Chloride Derivatives of Lanthanide Ortho‐Oxomolybdates:, 3. Crystal Structures,Spectroscopic Studies,and Magnetic Properties of the LnCl[MoO4] Representatives with the Large Lanthanides (Ln = La,Ce, Pr)

The lanthanide chloride ortho‐oxomolybdates LnCl[MoO₄] (Ln = La, Ce, Pr) crystallize in the monoclinic space group P2₁/c(a = 1921–1906 pm, b ≈? 580 pm, c = 804–789 pm, β ≈? 90.04°, Z = 8).In the crystal structure, two crystallographically unique Ln³⁺ cations are present, both with the same coordination environment of four Cl^– and six O^2– anions in the shape of a distorted tetracapped trigonal prism. The two distinguishable Cl^– anions both display a coordination sphere of three plus one Ln³⁺ cations, building up distorted tetrahedra. These are fused together via four common edges to form litharge‐analogous layers (e = edge‐connecting) parallel to the (100) plane. Two crystallographically different oxomolybdate units are also found in the structure, which can be best described as strandsof apically vertex‐shared [MoO₅]^4– trigonal bipyramids of the formula (v = vertex‐connecting, t = terminal) along [001]. These building blocks, the layers and the chains are alternately stacked along the a axis. The peculiarity of this structure is expressed by the position of the Mo⁶⁺ cations, which are not situated in the center of the bipyramids, but reside offset in their lower or upper trigonal pyramids (≈? tetrahedra). The Mo⁶⁺ cations with an x / a parameter between 0 and 0.5 can be found within the lower trigonal pyramids of those bipyramids (if viewed along the [001] direction), whereas those with 0.5 < x / a < 1 are located in the upper trigonal pyramid. Therefore, an alternating arrangement of the strands is observed. Due to the special constitution of the Ln³⁺ cations in distorted litharge‐analogous layers, a special magnetic effect was assumed, but in phase‐pure samples of e.g. CeCl[MoO₄] mainly Curie–Weiss behavior could be detected.     

Synthesis,Structure, Magnetic and Optical Properties of Ternary Thio‐germanates: Ln4(GeS4)3 (Ln = Ce,Nd)

Single crystals of two ternary thio‐germanates containing rare‐earth metals, Ln₄(GeS₄)₃ (Ln = Ce ( I ), Nd ( II )), have been isolated from the reaction of anhydrous rare‐earth trichloride (LnCl₃) and ternary sodium thio‐germanate (Na₂GeS₃) in evacuated quartz ampoules. We have determined the crystal structure of the compounds, which are isostructural to La₄(GeS₄)₃ and crystallize in trigonal system in the space group R3c with the cell dimensions: I , a = b = 19.375(3) Å, c = 8.028(2) Å, Z = 6; II , a = b = 19.250(3) Å, c = 7.949(2) Å, Z = 6. The structure is built with the complex network of two independent tricapped trigonal prisms of CeS₉, in which Ge atoms occupy tetrahedral holes of sulfur atoms. The bulk synthesis of the two compounds has also been achieved by the stoichiometric combination of the elements. The magnetic and optical properties of the compounds have been investigated. The magnetic moments of 2.32 and 3.49 μ_B for I and II , respectively, are in good agreement with the theoretical magnetic moments of Ce and Nd in the +3 oxidation state. The optical band gap of I is found to be located around 2.3 eV, while the optical band gap of II lies around 2.62 eV. In addition, Raman spectroscopic characterizations have also been performed for I , II , and La₄(GeS₄)₃.     

