Zur Dimorphie von Nd3Cl[SiO4]2

On the Dimorphism of Nd₃Cl[SiO₄]₂ On reacting NdCl₃, Nd₂O₃, and SiO₂ (molar ratio: 1 : 4 : 6) at 850 °C in evacuated silica tubes, pale violet, hydrolysis resistant neodymium(III) chloride ortho‐silicate Nd₃Cl[SiO₄]₂ can be obtained within seven days. If equimolar amounts of NaCl are added as flux, rod‐ or platelet‐shaped, transparent single crystals of two modifications accumulate simultaneously. The one with the higher density (A‐Nd₃Cl[SiO₄]₂) crystallizes monoclinically (C2/c, no. 15; a = 1416.6(1), b = 638.79(6), c = 872.21(9) pm, β = 98.403(7)°; V_m = 117.55 cm³/mol, Z = 4), whereas the one with the lower density (B‐Nd₃Cl[SiO₄]₂) exhibits orthorhombic symmetry (Pnma, no. 62; a = 709.36(7), b = 1815.7(2), c = 631.48(6) pm; V_m = 122.45 cm³/mol, Z = 4). Two crystallographically independent Nd³⁺ cations exist in each of both crystal structures, which in the A type are surrounded by nine (1 Cl^– + 8 O^2–) and ten (2 Cl^– + 8 O^2–), whilst those in the B type by only two times eight (1 Cl^– + 7 O^2– and 2 Cl^– + 6 O^2–) anions, respectively. Thereby all oxygen atoms of both forms represent members of discrete ortho‐silicate tetrahedra ([SiO₄]^4–). Although both crystal structures are built of alternating anionic double layers {(Nd1)₂[SiO₄]₂}^2– and cationic single layers {(Nd2)Cl}²⁺, there is a higher cross‐linkage of the building units in the A‐type lattice, where the cations are coordinated by three and four tetrahedra edges of ortho‐silicate anions, compared to only two times two of them in the B type. From this an about 4% higher density of Nd₃Cl[SiO₄]₂ results for the A‐type structure (D_x = 5.55 g/cm³) in comparison with B‐type Nd₃Cl[SiO₄]₂ (D_x = 5.33 g/cm³).     

Einkristalle von Y3F[Si3O10] im Thalenit-Typ

Single Crystals of Y₃F[Si₃O₁₀] with Thalenite-Type Structure Colourless, diamond-shaped single crystals of Y₃F[Si₃O₁₀] (monoclinic, P2₁/n; a = 730.38(5), b = 1112.47(8), c = 1037.14(7) pm, β = 97.235(6)°, Z = 4) with thalenite-type structure are obtained upon the reaction of YF₃ with Y₂O₃ and SiO₂ (1 : 4 : 9 molar ratio) in evacuated silica tubes at 700 °C in the presence of CsCl as flux within seven days. The crystal structure consists of triangular [FY₃]⁸⁺ cations and catena-trisilicate anions [Si₃O₁₀]^8–, which exhibit a horseshoe-shape resulting from two vertex-shared terminal [SiO₄] tetrahedra with both staggered and eclipsed conformation relative to the central one. The Y³⁺ cations have coordination numbers of seven plus one (Y1) or seven (Y2 and Y3), but only one F^– anion belongs to each and vice versa, the remainder ligands being oxygen members of [Si₃O₁₀]^8– anions.     

Pr4S3[Si2O7] und Pr3Cl3[Si2O7]: Durch weiche Fremdanionen modifizierte Derivate von Praseodymdisilicat

