Kristallstrukturen aus CaBe2Ge2‐ und CeMg2Si2‐analogen Blöcken: Die Phosphide LnPt2P2−x (Ln: La,Sm)

Crystal Structures of CaBe₂Ge₂ and CeMg₂Si₂ analogous Units: The Phosphides LnPt₂P_2?x (Ln: La, Sm) Single crystals of LaPt₂P_1.44 (a = 4.174(1), c = 19.212(5) Å) were grown by reaction of vaporous phosphorus with LaPt₂ at 1050 °C during two weeks, whereas SmPt₂P_1.50 (a = 4.131(1), c = 19.086(4) Å) was synthesized by heating mixtures of the elements at 900 and 1100 °C (60 h) and annealing at 1050 °C (300 h). Both phosphides were investigated by single crystal X‐ray methods. Their crystal structures (I4/mmm; Z = 4) consist of CaBe₂Ge₂ and CeMg₂Si₂ analogous units alternating with each other along [001]. The positions of the P1 atoms are occupied incompletely causing the deviation to the 1:2:2 stoichiometry. Another compounds LnPt₂P_2?x were studied by X‐ray powder diffraction resulting in the following lattice constants: a = 4.150(1), c = 19.132(5) Å for CePt₂P_2–x, a = 4.137(1), c = 19.085(4) Å for PrPt₂P_2?x, and a = 4.127(1), c = 19.040(2) Å for NdPt₂P_2?x.     

Neue Germanide mit geordneter Ce3Pt4Ge6‐Struktur – Die Verbindungen Ln3Pt4Ge6 (Ln: Pr–Dy)

New Germanides with an Ordered Variant of the Ce₃Pt₄Ge₆ Type of Structure – The Compounds Ln₃Pt₄Ge₆ (Ln: Pr–Dy) Six new germanides Ln₃Pt₄Ge₆ with Ln = Pr–Dy were synthesized by heating mixtures of the elements at 900 °C, annealing the inhomogeneous powders at 1050‐1100 °C for six days and then cooling down from 700 °C in the course of two months. The crystal structures of Pr₃Pt₄Ge₆ (a = 26.131(5), b = 4.399(1), c = 8.820(2) Å), Sm₃Pt₄Ge₆ (a = 25.974(3), b = 4.356(1), c = 8.748(1) Å), and Dy₃Pt₄Ge₆ (a = 26.079(5), b = 4.311(1), c = 8.729(2) Å) were determined by single crystal X‐ray methods. The compounds are isotypic (Pnma, Z = 4) and crystallize with an ordered variant of the Ce₃Pt₄Ge₆ type of structure (Cmcm, Z = 2) consisting of CaBe₂Ge₂‐ and YIrGe₂‐analogous units. The platinum atoms are located in distorted square pyramids of germanium atoms and build up with them a three‐dimensional network. The coordination polyhedra of the platinum and germanium atoms around the rare‐earth metal atoms are pentagonal and hexagonal prisms. These are completed by some additional atoms resulting in coordination numbers of 14 and 15 respectively. The other germanides were investigated by powder methods resulting in the following lattice constants: a = 26.067(6), b = 4.388(1), c = 8.800(2) Å for Ln = Nd; a = 25.955(7), b = 4.337(1), c = 8.728(2) Å for Ln = Gd; a = 25.944(5), b = 4.322(1), c = 8.698(2) Å for Ln = Tb. The atomic arrangement of Ln₃Pt₄Ge₆ is compared with the well‐known monoclinic structure of Y₃Pt₄Ge₆.     

Diversity of Strontium Nitridogermanates(IV): Novel Sr4[GeN4], Sr8Ge2[GeN4], and Sr17Ge2[GeN3]2[GeN4]2

Single crystals of three new strontium nitridogermanates(IV) were grown in sealed niobium ampules from sodium flux. Dark red Sr₄[GeN₄] crystallizes in space group P2₁/c with a = 9.7923(2) Å, b = 6.3990(1) Å, c = 11.6924(3) Å and β = 115.966(1)°. Black Sr₈Ge₂[GeN₄] contains Ge^4– anions coexisting with [Ge^IVN₄]^8– tetrahedra and adopts space group Cc with a = 10.1117(4) Å, b = 17.1073(7) Å, c = 10.0473(4) Å and β = 115.966(1)°. Black Sr₁₇Ge₆N₁₄ features the same anions alongside trigonal planar [Ge^IVN₃]^5– units. It crystallizes in P1 with a = 7.5392(1) Å, b = 9.7502(2) Å, c = 11.6761(2) Å, α = 103.308(1)°, β = 94.651(1)° and γ = 110.248(1)°.     

