Über Usovite Ba2M″ M″ M2″ F14 und die Hochdruckphasen von BaMnVF7 und BaMnFeF7: Verbindungen mit BaMnGaF7-Struktur

On Usovites Ba₂M^IIM′^IIM₂^IIIF₁₄ and the High Pressure Phases of BaMnVF₇ and BaMnFeF₇: Compounds with BaMnGaF₇ Structure The results of complete single crystal structure determinations of the monoclinic BaMnGaF₇ type compounds Ba₂CaCoV₂F₁₄ (and Ba₂CdMn Fe₂F₁₄) are reported: C2/c, Z = 4, a = 1369.7 (1381.2), b = 538.4 (537.2), c = 1491.6 (1489.5) pm, β = 91.49 (91.11)°, Rg = 0.036 (0.038) for 4389 (2521) reflections. The atoms Ca/Co (Cd/Mn) distribute not completely ordered on the 8? and 6?coordinated sites of this “usovite” structure (Ba₂CaMgAl₂F₁₄). This is also evident for Cd/Fe from Mössbauer spectra of Ba₂CdFeAl₂F₁₄. The lattice constants of this and further seven compounds Ba₂M^IIM′^IIM2_IIIF₁₄ (M^II = Ca, Cd; M′^II = Mg, Mn? Cu; M^II = Al, Ga) are given. Two novel representatives of the same structure with M^II = M′^II = Mn could be prepared in the form of the high pressure phases of BaMn VF₇ and BaMnFeF₇. The magnetic properties of both modifications of the iron compound and of BaMnGaF₇ are reported and discussed.     

Struktur‐ und magnetochemische Untersuchungen an Ba5Mn3F19 und verwandten Verbindungen AII5MIII3F19

Structural and Magnetochemical Studies of Ba₅Mn₃F₁₉ and Related Compounds A^II₅M^III₃F₁₉ Single crystal structure determinations by X‐ray methods were performed at the following compounds, crystallizing tetragonally body‐centred (Z = 4): Sr₅V₃F₁₉ (a = 1423.4(2), c = 728.9(1) pm), Sr₅Cr₃F₁₉ (a = 1423.5(2), c = 728.1(1) pm), Ba₅Mn₃F₁₉ (a = 1468.9(1), c = 770.3(1) pm, Ba₅Fe₃F₁₉ (a = 1483.5(1), c = 766.7(1) pm), and Ba₅Ga₃F₁₉ (a = 1466.0(2), c = 760.1(2) pm). Only Ba₅Mn₃F₁₉ was refined in space group I4cm (mean distances for elongated octahedra Mn1–F: 185/207 pm equatorial/axial; for compressed octahedra Mn2–F: 199/182 pm), the remaining compounds in space group I4/m. In all cases the octahedral ligand spheres of the M1 atoms showed disorder, the [M1F₆] octahedra being connected into chains in one part of the compounds and into dimers in the other. The magnetic properties of the V, Cr and Mn compounds named above and of Pb₅Mn₃F₁₉ and Sr₅Fe₃F₁₉ as well were studied; the results are discussed in context with the in part problematic structures.     

Kristallstrukturbestimmungen an vier monoklinen Weberiten Na2MIIMIIIF7 (MII = Fe,Co; MIII = V,Cr)

Crystal Structure Determinations of Four Monoclinic Weberites Na₂M^IIM^IIIF₇ (M^II = Fe, Co; M^III = V, Cr) By solid state reaction of the binary fluorides single crystals of the following weberites were prepared and their monoclinic structure (space group C2/c, Z = 16) determined by X-ray methods: Na₂FeVF₇ (a = 1 271.0(3), b = 742.9(1), c = 2 471.6(5) pm, β = 100.03(3)°; R₁ = 0.043 (1 545 Reflexe); Fe? F = 203.8, V? F = 193.0 pm); Na₂FeCrF₇ (a = 1 262.5(3), b = 739.1(1), c = 2 460.5(5) pm, β = 99.93(3)°; R₁ = 0.029 (2 340); Fe? F = 203.6, Cr? F = 190.5 pm); Na₂CoVF₇ (a = 1 270.3(5), b = 739.1(3), c = 2 465.1(10) pm, β = 100.02(3)°; R₁ = 0.028 (2 250); Co? F = 201.6, V? F = 193.6 pm); Na₂CoCrF₇ (a = 1 257.8(3), b = 733.5(1), c = 2 441.5(5) pm, β = 99.64(3)°; R₁ = 0.030 (2 227); Co? F = 201.2, Cr? F = 190.2 pm). Concerning the above average distances within the distorted [MF₆] octahedra and the shape of [NaF₈] coordination details are given and discussed.     