Pr₄S₃[Si₂O₇] and Pr₃Cl₃[Si₂O₇]: Derivatives of Praseodymium Disilicate Modified by Soft Foreign Anions For synthesizing both the disilicate derivatives Pr₄S₃[Si₂O₇] and Pr₃Cl₃[Si₂O₇], Pr, Pr₆O₁₁ and SiO₂ are brought to reaction with S and PrCl₃, respectively, in suitable molar ratios (850 °C, 7 d) in evacuated silica tubes. By using NaCl as a flux, Pr₄S₃[Si₂O₇] crystallizes as pale green, transparent single crystals (tetragonal, I4₁/amd, a = 1201.6(1), c = 1412.0(2) pm, Z = 8) with the appearance of slightly compressed octahedra. On the other hand, Pr₃Cl₃[Si₂O₇] emerges as pale green, transparent platelets and crystallizes monoclinically (space group: P2₁, a = 530.96(6), b = 1200.2(1), c = 783.11(8) pm, β = 109.07(1)°, Z = 2). In both crystal structures ecliptically conformed [Si₂O₇]^6– units of two corner‐linked [SiO₄] tetrahedra with Si–O–Si bridging angles of 131° in the sulfide and 148° in the chloride disilicate are present. In Pr₄S₃[Si₂O₇] both crystallographically independent Pr³⁺ cations show coordination numbers of 8 + 1 (5 S^2– and 3 + 1 O^2–) and 9 (3 S^2– and 6 O^2–). For Pr1, Pr2 and Pr3 in Pr₃Cl₃[Si₂O₇] coordination numbers of 10 (5 Cl^– and 5 O^2–) and 9 (2 ×; 4 Cl^– and 5 O^2– or 3 Cl^– and 6 O^2–, respectively) occur.     

Ce3Cl5[SiO4] und Ce3Cl6[PO4]: Ein chloridreiches Chloridsilicat und ‐phosphat des Cers im Vergleich

Ce₃Cl₅[SiO₄] and Ce₃Cl₆[PO₄]: A Chloride‐Rich Chloride Silicate of Cerium as Compared to the Phosphate By reacting CeCl₃ with CeO₂, cerium and SiO₂, or P₂O₅, respectively, in molar ratios of 5 : 3 : 1 : 3 or 8 : 3 : 1 : 2, respectively, in sealed evacuated silica tubes (7 d, 850 °C) colorless, rod‐shaped single crystals of Ce₃Cl₅[SiO₄] (orthorhombic, Pnma; a = 1619.7(2), b = 415.26(4), 1423.6(1) pm; Z = 4) and Ce₃Cl₆[PO₄] (hexagonal, P6₃/m; a = 1246.36(9), c = 406.93(4) pm; Z = 2) are obtained as products insensitive to air and water. Excess cerium trichloride as flux promotes crystal growth and can be rinsed off again with water after the reaction. The crystal structures are determined by discrete [SiO₄]^4– or [PO₄]^3– tetrahedra as isolated units. Both, the chloride silicate Ce₃Cl₅[SiO₄] and the chloride phosphate Ce₃Cl₆[PO₄], exhibit structural similarities to CeCl₃ (UCl₃ type), when four or three Cl^– anions are each substituted formally by one [SiO₄]^4– or [PO₄]^3– unit, respectively, in the tripled formula (Ce₃Cl₉). The coordination number for Ce³⁺ is thus raised from nine in CeCl₃ to ten in Ce₃Cl₅[SiO₄] and Ce₃Cl₆[PO₄], along with a drastic reduction of the molar volume with the transition from Ce₃Cl₉ (V_m = 186.17 cm³/mol) to Ce₃Cl₅[SiO₄] (V_m = 144.15 cm³/mol) and Ce₃Cl₆[PO₄] (V_m = 164.84 cm³/mol). The polyhedra of coordination around Ce³⁺ can be described as quadruple‐capped trigonal prisms, which in addition to seven Cl^– anions each also show another three oxygen atoms of two ortho‐silicate or ortho‐phosphate tetrahedra, respectively.     

