Transitions Between Lanthanum Cuprates: Crystal Structures of T′, Orthorhombic,and K2NiF4‐type La2CuO4

Through low‐temperature synthesis in CsOH flux, lanthanum cuprate La₂CuO₄ can be obtained in a metastable form, the so‐called T′ modification (tetragonal, I4/mmm, no. 139, a = 400.95(2) pm, c = 1254.08(7) pm). When heated, this T′ phase transforms into a K₂NiF₄‐type modification, whose crystal structure was now refined from X‐ray powder data (tetragonal, I4/mmm, no. 139, a = 383.29(3) pm, c = 1331.3(2) pm at T = 1073 K). The well‐known orthorhombic phase (s.g. Cmce, no. 64, a = 536.14(3) pm, b = 1315.53(8) pm, c = 540.20(3) pm) – usually obtained via conventional solid state synthesis – was observed to form upon cooling from the K₂NiF₄‐type modification. High‐temperature powder diffractometry allowed crystal structure refinements for all of the three phases.     

The Network Structure [SbHg2]GaCl4: An X‐Ray Study of a Temperature Driven Phase Transition

[SbHg₂]GaCl₄ is a new compound forming red, transparent, air sensitive crystals with a cationic network [SbHg₂]⁺ topologically related to cristobalite. Tetrahedral (GaCl₄)^? groups are located in suitable cavities. The title compound is the first example of this formula type with antimony and exists in a low (LT) and a high‐temperature (HT) modification (T_c = 277 K). The HT‐modification crystallizes in space group Pbcn (no. 60) with the lattice constants a = 1200.23(4) pm, b = 876.15(4) pm, c = 1750.83(6) pm (Z = 8, T = 293 K) whereas the LT‐modification crystallizes in Pna2₁ (no. 33) with a = 1743.30(6) pm, b = 874.36(5) pm, c = 1196.92(4) pm (T = 170 K). The phase transition is partially of first order and is investigated by a series of temperature dependent X‐ray single crystal measurements. The origin of the phase transition is most likely a significant librational disorder of the GaCl₄ tetrahedra at higher temperatures which is frozen out in the LT‐modification. This becomes obvious from only one type of GaCl₄ tetrahedra with unusual large anisotropic thermal parameters for the Cl atoms in the HT‐modification. In the LT‐modification two types of GaCl₄ groups with significantly reduced thermal parameters and slightly different orientations are found. A comparison of the interatomic distances between the Cl atoms of the GaCl₄ groups and atoms in the first coordination sphere gives evidence that in one orientation the interaction between Cl and Sb and in the other the interaction between Cl and Hg is optimized.     

The Crystal Structure of ζ2‐Al3Cu4‐δ

The crystal structure of the ζ₂‐phase Al₃Cu_4‐δ was determined by means of X‐ray powder diffraction: a = 409.72(1) pm, b = 703.13(2) pm, c = 997.93(3) pm, space group Imm2, Pearson symbol oI24‐3.5, R_I = 0.0696. ζ₂‐Al₃Cu_4‐δ forms a distinctive a × √3a × 2c superstructure of a metal deficient Ni₂In‐type‐related structure. The phase is meta‐stable at ambient temperature. Between 400 °C and 450 °C it decomposes into ζ₁‐Al₃Cu₄ and η₂‐AlCu. Entropic contributions to the stability of ζ₂‐Al₃Cu_4‐δ are reflected in three statistically or partially occupied sites.     

Subcell and Superstructure of a High‐Temperature (β‐) Modification of the Mercury(I) Dimolybdate(VI) Hg2Mo2O7