Über Oxotantalate der Lanthanide des Formeltyps MTaO4 (M = La – Nd,Sm – Lu)

About Lanthanide Oxotantalates with the Formula MTaO₄ (M = La – Nd, Sm – Lu) Besides being a by‐product of solid state syntheses in tantalum ampoules the lanthanide(III) oxotantalates of the formula MTaO₄ can be easily prepared by sintering lanthanide sesquioxide M₂O₃ and tantalum(V) oxide Ta₂O₅ with sodium chloride as flux. Under these conditions two structure types emerge depending upon the M³⁺ cationic radius. For M = La – Pr the MTaO₄‐type tantalates crystallize in the space group P2₁/c with lattice constants of a = 762(±1), b = 553(±4), c = 777(±4) pm, β = 101(±1)° and four formula units per unit cell. With M = Nd, Sm – Lu, the monoclinic cell dimensions (space group P2/c) shrink to the lattice constants like a = 516(±9), b = 551(±9), c = 534(±9) pm, β = 96.5(±0.3)° and there are only two formula units present. Both structures show a coordination sphere of eight oxygen atoms for the lanthanide trications shaped as distorted square antiprism for the structure with the larger lanthanides (in the following referred to as A‐type) and as trigonal dodecahedron for the structure with the smaller ones (called as B‐type in the following). The coordination environment about the Ta⁵⁺ cations can be described as a slightly distorted octahedron (CN = 6) for the A‐type structure of MTaO₄ and a heavily distorted one (CN = 6) for the B‐type. The difference between the two types results from the interconnection of these [TaO₆]^7? octahedra. Whereas they are connected via four vertices to form corrugated layers according to parallel the bc‐plane in the A‐type, the octahedra of the B‐type MTaO₄ structure share edges to built up zig‐zag chains along the c axis.     

Two Hexagonal Series of Lanthanoid(III) Oxide Fluoride Selenides: M6O2F8Se3 (M = La – Nd) and M2OF2Se (M = Nd,Sm, Gd – Ho)

Two hexagonal series of lanthanoid(III) oxide fluoride selenides with similar structure types can be obtained by the reaction of the components MF₃, M₂O₃, M, and Se in sealed niobium tubes at 850 °C using CsI as fluxing agent. The compounds with the lighter and larger representatives (M = La – Nd) occur with the formula M₆O₂F₈Se₃, whereas with the heavier and smaller ones (M = Nd, Sm, Gd – Ho) their composition is M₂OF₂Se. For both systems single‐crystal determinations were used in all cases. The compounds crystallize in the hexagonal crystal system (space group: P6₃/m) with lattice parameters of a = 1394–1331 pm and c = 403–372 pm (Z = 2 for M₆O₂F₈Se₃ and Z = 6 for M₂OF₂Se). The (M1)³⁺ cations show different square antiprismatic coordination spheres with or without an extra capping fluoride anion. All (M2)³⁺ cations exhibit a ninefold coordination environment shaped as tricapped trigonal prism. In both structure types the Se^2– anions are sixfold coordinated as trigonal prisms of M³⁺ cations, being first condensed by edges to generate trimeric units and then via faces to form strands running along [001]. The light anions reside either in threefold triangular or in fourfold tetrahedral cationic coordination. For charge compensation, both structures have to contain a certain amount of oxide besides fluoride anions. Since F^– and O^2– can not be distinguished by X‐ray diffraction, bond‐valence calculations were used to address the problem of their adjunction to the available crystallographic sites.     

Synthesen und Kristallstrukturen von neuen Alkalimetall‐Selten‐Erd‐Telluriden der Zusammensetzungen KLnTe2 (Ln = La,Pr, Nd,Gd), RbLnTe2 (Ln = Ce,Nd) und CsLnTe2 (Ln = Nd)

