Er4F2[Si2O7][SiO4]: Das erste Selten‐Erd‐Fluoridsilicat mit zwei verschiedenen Silicat‐Anionen

Er₄F₂[Si₂O₇][SiO₄]: The First Rare‐Earth Fluoride Silicate with Two Different Silicate Anions By the reaction of Er₂O₃ with ErF₃ and SiO₂ at 700 °C in sealed tantalum capsules using CsCl as flux (molar ratio 5 : 2 : 3 : 20), the compound Er₄F₂[Si₂O₇][SiO₄] (triclinic, P 1; a = 648.51(5), b = 660.34(5), c = 1324.43(9) pm, α = 87.449(8), β = 85.793(8), γ = 60.816(7)°; V_m = 148.69(1) cm³/mol, Z = 2) is obtained as pale pink platelets or lath‐shaped single crystals. It consists of disilicate anions [Si₂O₇]^6– in eclipsed conformation, ortho‐silicate anions [SiO₄]^4– and isolated [Er₄F₂]¹⁰⁺ units comprising two edge‐shared [Er₃F] triangles. Er³⁺ is surrounded by 7 + 1 (Er1) or 7 (Er2–Er4) anionic neighbors, respectively, of which two are F^– in the case of Er1 and Er4 but only one for Er2 and Er3. The other ligands recruit from oxygen atoms of the different oxosilicate groups. The crystal structure can be described as simple rowing up of the three building groups ([SiO₄]^4–, [Er₄F₂]¹⁰⁺, and [Si₂O₇]^6–) along [001]. The necessity of a large excess of fluoride for a successful synthesis of Er₄F₂[Si₂O₇][SiO₄] will be discussed.     

Er2S[SiO4]: Ein Erbiumsulfid‐ortho‐Oxosilicat mit ungewöhnlicher Sulfidionen‐Koordination

During the reaction of cadmium sulfide with erbium and sulfur in evacuated silica ampoules pink lath‐shaped crystals of Er₂S[SiO₄] occur as by‐product which were characterized by X‐ray single crystal structure analysis. The title compound crystallizes orthorhombically in the space group Cmce (a = 1070.02(8), b = 1235.48(9), c = 683.64(6) pm) with eight formula units per unit cell. Besides isolated ortho‐oxosilicate units [SiO₄]^4?, the crystal structure contains two crystallographically independent Er³⁺ cations which are both eightfold coordinated by six oxygen and two sulfur atoms. The sulfide anions are surrounded by four erbium cations each in the shape of very distorted tetrahedra. These excentric [SEr₄]¹⁰⁺ tetrahedra build up layers according to by vertex‐ and edge‐connection. They are piled parallel to (010) and separated by the isolated ortho‐oxosilicate tetrahedra.     

Synthese und Struktur von RbHfF5, Rb2Zr3F12O und Rb2Hf3F12O — zwei Oxidfluoride mit zentraler trigonal‐planarer [M3O]‐Gruppe

Synthesis and Structure of RbHfF₅, Rb₂Zr₃F₁₂O and Rb₂Hf₃F₁₂O — two Oxydefluorides with Central Trigonal‐plane [M₃O] Group Colorless RbHfF₅ crystallizes isotypic with (NH₄)ZrF₅ and TlHfF₅ monoclinic, space group P2₁/c ‐ C_2h (No. 14) with a = 776.6, b = 789.6, c = 789.8 pm, and β = 120.52°. Also colorless Rb₂Zr₃F₁₂O crystallizes trigonal, space group R3¯m — D₃d (No. 166), with a = 771.9 and c = 2963.0 pm, isotypic is Rb₂Hf₃F₁₂O with a = 769.2 pm and c = 2986.1 pm. Both compounds are isotypic with Tl₂Zr₃F₁₂O.     