ACu9X4 ‐ Neue Verbindungen mit der CeNi8, 5Si4, 5‐Struktur (A: Sr,Ba; X: Si,Ge)

ACu₉X₄ ‐ New Compounds with CeNi_{8, 5}Si_{4, 5} Structure (A: Sr, Ba; X: Si, Ge) The new compounds SrCu₉Si₄ (a = 8.146(1), c = 11.629(2)Å), BaCu₉Si₄ (a = 8.198(2), c = 11.735(2)Å), SrCu₉Ge₄ (a = 8.273(2), c = 11.909(5)Å), and BaCu₉Ge₄ (a = 8.338(4), c = 12.011(7)Å) are formed by reaction of the elements at 1000° ‐ 1100 °C. They are isotypic (I4/mcm, Z = 4) and crystallize in an ordered variant of the cubic NaZn₁₃ type structure, also built up by the binary phase BaCu₁₃. In the ternary compounds the positions of Cu2 are orderly occupied by copper and silicon and germanium, respectively. This results in a lowering of symmetry and a distortion of the polyhedra. The metallic conductivity of the compounds was confirmed by measurements on BaCu₉Si₄.     

Na2Ge3P3 and Na5Ge7P5 Comprising Heteroatomic Polyanions Mimicking the Structure of Fibrous Red Phosphorus

Recently lithium phosphidogermanates were discovered as fast lithium ion conductors for potential usage as solid electrolytes in all solid-state batteries. In this context we also studied sodium phosphidogermanates since sodium ion conductors are of equal interest. Na₂Ge₃P₃ and Na₅Ge₇P₅ both crystallize in the monoclinic space group C2/m with unit cell parameters of a = 17.639(4) Å, b = 3.6176(7) Å, c = 11.354(2) Å, β = 92.74(3)° and a = 16.168(5) Å, b = 3.6776(7) Å, c = 12.924(4) Å, β = 91.30(3)°, respectively. Both show linearly condensed 9-atom cages of four Ge / five P and five Ge / four P atoms, respectively. These cages contain Ge–Ge bonds and form one-dimensional tubes by sharing three atoms. The parallel tubes are paired through further Ge–Ge bonds. Both structures are closely related to the one of the fibrous type of crystalline red phosphorus. A comparison with other compounds such as NaGe₃P₃ and GeP reveals recurring structural motifs with a broad variety of connection patterns. According to the general formula Na_4+xGe_6+xP_6–x with x = 0 and 1, the two novel structures hint for the possibility of a variable Na content which might allow Na ion mobility.     

Die Kristallstruktur eines neuen Alkalidigermanats,Na4K2Ge2O7

Na₄K₂Ge₂O₇ is monoclinic, space group P 2₁ (No. 4),a=6.010 (3),b=6.020 (3),c=29.26 (1) Å, γ=119.9 (1)° andZ=4. Its crystal structure has been determined from 1210 single crystal X-ray reflections and refined toR=0.114. The structure contains two independent Ge₂O₇ groups, the (GeOGe) angles of which are 128 and 132°.     

Synthese und Kristallstrukturen von DyPt8P2 und Mg10−xPt9P7

Synthesis and Crystal Structures of DyPt₈P₂ and Mg_10?xPt₉P₇ Single crystals of DyPt₈P₂ (a = 9.260(2), b = 4.005(1), c = 9.633(2) Å, β = 102.64(3)°) were grown by heating the elements in a melt of NaCl/KCl at 1100 °C. The phosphide crystallizes in a new type of structure (I2/m; Z = 2) which consists of fragments in the shape of a cubic close packing built up by three fourths of the platinum atoms. The Dy atoms are coordinated by twelve Pt and four P atoms forming a distorted hexagonal prism which is fourfold capped by Pt atoms. Needles of Mg_10?xPt₉P₇ (a = 18.121(4), b = 23.316(5), c = 3.848(1) Å) were obtained by reaction of the elements in molten lead at 1000 °C. The main feature of the new type of structure (Pbam; Z = 4) is an oval ring of pentagonal prisms formed by each six Pt and four P atoms. The prisms are linked with each other via common faces and they are centered by Mg atoms. Another Mg atoms are located in holes of the three‐dimensional [Pt₉P₇] network. It is remarkable, that one of the ten different crystallographic sites of the Mg atoms is occupied incompletely inducing the composition Mg_10?xPt₉P₇ with x = 0.86.     