Syntheses and Crystal Structures of New Alkali Metal Rare‐Earth Tellurides of the Compositions KLnTe₂ (Ln = La, Pr, Nd, Gd), RbLnTe₂ (Ln = Ce, Nd) and CsLnTe₂ (Ln = Nd) Of the compounds ALnQ₂ (A = Na, K, Rb, Cs; Ln = rare earth‐metal; Q = S, Se, Te) the crystal structures of the new tellurides KLaTe₂, KPrTe₂, KNdTe₂, KGdTe₂, RbCeTe₂, RbNdTe₂, and CsNdTe₂ were determined by single‐crystal X‐ray analyses. They all crystallize in the α‐NaFeO₂ type with space group R3¯m and three formula units in the unit cell. The lattice parameters are: KLaTe₂: a = 466.63(3) pm, c = 2441.1(3) pm; KPrTe₂: a = 459.73(2) pm, c = 2439.8(1) pm; KNdTe₂: a = 457.83(3) pm, c = 2443.9(2) pm; KGdTe₂: a = 449.71(2) pm, c = 2443.3(1) pm; RbCeTe₂: a = 465.18(2) pm, c = 2533.6(2) pm; RbNdTe₂: a = 459.80(3) pm, c = 2536.5(2) pm, and CsNdTe₂: a = 461.42(3) pm, c = 2553.9(3) pm. Characteristics of the α‐NaFeO₂ structure type as an ordered substitutional variant of the rock‐salt (NaCl) type are layers of corner‐sharing [(A⁺/Ln³⁺)(Te^2—)₆] octahedra with a layerwise alternating occupation by the cations A⁺ and Ln³⁺.     

One‐dimensionally linked Chain Crown Ether Complexes. Syntheses and Crystal Structures of Complexes [K(18‐Crown‐6)]2[M(SeCN)4](H2O) (M = Pd,Pt)

18‐crown‐6(18‐C‐6) complexes with K₂[M(SeCN)₄] (M = Pd, Pt): [K(18‐C‐6)]₂[Pd(SeCN)₄] (H₂O) ( 1 ) and [K(18‐C‐6)]₂[Pt(SeCN)₄](H₂O) ( 2 ) have been isolated and characterized by elemental analysis, IR spectroscopy and single crystal X‐ray analysis. The complexes crystallize in the monoclinic space group P2₁/n with cell dimensions: 1 : a = 1.1159(3) Å, b = 1.2397(3) Å, c = 1.6003(4) Å, β = 92.798(4)°, V = 2.2111(8) ų, Z = 2, F(000) = 1140, R₁ = 0.0418, wR₂ = 0.0932 and 2 : a = 1.1167(3) Å, b = 1.2394(3) Å, c = 1.5968(4) Å, β = 92.945(4)°, V = 2.2071(9) ų, Z = 2, F(000) = 1204, R₁ = 0.0341, wR₂ = 0.0745. Both complexes form one‐dimensionally linked chains of [K(18‐C‐6)]⁺ cations and [M(SeCN)₄]^2— (M = Pd, Pt) anions bridged by K‐O‐K interactions between adjacent [K(18‐C‐6)]⁺ units.     

$^{2}_{\infty}\rm [Tb(Tz\ast)_{3}]$, A Homoleptic 2‐Dimensional Framework from a Solvent Free Synthesis of Terbium Metal with 1H‐1,2,3‐Triazole

Single crystalline , (Tz*)^– = 1,2,3‐triazolate anion, C₂H₂N₃^–, was obtained by the reaction of terbium metal with the amine 1H‐1,2,3‐triazole. As no additional solvent was used, the formation of a homoleptic framework without additional co‐ligands is accessible. Furthermore molecular hydrogen is produced. is a 2‐dimensional framework with a (6,6) topology including (Tz*)^– double bridges. The structure can be deduced from a basic structure type as it adopts the AlCl₃ structure with the triazolate ligands establishing the package. (Tz*)^– thus function as μ‐η¹:η²/μ‐η²:η¹ linkers between trivalent terbium ions that have a C.N. of nine. The framework exhibits an exceptional thermal stability up to 380 °C considering the three neighbouring nitrogen atoms of the triazolate ligands. At this point the framework decomposes in one single exothermic step under release of N₂.     