Synthesis and Structure of the new Fluoride Bromide Ba6.668(2)Ca0.332(2)F12Br2 and Solid Solutions with Composition Ba7−xCaxF12(ClyBr1−y)2 with x = ∼0.5, 0 < y < 1

Crystals of the chemical composition Ba₇F₁₂Cl₂ were modified by adding a small amount of Ca²⁺ to allow the synthesis of the corresponding bromine compound Ba^[Ca]₇F₁₂Br₂. These samples were prepared in a NaBr flux and characterized by single crystal x‐ray diffraction. The new structure crystallizes in a disordered arrangement in the hexagonal space group P6₃/m (176). The calcium ion has a coordination number of 6. Solid solutions on the heavy halide position can be synthesised in a NaCl/NaBr flux to obtain the compounds Ba_7?xCa_xF₁₂(Cl_yBr_1?y)₂ with x = ～0.5 and 0 < y < 1. Regardless the amount of calcium used in the preparation process, the Ca stoichiometry in the compound is always between 0.3 and 0.5. The lattice parameters differ depending on the Ca‐ and Br‐content between 1053.81(5) ? a = b ? 1058.93(3) pm and 421.21 ? c ? 426.78(3) pm.     

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.     

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.     

Verbindungen des Typs MII3MIII(PO4)3 mit Eulytinstruktur (MII = Pb,Sr, Ba; MIII = La,Lanthanide, Y,Sc, Bi,In, TI)1

A number of new phosphates of the formula M^II₃M^III(PO₄)₃ has been prepared. They have the cubic structure of eulytite (Bi₄(SiO₄)₃). Obviously all combinations of the cations being specified in the title for M^II and M^III seem to be possible; moreover, Ca₃Bi(PO₄)₃ does exist. The ions M^II and M^III are distributed on the positions of Bi in a statistical manner. The peculiar dependence of the lattive constants of the lanthanide compounds Pb₃Ln(PO₄)₃ (including La) on the (Atomic number of the lanthanide ions suggests the conclusion that the small trivalent cations (r < 1 Å) do not have a close contact with the surrounding oxygen ions forming a distorted octahedron.     

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’.     

Neue Komplexe Fluoride mit Ag2+ und Pd2+: NaMIIZr2F11 (MII = Ag,Pd) und AgPdZr2F11

New Complex Fluorides with Ag²⁺ and Pd²⁺: NaM^IIZr₂F₁₁ (M^II = Ag, Pd) and AgPdZr₂F₁₁ For the first time single crystals of NaAgZr₂F₁₁, NaPdZr₂F₁₁ and AgPdZr₂F₁₁ have been obtained and investigated by X-ray methods. The isotypic compounds NaM^IIZr₂F₁₁ (M^II = Ag, Pd) crystallize triclinic, spcgr. P1 ? C (No. 2) with a = 780.9, b = 570.0, c = 583.2 pm, α = 106.1°, β = 112.2°, γ = 97.9° (NaPdZr₂F₁₁), AgPdZr₂F₁₁ is monoclinic, spcgr. C2/m? C_2h (No. 12) with a = 935.1, b = 699.1, c = 780.1 pm, β = 115.7°, Z = 2 (Four circle diffractometer data, Siemens AED 2). Their structure is closeley related to the Ag₃Hf₂F₁₄-type of structure.     

Zur Konstitution von Ba2WO3F4 und Ba2MoO3F4

On the Structure of Ba₂Wo₃F₄ and Ba₂MoO₃F₄ Ba₂[WO_2/2O₂F₂]F₂ has been prepared for the first time as colourless single crystals (from powder, Au-tube, 680°C, 90 d). It crystallizes in the monoclinic (C c) crystal system with a = 1151.1, b = 938.2, c = 718.8 pm, ß = 126.17°, Z = 4. d_x = 6.17, d_pyk = 6.13 g · cm^?3. (Fourcirclediffractometer PW 1100, Fa. Philips, MoKα-, ω-2Θ-scan, 1832 I₀(hkl) R = 8.3, R_w = 7.4%). Parameters see in the text. The isotypic Ba₂MoO₃F₄ has been prepared as powder (a = 1147.5, b = 937.0, c = 725.1 pm, ß = 126.42°). The structure shows chains of (WO_2/2O₂F₂) groups along [001]. To establish O^2? and F^? on the positions IR and Raman Spectra are employed. The Madelung Part of Lattice Energy, MAPLE, is calculated and discussed.     