A new (β‐)modification of the mercury molybdate Hg₂Mo₂O₇, thermodynamically stable at temperatures above 390 ± 10 °C, was prepared by solid state reaction of HgO with MoO₂ in sealed silica tubes. Its crystal structure, determined from single‐crystal X‐ray data, has a very pronounced subcell: space group P2/c, a = 600.9(1) pm, b = 388.7(1) pm, c = 1428.4(2) pm, β = 105.88(1)°, Z = 2, R = 0.052 for 797 structure factors and 52 variable parameters. In the superstructure of this high‐temperature β‐modification the a and the b axes of the subcell are doubled: C2/c, a = 1201.9(2) pm, b = 777.3(1) pm, c = 1428.4(2) pm, β = 105.88(1)°, Z = 8, R = 0.040 for 1490 F values and 110 variables. Like the previously reported low‐temperature α‐modification, the β‐modification consists of two‐dimensionally infinite sheets of edge‐ and corner‐sharing MoO₆ octahedra. These sheets are linked by Hg₂ pairs. Thus, the structures of the two modifications (α and β) differ essentially only in the orientation of the Hg₂ pairs, which are located between the sheets of the MoO₆ octahedra. The superstructure of the β‐modification differs from the subcell‐structure by the puckering of the sheets of MoO₆ octahedra. A hypothetical displacive phase transition between the subcell‐structure (corresponding to the potential high‐temperature structure) and the superstructure of β‐Hg₂Mo₂O₇ is discussed.     

Strukturelle Vielfalt im pseudo‐ternären System M/Ge/I: α‐[NMe(nBu)3](GeI4)I, β‐[NMe(nBu)3](GeI4)I und [ImMe(nBu)][N(nBu)4](GeI4)3I2

By reaction of GeI₄, [N(nBu)₄]I as iodide donor, and [NMe(nBu)₃][N(Tf)₂] as ionic liquid, reddish‐black, plate‐like shaped crystals are obtained. X‐ray diffraction analysis of single crystals resulted in the compositions ;alpha;‐[NMe(nBu)₃](GeI₄)I (Pbca; a = 1495.4(3) pm; b = 1940.6(4) pm; c = 3643.2(7) pm; Z = 16) and β‐[NMe(nBu)₃](GeI₄)I (Pn; a = 1141.5(2) pm; b = 953.6(2) pm; c = 1208.9(2) pm; β = 100.8(1)°; Z = 2). Depending on the reaction temperature, the one or other compound is formed selectively. In addition, the reaction of GeI₄ and [N(nBu)₄]I, using [ImMe(nBu)][BF₄] (Im = imidazole) as ionic liquid, resulted in the crystallization of [ImMe(nBu)][N(nBu)₄](GeI₄)₃I₂ (P2₁/c; a = 1641.2(3) pm; b = 1903.0(4) pm; c = 1867.7(4) pm; β = 92.0(1)°; Z = 4). The anionic network of all three compounds is established by molecular germanium(IV)iodide, which is bridged by iodide anions. The different connectivity of (GeI₄–I^–) networks is attributed to the flexibility of I^– regarding its coordination and bond length. Here, a [3+1]‐, 4‐ and 5‐fold coordination is first observed in the pseudo‐ternary system M/Ge/I (M: cation).     

About Binary and Ternary Alkaline Earth Metal Nitrides

Binary and ternary alkaline earth metal nitrides compounds have been synthesized and characterized by the means of X‐ray structure analysis. By the reaction of the alkaline earth metals Be, Mg, and Ca with dry nitrogen, we obtained crystalline material of Be₃N₂ ( 1 ), Mg₃N₂ ( 2 ), and Ca₃N₂ ( 3 ), respectively. For these three compounds we could confirm the cubic anti bixbyite structure (Ia3 (#206); 1 : a = 814.92(1) pm; 2 : 997.26(6) pm and 3 : a = 1147.86(2) pm). By reacting 1 : 2 : 1 mixtures of Ae (Ae = Ca, Sr) : Mg : NaN₃ we synthesized the ternary nitrides CaMg₂N₂ ( 4 ) and SrMg₂N₂ ( 5 ). We confirmed the structural data obtained by Rietveld‐analysis of X‐ray powder diffraction data for 4 and found 5 to be isotypic (anti‐C–M₂O₃ structure, trigonal, P 3ml (#164); 4 : a = 354.77(5) pm, c = 609.60(12) pm; 4 : a = 362.20(5), c = 635.90(13) pm). The indexing of the powder diffractogram of “Ca₃Mg₃N₄” and refining the lattice parameters (hexagonal, a = 352.9(2) and c = 607.5(5) pm) suggest its identity with 4 . The black “low‐temperature phase of Ca₃N₂” has been synthesized and and the X‐ray powder diffractogram has been recorded. The reactions of this phase are also described. The yellow “high‐temperature phase of Ca₃N₂” was found to be Ca₄N₂(CN₂).     