ErF3‐reiche ternäre Erbiumfluoride mit den schweren Alkalimetallen: I. KEr3F10 und RbEr3F10

ErF₃‐Rich Ternary Erbium Fluorides with the Heavy Alkali Metals: I. KEr₃F₁₀ and RbEr₃F₁₀ The conversion of erbium trifluoride (ErF₃) with chlorides of the heavy alkali metals (ACl; A = K, Rb and Cs) at 700–800 °C in tantalum capsules sealed by arc‐welding surprisingly results in the formation of ErF₃‐rich ternary alkali‐metal erbium(III) fluorides with the compositions AEr₃F₁₀ (A = K and Rb) or CsEr₂F₇, respectively. The first‐mentioned compounds are characterized by high coordination numbers at the alkali‐metal cation (CN(A⁺) = 15 and 16) as well as by a uniform surrounding of the Er³⁺ cation (CN = 8, square antiprism). In KEr₃F₁₀ (cubic, Fm3m; a = 1154.06(7) pm, Z = 8) eight (F1)^? anions always arrange as a cube, whose six faces are each capped by an Er³⁺ cation. These [(F1)₈Er₆]¹⁰⁺ groups constitute a cubic closest sphere‐packing with K⁺ cations in all of the tetrahedral interstices. The [Er₆(μ₃‐F1)₈]¹⁰⁺ units are interconnected via the remainder fluoride anions (F2) to build up a three‐dimensional framework so that the characteristic [ErF₈]^5? polyhedra (d(Er³⁺?F^?) = 220 – 235 pm) emerge. In RbEr₃F₁₀ (hexagonal, P6₃mc; a = 818.43(5), c = 1336.54(8) pm, Z = 4) the analogous [ErF₈]^5? polyhedra (d(Er³⁺?F^?) = 219 – 237 pm) initially convene to triple groups [Er₃F₁₉]^10? through cis‐edge condensation, which are then further connected via F^? corners to arrange as a two‐dimensional network perpendicular to the c axis. Finally, the cross‐linking of these layers is achieved by common F^? vertices again, such that large cavities apt to take up the Rb⁺ cations are formed. A second part of these series will report on the syntheses and crystal structures of the ErF₃‐poorer AEr₂F₇‐type representatives with A = K, Rb and Cs.     

Cu1,45Er0,85S2: Ein Kupfer(I)‐Erbium(III)‐Sulfid mit kationendefekter CaAl2Si2‐Struktur

Cu_1.45Er_0.85S₂: A Copper(I) Erbium(III) Sulfide with Cation‐Deficient CaAl₂Si₂‐Type Structure Attempts to synthesize single‐phase CuYS₂‐type copper(I) erbium(III) disulfide (CuErS₂) from 1 : 1 : 2‐molar mixtures of the elements (Cu, Er and S) after seven days at 900 °C in sealed evacuated silica tubes failed with equimolar amounts of CsCl working as flux and reagent. In these cases, quaternary CsCu₃Er₂S₅ (orthorhombic, Cmcm; a = 394.82(4), b = 1410.9(1), c = 1667.2(2) pm, Z = 4) and ternary Cu_1.45Er_0.85S₂ (trigonal, P3m1; a = 389.51(4), c = 627.14(6) pm, Z = 1) become the unexpected by‐products. Both emerge even as yellow single crystals (lath‐shaped fibres and platelets, respectively, with triangular cross‐section) and both crystal structures contain condensed [CuS₄] and [ErS₆] units as dominating building blocks. The ternary sulfide Cu_1.45Er_0.85S₂ exhibits CdI₂‐analogous layers {[(Er³⁺)(S^2–)_6/3]^–} of edge‐shared [ErS₆] octahedra (d(Er–S) = 272 pm, 6 × ) which are piled up parallel (001) and interconnected by interstitial Cu⁺ cations in tetrahedral S^2– coordination (d(Cu–S) = 236 pm, 1 × ; 240 pm, 3 × ). The latter thereby form anionic layers {([(Cu⁺)(S^2–)_4/4]^–)₂} as well, consisting of [CuS₄] tetrahedra which share three cis‐oriented edges. When the S^2– anions arrange hexagonally closest‐packed and the corresponding layers are symbolized with capital Roman letters, the Er³⁺ cations (small Roman) and the Cu⁺ cations (small Greek letters) reside layerwise alternatingly within half of the octahedral (Er³⁺) and tetrahedral (Cu⁺) voids according to … AcB αβ AcB αβ A … . Since both kinds of cations occupy only a certain percentage (Cu⁺: 72.6%, Er³⁺: 85.1%) of their regular positions, the crystal structure of Cu_1.45Er_0.85S₂ can be addressed as a double cation‐deficient CaAl₂Si₂‐type arrangement according to (Er_0.85□_0.15)(Cu_1.45□_0.55)S₂. The partial occupation could be established by both released site occupation factors in the course of the crystal structure refinement and electron beam X‐ray microanalysis (EDX).     

