Synthesis and Structure of Ba7F12Cl2

Crystals of ordered and disordered Ba₇F₁₂Cl₂ were prepared by flux growth and solid state reactions. These new structures were characterized by single crystal and powder X‐ray diffraction. The disordered variant which shows disorder on one of the cation sites was obtained from a BaF₂ + BaCl₂ + NaCl/NaF flux. It has hexagonal space group P6₃/m (176) with one formula unit per unit cell. The lattice constants are a = b = 1059.55(5) pm and c = 420.10(4) pm (at 21 °C). The structure was refined to R(R_w) = 0.026(0.030) for 346 independent reflections and 26 parameters. Slow cooling of a mixture of BaF₂ and LiCl yields the ordered variant. This one crystallizes in the hexagonal space group P6 (174) with one formula per unit cell. Lattice constants at 21 °C are a = b = 1063.46(2) pm and c = 417.52(1) pm. The structure was refined to R(R_w) = 0.017 (0.017) for 638 independent reflections and 45 parameters. The structural arrangement and the interatomic distances of the two variants are mutually similar. The barium atoms have coordination number nine. Propeller‐type arrangements with a chloride ion on the axis and the fluoride ions as blades are observed. These latter ones are interconnected into ‘channels' of tricapped fluoride prisms. Occupation disorder of the barium sites in the channels of the disordered variant makes the main difference between the two. An unexpectedly high X‐ray density obtained for both variants of Ba₇F₁₂Cl₂ can be correlated to the density of other barium fluorohalides having a coordination number of nine for the barium ion.     

LiSr2[ReN4] und LiBa2[ReN4] – isotype Nitridorhenate(VII)

LiSr₂[ReN₄] and LiBa₂[ReN₄] – isotypic Nitridorhenates(VII) The quaternary nitridorhenates(VII) LiAE₂[ReN₄] (AE = Sr, Ba) were synthesized by reaction of the metals with molecular nitrogen at 850–900 °C. The plate‐like, nearly colourless crystals were investigated by X‐ray single crystal methods and were identified as isotypic phases: LiSr₂[ReN₄] (LiBa₂[ReN₄]); monoclinic, P2₁/m; a = 614.64(8) pm (651.04(12) pm), b = 585.97(6) pm (b = 598.86(9) pm), c = 689.70(17) pm (737.43(5) pm), β = 106.375(4)° (108.535(2)°); Z = 2. Crystals of the strontium compound were systematically twinned along [001]. In the crystal structures of the quaternary compounds the alkaline earth‐ and nitride‐ ions are arranged in the motif of the InNi₂‐type structure. Strontium and barium are in a trigonal prismatic coordination by nitrogen (Sr–N: 261.0(7)–284.3(4) pm; Ba–N: 278.0(7)–303.0(6) pm). One half of the tetrahedral voids within the partial structure formed by stacking of trigonal prismatic rod layers is occupied by rhenium (formation of [Re^VIIN₄]^5–‐tetrahedra; Re–N: 181.0(6)–184.5(8) pm), lithium takes the positions of the remaining tetrahedral sites (Li–N: 2 × 198(1) pm, 224(2) pm and 228(2) pm for the strontium phase). In the barium compound the lithium positions show a larger shift from the tetrahedral centres towards a tetrahedral plane (Li–N: 2 × 195(1) pm, 213(2) pm and 304(2) pm).     

BiGaIn2S6 – Synthese,Struktur und Eigenschaften

BiGaIn₂S₆ – Synthesis, Structure, and Properties The novel compound BiGaIn₂S₆ was obtained in the quaternary system Bi–Ga–In–S. BiGaIn₂S₆ forms red transparent platelets and exhibits a range of homogeneity between BiGa₁In₂S₆ and BiGa_0.8In_2.2S₆. The compound is a semiconductor with E_g(opt.) = 1.9 eV. – BiGaIn₂S₆ crystallizes monoclinically forming a new structure type (a = 1112.0 pm, b = 380.6 pm, c = 1228.0 pm, β = 116.30°, Z = 2, space group P2₁/m, no. 11). The S atoms form strongly corrugated 2 D fragments of the (hc)₂ sphere packing type. The In atoms occupy octahedral holes (d(In–S) = 262 pm) and the Ga atoms tetrahedral holes (d(Ga–S) = 234 pm) inside the 2 D-layers. The Bi atoms on the top of trigonal BiS₃ pyramids (d(Bi–S) = 265 pm) are at the periphery of the layers and have four additional S ligands from the neigbouring layer at much larger distances (d(Bi–S) = 319 pm). – The bonding of a Bi^III sulfide is analyzed for the first time by the Electron Localization Function (ELF).     