Struktur‐ und magnetochemische Untersuchungen an den ternären Phosphaten Ba2MII(PO4)2 (MII = Mn,Co) und Strukturverfeinerung von BaNi2(PO4)2

Structural and Magnetochemical Studies at the Ternary Phosphates Ba₂M^II(PO₄)₂ (M^II = Mn, Co) and Refinement of the Crystal Structure of BaNi₂(PO₄)₂ Single crystals of the following phosphates were grown by the floating zone technique using a mirror furnace and their crystal structures refined (0,02 < R₁ < 0,04 and 0,04 < wR₂ < 0,10, resp.): Ba₂Mn(PO₄)₂ (a = 531.1(1), b = 896.8(1), c = 1625.6(3) pm, β = 90.26(1)°), Ba₂Co(PO₄)₂ (a = 529.8(1), b = 884.4(1), c = 1614.4(3) pm, β = 90.68(2)°) and BaNi₂(PO₄)₂ (a = 480.0(1), c = 2327.3(5) pm, Z = 3, space group R3). Both compounds Ba₂M^II(PO₄)₂ crystallize with Z = 4 in space group P2₁/n of the monoclinic Ba₂Ni(PO₄)₂ type; BaNi₂(PO₄)₂ has the hexagonal‐rhombohedral structure of the BaNi₂(AsO₄)₂ type. Magnetic measurements of powders of Ba₂Mn(PO₄)₂ and Ba₂Co(PO₄)₂ yielded room temperature moments of μ_eff = 5,73 and 4,93 μ_B, resp., but only the manganese compound obeys the Curie‐Weiss law down to low temperatures. Weak antiferromagnetic interactions at both compounds only near T_M ≈ 5 K lead to a reciprocal susceptibility minimum.     

Die Kristallstrukturen der Vanadium-Weberite Na2MIIVIIIF7 (MII  Mn,Ni, Cu) und von NaVF4

The Crystal Structures of the Vanadium Weberites Na₂M^IIV^IIIF₇ (M^II ? Mn, Ni, Cu) and of NaVF₄ At single crystals of the vanadium(III) compounds NaVF₄ (a = 790.1, b = 531.7, c = 754.0 pm, β = 101.7°; P2₁/c, Z = 4), Na₂NiVF₇ (a = 726.0, b = 1031.9, c = 744.6 pm; Imma, Z = 4) and Na₂CuVF₇ (a = 717.6, b = 1043.5, c = 754.6 pm; Pmnb, Z = 4) X-ray structure determinations were performed, at Na₂MnVF₇ (a = 746.7, c = 1821.6 pm; P3₂21, Z = 6) a new refinement. NaVF₄ crystallizes in the layer structure type of NaNbO₂F₂. The fluorides Na₂M^IIVF₇ represent new orthorhombic (M^II ? Ni; Cu) resp. trigonal (M^II ? Mn) weberites. The average distances within the [VF₆] octahedra of the four compounds are in good agreement with each other and with data of related fluorides (V? F: 193.3 pm). The differences between mean bond lengths of terminal and bridging F ligands are 5% in NaVF₄, but less than 1% in the weberites. Details and data for comparison are discussed.     

Wasserstoffbrückenbindungen in o- und m-Phenylendiammonium-aquapentafluorometallaten(III) (MIII = Al,Cr, Fe)

Hydrogen Bonds in o- and m-Phenylenediammonium Aquapentafluoro Metallates(III) (M^III = Al, Cr, Fe) m- and o-Phenylenediammonium-[M^IIIF₅(H₂O)] compounds of Al, Cr and Fe were synthesized and characterized by X-ray single crystal structure analysis. All structures are described in the space group P2₁2₁2₁ (Z = 4). m-Ph(NH₃)₂²⁺ (Ph(NH₃)₂²⁺ = phenylenediammonium) compounds: Al : a = 6.489(2), b = 7.943(2), c = 18.204(2) Å, R/wR = 0.084/0.050 for 1 533 reflections; Cr : a = 6.571(2), b = 8.006(2), c = 18.456(3) Å, R/wR = 0.050/0.040 for 1 571 reflections; Fe : a = 6.608(2), b = 8.052(2), c = 18.424(4) Å, R/wR = 0.042/0.034 for 1 947 reflections. o-Ph(NH₃)₂²⁺ compounds: Al : a = 6.580(2), b = 7.891(2), c = 18.319(5) Å, R/wR = 0.050/0.045 for 2 370 reflections; Cr : a = 6.642(2), b = 7.954(2), c = 18.484(4) Å, R/wR = 0.065/0.043 for 2 041 reflections; Fe : a = 6.693(2), b = 7.995(4), c = 18.529(7) Å, R/wR = 0.035/0.033 for 2 651 reflections. Isolated distorted octahedral [M^IIIF₅(H₂O)]^2? anions are connected by double O? H ?F hydrogen bonds of alternating strength to form chains in the b direction. Those chains, packed in a pseudohexagonal way, are further linked by the ammonium functions of the phenylenediammonium cations to a 3 D hydrogen bond network.     