Na12Ge17: A Compound with the Zintl Anions [Ge4]4— and [Ge9]4— — Synthesis,Crystal Structure,and Raman Spectrum

Na₁₂Ge₁₇ is prepared from the elements at 1025 K in sealed niobium ampoules. The crystal structure reinvestigation reveals a doubling of the unit cell (space group:P2₁/c; a = 22.117(3)Å, b = 12.803(3)Å, c = 41.557(6)Å, β = 91.31(2)°, Z = 16; Pearson code: mP464), furthermore, weak superstructure reflections indicate an even larger C‐centred monoclinic cell. The characteristic structural units are the isolated cluster anions [Ge₉]^4— and [Ge₄]^4— in ratio 1:2, respectively. The crystal structure represents a hierarchical cluster replacement structure of the hexagonal Laves phase MgZn₂ in which the Mg and Zn atoms are replaced by the Ge₉ and Ge₄ units, respectively. The Raman spectrum of Na₁₂Ge₁₇ exhibits the characteristic breathing modes of the constituent cluster anions at ν = 274 cm^—1 ([Ge₉]^4—) and ν = 222 cm^—1 ([Ge₄]^4—) which may be used for identification of these clusters in solid phases and in solutions. Raman spectra further prove that Na₁₂Ge₁₇ is partial soluble both in ethylenediamine and liquid ammonia. The solution and the solid extract contain solely [Ge₉]^4—. The remaining insoluble residue is Na₄Ge₄. By heating the solvate Na₄Ge₉(NH₃)_n releases NH₃ and decomposes irreversibly at 742 K, yielding Na₁₂Ge₁₇ and Ge.     

Three Crystal Structures,One Chemical Formula – Barium Dihydrogen‐hypodiphosphate(IV)‐dihydrate,BaH2P2O6·2H2O

Three polymorphs of barium dihydrogen‐hypodiphosphate(IV)‐dihydrate, BaH₂P₂O₆ · 2H₂O ( A , B and C ), were obtained and structurally characterized by single‐crystal X‐ray diffraction. A crystallizes in the monoclinic space group P2₁/n (no. 14) with a = 7.459(1) Å, b = 8.066(1) Å, c = 12.460(2) Å, β = 91.27(1) ° and Z = 4. B crystallizes in the monoclinic space group C2/c (no. 15) with a = 11.049(8) Å, b = 6.486(3) Å, c = 10.956(6) Å, β = 106.89(5) ° and Z = 4. C crystallizes in the orthorhombic space group C222₁ (no. 20) with a = 9.193(3) Å, b = 6.199(2) Å, c = 12.888(4) Å and Z = 4. Discrete [H₂P₂O₆]^2– units, barium cations and water molecules, held together by intermolecular hydrogen bonds of the type O–H ··· O, build up the structures of the three polymorphs. The phase purity of A and C was verified by powder diffraction measurements.     

Synthesis,Structures, and Properties of Layered Quaternary Chalcogenides of the General Formula ALnEQ4 (A = K,Rb; Ln = Ce,Pr, Eu; E = Si,Ge; Q = S,Se)

Four related quaternary compounds containing rare‐earth metals have been synthesized employing the molten flux method and metathesis. The reactions of Eu and Rb₂S₅ with Si and Ge in evacuated fused silica ampoules at 725 °C for 150 h yielded RbEuSiS₄ ( I ) and RbEuGeS₄ ( II ), respectively. On the other hand, a reaction between CeCl₃ and K₄Ge₄Se₁₀ at 650 °C for 148 h has yielded KCeGeSe₄ ( III ) and KPrSiSe₄( IV ) was obtained by the reaction of elemental Pr, Si and Se in KCl flux at 850 °C for 168 h. Crystal data for these compounds are as follows: I , orthorhombic, space group P2₁2₁2₁ (#19), a = 6.392(1), b = 6.634(2), c = 17.001(3) Å, α = β = γ = 90°, Z = 4; II , monoclinic, space group P2₁/m (#11), a = 6.498(2), b = 6.689(3), c = 8.964(3) Å, β = 108.647(6)°, Z = 2; III , monoclinic, space group P2₁ (#4), a = 6.852(2), b = 7.025(2), c = 9.017(3) Å, β = 108.116(2)°, Z = 2; IV , monoclinic, space group P2₁ (#4), a = 6.736(2), b = 6.943(2), c = 8.990(1) Å, β = 108.262(2)°, Z = 2. The crystal structures of I ‐ IV contain two‐dimensional corrugated anionic layers of the general formula, [LnEQ₄]^? (Ln = Ce, Pr, Eu; E = Si, Ge and Q = S, Se) alternately piled upon layers of alkali cations. In addition to structural elucidation, Raman and UV‐visible spectroscopy, and magnetic measurements for compound III (KCeGeSe₄) are also discussed.     