Zur Kenntnis des Bariumhexahydroxoplatinats BaPt(OH)6 · H2O

On Barium Hexahydroxoplatinate BaPt(OH)₆ · H₂O The crystal structure of BaPt(OH)₆ · H₂O, monoclinic, space group P2₁/m, a = 628.4, b = 624.6, c = 857.4 pm, β = 108.19°, Z = 2, contains octahedral Pt(OH)₆ groups and ninefold-coordinated barium. The water molecules are not coordinated to metal atoms but connected with Pt(OH)₆ groups only by very weak hydrogen bonds with oxygen-oxygen distances of 292—296 pm. The compound is dehydrated readily when dried gently. This explains contradictory evidence concerning its water content.     

Nd3Si5AlON10 – Synthese,Kristallstruktur und Eigenschaften eines Sialons im La3Si6N11‐Strukturtyp

Nd₃Si₅AlON₁₀ – Synthesis, Crystal Structure, and Properties of a Sialon Isotypic with La₃Si₆N₁₁ Nd₃Si₅AlON₁₀ was synthesized by the reaction of silicon diimide, aluminium nitride, aluminium oxide, and neodymium in a pure nitrogen atmosphere at 1650 °C using a radiofrequency furnace. The compound was obtained as a coarsely crystalline solid. According to the single‐crystal structure determination the title compound is isotypic with Ln₃Si₆N₁₁ (Ln = La, Ce, Pr, Nd, Sm). Nd₃Si₅AlON₁₀ (P4bm, a = 1007.8(1), c = 486.3(1) pm, Z = 2, R₁ = 0.016, wR₂ = 0.031) is built up by a three‐dimensional network structure of corner sharing SiON₃ and (Si/Al)N₄ tetrahedra (molar ratio Si : Al = 3 : 1). According to lattice energetic calculations using the MAPLE concept a differentiation of O and N seems to be reasonable. One of the two different sites for the tetrahedral centres is probably occupied by Si (distances: Si–O: 168.4(1), Si–N: 173.6(3)–176.0(4) pm) the second site by Si and Al with the molar ratio 3 : 1 (distances: (Si/Al)–N: 172.0(3)–176.6(2) pm). The Nd³⁺ ions are located in the voids of the (Si₅AlON₁₀)^9– framework (distances: Nd–O: 261.07(8), Nd–N: 246.1(2)–286.6(2) pm).     

Chromhexacyano‐Komplexe: Die Kristallstrukturen der Cyanoelpasolithe (NMe4)2ACr(CN)6 (A = K,Cs) und der kubischen Bariumverbindung Ba3[Cr(CN)6]2 · 20 H2O

Chromium Hexacyano Complexes: The Crystal Structures of the Cyano Elpasolites (NMe₄)₂ACr(CN)₆ (A = K, Cs) and of the Cubic Barium Compound Ba₃[Cr(CN)₆]₂ · 20 H₂O The crystal structures of the cyano elpasolites (NMe₄)₂KCr(CN)₆ (a = 1527.3(1), b = 888.1(1), c = 1539.0(1) pm, β = 109.92(1)°; C2/c, Z = 4) and (NMe₄)₂CsCr(CN)₆ (a = 1278.9(1) pm; Fm3m, Z = 4), as well as of the cubic compound Ba₃[Cr(CN)₆]₂ · 20 H₂O (a = 1631.0(1) pm; Im3m, Z = 4) were determined by X‐ray methods with single crystals. Reasons for the enlarged distances within the [Cr(CN)₆]^3–‐octahedron of the K compound (Cr–C: 209.3 pm) compared to the observations within both cubic complexes (206.1 resp. 206.9 pm) are discussed in context with the tolerance factors of cyano elpasolites. As is the case there concerning the cyano bridges Cr–CN–A towards the alkali ions the novel structure type of the barium compound, too, exhibits nearly linear bridging towards Ba. It contributes, however, only four N ligands to the ninefold [BaN₄O₅] coordination; part of the aqua ligands show disorder (Ba–N: 287.5, Ba–O: 281/293 pm).     