Über hexagonale Perowskite mit Kationenfehlstellen. XXVII. Die Systeme Ba4−xSrxBIIRe2□O12′, Ba4BCaxRe2□O12 und Ba4−xLaxBIIRe2−xWx□O12 mit BII = Co,Ni

On Hexagonal Perovskites with Cationic Vacancies. XXVII. Systems Ba_4?xSr_xB^IIRe₂□O₁₂, Ba₄B Ca_xRe₂□O₁₂, and Ba_4?xLa_xB^IIRe_2?xW_x□O₁₂ with B^II = Co, Ni In the systems Ba_4?xSr_xB^IIRe₂□O₁₂, Ba₄BCa_xRe₂□O₁₂ and Ba_4?xLa_xB^IIRe_2?xW_x□O₁₂ (B^II = Co, Ni) hexagonal perovskites with a rhombohedral 12 L structure (general composition A₄BM₂□O₁₂; sequence (hhcc)₃; space group R&3macr;m) are observed. With the exception of Ba₄NiRe₂□O₁₂ the octahedral net consists of BO₆ single octahedra and M₂□O₁₂ face connected blocks (type 1). In type 2 (Ba₄NiRe₂□O₁₂) the M ions are located in the single octahedra and in the center of the groups of three face connected octahedra. The two outer positions of the latter are occupied by B ions and vacancies in the ratio 1:1. The difference between type 1 and 2 are discussed by means of the vibrational and diffuse reflectance spectra.     

Die Kristallstruktur der hydratisierten Cyanokomplexe NMe4MnII[(Mn, Cr)III(CN)6] · 3 H2O und NMe4Cd[MIII(CN)6] · 3 H2O (MIII = Fe,Co): Verwandte des Berliner Blaus

The Crystal Structure of the Hydrated Cyano Complexes NMe₄Mn^II[(Mn, Cr)^III(CN)₆] · 3 H₂O and NMe₄Cd[M^III(CN)₆] · 3 H₂O (M^III = Fe, Co): Compounds Related to Prussian Blue The crystal structures of the isotypic tetragonal compounds (space group I4, Z = 10) NMe₄Mn^II · [(Mn, Cr)^III(CN)₆] · 3 H₂O (a = 1653.2(4), c = 1728.8(6) pm), NMe₄Cd[Fe(CN)₆] · 3 H₂O (a = 1642.7(1), c = 1733.1(1) pm) and NMe₄Cd[Co(CN)₆] · 3 H₂O (a = 1632.1(2), c = 1722.4(3) pm) were determined by X‐rays. They exhibit ⊥ c cyanobridged layers of octahedra [M^III(CN)₆] and [M^IIN₄(OH₂)₂], which punctually are interconnected also || c to yield altogether a spaceous framework. The M^II atoms at the positions linking into the third dimension are only five‐coordinated and form square pyramids [M^IIN₅] with angles N–M^II–N near 104° and distances of Mn–N: 1 × 214, 4 × 219 pm; Cd–N: 1 × 220 resp. 222, 4 × 226 resp. 228 pm. Further details and structural relations within the family of Prussian Blue are reported and discussed.     

Fluoride‐Bridged {GdIII3MIII2} (M=Cr,Fe, Ga) Molecular Magnetic Refrigerants

The reaction of fac‐[M^IIIF₃(Me₃tacn)]⋅x H₂O with Gd(NO₃)₃⋅5H₂O affords a series of fluoride‐bridged, trigonal bipyramidal {Gd^III₃M^III₂} (M=Cr ( 1 ), Fe ( 2 ), Ga ( 3 )) complexes without signs of concomitant GdF₃ formation, thereby demonstrating the applicability even of labile fluoride‐complexes as precursors for 3d–4f systems. Molecular geometry enforces weak exchange interactions, which is rationalized computationally. This, in conjunction with a lightweight ligand sphere, gives rise to large magnetic entropy changes of 38.3 J kg⁻¹ K⁻¹ ( 1 ) and 33.1 J kg⁻¹ K⁻¹ ( 2 ) for the field change 7 T→0 T. Interestingly, the entropy change, and the magnetocaloric effect, are smaller in 2 than in 1 despite the larger spin ground state of the former secured by intramolecular Fe–Gd ferromagnetic interactions. This observation underlines the necessity of controlling not only the ground state but also close‐lying excited states for successful design of molecular refrigerants.     