Sm3Cl[SiO4]2: Ein chlorarmes Chloridorthosilicat des Samariums

Sm₃Cl[SiO₄]₂: A Chlorine‐poor Chloride Orthosilicate of Samarium Pale yellow, plate‐like single crystals of Sm₃Cl[SiO₄]₂ (orthorhombic, Pnma; a = 701.74(8), b = 1800.8(2), c = 626.63(7) pm; Z = 4) are obtained upon the reaction of SmCl₃, Sm₂O₃ and SiO₂ (”︁Kieselgel”︁”︁) in 1 : 4 : 6 molar ratios, most advantageously in the presence of substantial amounts of NaCl as fluxing agent, after seven days at 850 °C in evacuated silica ampoules. The B‐type crystal structure (isotypic with e. g. Yb₃Cl[SiO₄]₂) contains discrete orthosilicate tetrahedra [SiO₄]^4– which form anionic double layers ({(Sm1)₂[SiO₄]₂}^2–) with (Sm1)³⁺. These are alternatingly sheethed along [010] with cationic monolayers ({(Sm2)Cl}²⁺) consisting of (Sm2)³⁺ and Cl^–. Both crystallographically independent Sm³⁺ cations exhibit coordination numbers of eight (Sm1: 1 Cl + 7 O; Sm2: 2 Cl + 6 O) with respect to the involved electronegative particles.     

Sm4S3[Si2O7] und NaSm9S2[SiO4]6: Zwei Sulfidsilicate mit dreiwertigem Samarium

Sm₄S₃[Si₂O₇] and NaSm₉S₂[SiO₄]₆: Two Sulfide Silicates with Trivalent Samarium The sulfide silicates Sm₄S₃[Si₂O₇] and NaSm₉S₂[SiO₄]₆ are obtained as light yellow transparent crystals by the reaction of Sm, Sm₂O₃, S, and SiO₂ with fluxing SmCl₃ or NaCl, respectively, in suitable molar ratios in fused evacuated silica tubes (850 °C, 7 d). Tetragonal crystals of Sm₄S₃[Si₂O₇] (I4₁/amd; Z = 8; a = 1186.4(1); c = 1387.0(2) pm) with ecliptically conformed [Si₂O₇]^6–‐groups of corner sharing [SiO₄]‐tetrahedra are formed. These double tetrahedra as well the sulfide anions (S^2–) coordinate two crystallographically independent metal cations. They provide coordination numbers of 8 + 1 (5 S^2– and 3 + 1 O^2–) for Sm1 and 9 (3 S^2– and 6 O^2–) for Sm2. NaSm₉S₂[SiO₄]₆ crystallizes hexagonally (P6₃/m; Z = 1; a = 975.32(9); c = 676.46(7) pm) in a modified bromapatite‐type structure. The coordination spheres about the two crystallographically different Sm³⁺ cations are built up by oxygen atoms of the orthosilicate units ([SiO₄]^4–) and sulfide anions (S^2–). As a result, Sm1 and Sm2 have coordination numbers of 9 and 8, respectively. Na⁺ and (Sm1)³⁺ occupy the position 4 f in a molar ratio of 1 : 3 whereas the lower coordinated (Sm2)³⁺ occupies the 6 h position.     

[Te8]2[Ta4O4Cl16]: A Two‐dimensional Tellurium Polycation obtained via Ionic Liquid‐Based Synthesis

By reaction of elemental tellurium, tellurium(IV) chloride, tantalum(V) chloride and tantalum(V) oxychloride in the ionic liquid [BMIM]Cl ([BMIM]Cl:1‐Butyl‐3‐methylimidazolium chloride),[Te₈]₂[Ta₄O₄Cl₁₆] is obtained in the form of lucent black crystals. The title compound consists of infinite [Te–Te–(Te₆)]_n²⁺ chains (Te–Te: 264.9(1)–284.3(1) pm) and isolated [Ta₄O₄Cl₁₆]^4– anions. The [Te–Te–(Te₆)]_n²⁺ chains are interconnected to form a two‐dimensional tellurium network (Te–Te: 335.9 pm). Due to this interaction the [Te–Te–(Te₆)]_n²⁺ chains in [Te₈]₂[Ta₄O₄Cl₁₆] show an arrangement that differs significantly from known polycationic [Te₈]_n²⁺ chains. The two‐dimensional tellurium network is finally separated by tetrameric, corner‐sharing oxidochloridotantalate anions [(TaO_2/2Cl_4/1)₄]^4– that are firstly observed. The composition of [Te₈]₂[Ta₄O₄Cl₁₆] is confirmed by EDX analysis; its optical band gap is estimated to 1.1–1.2 eV via UV/Vis spectroscopy.     

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.     