Studied and Forgotten. A Fresh Look at the Li–Mn–Ge System

The crystal structure of the ternary germanide Li₂MnGe has been re-evaluated from single-crystal X-ray diffraction data. This compound crystallizes in a non-centrosymmetric superstructure of the ZrCuSiAs type (space group P4bm, Pearson code tP16), with the lattice parameters a = 6.088(4) Å, c = 6.323(4) Å. First-principle calculations for the idealized structure predict antiferromagnetic exchange in the square Mn nets and semimetallic ground state. In addition, a new ternary phase with the composition Li_2–xMn_4+xGe₅ (x ≈ 1.2) was discovered. It adopts the V₆Si₅ structure type (space group Ibam, Pearson code oI44), with the lattice parameters a = 7.570(2) Å, b = 16.323(3) Å, c = 5.057(1) Å. DSC/TG measurements show that this compound is thermally stable below 995 K.     

Structural,Magnetic and Thermoelectric Properties of hp-Mn3Ge5

Mn₃Ge₅ was obtained by high-pressure, high temperature synthesis. The compound adopts a Nowotny-Chimney-Ladder type crystal structure [tetragonal, space group P4 n2, a = 5.7449(1) Å, c = 13.9096(4) Å, Z = 4]. Magnetic measurements reveal a ferromagnetic transition around 40 K and metallic conductivity in the temperature range from 3 K to 350 K. Despite a low thermal conductivity, the metallic character of the sample and the low Seebeck coefficient result in low values for the thermoelectric Figure of merit, ZT. Band-structure calculations show that the Fermi level is located slightly below a pseudo-gap in the electronic density of states. Chemical bonding analysis in position space discloses moderate charge transfer and two- as well as three-atomic directed, heteroatomic bonding involving both the manganese and the germanium atoms.     

Crystal structure of a new digermanate: Al2Ge2O7

The structure of Al₂Ge₂O₇ has been determined by using a single crystal. The symmetry is monoclinic ($\text{C2}\text{c}\text{, Z = 4}$) with unit cell parameters a = 7.132(1) Å, b = 7.741(1) Å, c = 9.702(2) Å, β = 110.62(2)°. The structure is characterized by digermanate groups (Ge₂O₇) and by AlO₅ bipyramids with two common edges forming (AlO₃)_∞ chains. The relationship with the thortveitite structure is discussed in terms of coordination polyhedra.     

Synthesis,Crystal Structure,and Vibrational Spectroscopy of the Alkali Diselenates A2Se2O7 (A = Li – Cs)

The reaction of alkali carbonates and selenium acid yielded the “pyroanions” [Se₂O₇]^2– containing alkali diselenates. By varying the alkali carbonates we were able to synthesize and determinate the crystal structures of the whole row from Li to Cs. Li₂Se₂O₇ crystallizes isotypic to Li₂S₂O₇ [Pnma, Z = 4, a = 13.815(3), b = 8.452(2) c = 5.0585(10) Å]. The structure of Na₂Se₂O₇ [P$\bar{1}$ , Z = 2, a = 6.9896(14), b = 6.9938(14), c = 7.0829(14) Å, α = 83.32(3), β = 64.56(3), γ = 83.18(3)°] is isotypic to Ag₂S₂O₇. A₂Se₂O₇ (A = K, Rb) [A = K: C2/c, Z = 4, a = 12.851(3), b = 7.5677(15), c = 7.5677(15) Å, β = 93.35(3)°; A = Rb: C2/c, Z = 4, a = 13.118(3), b = 7.7963(16), c = 7.7811(16) Å, β = 94.03(3)°] are isotypic to K₂S₂O₇. The crystal structure of Cs₂Se₂O₇ [P$\bar{1}$ , Z = 10, a = 7.7271(3), b = 16.2408(8), c = 18.4427(8) Å, α = 89.685(2), β = 89.193(2), γ = 76.251(2)°] seems to be isotypic to the averaged room‐temperature modification of Cs₂S₂O₇. With exception of the caesium compound all diselenate anions show an ecliptic arrangement and can be therefore classified as dichromate‐like structures. In Cs₂Se₂O₇ most of the [Se₂O₇]^2– units have a staggered alignment. The transition between both orientations can be explained by the increase of the cations size. Additionally the vibrational spectra of A₂Se₂O₇ with A = Li – Cs are discussed as well as the resulting bond forces.     

