₄K{[F₃M^IIIF₃]Li[F₃M^IIIF₃]}, M^III = Ga, Fe Colourless single crystals of Cs₄K{Li[Ga₂F₁₂]} ( A ) and Cs₄K{Li[Fe₂F₁₂]} ( B ) have been obtained by solid state reaction from intimate mixtures of the corresponding binary fluorides (Pt-tube, 750°C, 40 d). The trigonal unit cells with ( A ) a = 631,3(1)pm; c = 3059,9(6)pm and ( B ) a = 635,0(1)pm; c = 3089,2(7)pm, respectively (Z = 3, Guinier-Simon data, Cu-Kα₁), are confirmed by single crystal investigations. The compounds crystalize isostructural in the space group R3 m (No. 166). The structures were determined using four-circle diffractometer data (Siemens AED 2) with ( A ) R = 2.95%, 3627 I_o and ( B ) R = 1.86%, 4179 I_o, respectively (SHELX-76), and are characterized by triplets of facesharing octahedra parallel [00.1] with the cation-sequence M^III? Li? M^III, six of which are connected by [KF₆]-octahedra via common corners and each triplet is surrounded by six different [KF₆]-octahedra. The structure is completed by Cs⁺ filling the cavities. The Madelung Part of Lattice Energy (MAPLE), Mean Fictive Ionic Radii (MEFIR) and Effective Coordination Numbers (ECoN) are calculated and compared. The classification as lithometallate could be verified by a new MAPLE concept. The Charge Distribution (CHARDI) was calculated and compared with the results according to ‘bond length-bond strength’.     

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.     

Crystal Structure of the High Temperature Form of Cs4Ni3CdF12: A New 10 H Hexagonal Perovskite Type

Above 850°C Cs₄Ni₃CdF₁₂ (which corresponds to the x = 0.25 composition of the CsNi_1?xCd_xF₃ solid solution) shows an allotropic transformation from a 12 R to a 10 H-type structure. The high temperature form crystallizes in the hexagonal P6₃/mmc space group with a = 6.238 Å and c = 25.362 Å. A crystal structure determination shows that the 10-layer packing sequence corresponds to a new structural arrangement of CsF₃ layers and divalent cations. The structure is characterized by units of four octahedra linked by faces and connected to each other by an octahedron sharing only corners. Ni and Cd atoms are partially disordered in the tetrameric units, while the unique octahedron is occupied by cadmium. A phase corresponding to the Cs₅Ni₄CdF₁₅ formula has been isolated, which shows an isostructural powder pattern.     

Ba2(Ni1−xLix)Ni2N2: Ein niedervalentes Nitridoniccolat mit gewellten Schichten [(NiN2/2)?(Ni1−xLix)?(NiN2/2)]

Ba₂(Ni_1?xLi_x)Ni₂N₂: A Low-Valency Nitridoniccolate with Puckered Layers [(NiN_2/2)? (Ni_1?xLi_x)? (NiN_2/2)] Ba₂(Ni_1?xLi_x)Ni₂N₂ is obtained by reaction of lithium-barium-melts (molar ratios Li : Ba between 1 : 1 and 3 : 1) with nitrogen (1 atm.) in nickel-crucibles within a period of 15 h. Single crystals with a dark-metallic lustre are formed by cooling the melt to room temperature with a rate of 10°C/h (orthorhombic, Cmca; a = 713.3(2)pm, b = 1027.4(7)pm, c = 752.2(4)pm; z = 4; D_xr = 5.50 g/cm³ with x = 0.43). The crystal structure contains nearly liner [NiN_2/2]-chains (N? Ni? N: 178.5(7)°, Ni? N? Ni 173.4(7)°; Ni? N: 178.6(1)pm), running parallel to the [100] direction, which are interconnected via (Ni_1?xLi_x)-sites (linear units (N? (Ni_1?xLi_x)? N); bond-lenths: 194.5(12)pm with x = 0.43) to form puckered layer [(Nin_2/2)? (Ni_1?xLi_x)? (NiN_2/2)]. Barium is in a distorted trigonal-planar coordination by nitrogen atoms (Ba? N: 281.1(11)pm ? 285.5(11)pm. The nitrogen-coordination corresponds to a distorted octahedron, NBa₃(Ni_1?xLi_x)Ni₂, with nickel in trans-position. The crystal structure of Ba₂(Ni_1?xLi_x)Ni₂N₂ is closely related to the Li₃N-type structure: Li₂[LiN] ? Ba{(Ni_1?xLi_x)_0.5 □ _0.5}[NiN]. Furthermore, this structure enlarges the scope of barium-nitrido-niccolates which up to now were found to contain merely [NiN_2/2]-chains(BaNiN: Planar zigzag-chains; Ba₈Ni₆N₇ helical zigzag-chains).     

