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.     

Untersuchungen an quaternären Fluoriden LiMIIMIIIF6, Über die Kationenverteilung in Fluortrirutilen

Inhaltsübersicht. Fluortrirutile LiM^IIM^IIIF₆ kristallisieren tetragonal in dor Raumgruppe P4₂/mnm mit Li in Position (2a) und M^II und M^III statistisch vorteilt in (4e). An Einkristallen und durch Pulvermessungen wurde die Verteilung der Kationen untersucht, wozu die neu dargestellte Rhodiumverbindung LiZnRhF₆ auf Grund des unterschiedlichen Streuvermögens der Kationen besonders geeignet war. Verbindungen LiCuM^IIIF₆ zeigen die einfache Rutilstruktur. Investigations of the Quaternary Fluorides LiM^IIM^IIIF₆. On the Distribution of Cations in Fluorotrirutiles Abstract. Trirutiles LiM^IIM^IIIF₆ crystallize tetragonally in the space group P4₂/mnm with Li in position (2a) und M^II and M^III statistically distributed in (4e). By single-crystal X-Ray diffraction and by powder work cation ordering was examined for which the new compound LiZnRhF, was especially adapted. Compounds LiCuM^IIIF₆ are disordered rutile phases.     

Strukturuntersuchungen an Usoviten: Ba2CaMIIV2F14 (MIII = Mn,Fe), Ba2CaMnFe2F14 und Ba2CaCuM2IIIF14 (MIII = Mn,Fe, Ga)

Structural Studies with Usovites: Ba₂CaM^IIV₂F₁₄ (M^III = Mn, Fe), Ba₂CaMnFe₂F₁₄ and Ba₂CaCuM₂^IIIF₁₄ (M^III = Mn, Fe, Ga). Single crystals of six compounds Ba₂CaM^IIM₂^IIIF₁₄ were prepared to refine their usovite type structure (space group C2/c, Z = 4) using X‐ray diffractometer data. The cell parameters of the phases studied with M^IIM₂^III= MnV₂, FeV₂, CuMn₂, MnFe₂, CuFe₂ und CuGa₂ are within the range 1374≤a/pm≤1384, 534≤b/pm≤542, 1474≤c/pm≤1510, 91, 3≤ß/°≤93, 2. The atoms Ca and M^II are incompletely ordered on the 8‐ and 6‐coordinated positions, 4e and 4b, respectively. In the case of Ba₂CaFeV₂F₁₄ and Ba₂CaCuGa₂F₁₄ there is reciprocal substitution (x≈0, 1): (Ca_1‐xM_x^II) (4e) and (M_1‐x^IICa_x) (4b). In the case of the other usovites Ca‐enriched phases Ba₂Ca(M_1‐y^IICa_y)M₂^IIIF₁₄ occured (up to y≈0, 35), exhibiting partial substitution at the octahedral position (4b) only, showing a corresponding increase in M^II‐F distances. The distortion of [M^IIF₆] and [M^IIIF₆] octahedra within the structure is considerably enhanced on replacement by Cu^II and Mn^III. The results of powder magnetic susceptibility measurements of Ba₂CaMnV₂F₁₄ and Ba₂CaFeV₂F₁₄ (T_N≈7K) are reported.     

Über röntgenographische Einkristalluntersuchungen an Na2FeAlF7, Na2MIIGaF7 (MII = Ni,Zn) und Na2ZnFeF7 und die Strukturchemie der Weberite

On X-Ray Single Crystal Studies of Na₂FeAlF₇, Na₂M^IIGaF₇ (M^II = Ni, Zn), and Na₂ZnFeF₇ and the Structural Chemistry of Weberites At single crystals of the orthorhombic weberite Na₂NiGaF₇ (a = 716.1, b = 1021.6, c = 740.9 pm; Imma, Z = 4) and of the monoclinic variants (C2/c, Z = 16) Na₂FeAlF₇ (a = 1242.6, b = 727.8, c = 2420.6 pm, β = 99.99°), Na₂ZnGaF₇ (a = 1251.9, b = 730.3, c = 2435.3 pm, β = 99.74°) and Na₂ZnFeF₇ (a = 1261.0, b = 7.359, c = 2453.8 pm, β = 99.70°) complete X-ray structure determinations were performed. The results and the influence of radii on the bridge angles M^II–F–M^II and M^II–F–M^III are discussed in connection with general features within the structural chemistry of 28 weberites.     