Über Oxidtelluride (M2O2Te) der leichten Lanthanide (M = La–Nd,Sm–Ho) im A-Typ mit anti-ThCr2Si2-Struktur

On Oxytellurides (M₂O₂Te) of the Early Lanthanides (M = La–Nd, Sm–Ho) with A- or anti -ThCr₂Si₂-Type Crystal Structure By reacting elementary lanthanide metal (M = La–Nd, Sm–Ho) with tellurium dioxide (TeO₂) in a 2 : 1 molar ratio, it is possible to obtain pure and single-phase oxytellurides of the composition M₂O₂Te at 750 °C in evacuated silica tubes within a few days. When larger quantities of cesium chloride (CsCl) are added as flux, plate-like single crystals with square cross-section are formed which are not sensitive to hydrolysis and very suitable for crystal structure refinements from X-ray data. In the anti-ThCr₂Si₂ analogous crystal structure (tetragonal, I4/mmm, Z = 2; La₂O₂Te: a = 412.31(4), c = 1309.6(1) pm; Ce₂O₂Te: a = 408.17(4), c = 1294.7(1) pm; Pr₂O₂Te: a = 405.62(4), c = 1285.8(1) pm; Nd₂O₂Te: a = 403.08(4), c = 1277.1(1) pm; Sm₂O₂Te: a = 399.83(4), c = 1265.5(1) pm; Eu₂O₂Te: a = 397.56(4), c = 1257.9(1) pm; Gd₂O₂Te: a = 396.20(4), c = 1253.2(1) pm; Tb₂O₂Te: a = 393.89(4), c = 1245.4(1) pm; Dy₂O₂Te: a = 392.34(4), c = 1240.3(1) pm; Ho₂O₂Te: a = 390.57(6), c = 1239.0(3) pm) the M³⁺ cations are surrounded by nine anions (4 O^2– und 4 + 1 Te^2–) in the shape of a capped square antiprism. The anions show coordination numbers of four (O^2–: tetrahedra) and eight plus two (Te^2–: bicapped cubes) with respect to the cations. PbO-analogous square {[OM_4/4]₂}²⁺ triple layer slabs are present parallel (001), which originate through two-dimensional infinite linking of [OM₄]¹⁰⁺ tetrahedra via two trans-orientated pairs of edges (i. e. four edges altogether). These cationic layers are piled alternatingly along [001] with likewise quadratic single layers of Te^2– anions, which take care of the three-dimensional coherence as well as of the charge balance.     

Syntheses,Crystal Structures,and Optical and Magnetic Properties of Some CsLnCoQ3 Compounds (Ln = Tm and Yb,Q = S; Ln = Ho and Yb,Q = Se)

The four new compounds CsTmCoS₃, CsYbCoS₃, CsHoCoSe₃, and CsYbCoSe₃ have been synthesized at 1123 K. These black‐colored isostructural compounds crystallize in the KZrCuS₃ structure type with four formula units in space group Cmcm of the orthorhombic system. The structure of these compounds is composed of layers separated by Cs atoms. Because there are no Q–Q bonds, the formal oxidation states of Cs/Ln/Co/Q are 1+/3+/2+/2?, respectively. CsHoCoSe₃ shows paramagnetic behavior with μ_eff = 11.9(1) μ_B, whereas CsYbCoS₃ displays an antiferromagnetic‐like transition at ～2.7 K with μ_eff = 5.85(1) μ_B. Both CsYbCoS₃ and CsYbCoSe₃ exhibit optical band gaps in the near infrared region and broad absorption bands at lower energies.     