Crystal Structures and Raman Spectra of cis‐[SnCl4(H2O)2]·2H2O,cis‐[SnCl4(H2O)2]·3H2O, [Sn2Cl6(OH)2(H2O)2]·4H2O,and [HL][SnCl5(H2O)]·2.5H2O (L=3‐acetyl‐5‐benzyl‐1‐phenyl‐4, 5‐dihydro‐1, 2, 4‐triazine‐6‐one oxime,C18H18N4O2)

The complexes cis‐[SnCl₄(H₂O)₂]·2H₂O ( 1 ), [Sn₂Cl₆(OH)₂(H₂O)₂]·4H₂O ( 3 ), and [HL][SnCl₅(H₂O)]·2.5H₂O ( 4 ) were isolated from a CH₂Cl₂ solution of equimolar amounts of SnCl₄ and the ligand L (L=3‐acetyl‐5‐benzyl‐1‐phenyl‐4, 5‐dihydro‐1, 2, 4‐triazine‐6‐one oxime, C₁₈H₁₈N₄O₂) in the presence of moisture. 1 crystallizes in the monoclinic space group Cc with a = 2402.5(1) pm, b = 672.80(4) pm, c = 1162.93(6) pm, β = 93.787(6)° and Z = 8. 4 was found to crystallize monoclinic in the space group P2₁, with lattice parameters a = 967.38(5) pm, b = 1101.03(6) pm, c = 1258.11(6) pm, β = 98.826(6)° and Z = 2. The cell data for the reinvestigated structures are: [SnCl₄(H₂O)₂]·3H₂O ( 2 ): a = 1227.0(2) pm, b = 994.8(1) pm, c = 864.0(1) pm, β = 103.86(1)°, with space group C2/c and Z = 4; 3 : a = 961.54(16) pm, b = 646.29(7) pm, c = 1248.25(20) pm, β = 92.75(1)°, space group P2₁/c and Z = 4.     

Preparation and Crystal Structures of some Binary Pnictides of Scandium,Zirconium, and Hafnium: Sc5Bi3, ZrBi, α‐HfSb,HfBi, HfBi2, and the Compound Zr5Bi3X1–x,Possibly Stabilized by an Impurity (X)

The title compounds were prepared by reaction of the elemental components. Of these Sc₅Bi₃ is a new compound. Its orthorhombic β‐Yb₅Sb₃ type crystal structure was determined from single‐crystal X‐ray data: Pnma, a = 1124.4(1) pm, b = 888.6(1) pm, c = 777.2(1) pm, R = 0.024 for 1140 structure factors and 44 variable parameters. For the other compounds we have established the crystal structures. ZrBi has ZrSb type structure with a noticeable homogeneity range. This structure type was also found for the low temperature (α) form of HfSb and for HfBi. For α‐HfSb this structure was refined from single‐crystal X‐ray data: Cmcm, a = 377.07(4) pm, b = 1034.7(1) pm, c = 1388.7(1) pm, R = 0.043 for 432 F values and 22 variables. HfBi₂ has TiAs₂ type structure: Pnnm, a = 1014.2(2) pm, b = 1563.9(3) pm, c = 396.7(1) pm. The structure was refined from single‐crystal data to a residual of R = 0.074 for 1038 F values and 40 variables. In addition, a zirconium bismuthide, possibly stabilized by light impurity elements X and crystallizing with the hexagonal Mo₅Si₃C_1–x type structure, was observed: Zr₅Bi₃X_1–x, a = 873.51(6) pm, c = 599.08(5) pm. The positions of the heavy atoms of this structure were refined from X‐ray powder film data. Various aspects of impurity stabilization of intermetallics are discussed.     