One‐Dimensional Zinc Selenophosphates: A2ZnP2Se6 (A = K,Rb, Cs)

The new compounds A₂ZnP₂Se₆ (A = K, Rb, Cs) were synthesized via molten salt flux syntheses. The crystals feature one‐dimensional ¹/_∞[ZnP₂Se₆]^2– chains charge balanced by alkali metal ions between the chains. K₂ZnP₂Se₆ crystallizes in the monoclinic space group P2₁/c; cell parameters a = 12.537(3) Å, b = 7.2742(14) Å, c = 14.164(3) Å, β = 109.63(3)°, Z = 4, and V = 1216.7(4) ų. Rb₂ZnP₂Se₆ and Cs₂ZnP₂Se₆ are isotypic, crystallizing in the triclinic space group P$\bar{1}$ . Rb₂ZnP₂Se₆ has cell parameters of a = 7.4944(15) Å, b = 7.6013(15) Å, c = 12.729(3) Å, α = 96.57(3)°, β = 105.52(3)°, γ = 110.54(3)°, Z = 2, and V = 636.6(2) ų. Cs₂ZnP₂Se₆ has cell parameters of a = 7.6543(6) Å, b = 7.7006(6) Å, c = 12.7373(11) Å, α = 97.007(7)°, β = 104.335(7)°, γ = 109.241(6)°, Z = 2, and V = 669.54(10) ų.     

Konformation und Vernetzung von (CuCN)6‐Ringen in polymeren Cyanocupraten(I) [Cu2(CN)3—] (n = 2, 3)

Conformation and Cross Linking of (CuCN)₆‐Rings in Polymeric Cyanocuprates(I) equation/tex2gif-stack-8.gif [Cu₂(CN)₃^—] (n = 2, 3) The alkaline‐tricyano‐dicuprates(I) Rbequation/tex2gif-stack-9.gif[Cu₂(CN)₃] · H₂O ( 1 ) and Csequation/tex2gif-stack-10.gif[Cu₂(CN)₃] · H₂O ( 2 ) were synthesized by hydrothermal reaction of CuCN and RbCN or CsCN. The dialkylammonium‐tricyano‐dicuprates(I) [NH₂(Me)₂]equation/tex2gif-stack-11.gif[Cu₂(CN)₃] ( 3 ), [NH₂(iPr)₂]equation/tex2gif-stack-12.gif[Cu₂(CN)₃] ( 4 ), [NH₂(Pr)₂]equation/tex2gif-stack-13.gif[Cu₂(CN)₃] ( 5 ) and [NH₂(secBu)₂]equation/tex2gif-stack-14.gif[Cu₂(CN)₃] ( 6 ) were obtained by the reaction of dimethylamine, diisopropylamine, dipropylamine or di‐sec‐butylamine with CuCN and NaCN in the presence of formic acid. The crystal structures of these compounds are built up by (CuCN)₆‐rings with varying conformations, which are connected to layers ( 1 ) or three‐dimensional zeolite type cyanocuprate(I) frameworks, depending on the size and shape of the cations ( 2 to 6 ). Crystal structure data: 1 , monoclinic, P2₁/c, a = 12.021(3)Å, b = 8.396(2)Å, c = 7.483(2)Å, β = 95.853(5)°, V = 751.4(3)ų, Z = 4, d_c = 2.728 gcm^—1, R₁ = 0.036; 2 , orthorhombic, Pbca, a = 8.760(2)Å, b = 6.781(2)Å, c = 27.113(5)Å, V = 1610.5(5)ų, Z = 8, d_c = 2.937 gcm^—1, R₁ = 0.028; 3 , orthorhombic, Pna2₁, a = 13.504(3)Å, b = 7.445(2)Å, c = 8.206(2)Å, V = 825.0(3)ų, Z = 4, d_c = 2.023 gcm^—1, R₁ = 0.022; 4 , orthorhombic, Pbca, a = 12.848(6)Å, b = 13.370(7)Å, c = 13.967(7)Å, V = 2399(2)ų, Z = 8, d_c = 1.702 gcm^—1, R₁ = 0.022; 5 , monoclinic, P2₁/n, a = 8.079(3)Å, b = 14.550(5)Å, c = 11.012(4)Å, β = 99.282(8)°, V = 1277.6(8)ų, Z = 4, d_c = 1.598 gcm^—1, R₁ = 0.039; 6 , monoclinic, P2₁/c, a = 16.215(4)Å, b = 13.977(4)Å, c = 14.176(4)Å, β = 114.555(5)°, V = 2922(2)ų, Z = 8, d_c = 1.525 gcm^—1, R₁ = 0.070.     