Synthese und Kristallstrukturen neuer komplexer Chloride der Lanthanide mit 3, 5‐Dimethylpyridiniumkationen: (3, 5‐Dimethylpyridinium)2[LnCl4(H2O)2]Cl (Ln = La,Pr) und (3, 5‐Dimethylpyridinium)3[TbCl6]

Preparation and Crystal Structures of New Complex Clorides of Lanthanides containing 3, 5‐Dimethylpyridinium Cations: (3, 5‐Dimethylpyridinium)₂[LnCl₄(H₂O)₂]Cl (Ln = La, Pr) and (3, 5‐Dimethylpyridinium)₃[TbCl₆] Crystals of the complex chlorides (3, 5‐dimethylpyridinium)₂[LaCl₄(H₂O)₂]Cl ( 1 ), (3, 5‐dimethylpyridinium)₂[PrCl₄(H₂O)₂]Cl ( 2 ) and (3, 5‐dimethylpyridinium)₃[TbCl₆] ( 3 ) have been prepared by reaction of LnCl₃ · x H₂O (Ln = La, Pr, Tb; x = 6‐7) with 3, 5‐dimethylpyridiniumchloride in ethanol/butanol solution. The crystal structures have been determined from single crystal X‐ray diffraction data. The compounds 1 and 2 are isotypic with each other and crystallize in the triclinic space group P1¯ (Z = 2). The 3, 5‐dimethylpyridinium cations are linked by hydrogen bonds to the anionic part of the structure built up by isolated chloride ions and strings of edge coupled triangulated dodecahedra [LnCl_4/2Cl₂(H₂O)₂]^—. The organic units are arranged forming a “π‐stacking”. 3 cristallizes monoclinically in the space group P2₁/c (Z = 4). The structure contains octahedral building units [TbCl₆]^3—. These octahedra are interconnected by the organic cations via hydrogen bonds forming chains parallel to [0 0 1].     

Crystal Structure Investigation of RE–Ni–Zn Ternary Compounds (RE = La,Ce, Tb)

The RENiZn (RE = La, Tb), RE₂Ni₂Zn (RE = La, Ce, Tb) and La₃Ni₃Zn ternary compounds were synthesized by two methods: by heating in a resistance furnace evacuated quartz ampoules containing Al₂O₃‐crucibles with element pieces and by induction melting in sealed Ta crucibles with subsequent annealing at 400 °C. Scanning electron microscopy (SEM) coupled with energy dispersive X‐ray spectroscopy (EDXS) was used for examining microstructure and phase composition of some of the alloys. The crystal structures for all the investigated phases were solved or confirmed on single crystal data by applying the direct methods refined by a standard least square procedure: LaNiZn – str. type ZrNiAl, hexagonal, , hP9, a = 0.7285(1), c = 0.3938(1) nm, wR₂ = 0.0534, 257 F² values, 14 variables; a = 0.7044(1), c = 0.3782(1) nm, wR₂ = 0.0447, 236 F² values, 14 variables for TbNiZn; La₂Ni₂Zn – str. type Pr₂Ni₂Al, orthorhombic, Immm, oI10, a = 0.4381(1), b = 0.5459(1) c = 0.8605(2) nm, wR₂ = 0.0824, 223 F² values, 13 variables; a = 0.4365(1), b = 0.5430(1) c = 0.8279(2) nm, wR₂ = 0.0635, 209 F² values, 13 variables for Ce₂Ni₂Zn; a = 0.4209(1), b = 0.5366(1) c = 0.8165 (1) nm, wR₂ = 0.0757, 200 F² values, 13 variables for Tb₂Ni₂Zn; La₃Ni₃Zn – str. type Y₃Co₃Ga, orthorhombic, Cmcm, oS28, a = 0.4276(1), b = 1.0310(2) c = 1.3636(3) nm, wR₂ = 0.0859, 579 F² values, 26 variables. The structural peculiarities of these compounds and their relations are discussed.     

Structural Link between Giant Molybdenum Oxide Based Ions and Derived Keggin Structure: Modular Assemblies Based on the [BW11O39]9− Ion and Pentagonal {M′M5} Units (M′=W; M=Mo,W)

Linked to the Pentagon : The addition of molybdate to [HBW₁₁O₃₉]^8? ions leads to the formation of mixed pentagonal units {W(Mo₅)} and {W(WMo₄)} trapped as linkers in the resulting modular assemblies, thus establishing the first link between the conventional Keggin ion derivatives and the giant molybdenum oxide and keplerate ions.