Synthese,Struktur und magnetische Eigenschaften der Verbindungen NaMIIZr2F11 (MII = Ti,V und Cu) und einem Anhang über NaPdZr2F11

Synthesis, Structure, and Magnetic Properties of Compounds NaM^IIZr₂F₁₁ (M^II = Ti, V, Cu) and a Notice on NaPdZr₂F₁₁ By synthesizing NaTiZr₂F₁₁ in form of red single crystals, it was possible to obtain a complex fluoride with Ti²⁺ for the first time. It crystallizes like the analogous greenish blue vanadium compound isotypic to AgPdZr₂F₁₁ [1] monoclinic, spacegroup C2/m–C (No. 12) with a = 918.0/911.5 pm, b = 682.6/675.7 pm, c = 780.8/776.6 pm, β = 116.2/116.2º and Z = 2. Colourless NaCuZr₂F₁₁ however crystallizes as a result of the Jahn-Teller distortion of Cu²⁺ triclinic (space group P1 –C (No. 2), a = 552.7 pm, b = 568.2 pm, c = 768.0 pm, α = 111.0º, β = 97.4º, γ = 106.4º) and is – as expected – isotypic to NaAgZr₂F₁₁ [1].     

Fluoride‐Bridged {GdIII3MIII2} (M=Cr,Fe, Ga) Molecular Magnetic Refrigerants

The reaction of fac‐[M^IIIF₃(Me₃tacn)]?x H₂O with Gd(NO₃)₃?5H₂O affords a series of fluoride‐bridged, trigonal bipyramidal {Gd^III₃M^III₂} (M=Cr ( 1 ), Fe ( 2 ), Ga ( 3 )) complexes without signs of concomitant GdF₃ formation, thereby demonstrating the applicability even of labile fluoride‐complexes as precursors for 3d–4f systems. Molecular geometry enforces weak exchange interactions, which is rationalized computationally. This, in conjunction with a lightweight ligand sphere, gives rise to large magnetic entropy changes of 38.3 J kg^?1 K^?1 ( 1 ) and 33.1 J kg^?1 K^?1 ( 2 ) for the field change 7 T→0 T. Interestingly, the entropy change, and the magnetocaloric effect, are smaller in 2 than in 1 despite the larger spin ground state of the former secured by intramolecular Fe–Gd ferromagnetic interactions. This observation underlines the necessity of controlling not only the ground state but also close‐lying excited states for successful design of molecular refrigerants.     

Zur Kristallstruktur von Ba3Al2F12

Concerning the Crystal Structure of Ba₃Al₂F₁₂ Preparing BaMnAlF₇ we obtained single crystals of Ba₃Al₂F₁₂ as a by‐product (a = 1020.3(2), b = 988.5(1), c = 952.2(1) pm, space group Pnnm, Z = 4). The redetermination confirmed the structure already known, but improved the results (R₁′ = 0.028 and wR₂ = 0.06 for 1908 and 2717 reflections, resp.). An interpretation is given for the relation of distances within the tetrameric anion [Al₄F₂₀]^8— (average Al—F: 180, 1 pm). The construction of the cationic frame [Ba₃F₂]⁴⁺ is discussed.     

Die Kristallstruktur des gemischtvalenten Eisenfluoridhydrates Fe3F8 · 2 H2O

Crystal Structure of the Mixed-Valence Iron Fluorid Hydrate Fe₃F₈ · 2 H₂O Newly prepared was the red, monoclinic compound Fe₃F₈ · 2 H₂O, single crystals of which could be obtained under hydrothermal high pressure conditions (space group C2/m with a = 761.2(3), b = 750.0(1), c = 746.9(3) pm, β = 118.38(2)° and Z = 2). The X-ray structure determination (R_G = 0.0192 and 635 reflexions) yielded a framework structure, in which layers of octahedra 2[Fe^IIIF_6/2] are connected via corners of [Fe^IIF_4/2(H₂O)₂]-octahedra. The average distances in the nearly ideal octahedra are Fe^III? F = 193.0, Fe^II? F = 208.1 and Fe^II? OH₂ = 211.5 pm.