Syntheses and Crystal Structures of Brominated Polyhedral Arsa‐ and Phosphaboranes

The synthesis of the perbrominated arsaboranes closo‐1,2‐As₂B₄Br₄ ( 1 ) and closo‐1,2‐As₂B₁₀Br₁₀ ( 2 ) occurs by co‐pyrolysis of B₂Br₄ and AsBr₃ at 500 °C. Repeated fractionation of the sublimable products in vacuo yields both compounds in pure form. The X‐ray structure determination for orthorhombic closo‐1,2‐As₂B₄Br₄ ( 1 ) [space group: Pbcn, a = 2345.48(17) pm, b = 627.31(4) pm, c = 1294.02(9) pm for Z = 8] and the corresponding phosphorus compound, monoclinic closo‐1,2‐P₂B₄Br₄ ( 3 ) [space group: P2₁/n, a = 806.84(6) pm, b = 1247.96(9) pm, c = 974.91(7) pm, β = 90.493(3)° and Z = 4] confirmed that both 1 and 3 , consistent with their 14‐skeletal electron counts, adopt octahedral structures distorted from regular by two arsenic or phosphorus atoms in the 1,2‐positions. The shortest boron–boron bonds within the cluster frameworks are located between the boron atoms antipodal to the heteroatoms.     

[Ag(NH3)2]ClO4: Kristallstrukturen,Phasenumwandlung, Schwingungsspektren

[Ag(NH₃)₂]ClO₄: Crystal Structures, Phase Transition, and Vibrational Spectra [Ag(NH₃)₂](ClO₄) is obtained from a solution of AgClO₄ in conc. ammonia as colourless single crystals (orthorhombic, Pnmn, Z = 4, a = 795.2(1) pm, b = 617.7(1) pm, c = 1298.2(2) pm, R_all = 0.0494). The structure consists of linearly coordinated cations, [Ag(NH₃)₂]⁺, stacked in a staggered conformation and of tetrahedral (ClO₄)^‐ anions. A first order phase transition was observed between 210 and 200 K and the crystal structure of the low‐temperature modification (monoclinic, P2/m, Z = 4, a = 789.9(5) pm, b = 604.1(5) pm, c = 1290.4(5) pm, β = 97.436(5)°, at 170 K, R_all = 0.0636) has also been solved. Spectroscopic investigations (IR/Raman) have been carried out and the assignment of the spectra is discussed.     

Hydrothermalsynthese und Kristallstruktur der Münzmetall‐Quecksilber‐Chalkogenidhalogenide CuHgSeBr,AgHgSBr und AgHgSI

Hydrothermal Synthesis and Crystal Structure of the Coinage Metal Mercury Chalcogenide Halides CuHgSeBr, AgHgSBr, and AgHgSI The hydrothermal reaction of CuBr and HgSe in concentrated aqueous HBr as solvent at 285 °C yields red crystals of CuHgSeBr, the hydrothermal reaction of AgX (X = Br, I) and HgS in half‐concentrated aqueous HX (X = Br, I) as solvent at 300/400 °C yields yellow crystals of AgHgSBr and AgHgSI. The compounds crystallize isotypically (orthorhombic, Pmma, a = 1020.1(3) pm, b = 431.2(1) pm, c = 925.6(3) pm for CuHgSeBr, a = 964.8(8) pm, b = 466.1(4) pm, c = 942.6(6) pm for AgHgSBr und a = 1015.9(2) pm, b = 464.77(5) pm, c = 984.9(2) pm for AgHgSI, Z = 4). The structures consist of plane folded Hg–Y chains connected by pairs of distorted Y₂X₂ terahedra sharing the X–X‐edge (M = Cu, Ag; X = Br, I; Y = S, Se). Atoms of the monovalent metals M have a strongly distorted tetrahedral coordination of two halogen and two chalcogen atoms. The new structure type shows distinct differences in the arrangement of the Hg–Y chains in comparision to the already known CuHgSeCl, but represents the superposition structure of the order‐disorder phase γ‐Hg₃S₂Cl₂.     