Zur Struktur der LiMIIMIIIF6-Verbindungen. Neue Verbindungen mit MIII=In und Ti

On the Structure of LiM^IIM^IIIF₆ Compounds. New Compounds with M^III=IN and Ti LiMn^IIInF₆ compounds with M^II = Mg, Mn, Co, Ni, Zn, Cd and Ca crystallize in the Na₂SiF₆ structure. The Ti(III) compound LiMgTiF₆ has trirutile structure, LiMnTiF₆ has Na₂SiF₆ and trirutile structure (H.-T. modification), LiCaTiF₆ and LiCdTiF₆ have Li₂ZrF₆ superstructure. With M^II = Co, Ni and Zn solid solutions trirutile — MF₂(rutile) could be only prepared. The lattice constants of all compounds are reported. For LiMnVF₆ and LiFeGaF₆ too dimorphism Na₂SiF₆ trirutile was observed. In the system LiNiCrF₆ (trirutile) — LiMnCrF₆ (Na₂SiF₆ structure) phase limits of both structures are determined in dependence on the ratio of ionic radii r/r. Magnetic data of the In compounds with M^II = Co and Ni and of the Ti(III) compounds with M^II = Mg, Zn, Mn, just as of α- and β-LiMnVF₆ are also given. The three structures only exist if r reaches from 0.6 to 1.2 Å and r from 0.5 to 0.8 Å. The stability-fields are determined by the ratio of ionic radii r/r_Li, r/r_Li and r/r: trirutile 0.9–1.2, Na₂SiF₆ type 1.2–～1.4 and Li₂ZrF₆ superstructure >1.4. The dependence of rate of ionic radii is explained by the different sharing of MF₆ octahedra.     

The structure of [M(H2O)6][LiFeIII(ox)3] (M=MnII,FeII) – A heterobimetallic 2-D tris(oxalato) framework compound

[Mn^II_xFe^II_1?x(H₂O)₆][LiFe^III(ox)₃] (with 0 ≤ x ≤ 1) crystallizes in the space group P31c with a = 9.341(3) Å, c = 10.226(3) Å, c/a = 1.0947, and V = 772.8(5) Å³ for Z = 2. The compound has a layered structure with two enantiomeric layers per unit cell. The layers are built up by an iron and lithium oxalate framework with intercalated M(II)-water octahedra of the formula [Mn^II_xFe^II_1?x(H₂O)₆][M^IM^III(ox)₃]. The value of x cannot be specified at present. The structure displays intermolecular hydrogen bonding between the layers.     

Struktur und Bindung in Übergangsmetall-Fluoriden MIIMeIVF6 A. Phasenübergänge

Structure and Bonding in Transitition Metal Fluorides M^IIMe^IVF₆ A. Phase Transitions A summary outline of the structure types of all compounds M^IIMe^IVF₆ known so far is given. Compounds with a 3d transition metal ion in the M^II site crystallize in the cubic ordered ReO₃ lattice and the hexagonal LiSbF₆ structure. For cations with a Jahn- Teller unstable E_g ground state we have found a symmetry reduction to tetragonal and triclinic variants of those two lattice types in addition. Phase transitions between the different structures could be observed by Guinier techniques in the temperature range 80 K < T < 800 K in many cases. The relative stability of the hexagonal low temperature phases in comparison to the cubic high temperature modifications is extensively discussed on the basis of geometric parameters and the electronic properties of the Me^IV and M^II ions. Quite a number of compounds M^IIMe^IVF₆ was prepared and characterized for the first time. The results of the spectroscopic investigation will be published later.     