Zwei neue Silicat-Chloride mit zweiwertigem Europium: LiEu3[SiO4]Cl3 und Li7Eu8[SiO4]4Cl7

Two New Silicate-Chlorides with Divalent Europium: LiEu₃[SiO₄]Cl₃ and Li₇Eu₈[SiO₄]₄Cl₇ LiEu₃[SiO₄]Cl₃ was prepared by reaction of LiCl with Eu₂SiO₄ and Li₇Eu₈[SiO₄]₄Cl₇ from Li with Eu₂O₃, SiO₂ and LiCl. The crystal structures of LiEu₃[SiO₄]Cl₃ (Pmna, a = 946.95(13); b = 699.52(8); c = 1 368.0(2) pm; Z = 4; R1 = 0.0325, R2_w = 0.0642) and Li₇Eu₈[SiO₄]₄Cl₇ (P2₁/c; a = 851.85(5); b = 948.62(7); c = 1 679.0(2) pm; β = 96.221(8)°; Z = 2; R1 = 0.0352, R2_w = 0.0744) were determined from four-circle diffractometer data. LiEu₃[SiO₄]Cl₃ contains [Li(SiO₄)₂] units and LiCl₆ octahedra while in Li₇Eu₈[SiO₄]₄Cl₇ larger ?lithosilicate”? groups are found. In both structures, the Eu²⁺ ions are coordinated mostly eightfold by O^2? and Cl^? ligands.     

La2Si2O7 im I—Typ: Gemäß La6[Si4O13][SiO4]2 kein echtes Lanthandisilicat

I‐Type La₂Si₂O₇: According to La₆[Si₄O₁₃][SiO₄]₂ not a Real Lanthanum Disilicate In attempts to synthesize lanthanum telluride silicate La₂Te[SiO₄] (from La, TeO₂, SiO₂ and CsCl, molar ratio: 1 : 1: 1 : 20, 950 °C, 7 d) or fluoride‐rich lanthanum fluoride silicates (from LaF₃, La₂O₃, SiO₂ and CsCl, molar ratio: 5 : 2 : 3 : 17, 700 °C, 7 d) in evacuated silica tubes, colourless lath‐shaped single crystals of hitherto unknown I‐type La₂Si₂O₇ (monoclinic, P2₁/c; a = 726.14(5), b = 2353.2(2), c = 1013.11(8) pm, β = 90.159(7)°) were found in the CsCl‐flux melts. Nevertheless, this new modification of lanthanum disilicate does not contain any discrete disilicate groups [Si₂O₇]^6‐ but formally three of them are dismutated into one catena‐tetrasilicate ([Si₄O₁₃]^10‐ unit of four vertex‐linked [SiO₄]^4‐ tetrahedra) and two ortho‐silicate anions (isolated [SiO₄]^4‐ tetrahedra) according to La₆[Si₄O₁₃][SiO₄]₂. This compound can be described as built up of alternating layers of these [SiO₄]^4‐ and the horseshoe‐shaped [Si₄O₁₃]^10‐ anions along [010]. Between and within the layers the high‐coordinated La ³⁺ cations (CN = 9 ‐ 11) are localized. The close structural relationship to the borosilicates M₃[BSiO₆][SiO₄](M = Ce ‐ Eu) is discussed and structural comparisons with other catena‐tetrasilicates are presented.     

Darstellung von trans-[Mo6Cl8]Cl4Br22−ausgehend von kristallisierten [Mo6Cl8]Cl4(H2O)2 und die Kristallstruktur von [(C6H5)4As]2[Mo6Cl8]Cl4Br2