The Sodium Antimony Telluridogermanate(III) Na9Sb[Ge2Te6]2

Systematic studies in the quaternary system Na/Ge/Sb/Te yielded the new compound Na₉Sb[Ge₂Te₆]₂. Its crystal structure is isotypic to Na₉Sb[Ge₂Se₆]₂ (space group C2/c with a = 9.541(2), b = 26.253(7), c = 7.5820(18) Å and β = 122.233(15)°, Z = 2). The structure is characterized by Ge–Ge dumbbells that are octahedrally coordinated by Te, forming ethane‐like [Ge₂Te₆]^6– anions. Cation sites are occupied by Na⁺ as well as shared by Na⁺ and Sb³⁺. Na₉Sb[Ge₂Te₆]₂ is formally obtained from the reaction of one equivalent Na₈[Ge₄Te₁₀] and one equivalent NaSbTe₂. In contrast to members of the metastable solid solution series (NaSbTe₂)_1–x(GeTe)_x, Na₉Sb[Ge₂Te₆]₂ is a thermodynamically stable compound. It is a semiconductor with a bandgap of 1.51 eV.     

Neue Hexachalcogeno‐Hypodiphosphate der Erdalkalimetalle und des Europiums

New Hexachalcogeno‐Hypodiphosphates of Alkaline‐Earth Metals and Europium Six hexathio‐ and hexaseleno‐hypodiphosphates respectively with the formula M₂P₂X₆ (M = Ca, Sr, Eu, Ba; X = S, Se) were prepared by heating the elements at 750 °C (60 h) and their crystal structures were determined by single crystal X‐ray methods. Eu₂P₂S₆ (a = 9.396(2), b = 7.531(2), c = 6.593(2) Å, β = 91.48(2) °), Ba₂P₂S₆ (a = 9.966(1), b = 7.580(2), c = 6.737(2) Å, β = 91.17(3) °), Ca₂P₂Se₆ (a = 9.664(2), b = 7.519(2), c = 6.859(1) Å, β = 92.02(3) °), Sr₂P₂Se₆ (a = 9.844(2), b = 7.788(2), c = 6.963(1) Å, β = 91.50(3) °), Eu₂P₂Se₆ (a = 9.779(2), b = 7.793(2), c = 6.957(1) Å, β = 91.29(3) °), and Ba₂P₂Se₆ (a = 10.355(2), b = 7.862(2), c = 7.046(1) Å, β = 90.83(3) °) are isotypic and crystallize in the high temperature form of Sn₂P₂S₆ (P2₁/n; Z = 2). The discrete ethanlike (P₂X₆)^4— anions in staggered conformation are linked via X—M—X bonds to a three‐dimensional structure and in the course of this Ca²⁺, Sr²⁺, and Eu²⁺ are coordinated by 8 and Ba²⁺ by 8+1 S and Se atoms respectively. Susceptibility measurements of Eu₂P₂S₆ from 2 K to room temperature show Curie‐Weiss behavior with an experimental magnetic moment of 7.43(2) μ_B/Eu. No magnetic ordering was observed down to 2 K. A ¹⁵¹Eu Mössbauer spectrum at 77 K shows only one signal at an isomer shift of δ = —12.6(1) mm/s. The europium atoms in Eu₂P₂S₆ are therefore in a stable divalent oxidation state.     