Na3F[WO4]: A Sodium Fluoride Ortho‐Oxotungstate(VI) with Strands of Face‐Shared Fluoride‐Centred Sodium Octahedra According to $^{1}_{\infty}\rm \{[FNa_{6/2}]^{2+}\}$

During the reaction of Na₂[WO₄] with YF₃ purposed to yield fluoride‐derivatized yttrium oxotungstates(VI), colourless platelet‐shaped single crystals of Na₃F[WO₄] emerged as main product. The title compound crystallizes orthorhombically in the space group Pnma (a = 559.59(5), b = 751.02(7), c = 1285.98(9) pm) with four formula units per unit cell. Besides isolated ortho‐oxotungstate units [WO₄]^2? (d(W–O) = 176–178 pm) the crystal structure contains two crystallographically independent Na⁺ cations which are both octahedrally coordinated by four oxygen atoms and two fluoride anions. The F^? anions are surrounded by six sodium cations (d(F–Na) = 224–242 pm) also in an octahedral fashion. These octahedra built up chains along [100] by sharing trans‐oriented faces according to , which are stacked according to a hexagonal closest rod‐packing. The cationic strands are surrounded, interconnected and charge‐balanced by isolated [WO₄]^2? tetrahedra with almost ideal shape and every O^2? ligand is terminally coordinated by three Na⁺ cations.     

LaCl(BO2)2 und Er2Cl2[B2O5]: Zwei Chlorid‐Oxoborate dreiwertiger Lanthanide

LaCl(BO₂)₂ and Er₂Cl₂[B₂O₅]: Two Chloride Oxoborates of Trivalent Lanthanides Er₂Cl₂[B₂O₅] is obtained as single crystals by the reaction of ErCl₃, Er₂O₃ and B₂O₃ with an excess of ErCl₃ as flux in evacuated silica tubes after two weeks at 850 °C. The compound crystallizes as long, pale pink needles and appears to be air‐ and water‐resistant. Single‐crystalline LaCl(BO₂)₂ emerges from the reaction of La₂O₃, LaCl₃, and B₂O₃ with an excess of B₂O₃ as flux in evacuated silica tubes after four weeks at 900 °C. LaCl(BO₂)₂ crystallizes as thin, colourless, air‐ and water‐resistant needles which tend to severe twinning due to their fibrous habit. The crystal structure of Er₂Cl₂[B₂O₅] (orthorhombic, Pbam; a = 1489.65(9), b = 1004.80(6), c = 524.86(3) pm; Z = 4) contains two crystallographically different erbium cations. (Er1)³⁺ resides in pentagonal‐bipyramidal coordination of seven anions while (Er2)³⁺ is surrounded by only six anions with the shape of an octahedron. The planar oxodiborate units [B₂O₅]^4— consisting of two vertex‐shared [BO₃]^3— triangles are isolated according to {([BOO]₂)^4—}. LaCl(BO₂)₂ crystallizes isostructurally with PrCl(BO₂)₂ in the triclinic space group P1¯ (a = 423.52(4), b = 662.16(7), c = 819.33(8) pm; α = 82.081(8), β = 89.238(9), γ = 72.109(7)°; Z = 2). The characteristic unit consists of endless chains built up by corner‐linked [BO₃]^3— triangles. These quasi‐planar zigzag chains of the composition {[(B1)OO(B2)OO]^2—} (≡ {[BO₂]^—} run parallel [100]. The La³⁺ cations exhibit coordination numbers of ten and are coordinated by three Cl^— and seven O^2— anions.     