Bridging Nonaselenium Ring in [Se9(IrBr3)2], and Three Modifications of the Mononuclear Complex [IrBr3(SeBr2)3]

The reaction of iridium powder with an excess of selenium and SeBr₄ yielded lustrous, vermillion crystals of the mononuclear iridium complex [IrBr₃(SeBr₂)₃]. The transition metal is coordinated octahedrally by three SeBr₂ and three bromide ligands with facial or meridional configuration. Three different modifications were obtained under similar conditions: a‐fac‐IrBr₃(SeBr₂)₃, space group P$\bar{1}$ , with a = 789.4(1) pm, b = 830.4(1) pm, c = 1334.4(1) pm, α = 81.634(5)°, β = 84.948(5)°, γ = 67.616(4)°; m‐fac‐IrBr₃(SeBr₂)₃, space group P2₁/n, with a = 1205.3(1) pm, b = 962.4(1) pm, c = 1383.9(1) pm, β = 91.114(3)°; mer‐IrBr₃(SeBr₂)₃, space group P2₁/n with a = 859.7(1) pm, b = 1284.3(1) pm, c = 1437.5(1) pm, β = 94.427(3)°. A lower bromine content in the starting composition resulted in shiny, deep‐red crystals of [Se₉(IrBr₃)₂]. X‐ray diffraction on a single‐crystal revealed a tetragonal lattice (space group I4₁/a) with a = 1245.4(1) pm and c = 2486.8(1) pm at 296(1) K. In the [Se₉(IrBr₃)₂] complex, a crown‐shaped uncharged Se₉ ring coordinates two iridium(III) cations as a bridging bis‐tridentate ligand. Three terminal bromide ions complete the distorted octahedral coordination of each transition metal atom.     

Synthesis,Crystal Structure and Magnetic Properties of Rb2Mn3O4

Rb₂Mn₃O₄, which is the first rubidium oxomanganates(II), has been synthesized via the azide/nitrate route from a stoichiometric mixture of the precursors RbN₃, RbNO₃, and MnO, as well as from Rb₂O and MnO, through an all solid state reaction. Its crystal structure (C2/c, Z = 4, a = 1546.9(2) pm, b = 666.22(7) pm, c = 588.06(6) pm) consists of a 3D arrangement of edge‐ and corner‐sharing MnO₄ tetrahedra with rubidium filling the space between. Magnetic susceptibility measurements indicate a magnetic phase transition at 126 K. The magnetic response as a function of temperature is complex, indicating strong, partly frustrated magnetic exchange interactions.     

Über Münzmetall‐Quecksilber‐Chalkogenidhalogenide. IV1) Hydrothermalsynthese und Kristallstruktur von CuHgSI und CuHg2S2I

On Coinage Metal Mercury Chalcogenide Halides. IV Hydrothermal Synthesis and Crystal Structure of CuHgSI and CuHg₂S₂I The hydrothermal reaction of CuI with α‐HgS in diluted aqueous HI‐solution as solvent at 180 °C yields dark red crystals of CuHgSI. The compound crystallizes orthorhombic in the space group Pna2₁ with a = 718.3(1) pm, b = 834.3(2) pm and c = 698.9(1) pm and Z = 4. CuHg₂S₂I was obtained by the hydrothermal reaction of CuI with α‐HgS in diluted HI‐solution at 300 °C as black crystals. The compound crystallizes orthorhombic in the space group Cmc2₁ with a = 1261.8(3) pm, b = 722.4(1) pm and c = 693.7(1) pm and Z = 4. Both crystal structures could be explained as distorted version of the Wurtzite structure type in which two different types of anion‐lattices are built up.     

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.     

Syntheses and Crystal Structures of Two Cadmium Methanetetrabenzoates Featured by Open Framework and Infinite Layers