     

Quaternäre Caesium‐Kupfer(I)‐Lanthanoid(III)‐Selenide vom Typ CsCu3M2Se5 (M = Sm,Gd — Lu)

Quaternary Cesium Copper(I) Lanthanoid(III) Selenides of the Type CsCu₃M₂Se₅ (M = Sm, Gd — Lu) By oxidation of mixtures of copper and lanthanoid metal with elemental selenium in molar ratios of 1 : 1 : 2 and in addition of CsCl quaternary cesium copper(I) lanthanoid(III) selenides with the formula CsCu₃M₂Se₅ (M = Sm, Gd — Lu) were obtained at 750 °C within a week from torch‐sealed evacuated silica tubes. An excess of CsCl as flux helps to crystallize golden yellow or red, needle‐shaped, water‐resistant single crystals. The crystal structure of CsCu₃M₂Se₅ (M = Sm, Gd — Lu) (orthorhombic, Cmcm, Z = 4; e. g. CsCu₃Sm₂Se₅: a = 417.84(3), b = 1470.91(8), c = 1764.78(9) pm and CsCu₃Lu₂Se₅: a = 407.63(3), b = 1464.86(8), c = 1707.21(9) pm, respectively) contains [MSe₆]^9— octahedra which share edges to form double chains running along [100]. Those are further connected by vertices to generate a two‐dimensional layer parallel to (010). By edge‐ and vertex‐linking of [CuSe₄]^7— tetrahedra two crystallographically different Cu⁺ cations build up two‐dimensional puckered layers parallel to (010) as well. These sheet‐like structure interconnects the equation/tex2gif-stack-3.gif{[M₂Se₅]^4—} layers to create a three‐dimensional network according to equation/tex2gif-stack-4.gif{[Cu₃M₂Se₅]^—}. Thus empty channels along [100] form, apt to take up the Cs⁺ cations. These are surrounded by eight plus one Se^2— anions in the shape of (2+1)‐fold capped trigonal prisms with Cs—Se distances between 348 and 368 pm (8×) and 437 (for M = Sm) or 440 pm (for M = Lu), respectively, for the ninth ligand.     

Selten-Erd-Hydrogensulfate M(HSO4)3 (M = La,Ce–Nd): Derivate des UCl3-Typs

Rare Earth Hydrogensulfates M(HSO₄)₃ (M = La, Ce–Nd): Derivatives of the UCl₃ Type of Structure Hydrogensulfates of the lighter lanthanides are obtained from the reaction of the respective anhydrous sulfates with conc. sulfuric acid at 200 °C. According to X-ray single crystal determinations on La(HSO₄)₃ (hexagonal, P6₃/m, a = 945.64(9) pm, c = 590.87(5) pm), Ce(HSO₄)₃ (a = 943.34(10) pm, c = 587.88(5) pm), Pr(HSO₄)₃ (hexagonal, P6₃/m, a = 939.8(1) pm, c = 584.82(9) pm) and Nd(HSO₄)₃ (hexagonal, P6₃/m, a = 935.67(8) pm, c = 582.36(4) pm) they all crystallize analogous to the UCl₃ type of structure with nine-coordinate M³⁺ ions. The OH groups of the [HOSO₃]^– ”︁tetrahedra”︁”︁ build up channels parallel [00.1] typical for this type of structure. Hydrogen bonding, however, is only weak in these compounds.     