Preparation of trans-[Mo₆Cl₈]Cl₄Br₂^2? Starting from Crystalline [Mo₆Cl₈]Cl₄(H₂O)₂ and Crystal Structure of [(C₆H₅)₄As]₂[Mo₆Cl₈]Cl₄Br₂ The synthesis of the title compound is successful if the crystallized [(Mo₆Cl₈)Cl₄(H₂O)₂] containing the H₂O molecules in trans-position reacts with HBr + [(C₆H₅)₄As]Br in ethanol in a heterogeneous reaction. The X-ray structure investigation confirms the existence of discrete trans-Br-substituted cluster anions of composition [(Mo₆Cl₈)Cl₄Br₂]^2? in the crystal. The reaction in homogeneous solutions proceeds to Br-enriched compounds. [(C₆H₅)₄As]₂[(Mo₆Cl₈)Cl₄Br₂] crystallizes in the triclinic space group P¯1 with a = 11.071(2), b = 11.418(2), c = 12.813(2) Å, α = 116.10(2), β = 95.27(2) and γ = 94.41(2)° (?133°C). The crystal structure at ?133°C was determined from single crystal X-ray diffraction data (R₁ = 0.026). The [(Mo₆Cl₈)Cl₄Br₂]^2?-anions are not completely ordered but distributed statistically among the three positions which are possible within the limits of the ordered [Mo₆Cl₈]-cores (ratio 11:5:4). The frameworks of the anions consist of Mo₆ cluster units with (slightly distorted) octahedral arrangement of the metal atoms (d(Mo? Mo): 2.600(1) up to 2.614(1) Å), which are coordinated by the halogeno ligands in a square-pyramidal manner. The details of the structure will be discussed and compared with similar [(Mo₆X₈)Y₄] cluster units (X, Y ? Cl, Br).     

Über Thallium(I)-chlorooxomolybdate: Synthese und Kristallstrukturen von Tl[MoOCl4(NCCH3)], Tl[Mo2O2Cl7] und Tl2[Mo4O4Cl14] und die Struktur von Tl2[MoCl6]

On Thallium(I)-oxochloromolybdates: Synthesis and Crystal Structures of Tl[MoOCl₄(NCCH₃)], Tl[Mo₂O₂Cl₇], and Tl₂[Mo₄O₄Cl₁₄] and the Structure of Tl₂[MoCl₆] Black crystals of Tl₂[MoCl₆] are formed in the reaction of TlCl with MoOCl₃ in a sealed evacuated glass ampoule at 350 °C. The crystal structure analysis shows that Tl₂[MoCl₆] (cubic, Fm 3¯m, a = 986.35(7) pm) adopts the K₂[PtCl₆] structure with a Mo–Cl bond length of 236.6 pm. Tl[MoOCl₄(NCCH₃)] was obtained by the reaction of TlCl with MoOCl₃ in acetonitrile in form of yellow, moisture sensitive crystals. The structure (orthorhombic, Cmcm, a = 746.0(1), b = 1463.8(3), c = 857.3(2) pm) is built of Tl⁺ cations and octahedral [MoOCl₄(NCCH₃)]^– anions in which the acetonitrile ligand is bound in trans position to the oxygen. The reaction of TlCl and MoOCl₃ in dichloromethane yields Tl[Mo₂O₂Cl₇] and Tl₂[Mo₄O₄Cl₁₄] as green moisture sensitive crystals. The structure of Tl[Mo₂O₂Cl₇] (orthorhombic, Pmmn, a = 694.3(1), b = 951.9(2), c = 904.7(1) pm) consists of Tl⁺ cations and dinuclear [Mo₂O₂Cl₇]^– anions, with two equidistant chlorine bridges of 248.2 and one longer chlorine bridge of 265.7 pm. The oxygen atoms are located in the trans positions of the longer chloro bridge. The structure of Tl₂[Mo₄O₄Cl₁₄] (triclinic, P1¯, a = 692.8(1), b = 919.6(1), c = 998.9(1) pm, α = 104.94(1)°, β = 90.31(1)°, γ = 108.14(1)°) is build of Tl⁺ cations and [Mo₄O₄Cl₁₄]^2– anions which form tetramers of distorted octahedral, edgesharing (MoOCl₅) units with chlorine atoms in the bridging positions. The oxygen atoms are located in the trans positions of the longest chlorine bridges.     