Colorless single crystals of Cd₂[μ₈‐MTB] · 3H₂O · DMF ( 1 ) were prepared in DMF/H₂O solution [ 1 : space group C2/c (no. 15) with a = 1821.30(6), b = 2175.08(6), c = 1269.87(4) pm, β = 129.684(1)°]. The connection between the methane‐p‐benzoate tetraanions (MTB^4–) and the Cd²⁺ cations leads to a three‐dimensional framework with channels extending along [1 10] and [110] with openings of 670 pm × 360 pm. The channel‐like voids accommodate water molecules and N,N‐dimethylformamide (DMF) molecules not bound to Cd²⁺. Colorless single crystals of [Cd₄(2,2′‐bipy)₄(μ₇‐MTB)₂] · 7DMF ( 2 ) were prepared in DMF in the presence of 2,2′‐bipyridine [ 2 : space group P1 (no. 2) with a = 1224.84(4), b = 1418.85(5), c = 2033.49(4) pm, α = 85.831(2)°, β = 88.351(2)°, γ = 68.261(1)°]. The coordination of MTB^4– to Cd²⁺ results in infinite layers parallel to (001). The layers, not connected by any hydrogen bonds, contain small openings of about 320 pm × 340 pm.     

New Ternary Alkaline Earth Metal Cerium(IV) Nitrides: CaCeN2 and SrCeN2

CaCeN₂ and SrCeN₂ were prepared by reactions of Li₂CeN₂ with Ca₃N₂ or Sr₂N in a nitrogen atmosphere at 1020 K. According to measurements of the magnetic susceptibilities both compounds contain Ce^IV. The crystal structures were determined by full‐profile Rietveld refinements of the X‐ray powder diffraction patterns. CaCeN₂ crystallizes in a rocksalt‐type structure with disordered Ca and Ce (space group Fm3¯m, a = 499.21(1) pm, R_profile = 0.061, R_Bragg = 0.034). The low temperature modification of SrCeN₂ crystallizes in the α‐NaFeO₂ type structure (space group R3¯m, a = 362.18(4) pm, c = 1795.8(2) pm, R_profile = 0.085, R_Bragg = 0.031). At elevated temperatures an order‐disorder phase transition leads to HT‐SrCeN₂ (space group Fm3¯m, a = 515.01(2) pm, quenched from 1273 K) with a cubic unit cell and complete disorder of Sr and Ce.     

Strong Attraction of Caffeine to the Mercurous Dumbbell in the Salt [Hg2(Caf)2](ClO4)2(H2O)2

Colourless single crystals of the caffeine adduct of mercurous perchlorate dihydrate, [Hg₂(Caf)₂](ClO₄)₂(H₂O)₂, were grown from aqueous solutions of mercurous perchlorate and caffeine by isothermal evaporation at ambient temperature. The crystal structure (monoclinic, P2₁/n, Z = 4, a = 1628.0(2), b = 780.4(1), c = 2229.6(3) pm, β = 99.84(1)°, R₁(all data) = 0.0894) contains [trans‐Caf‐Hg‐Hg‐Caf]²⁺ cations with a Hg‐Hg distance of 250.88(6) pm, Hg‐N (bond) distances of 214.4(6) and 215.1(6) pm and Hg‐Hg‐N angles of 176.9(2) and 165.1(2)°, respectively. These cations are attached via weak Hg‐O contacts to dimers which are further arranged to leave large channels into which one crystal water molecule is included. The second water molecule and the two perchlorate anions are weakly attracted to one Hg atom.     

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.     

Synthese und Kristallstrukturen von (2‐Methylpyridinium)3[TbCl6] und (2‐Methylpyridinium)2[TbCl5(1‐Butanol)]

Preparation and Structure of (2‐Methylpyridinium)₃[TbCl₆] and (2‐Methylpyridinium)₂[TbCl₅(1‐Butanol)] The complex chlorides (2‐Methylpyridinium)₃[TbCl₆] (1) and (2‐Methylpyridinium)₂[TbCl₅(1‐Butanol)] (2) have been prepared for the first time. The crystal structures have been determinated from single crystal X‐ray diffraction data. 1 crystallizes in the monoclinic space group C2/c (Z = 8) with a = 3241,2(5) pm, b = 897,41(9) pm, c = 1774,2(2) pm and β = 97,83(2)°, 2 in the monoclinic space group P2₁/n (Z = 4) with a = 1372,96(16) pm, b = 997,57(9) pm, c = 1820,5(2) pm and β = 108,75(1)°. The structures contain isolated octahedral building units [TbCl₆]^3– and [TbCl₅(1‐Butanol)]^2–, respectively.