Synthesis and Structural Analysis of ϵ‐Fe2O3

Powder material of ?‐Fe₂O₃ was obtained by thermal decomposition of the clay mineral nontronite and subsequent isolation of the ferric oxide by leaching the silicate phases. Additionally, crystals of ?‐Fe₂O₃ were grown as precipitates by internal oxidation of a Pd₉₆Fe₄ alloy. Analysis of the precipitate crystals by electron diffraction yields an orthorhombic crystal system and space group Pna2₁ ab initio. X‐ray diffraction data of the powder containing small amounts of Al substituting Fe were refined by the Rietveld method. The refinement yields lattice parameters a = 507.15 pm, b = 873.59 pm and c = 941.78 pm, and atom positions. ?‐Fe₂O₃ is isostructural with κ‐Al₂O₃, AlFeO₃, and GaFeO₃ having an anion stacking sequence /ABAC/, and 1/4 of the cations in tetrahedral co‐ordination. Some strongly distorted FeO₆ octahedrons with one large Fe‐O distance, which may be considered as a 5+1 co‐ordination, appear to be characteristic for ?‐Fe₂O₃. The structure shows elements known from silicates and oxyhydroxides of iron, respectively.     

K3Er7S12 und Rb3Er7S12: Zwei ternäre Erbium(III)‐sulfide mit Kanalstruktur

K₃Er₇S₁₂ and Rb₃Er₇S₁₂: Two Ternary Erbium(III) Sulfides with Channel Structures The isotypic ternary erbium(III) sulfides K₃Er₇S₁₂ (a = 1185.38(9), b = 2461.5(2), c = 393.59(3) pm) and Rb₃Er₇S₁₂ (a = 1203.51(9), b = 2483.0(2), c = 394.85(3) pm; both orthorhombic, Pnnm, Z = 2) are obtained by reacting erbium metal and sulfur with an excess of alkali chloride (KCl or RbCl, respectively) serving as flux and reagent within seven days at 900 °C. The rod—shaped, yellow, transparent single crystals distinguish themselves in their crystal structure by a framework of corner— and edge—linked [ErS₆] octahedra (d(Er³⁺—S^2—) = 265—285 pm), in which the alkali metal cations (K⁺ and Rb⁺, respectively; CN = 6 and 7 + 1) are inserted into channels running along [001]. Under consideration of the ionic radius quotients r_i(A⁺)/r_i(Ch^2—) (A = K—Cs, Ch = S—Te) the existence range of this Cs₃Y₇Se₁₂—type of structure is discussed.     

Synthesis and Crystal Structure of the Fluoride‐Rich Rubidium Scandium Fluoride Oxosilicate Rb3Sc2F5Si4O10

The new quinary fluoride‐rich rubidium scandium oxosilicate Rb₃Sc₂F₅Si₄O₁₀ was obtained from mixtures of RbF, ScF₃, Sc₂O₃ and SiO₂ in sealed platinum ampoules after seventeen days at 700 °C. The colourless compound crystallises orthorhombically in space group Pnma with a = 962.13(5), b = 825.28(4), c = 1838.76(9) pm and Z = 4. For the oxosilicate partial structure, [SiO₄]^4– tetrahedra are connected in (001) by vertex‐sharing to form corrugated unbranched vierer single layers ${2}\atop{{\infty}}$ {[Si₄O₁₀]^4–} (d(Si–O) = 158–165 pm, ∠(O–Si–O) = 103–114°, ∠(Si–O–Si) = 125–145°) containing six‐membered rings. Similar oxosilicate layers with 6³‐net topology are well‐known for the mineral group of micas or in sanbornite Ba₂Si₄O₁₀. Regarding other systems, identical tetrahedral layers can be found in the synthetic borophosphate Mg(H₂O)₂[B₂P₂O₈(OH)₂] · H₂O. The Sc³⁺ cations are coordinated octahedrally by four F^– and two O^2– anions. These cis‐[ScF₄O₂]^5– octahedra (d(Sc–F) = 200–208 pm, d(Sc–O) = 202–205 pm) share one equatorial and two apical F^– anions with others to build up slightly corrugated ${1}\atop{{\infty}}$ {[Sc₂F${t}\atop{2/1}$ F${v}\atop{6/2}$ O${t}\atop{4/1}$ ]^7–} double chains along [010]. These are linked with the oxosilicate layers via two oxygen vertices to construct a three‐dimensional framework with cavities apt to host the three crystallographically independent Rb⁺ cations with coordination numbers of eleven, twelve and thirteen.     