Rb6LiPr11Cl16[SeO3]12: Ein chloridisch derivatisiertes Rubidium‐Lithium‐Praseodym(III)‐Oxoselenat(IV)

Rb₆LiPr₁₁Cl₁₆[SeO₃]₁₂: A Chloride‐Derivatized Rubidium Lithium Praseodymium(III) Oxoselenate(IV) Transparent green square platelets with often truncated edges and corners of Rb₆LiPr₁₁Cl₁₆[SeO₃]₁₂ were obtained by the reaction of elemental praseodymium, praseodymium(III,IV) oxide and selenium dioxide with an eutectic LiCl–RbCl flux at 500 °C in evacuated silica ampoules. A single crystal of the moisture and air insensitive compound was characterized by X‐ray diffraction single‐crystal structure analysis. Rb₆LiPr₁₁Cl₁₆[SeO₃]₁₂ crystallizes tetragonally in the space group I4/mcm (no. 140; a = 1590.58(6) pm, c = 2478.97(9) pm, c/a = 1.559; Z = 4). The crystal structure is characterized by two types of layers parallel to the (001) plane following the sequence 121′2′1. Cl^? anions form cubes around the Rb⁺ cations (Rb1 and Rb2; CN = 8; d(Rb⁺?Cl^?) = 331 – 366 pm) within the first layer. One quarter of the possible places for Rb⁺ cations within this CsCl‐type kind of arrangement is not occupied, however the Cl^? anions of these vacancies are connected to Pr³⁺ cations (Pr4) above and below instead, forming square antiprisms of [(Pr4)O₄Cl₄]^9? units (d(Pr4?O) = 247–249 pm; d(Pr4?Cl) = 284–297 pm) that work as links between layer 1 and 2. Central cations of the second layer consist of Li⁺ and Pr³⁺. While the Li⁺ cations are surrounded by eight O^2? anions (d(Li?O5) = 251 pm) in the shape of cubes again, the Pr³⁺ cations are likewisely coordinated by eight O^2? anions as square antiprisms (for Pr1, d(Pr1?O2) = 242 pm) and by ten O^2? anions (for Pr2 and Pr3), respectively. The latter form tetracapped trigonal antiprisms (Pr2, d(Pr2?O) = 251–253 pm and 4 × 262 pm) or bicapped distorted cubes (Pr3, d(Pr3?O) = 245–259 pm and 2 × 279 pm). The non‐binding electron pairs (“lone pairs”) at the two crystallographically different Ψ¹‐tetrahedral [SeO₃]^2? anions (d(Se⁴⁺?O^2?) = 169–173 pm) are directing towards the empty cavities between the layer‐connecting [(Pr4)O₄Cl₄]^9? units.     

Zur Kenntnis des Natrium-tetrahydroxoaluminat-chlorids Na2[Al(OH)4]Cl

On the Sodium Tetrahydroxoaluminate Chloride Na₂[Al(OH)₄]Cl The hitherto unknown compound Na₂[Al(OH)₄]Cl was prepared by crystallisation from a NaCl containing sodium aluminate solution. According to the X-ray single crystal investigation (tetragonal, space group P4/nmm, a = 7.541 Å, c = 5.059 Å, Z = 2) the compound represents the first example of a crystalline hydroxoaluminate with monomeric [Al(OH)₄]^? anions. Cl^? shows a quadratic anti prismatic coordination to 4 Na⁺ and over hydrogen bonds to 4 O^2? while Na⁺ is octahedrally coordinated by 4 O^2? and 2 Cl^? (axial). The results of the crystal structure analysis are confirmed by ²⁷Al and ²³Na MAS NMR investigations. Na₂[Al(OH)₄]Cl decomposes at about 200°C without intermediates under formation of β-NaAlO₂ and NaCl.     

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.     