Structure,Chemical Bonding,and Properties of Sc2Ni2In

Sc₂Ni₂In was prepared by a reaction of the elemental components in an are furnace and subsequent annealing at 1070 K. Sc₂Ni₂In is a Pauli paramagnet and a poor metallic conductor with a specific resistivity of 224 mΩcm at room temperature. Its crystal structure was refined from X-ray powder data: P4/mbm, a = 716.79(1) pm, c = 333.154(8) pm, Z = 2, R_wp = 0.040, and R_B(I) = 0.026. Sc₂Ni₂In crystallizes with a ternary ordered version of the U₃Si₂-type structure. The nickel and indium atoms occupy [NiSc₆] trigonal prisms and [InSc₈] square prisms, respectively. These structural fragments are derived from the AlB₂ and CsCl-type structures. Semi-empirical band structure calculations reveal Sc₂Ni₂In to be a nickelide, and the strongest bonding interactions are found for the Sc? Ni contacts, followed by Sc? In and Ni? In. A rigidband model suggests the existence of the isotypic phase Sc₂Ni₂Sb.     

Die Antimonid–Triantimonidometallate(III) Cs6K3Sb[AlSb3] und Cs6K3Sb[GaSb3]

The Antimonide Triantimonidometallates(III) Cs₆K₃Sb[AlSb₃] and Cs₆K₃Sb[GaSb₃] The novel compounds Cs₆K₃Sb[AlSb₃] and Cs₆K₃Sb[GaSb₃] are formed from stoichiometric mixtures of Cs, AlSb (GaSb) and KSb in sealed niobium ampoules at 950 K. The hexagonal structures are especially characterized by one-dimensional rod packings ¹∞[Cs₆K₃Sb] which are formed from columns of condensed (Cs₆K_6/2) icosahedra. The icosahedra are centered by Sb^3-? anions. The trigonal planar anions [AlSb₃]^6-? and [GaSb₃]^6-? are embedded between the icosahedra columns, and they are coordinated by alkali metal atoms. The FIR spectra were assigned to the vibrations of the [MSb₃]^6-? anions, with respect to the 6 m2-D_3h symmetry. (P6₃/mmc, No. 194; a = 1101.7 and 1097.2 pm; c = 1158.9 and 1150.1 pm; Z = 2; Single crystal data: 574 and 546 reflections; R = 0.073 and 0.029. Distances:d(Al? Sb) = 265.4 pm; d(Ga? Sb) = 265.1 pm; d(Sb? Cs) = 401.6–423.0 pm; d(Sb? K) = 358.6–367.3 pm).     

Tetragonale Fluorperowskite AM0,75 ▭ 0,25F3 mit Kationendefizit: K4MnIIMn2IIIF12 und Ba2Cs2Cu3F12

Tetragonal Fluoroperovskites AM_0,75 □ _0,25F₃ Deficient in Cations: K₄Mn^IIM₂^IIIF₁₂ and Ba₂Cs₂Cu₃F₁₂ By heating 2KMnF₃ + K₂MnF₆ and BaF₂, CsF + CuF₂ respectively, the isostructural tetragonal compounds K₄Mn₃F₁₂ (a = 832.2, c = 1643.0 pm) and Ba₂Cs₂Cu₃F₁₂ (a = 854.1, c = 1704.1 pm) were prepared. They crystallize in a cation-deficient perovskite structure exhibiting ordering of octahedral vacancies. Single crystal structures determinations in the space group I4₁/amd, Z = 4, yielded the following average distances within the octahedra, which are Jahn-Teller distorted for Mn^III and Cu^II:Mn^II? F = 208.3 pm, Mn^III? F = 4 × 183.0/2 × 209.7 pm; Cu? F = 190.7/227.1 and 190.6/236.4 pm, respectively. The results are discussed in comparison with related compounds.     

Einkristallstrukturuntersuchungen an hexagonalen Fluorperowskiten AMIIF3 (MII = Mg,Mn, Fe,Co, Ni)

Single Crystal Structural Studies at Hexagonal Fluoride Perovskites AM^IIF₃ (M^II = Mg, Mn, Fe, Co, Ni) At single crystals of nine fluoride phases AMF₃ the hexagonal perovskite structures were refined by X‐ray methods, of RbNiF₃ below T_C £ 145 K, too. The hexagonal 6 L type (P6₃/mmc, Z = 6) is found at: RbMgF₃ (a = 585.7(1); c = 1426.0(1) pm), CsMnF₃ (624.4(1); 1515.4(4) pm), CsFeF₃ (616.8(1); 1488.4(6) pm), Rb_0.63Cs_0.37CoF₃ (599.1(1); 1460.3(4) pm), RbNiF₃ (128 K: 582.6(1); 1426.4(6) pm), Cs₂BaLiNi₂F₉ (593.1(1); 1447.1(4) pm). Of the hexagonal‐rhombohedral 9 L type (R 3 m, Z = 9) are CsCoF₃ (620.1(1); 2264.0(7) pm) and yellow CsNiF₃ (614.7(1); 2235.3(6) pm), prepared at lower temperatures resp. under high pressure, whereas light green CsNiF₃ (625.5(1); 524.2(1) pm) belongs to the 2 L type (P6₃/mmc, Z = 2). The occurence of these structures and the interatomic distances observed, comparing also normal and high pressure phases, are discussed in connection with the tolerance factor.     