Synthesis and Structure of a One‐Dimensional Aluminum Phosphate, [NH3(CH2)2NH2(CH2)3NH3]3+ [Al(PO4)2]3—

A one‐dimensional aluminum phosphate, [NH₃(CH₂)₂NH₂(CH₂)₃NH₃]³⁺ [Al(PO₄)₂]^3—, has been synthesized hydrothermally in the presence of N‐(2‐Aminoethyl‐)1, 3‐diaminopropane (AEDAP) and its structure determined by single crystal X‐ray diffraction. Crystal data: space group = Pbca (no. 61), a = 16.850(2), b = 8.832(1), c = 17.688(4)Å, V = 2632.4(2)ų, Z = 8, R₁ = 0.0389 [5663 observed reflections with I > 2σ(I)]. The structure consists of anionic [Al(PO₄)₂]^3— chains built up from AlO₄ and PO₄ tetrahedra, in which all the AlO₄ vertices are shared and each PO₄ tetrahedron possesses two terminal P=O linkages. The cations, which balances the negative charge of the chains, are located in between the chains and interact with the oxygen atoms through strong N—H···O hydrogen bonds. Additional characterization of the compound by powder XRD and MAS‐NMR has also been performed and described.     

Self‐Assembly of Polyoxometalate‐Supported Ln‐H nydroxo/Oxo Clusters with 1D Extended Structure: [LnIII(H2O)7Cr(OH)6Mo6O18]n·4nH2O (Ln = Ce,Sm, Eu)

Three novel polyoxometalate compounds consisting of Anderson‐type anions and trivalent lanthanide cations, [Ln(H₂O)₇Cr(OH)₆Mo₆O₁₈]_n·4nH₂O (Ln = Ce 1 ; Sm 2 ; Eu 3 ), have been synthesized in aqueous solution and characterized by single crystal X‐ray diffraction, elemental analyses, IR spectra, and TG analyses. Single crystal X‐ray diffractions reveal that the structures of the 1:1 composite compound formed by the heteropolyanion [Cr(OH)₆Mo₆O₁₈]^3? as the building unit and the [Ln(H₂O)₇]³⁺ complex fragment as the linker, which exhibit a type of zig‐zag chain with alternating cations and anions through the Mo‐Ot′‐Ln‐Ot′‐Mo linkage in the crystal. The magnetic properties of 1 ? 3 have been studied by measuring their magnetic susceptibility over the temperature range of 2‐300 K. The UV‐vis spectra of 1 give the Mo‐O and Cr^III‐O charge transfer transitions at 203 and 543 nm, respectively. In addition, the fluorescent characteristic transition of the Eu³⁺ ions in compound 3 is reported.     

Darstellung und Aufbau der Lanthanoidfluorid‐catena‐Trisilicate M3F[Si3O10] (M = Dy,Ho, Er) im Fluorthalenit‐Typ (Y3F[Si3O10])

Synthesis and Constitution of Fluorothalenite‐Type (Y₃F[Si₃O₁₀]) Fluoride catena‐ Trisilicates M₃F[Si₃O₁₀] with the Lanthanides (M = Dy, Ho, Er) By the reaction of the sesquioxides M₂O₃ with the corresponding trifluorides MF₃ (M = Dy, Ho, Er), SiO₂ and CsCl as flux (molar ratio: 1 : 1 : 3 : 6; 700 °C, 7 d) in evacuated silica tubes and gastight sealed metal capsules made of platinum, niobium or tantalum, respectively, single crystals of the fluoride silicates M₃F[Si₃O₁₀] (monoclinic, P2₁/n; Z = 4; M = Dy: a = 734.06(6), b = 1116.55(9), c = 1040.62(8) pm, β = 97.281(7)°; M = Ho: a = 730.91(6), b = 1111.68(9), c = 1037.83(8) pm, β = 97.238(7)°; M = Er: a = 727.89(6), b = 1107.02(9), c = 1035.21(8) pm, β = 97.209(7)°) were obtained. The most important building groups in the crystal structures of the thalenite type are “isolated” [FM₃]⁸⁺ triangles and catena‐trisilicate anions [Si₃O₁₀]^8–, which contain three [SiO₄] tetrahedra linked to a chain fragment via common corners. This has the shape of a horseshoe where both the terminal tetrahedra show different conformations (eclipsed and staggered) relative to the central unit. Therefore a chelatizing coordination on the same M³⁺ cation via oxygen atoms of both terminal [SiO₄] groups is possible. The narrow area of existence of these fluoride silicates within the lanthanide series will be discussed and structural comparisons with other catena‐trisilicates are presented.     