Selten‐Erd‐Metall‐Koordinationspolymere: Synthesen und Kristallstrukturen von drei neuen Glutaraten, [Pr2(Glu)3(H2O)4] · 10,5H2O, [Pr(Glu)(H2O)2]Cl und [Er(Glu)(GluH)(H2O)2]

Rare‐Earth‐Metal Coordination Polymers: Syntheses and Crystal Structures of Three New Glutarates, [Pr₂(Glu)₃(H₂O)₄] · 10.5H₂O, [Pr(Glu)(H₂O)₂]Cl, and [Er(Glu)(GluH)(H₂O)₂] The new rare‐earth dicarboxylates [Pr₂(Glu)₃(H₂O)₄] · 10.5H₂O ( 1 ), [Pr(Glu)(H₂O)₂]Cl ( 2 ) and [Er(Glu)(GluH)(H₂O)₂] ( 3 ) were obtained from the reactions of glutaric acid with PrCl₃·6H₂O and Er(OH)₃, respectively. The crystal structures were determined by single‐crystal X‐ray diffraction. [Pr₂(Glu)₃(H₂O)₄] · 10,5H₂O crystallizes in the orthorhombic space group Pnma (no. 62) with a = 871.7(4), b = 3105.0(9), c = 1308.3(9) pm and Z = 4. The crystals of [Pr(Glu)(H₂O)₂]Cl are monoclinic (I2/a; no. 15) with a = 786.2(1), b = 1527.6(2) c = 801.2(1) pm, β = 99.78(1)° and Z = 4. [Er(Glu)(GluH)(H₂O)₂] crystallizes in the monoclinic space group P2₁/a (no. 14) with lattice parameters of a = 882.4(1), b = 1375.3(2), c = 1267.4(2) pm, β = 107.13(1)° and Z = 4. The rare‐earth cations have the coordination numbers 10 ( 1 ), 8 + 1 ( 2 ) and 9 ( 3 ). The individual polyhedra are connected to chains and further to sheets in 1 and 2 and to double chains in 3 . Only in the water‐rich compound 1 there are channels that contain crystal water molecules. It, therefore, has a considerably lower density than 2 and 3 .     

Er2(CO3)2(C2O4)(H2O)2 — Synthese,Kristallstruktur und thermischer Abbau eines Carbonat‐Oxalat‐Hydrates des Erbiums

Er₂(CO₃)₂(C₂O₄)(H₂O)₂ — Synthesis, Crystal Structure and the Thermal Decomposition of a Carbonate‐Oxalate‐Hydrate of Erbium The hydrothermal reaction of an equimolar ratio of Er₂O₃ with the aminoacid L‐cysteine in evacuated glass ampoules in H₂O at 130 °C gave transparent, pink crystals of the formula Er₂(CO₃)₂(C₂O₄)(H₂O)₂. It crystallises in the monoclinic space group Cm (Z = 2, a = 777.3(2) pm, b = 1492.0(3) pm, c = 473.09(8) pm, b = 90.12(9)°). The thermal decomposition of Er₂(CO₃)₂(C₂O₄)(H₂O)₂ was investigated.     