Thermal expansion in 3d-metal Prussian Blue Analogs—A survey study

We present a comprehensive study of the structural properties and the thermal expansion behavior of 17 different Prussian Blue Analogs (PBAs) with compositions M^II₃[(M′)^III(CN)₆]₂·nH₂O and M^II₂[Fe^II(CN)₆]·nH₂O, where M^II=Mn, Fe, Co, Ni, Cu and Zn, (M′)^III=Co, Fe and n is the number of water molecules, which range from 5 to 18 for these compounds. The PBAs were synthesized via standard chemical precipitation methods, and temperature-dependent X-ray diffraction studies were performed in the temperature range between −150 °C (123 K) and room-temperature. The vast majority of the studied PBAs were found to crystallize in cubic structures of space groups Fm3?m, F4?3m and Pm3?m. The temperature dependence of the lattice parameters was taken to compute an average coefficient of linear thermal expansion in the studied temperature range. Of the 17 compounds, 9 display negative values for the average coefficient of linear thermal expansion, which can be as large as 39.7×¹0⁻⁶ K⁻¹ for Co₃[Co(CN)₆]₂·12H₂O. All of the M^II₃[Co^III(CN)₆]₂·nH₂O compounds show negative thermal expansion behavior, which correlates with the Irving–Williams series for metal complex stability. The thermal expansion behavior for the PBAs of the M^II₃[Fe^III(CN)₆]₂·nH₂O family are found to switch between positive (for M=Mn, Co, Ni) and negative (M=Cu, Zn) behavior, depending on the choice of the metal cation (M). On the other hand, all of the M^II₂[Fe^II(CN)₆]·nH₂O compounds show positive thermal expansion behavior.     

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).     

Magnetic Anisotropy in a Family of Experimentally Synthesized and Theoretically Modeled M′6M8(CN24) Systems

A theoretical density functional study of the magnetic coupling interactions and magnetic anisotropy in a family of experimentally synthesized and theoretically modeled M′₆M₈(CN₂₄) (M′=Cu^II, Ni^II or Co^II; M=Fe^III or Cr^III) systems is presented. The calculations show that the interactions in the selected M′₆M₈(CN₂₄) are all ferromagnetic and the near cubic symmetry of Cu₆Fe₈ is the origin of its negative magnetic anisotropy parameter D.     

Iron-57 Mössbauer effect study of the distribution of divalent and trivalent ions in potassium transition metal fluorides having the tetragonal bronze structure

Mössbauer studies are reported for compounds of the type KM^IIM^IIIF₆ (M = first-row transition metal ion, Zn, or Mg) which have the tetragonal bronze structure. The results of this investigation provide evidence that the trivalent ions are located on the 8(j) sites of the bronze structure and that the divalent ions are distributed over both the 8(j) and 2(c) sites.     

Zur Kenntnis des RbNiCrF6-Typs: über CsCuMF6 (M  NiIII,TiIII), CsMgMF6 (M  Co,Fe, Ga) und CsZnMF6 (M  NiIII,CoIII, FeIII)

On the RbNiCrF₆ Type(¹): On CsCuMF₆ (M?Ni^III, Ti^III), CsMgMF₆ (M ?Co, Fe, Ga), and CsZnMF₆ (M?Ni^III, Co^III, Fe^III) New prepared are the cubic compounds CsCuNi^IIIF₆ (dark brown, a = 10.14 Å); CsZnNi^IIIF₆ (dark brown, a = 10.17 Å); CsCuTi^IIIF₆ (light grey, a = 10.39 Å); CsMgGaF₆ (colourless, a = 10.23 Å); CsMgFeF₆ (colourless, a = 10.53 Å); CsZnFeF₆ (colourless, a = 10.42 Å); CsMgCo^IIIF₅ (light blue, a = 10.27 Å) and CsZnCo^IIIF₆ (light blue, a = 10.34 Å), all RbNiCrF₆-type of structure. The Madelung part of lattice energy, MAPLE, is calculated and discussed.     

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’.     