Einkristalle des Cer(III)‐Borosilicats Ce3[BSiO6][SiO4]

Single Crystals of the Cerium(III) Borosilicate Ce₃[BSiO₆][SiO₄] Colorless, lath‐shaped single crystals of Ce₃[BSiO₆]‐ [SiO₄] (orthorhombic, Pbca; a = 990.07(6), b = 720.36(4), c = 2329.2(2) pm, Z = 8) were obtained in attempts to synthesize fluoride borates with trivalent cerium in evacuated silica tubes by reaction of educt mixtures of elemental cerium, cerium dioxide, cerium trifluoride, and boron sesquioxide (Ce, CeO₂, CeF₃, B₂O₃; molar ratio 3 : 1 : 3 : 3) in fluxing CsCl (700 °C, 7 d) with the glass wall. The crystal structure contains eight‐ (Ce1) and ninefold coordinated Ce³⁺ cations (Ce2 and Ce3) surrounded by oxygen atoms. Charge balance is achieved by both discrete borosilicate ([BSiO₆]^5– ≡ [O₂BOSiO₃]^5–) and ortho‐silicate anions ([SiO₄]^4–). The former consists of a [BO₃] triangle linked to a [SiO₄] tetrahedron by a single vertex. The anions form layers in [001] direction alternatingly built up from [BSiO₆]^5– and [SiO₄]^4– groups while Ce³⁺ cations are located in between.     

Bis(N‐acetyltriethylphosphaniminium)‐tetraacetato‐dichloro‐dicuprat(II), [MeC(O)N(H)PEt3]2[Cu2(O2C–Me)4Cl2]

Bis(N‐acetyltriethylphosphaneiminium)‐tetraacetato‐dichloro‐dicuprate(II), [MeC(O)N(H)PEt₃]₂[Cu₂(O₂C–Me)₄Cl₂] The title compound has been prepared by the reaction of Me₃SiNPEt₃ with [Cu₂(O₂C–Me)₄] and MeC(O)Cl in dichloromethane solution to give colourless crystals which include four molecules CH₂Cl₂ per formula unit. The complex is characterized by IR spectroscopy and by a crystal structure determination. [MeC(O)N(H)PEt₃]₂[Cu₂(O₂C–Me)₄Cl₂] · 4 CH₂Cl₂: Space group P2₁/n, Z = 2, lattice dimensions at –70 °C: a = 794.1(1), b = 2356.9(6), c = 1327.3(2) pm; β = 91.00(1)°; R₁ = 0.0597. The structure consists of N‐acetyltriethylphosphaneiminium cations and dianions [Cu₂(O₂C–Me)₄Cl₂]^2– which form an iontriple with N–H…Cl hydrogen bridges.     

Synthese,Kristallstrukturen und Magnetismus von (Hg6As4)[MoCl6]Cl, (Hg6As4)[TiCl6]Cl und (Hg6As4)[TiBr6]Br

Polycationic Hg–As Frameworks with Trapped Anions. II Synthesis, Crystal Structure, and Magnetism of (Hg₆As₄)[MoCl₆]Cl, (Hg₆As₄)[TiCl₆]Cl, and (Hg₆As₄)[TiBr₆]Br (Hg₆As₄)[MoCl₆]Cl is obtained by reaction of Hg₂Cl₂, Hg, As, and MoCl₄ in closed, evacuated glass ampoules in a temperature gradient 450 → 400 °C in form of dark red cubelike crystals. (Hg₆As₄)[TiCl₆]Cl and (Hg₆As₄)[TiBr₆]Br are also formed in closed, evacuated ampoules from Hg₂X₂ (X = Cl, Br), Hg, As, and Ti metal at 275 °C and 245 °C in form of dark green and black crystals, respectively. All three compounds are air and light sensitive. They crystallize isotypically (cubic, Pa 3, a = 1207.8(4) pm for (Hg₆As₄)[MoCl₆]Cl, a = 1209.4(3) pm for (Hg₆As₄)[TiCl₆]Cl, a = 1230.9(3) pm for (Hg₆As₄)[TiBr₆]Br, Z = 4). The structures consist of a three‐dimensionally connected Hg–As framework which is made up of As₂ groups (As–As distance averaged 242 pm) each connected via six Hg atoms to six neighbouring As₂ groups. There are two cavities of different size in the polycationic framework. The bigger cavity is filled with [MoCl₆]^3–, [TiCl₆]^3–, and [TiBr₆]^3– ions of nearly ideal octahedral shape, the smaller cavity with discrete halide ions. The magnetic properties of the two Ti containing compounds are in accordance with a d¹ paramagnetism. The temperature dependence and the magnitude of the magnetic moment can be interpreted with consideration of the spin‐orbit coupling. The so far known representatives of this structure type can be characterised by the ionic formula (Hg₆Y₄)⁴⁺[MX₆]^3–X^– (Y = As, Sb; M = Sb³⁺, Bi³⁺, Mo³⁺, Ti³⁺; X = Cl, Br).     