Ein neues Selten‐Erd‐Metall(III)‐Fluorid‐Oxoselenat(IV): YF[SeO3]

A New Rare‐Earth Metal(III) Fluoride Oxoselenate(IV): YF[SeO₃] Just two representatives of the rare‐earth metal(III) fluoride oxoselenates(IV) with the formula type MF[SeO₃] (M = La and Lu) exist so far, whereas for the intermediate lanthanoids only M₃F[SeO₃]₄‐type compounds (M = Gd and Dy) were accessible. Because of the similar radius of Y³⁺ to the radii of the heavier lanthanoid cations, a missing link within the MF[SeO₃] series could be synthesized now with the example of yttrium(III) fluoride oxoselenate(IV). Contrary to LuF[SeO₃] with its triclinic structure, YF[SeO₃] crystallizes monoclinically in space group P2₁/c (no. 14, a = 657.65(7), b = 689.71(7), c = 717.28(7) pm, β = 99.036(5)° and Z = 4). A single Y³⁺ cation occupying the general site 4e is surrounded by six oxide and two fluoride anions forming [YO₆F₂]^11? polyhedra (d(Y–O) = 228–243 plus 263 pm, d(Y–F) = 219–220 pm). These are linked via common O···O edges to chains running along [010] and adjacent chains get tied to each other by sharing common O3···O3 and O3···F edges which results in sheets parallel to (100). The Se⁴⁺ cations connect these sheets as ψ¹‐tetrahedral [SeO₃]^2? anions (d(Se–O) = 168–174 pm) for charge balance via all oxygen atoms. Despite the different coordination numbers of seven and eight for the rare‐earth metal(III) cations the structures of LuF[SeO₃] and YF[SeO₃] appear quite similar. The chains containing pentagonal bipyramids [LuO₅F₂]^9? are connected to layers running parallel to the (100) plane again. In fact it is only necessary to shorten the partial structure of the straight chains along [001] to achieve the angular chains in YF[SeO₃]. As a result of this shortening one oxide anion at a time moves into the coordination sphere of a neighboring Y³⁺ cation and therefore adds up the coordination number for Y³⁺ to eight. For the synthesis of YF[SeO₃] yttrium sesquioxide (Y₂O₃), yttrium trifluoride (YF₃) and selenium dioxide (SeO₂) in a molar ratio of 1 : 1 : 3 with CsBr as fluxing agent were reacted within five days at 750 °C in evacuated graphitized silica ampoules.     

Synthesis of Er5(BO3)2F9 and Properties of RE5(BO3)2F9 (RE = Er,Yb)

Er₅(BO₃)₂F₉ was synthesised under conditions of 3 GPa and 800 °C in a Walker‐type multianvil apparatus. The crystal structure was determined on the basis of single‐crystal X‐ray diffraction data, collected at room temperature. Er₅(BO₃)₂F₉ is isotypic to the recently synthesised Yb₅(BO₃)₂F₉ and crystallises in C2/c with the lattice parameters a = 2031.2(4) pm, b = 609.5(2) pm, c = 824.6(2) pm, and β = 100.29(3)°. The physical properties of RE₅(BO₃)₂F₉ (RE = Er, Yb) including high temperature behaviour and single crystal IR‐ / Raman spectroscopy were investigated.     

LiLa2F3(SO4)2 und LiEr2F3(SO4)2: Fluoridsulfate der Selten‐Erd‐Elemente mit Lithium

LiLa₂F₃(SO₄)₂ and LiEr₂F₃(SO₄)₂: Fluoride‐Sulfates of the Rare‐Earth Elements with Lithium The reaction of LiF with the anhydrous sulfates M₂(SO₄)₃ (M = La, Er) in sealed gold ampoules yields single crystals of the pseudo quaternary compounds LiLa₂F₃(SO₄)₂ and LiEr₂F₃(SO₄)₂. According to X‐ray single crystal investigations, LiLa₂F₃(SO₄)₂ crystallizes with the monoclinic (I2/a, Z = 4, a = 828.3(2), b = 694.7(1), c = 1420.9(3) pm, β = 95.30(2)°, R_all = 0.0214) and LiEr₂F₃(SO₄)₂ with the orthorhombic crystal system (Pbcn, a = 1479.1(2), b = 633.6(1), c = 813.7(1) pm, R_all = 0.0229). A common feature of both structures is a dimeric unit of metal atoms connected via three fluoride ions. This leads to relatively short metal‐metal distances (La³⁺–La³⁺: 389 pm, Er³⁺–Er³⁺: 355 pm). In LiLa₂F₃(SO₄)₂, Li⁺ is surrounded by four oxygen atoms of four sulfate groups and one fluoride ion in form of a trigonal bipyramid, in LiEr₂F₃(SO₄)₂ two further fluoride ligands are attached.     