The structure of R-NiF3, and synthesis,and magnetism of new R3 MIINiIVF6 (M = Fe,Co, Cu,Zn), and MIINiIIF4 (M = Co,Cu)

Neutron diffraction, at 2 K, of R-NiF₃ indicates the formulation approaches Ni^IINi^IVF₆, with Ni^II − F = 1.959(3) and Ni^IV − F = 1.811(3) Å, but 295 K data allow for only a slight increase in any Ni^III. Relatives have been precipitated from liquid anhydrous HF, at ≤ 20 °C, by adding K₂NiF₆ to M(SbF₆)₂ (M = Co, Cu, Zn) or M(AsF₆)₂ (M = Fe). CuNiF₆ like NiNiF₆ is metastable and loses F₂ easily, above 40 °C. CuNiF₆ is reduced by Xe or C₃F₆ at −20 °C; CoNiF₆ by H₂ at 350 °C, each giving pseudo-rutile MNiF₄. Magnetic data indicate the dominant formulation is M^IINi^IVF₆ (Ni(IV) low spin d⁶) with field dependence in CoNiF₆ (≤ 220 K) and FeNiF₆ (≤ 295 K).     

Synthesis and thermodynamic studies of the dinuclear adducts between dimethyltin(IV) dichloride with SalenH2 and MII(Salen) complexes in chloroform

A UV-Vis spectrophotometric study of adduct formation of SalenH₂ (1) and M^II(Salen), where M?=?Mn (2), Fe (3), Co (4), Ni (5) and Cu (6) as donors with Me₂SnCl₂ as acceptor have been investigated in chloroform. Adducts (1a–6a) have been characterized by ¹H, ¹³C and ¹¹⁹Sn NMR, IR and electronic spectroscopy and microanalysis. Formation constants and thermodynamic parameters were measured for 1 : 1 and 2 : 1 adducts at various temperatures (T?=?278 to 308 K). The data refinement was carried out with the SQUAD 84 program. The trend of formation constants of M^II(Salen) complexes with Me₂SnCl₂ follows the order: Mn>Fe>Cu>Co>Ni. The formation constants for the free 1 and M^II(Salen) with Me₂SnCl₂ changes according to the following trend: M^II(Salen)>SalenH₂     

Synthesis and Crystal Structure of CuIIMoIVF6 and CrIINbIVF6 (LT Form)

The fluorides CuMoF₆ and CrNbF₆ are triclinic, isostructural with CuSnF₆. Their crystal structures were solved in the space group P1, by the Rietveld method using the data of their X-ray powder patterns. Both crystal structures can be described as a three-dimensional framework of alternating 6 corner-sharing [M^IIF₆] and [M′^IVF₆] octahedra (M^II = Cr, Cu; M′^IV = Nb, Mo) with ferrodistortive Jahn-Teller ordering.     

Crystal structure and magnetic properties of a new form of NH4MnFeF6

The hydrothermal synthesis at 380°C, 200 MPa of NH₄MnFeF₆, NH₄MnCrF₆, and RbMnFeF₆ leads to a new AM^IIM^IIIF₆ structural type of orthorhombic symmetry with Z = 8. Lattice constants are found to be, respectively, a = 7.844 (4), b = 12.819 (8), c = 10.582 (6); a = 7.808 (5), b = 12.755 (9), c = 10.501 (7); and a = 7.913 (5), b = 12.858 (9), c = 10.619 (5). The structure was solved for NH₄MnFeF₆ from 755 X-Ray reflections and refined to R_ω = 0.029 in the space group Pb2nC⁶_2v. The network is built from edge-sharing MnFeF₁₀ bioctahedra connected to each other by their vertices. RbMnFeF₆ upon heating transforms irreversibly to the modified pyrochlore structure at 881 K. From magnetic and Mössbauer experiments, NH₄MnFeF₆ and NH₄MnCrF₆ are established to be antiferromagnetic with T_N = 117.7 ± 0.5 K and < 6 K, respectively.     

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.     

Magnetic exchange coupling in transition metal complexes with bidentate bridging ligands: a quantum chemical study

The exchange coupling constants (J) were calculated and the spin density distributions were analyzed in the B3LYP/TZV approximation for the complex anions [L₂M(1)^IIILM(2)^IIL₂] ⁿ⁻, where L is ligand (L is oxalate, oxamide, dithiooxamide, hydroxamate) and M(1) and M(2) are atoms of the tri- and divalent 3d-transition metals, respectively, and n- is the charge of the anion. The largest J values were found for the complexes formed by the Cr^III-Ni^II and Cr^III-Co^II pairs with the dithiooxamide ligands. Differences between the calculated and experimental J values are at most a few cm⁻¹.