Synthese und Kristallstruktur des Fluorid‐ino‐Oxosilicats Cs2YFSi4O10

Synthesis and Crystal Structure of the Fluoride ino‐Oxosilicate Cs₂YFSi₄O₁₀ The novel fluoride oxosilicate Cs₂YFSi₄O₁₀ could be synthesized by the reaction of Y₂O₃, YF₃ and SiO₂ in the stoichiometric ratio 2 : 5 : 3 with an excess of CsF as fluxing agent in gastight sealed platinum ampoules within seventeen days at 700 °C. Single crystals of Cs₂YFSi₄O₁₀ appear as colourless, transparent and water‐resistant needles. The characteristic building unit of Cs₂YFSi₄O₁₀ (orthorhombic, Pnma (no. 62), a = 2239.75(9), b = 884.52(4), c = 1198.61(5) pm; Z = 8) comprises infinite tubular chains of vertex‐condensed [SiO₄]^4? tetrahedra along [010] consisting of eight‐membered half‐open cube shaped silicate cages. The four crystallographically different Si⁴⁺ cations all reside in general sites 8d with Si–O distances from 157 to 165 pm. Because of the rigid structure of this oxosilicate chain the bridging Si–O–Si angles vary extremely between 128 and 167°. The crystallographically unique Y³⁺ cation (in general site 8d as well) is surrounded by four O^2? and two F^? anions (d(Y–O) = 221–225 pm, d(Y–F) = 222 pm). These slightly distorted trans‐[YO₄F₂]^7? octahedra are linked via both apical F^? anions by vertex‐sharing to infinite chains along [010] (?(Y–F–Y) = 169°, ?(F–Y–F) = 177°). Each of these chains connects via terminal O^2? anions to three neighbouring oxosilicate chains to build up a corner‐shared, three‐dimensional framework. The resulting hexagonal and octagonal channels along [010] are occupied by the four crystallographically different Cs⁺ cations being ten‐, twelve‐, thirteen‐ and fourteenfold coordinated by O^2? and F^? anions (viz.[(Cs1)O₁₀]^19?, [(Cs2)O₁₀F₂]^21?, [(Cs3)O₁₂F]^24?, and [(Cs4)O₁₂F₂]^25? with d(Cs–O) = 309–390 pm and d(Cs–F) = 360–371 pm, respectively).     

Metallampullen als Mini‐Autoklaven: Synthese und Kristallstrukturen der Ammoniakate [Al(NH3)4Cl2][Al(NH3)2Cl4] und (NH4)2[Al(NH3)4Cl2][Al(NH3)2Cl4]Cl2

Metal Ampoules as Mini‐Autoclaves: Syntheses and Crystal Structures of [Al(NH₃)₄Cl₂][Al(NH₃)₂Cl₄] and (NH₄)₂[Al(NH₃)₄Cl₂][Al(NH₃)₂Cl₄]Cl₂ The salts [Al(NH₃)₄Cl₂]⁺[Al(NH₃)₂Cl₄]^–≡AlCl₃ · 3 NH₃ ( 1 ) and (NH₄⁺)²[Al(NH₃)₄Cl₂]⁺[Al(NH₃)₂Cl₄]^–(Cl^–)₂≡ AlCl₃ · 3 NH₃ · (NH₄)Cl ( 2 ) have been obtained as single crystals during the reactions of aluminum and aluminum trichloride, respectively, with ammonium chloride in sealed Monel metal containers. The crystal structure of 1 was determined again [triclinic, P‐1; a = 574.16(10); b = 655.67(12); c = 954.80(16) pm; α = 86.41(2); β = 87.16(2); γ = 84.89(2)°], that of 2 for the first time [monoclinic, I2/m; a = 657.74(12); b = 1103.01(14); c = 1358.1(3) pm; β = 103.24(2)°].