Synthesis and Structure of Anhydrous Rare‐Earth Perchlorates M(ClO4)3 (M = La,Ce–Er,Y): Derivatives of the UCl3 Type of Structure

Anhydrous perchlorates M(ClO₄)₃ (M = La, Ce–Er, Y) were obtained by drying the products formed in the reaction of the respective lanthanide oxide with perchloric acid (70%). According to X‐ray powder investigations, they all crystallize with the hexagonal space group P6₃/m isostructural with the hydrogensulfates of the lighter lanthanides. For the example of Pr(ClO₄)₃ a full profile Rietveld refinement based on X‐ray powder data has been undertaken successfully (a = 933.61(3) pm, c = 584.88(2) pm; R_p = 0.207, R_Bragg = 0.068). The structure of Er(ClO₄)₃ was refined from neutron diffraction data (a = 919.7(1) pm, c = 559.8(1) pm; R_p = 0.190, R_Bragg = 0.106). High temperature X‐ray powder investigations show that thermal expansion occurs mainly in the (001) plane while the c axis remains nearly constant.     

K13CoSn17–x (x = 0.1): A New Ternary Phase Containing ­Cobalt Centered [Sn9] Cluster Synthesized via High‐Temperature Reaction

A new ternary potassium cobalt stannide, K₁₃CoSn_17–x (x = 0.1), was obtained by reacting the mixture of the corresponding pure elements at high temperature, and structurally characterized by single‐crystal X‐ray diffraction study. K₁₃CoSn_17–x (x = 0.1) crystallizes in the orthorhombic space group Pbca (No. 61) with a = 26.2799(7) Å, b = 24.1541(6) Å, c = 29.8839(6) Å, V = 18969.3(8) ų, and Z = 16. Its structure contains isolated [CoSn₉] monocapped square antiprism and [Sn₄] tetrahedron in the ratio 1:2, forming a hierarchical variant of Laves phase MgZn₂. The structural relation between the title compound with MgZn₂ as well as other binary stannides is also discussed.     

Metamagnetism and Single‐Chain Magnetic Behavior in a Homospin One‐Dimensional Iron(II) Coordination Polymer

Reaction of FeCl₂?4 H₂O with KNCSe and pyridine in ethanol leads to the formation of the discrete complex [Fe(NCSe)₂(pyridine)₄] ( 1 ) in which the Fe^II cations are coordinated by two N‐terminal‐bonded selenocyanato anions and four pyridine co‐ligands. Thermal treatment of compound 1 enforces the removal of half of the co‐ligands leading to the formation of a ligand‐deficient (lacking on neutral co‐ligands) intermediate of composition [Fe(NCSe)₂(pyridine)₂]_n ( 2 ) to which we have found no access in the liquid phase. Compound 2 is obtained only as a microcrystalline powder, but it is isotypic to [Cd(NCSe)₂(pyridine)₂]_n and therefore, its structure was determined by Rietveld refinement. In its crystal structure the metal cations are coordinated by two pyridine ligands and four selenocyanato anions and are linked into chains by μ‐1,3 bridging anionic ligands. Magnetic measurements on compound 1 show only paramagnetic behavior, whereas for compound 2 an unexpected magnetic behavior is found, which to the best of our knowledge was never observed before for a iron(II) homospin compound. In this compound metamagnetism and single‐chain magnetic behavior coexist. The metamagnetic transition between the antiferromagnetically ordered phase and a field‐induced ferromagnetic phase of the high‐spin iron(II) spin carriers is observed at a transition field H_C of 1300 Oe and the single‐chain magnetic behavior is characterized by a blocking temperature T_B, estimated to be about 5 K.