Darstellung,Struktur und Schwingungsspektren der Oxofluorowolframate(VI) Cs2[WO3F2] und Cs3[W2O4F7]

Synthesis, Structure, and Vibrational Spectra of the Oxofluorotungstates(VI) Cs₂[WO₃F₂] and Cs₃[W₂O₄F₇] Cs₂[WO₃F₂] crystallizes from a melt with the same composition. The orthorhombic unit cell with a = 6.779(2), b = 7.668(1) and c = 11.626(3) Å, space group Pn2₁a, contains 4 formula units. The WO₃F₂^2? anion is polymer, W octahedrally coordinated according to the results of the X-ray crystal structure determination. Planar dioxodifluoro groups are linked into chains by oxygen atoms. The lengths of the W? O bonds are alternating. Cs₃[W₂O₄F₇] crystallizes trigonal, space group P3 m1, with a = 21.118(4) and c = 8.434(2) Å, Z = 9. The structure consists of two sets of crystallographically non equivalent dimeric anions with the formula [O₂F₃W? F? WO₂F₃]^3?. Part of the ligand atoms are disordered. The vibrational spectra of both compounds show the presence of cis-dioxo groups of the terminal ligands.     

Zur Kenntnis der Hexafluorocuprate(III)

On Hexafluorocuprates (III) New prepared are: Cs₂LiCuF₆ (green, trigonal isotypic to Cs₂LiGaF₆; a = 621.5, c = 503.3 pm, γ = 120° from CsCuCl₃, CsCl, Li₂CO₃, p_F2 = 1 bar, 350°C, 2w); K₂LiCuF₆ (green, cubic isotypic to K₂NaCrF₆; a = 792.5 pm from KCuCl₃, Li₂CO₃, KCl, p_F2, = 35 bar, 480°C, 3 d); CsRb₂CuF₆ (green, cubic isotypic to inv. K₂NaCrF₆; a =899,6 pm from CsCuCl₃, RbCl, p_F2 = 1 bar, 400°C, 7 d); CsRbKCuF₆ (green, cubic isotypic to K₂NaCuF₆; a = 886.1 pm from KCuCl₃, CsCl, RbCl, p_F2 = 1 bar, 400°C, 7 d); CsCuCuF₆ (black, orthorhombic isotypic to CsNiNiF₆; a = 706.7, b = 727.7, c = 1032.2 pm from CsCuCl₃, CuCl₂ · 2H₂O, p_F2 = 30 bar, 400°C, 20 h); CsBaCuF₆ (green, tetragonal; a = 598.1, c = 864.6 pm from ?BaCuO₂’?, CsCl, p_F2 = 350 bar, 400°C, 7 d). Also prepared: Cs₂RbCuF₆, Cs₂KCuF₆, Cs₂NaCuF₆, Rb₂KCuF₆, Rb₂NaCuF₆, Rb₂LiCuF₆, K₂NaCuF₆, Na₃CuF₆, K₃CuF₆, Rb₃CuF₆, Cs₃CuF₆ and CsZnCuF₆ (parameters see text). The Madelungpart of Lattice Energy, MAPLE are calculated and discussed. All samples are paramagnetic and follow (exception: CsZnCuF₆) the Curie-Weiss-Law.     

Crystal structure and magnetic properties of Ba2Ni3F10

Ba₂Ni₃F₁₀ is monoclinic (space group $\text{C2}\text{m}$), a = 18.542(7) Å, b = 5.958(2) Å, c = 7.821(3) Å, β = 111°92(10). Ba₂Co₃F₁₀ and Ba₂Zn₃F₁₀ are isostructural. The structure has been refined from 995 reflections by full-matrix least-squares refinement to a weighted R value of 0.048 (unweighted R, 0.047). The three-dimensional network can be described either by complex chains connected to each other by octahedra sharing corners or with an 18L dense-packing sequence. The basic unit (Ni₃F₁₀)^4? is discussed and compared to the different unit existing in Cs₄Mg₃F₁₀. Antiferromagnetic properties of Ba₂Ni₃F₁₀ (T_N = 50 K are described.     

Cs2Cu3MIVF12 (MIV = Zr,Hf) – Kristallstruktur und magnetische Eigenschaften

Cs₂Cu₃M^IVF₁₂ (M^IV = Zr, Hf) – Crystal Structure and Magnetic Behaviour Colourless single crystals of Cs₂Cu₃ZrF₁₂ are obtained by heating the binary fluorides in sealed Pt-tubes under dry argon (solid state reaction, T ≈? 700°C, t ≈? 7–10 d). The compound crystallizes trigonal-rhomboedrical in the space group R3 m-D (Nr. 166); lattice parameters are a = 716.61(6) pm, c = 2 046.4(2) pm, Z = 3 (Four cycle diffractometer data, AED 2). The structure is dominated by layers of corner-sharing, Jahn-Teller-distorted [CuF₆]-Octahedra, which are connected via regular [ZrF₆]-Octahedra to stackings parallel [00.1]. Cs⁺-ions are located in the spacings of the octahedra-network. From powder data Cs₂Cu₃HfF₁₂ with a = 716.32(4) pm, c = 2 048.6(2) pm is isotypic. Both compounds show antiferromagnetic behaviour already at temperatures about 200 K.