Drei Alkalimetall‐Erbium‐Thiophosphate: Von der Schichtstruktur bei KEr[P2S7] zur dreidimensionalen Vernetzung in NaEr[P2S6] und Cs3Er5[PS4]6

Three Alkali‐Metal Erbium Thiophosphates: From the Layered Structure of KEr[P₂S₇] to the Three‐Dimensional Cross‐Linkage in NaEr[P₂S₆] and Cs₃Er₅[PS₄]₆ The three alkali‐metal erbium thiophosphates NaEr[P₂S₆], KEr[P₂S₇], and Cs₃Er₅[PS₄] show a small selection of the broad variety of thiophosphate units: from ortho‐thiophosphate [PS₄]^3? and pyro‐thiophosphate [S₃P–S–PS₃]^4? with phosphorus in the oxidation state +V to the [S₃P–PS₃]^3? anion with a phosphorus‐phosphorus bond (d(P–P) = 221 pm) and tetravalent phosphorus. In spite of all differences, a whole string of structural communities can be shown, in particular for coordination and three‐dimensional linkage as well as for the phosphorus‐sulfur distances (d(P–S) = 200 – 213 pm). So all three compounds exhibit eightfold coordinated Er³⁺ cations and comparably high‐coordinated alkali‐metal cations (CN(Na⁺) = 8, CN(K⁺) = 9+1, and CN(Cs⁺) ≈ 10). NaEr[P₂S₆] crystallizes triclinically ( ; a = 685.72(5), b = 707.86(5), c = 910.98(7) pm, α = 87.423(4), β = 87.635(4), γ = 88.157(4)°; Z = 2) in the shape of rods, as well as monoclinic KEr[P₂S₇] (P2₁/c; a = 950.48(7), b = 1223.06(9), c = 894.21(6) pm, β = 90.132(4)°; Z = 4). The crystal structure of Cs₃Er₅[PS₄] can also be described monoclinically (C2/c; a = 1597.74(11), b = 1295.03(9), c = 2065.26(15) pm, β = 103.278(4)°; Z = 4), but it emerges as irregular bricks. All crystals show the common pale pink colour typical for transparent erbium(III) compounds.     

Zwei Fluoridborate des Gadoliniums: Gd2F3[BO3] und Gd3F3[BO3]2

Two Fluoride Borates of Gadolinium: Gd₂F₃[BO₃] and Gd₃F₃[BO₃]₂ By flux‐supported solid‐state reaction of Gd₂O₃ and GdF₃ with B₂O₃ (flux: CsCl, molar ratio: 1 : 1 : 1 : 6, sealed tantalum capsule, 700 °C, 7 d) the new gadolinium fluoride borate Gd₂F₃[BO₃] (monoclinic, P2₁/c; a = 1637.2(1), b = 624.78(4), c = 838.04(6) pm, β = 93.341(8)°; V_m = 64.418(6) cm³/mol, Z = 8) was obtained as colourless, prismatic, face‐rich single crystals. The four crystallographically different Gd³⁺ cations (CN = 9) are all capped square‐antiprismatically surrounded by fluoride and oxide anions, in which the latter represent always components of isolated trigonal planar [BO₃]^3— anions. The six crystallographically independent F^— anions all reside in more or less planar coordination of three Gd³⁺ cations. Thus the constitution of Gd₂F₃[BO₃] can be described as a sequence of alternating layers each of the composition Gd[BO₃] and GdF₃ parallel (100), respectively. The crystal structures of Gd₂F₃[BO₃] and the shortly published Gd₃F₃[BO₃]₂ (monoclinic, C2/c; a = 1253.4(1), b = 623.7(1), c = 836.0(1) pm, β = 97.404(6)°; V_m = 97.571(9) cm³/mol, Z = 4) are compared with each other. Due to the structural analogies between these two gadolinium fluoride borates, a disorder model of the boron atoms frequently found for Gd₂F₃[BO₃] is able to be transferred to Gd₃F₃[BO₃]₂ as well.     

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.