Intermetallic Phases in the Ca‐Cu‐Sn System

Twelve ternary alloys in the Ca‐Cu‐Sn system were synthesized as a test on the existing phases. They were prepared from the elements sealed under argon in Ta crucibles, melted in an induction furnace and annealed at 700 °C or 600 °C. Four ordered compounds were found: CaCuSn (YbAuSn type), Imm2, a = 4.597(1) Å, b = 22.027(2) Å, c = 7.939(1) Å, Z = 12, wR2 = 0.080, 1683 F² values; Ca₃Cu₈Sn₄ (Nd₃Co₈Sn₄ type), P6₃mc, a = 9.125(1) Å, c = 7.728(1) Å, Z = 2, wR2 = 0.087, 704 F² values; CaCu₂Sn₂ (new structure type), C2/m, a = 10.943(3) Å, b = 4.222(1) Å, c = 4.834(1) Å, β = 107.94(1)°, Z = 2, wR2 = 0.051, 343 F² values; CaCu₉Sn₄ (LaFe₉Si₄ type), I4/mcm, a = 8.630(1) Å, c = 12.402(1) Å, Z = 4, wR2 = 0.047, 566 F² values. In all phases the shortest Cu‐Sn distances are in the range 2.59‐2.66Å, while the shortest Cu‐Cu distances are practically the same, 2.53‐2.54Å, except CaCuSn where no Cu‐Cu contacts occur.     

Alkoxo‐Verbindungen des dreiwertigen Eisen: Synthese und Charakterisierung von [Fe2(OtBu)6], [Fe2Cl2(OtBu)4], [Fe2Cl4(OtBu)2] und [N(nBu)4]2[Fe6OCl6(OMe)12]

Alkoxo Compounds of Iron(III): Syntheses and Characterization of [Fe₂(OtBu)₆], [Fe₂Cl₂(OtBu)₄], [Fe₂Cl₄(OtBu)₂] and [N(nBu)₄]₂[Fe₆OCl₆(OMe)₁₂] The reaction of iron(III)chloride in diethylether with sodium tert‐butylat yielded the homoleptic dimeric tert‐‐butoxide Fe₂(OtBu)₆ ( 1 ). The chloro‐derivatives [Fe₂Cl₂(OtBu)₄] ( 2 ), and [Fe₂Cl₄(OtBu)₂] ( 3 ) could be synthesized by ligand exchange between 1 and iron(III)chloride. Each of the molecules 1 , 2 , and 3 consists of two edge‐sharing tetrahedrons, with two tert‐butoxo‐groups as μ₂‐bridging ligands. For the synthesis of the alkoxides 1 , 2 , and 3 diethylether plays an important role. In the first step the dietherate of iron(III)chloride FeCl₃(OEt₂)₂ ( 4 ) is formed. The reaction of iron(III)chloride with tetrabutylammonium methoxide in methanol results in the formation of a tetrabutylammonium methoxo‐chloro‐oxo‐hexairon cluster [N(nBu)₄]₂[Fe₆OCl₆(OMe)₁₂] ( 5 ). Crystal structure data: 1 , triclinic, P1¯, a = 9.882(2) Å, b = 10.523(2) Å, c = 15.972(3) Å, α = 73.986(4)°, β = 88.713(4)°, γ = 87.145(4)°, V = 1594.4(5) ų, Z = 2, d_c = 1.146 gcm^—1, R₁ = 0.044; 2 , monoclinic, P2₁/n, a = 11.134(2) Å, b = 10.141(2) Å, c = 12.152(2) Å und β = 114.157(3)°, V = 1251.8(4) ų, Z = 2, d_c = 1.377 gcm^—1, R₁ = 0.0581; 3 , monoclinic, P2₁/n, a = 6.527(2) Å, b = 11.744(2) Å, c = 10.623(2), β = 96.644(3)°, V = 808.8(2) ų, Z = 2, d_c = 1.641 gcm^—1, R₁ = 0.0174; 4 , orthorhombic, Iba2, a = 23.266(5) Å, b = 9.541(2) Å, c = 12.867(3) Å, V = 2856(2) ų, Z = 8, d_c = 1.444 gcm^—1, R₁ = 0.0208; 5 , trigonal, P3₁, a = 13.945(2) Å, c = 30.011(6) Å, V = 5054(2) ų, Z = 6, d_c = 1.401 gcm^—1; R_c = 0.0494.