Synthese und Kristallstruktur von PbMo5O8; ein reduziertes Oxomolybdat mit Mo10O28-Oktaederdoppeln

Synthesis and Crystal Structure of PbMo₅O₈; a reduced Oxomolybdate with Mo₁₀O₂₈ Double Octahedra The crystal structure of the new phase PbMo₅O₈ contains oligometric Mo clusters which consist of two edge-sharing Mo₆ octahedra connected according to Mo₁₀OOO. The compound is isotypic with LaMo₅O₈. Isolated, divalent Pb atoms are located in the “channels” of the monoclinic structure (a = 999.3(2) pm, b = 924.7(1) pm, c = 753.6(2) pm, β = 109.39(2)°, P2₁/a. Compared to the compound In ₁₁Mo₄₀O₆₂ the Mo? O distances (average 206 pm) and the Mo? Mo distances within the octahedral units (average 275 pm) are slightly decreased by 1 and 4 pm, respectively. The very short Mo? Mo distances (278 pm) between the cluster units which are not observed in In₁₁Mo₄₀O₆₂ (320 pm) are due to excess electrons in these inter-cluster bonds which would otherwise occupy antibonding cluster states.     

Die Kristallstrukturen der Polyselenide [Cs(18-Krone-6)]2Se5 · DMF, [Rb(222-Crypt)]2Se6, [Ba(15-Krone-5)2]Se6 · DMF und [Na(12-Krone-4)2]2Se7

Crystal Structures of the Polyselenides [Cs(18-Crown-6)]₂Se₅ · DMF, [Rb(222-Crypt)]₂Se₆, [Ba(15-Crown-5)₂]Se₆ · DMF, and [Na(12-Crown-4)₂]Se₇ . The title compounds have been prepared by reactions of the corresponding diselenides with excess selenium in the presence of crown ethers in dimethylformamide solutions, forming black crystals. [Cs(18-Crown-6)]₂Se₅ · DMF: Space group P2₁/m, Z = 2, 2 194 observed unique reflections, R = 0.119. Lattice dimensions at 20°C: a = 1 041.2; b = 1 496.3; c = 1 459.7 pm; β = 100.39°. The compound forms an ionic triple with Cs…Se-contacts between 374 and 381 pm. [Rb(222-Crypt)]₂Se₆: Space group P1 , Z = 2, 7 405 observed unique reflections, R = 0.056. Lattice dimensions at – 70°C: a = 1 106.8; b = 1 460.8; c = 1 718.8 pm; α = 89.22°; β = 86.65°; γ = 71.53°. The compound contains Se₆^2? chains without direct contact with each other. [Ba(15-Crown-5)₂]Se₆ · DMF: Space group P2₁/n, Z = 4, 2 680 observed unique reflections, R = 0.055. Lattice dimensions at – 80°C: a = 1 051.9; b = 1 322.4; c = 2 729.9 pm; β = 100.93°. The compound contains Se₆^2? chains, which are isolated from each other by the cations and the included DMF molecules. [Na(12-Crown-4)₂]₂Se₇: Space group P1 , Z = 2, 7 313 observed unique reflections, R = 0.042. Lattice dimensions at – 70°C: a = 1 260.9; b = 1 433.6; c = 1 462.9 pm; α = 80.27°; β = 78.60°; γ = 69.34°. The compound contains Se₇^2? chains without direct contacts with each other.     

Synthesis and Crystal Structure of BaLaSi2H0.80

The polyanionic compound BaLaSi₂ featuring cis-trans silicon chains takes up hydrogen to form a hydride BaLaSi₂H_0.80. The crystal structure of the parent intermetallic compound is largely retained upon hydrogenation with the same space group type, a unit cell volume increase of 3.29 % and very similar atomic positions in the hydride. Hydrogen could be located in the crystal structure by neutron diffraction on the deuteride. Deuterium atoms occupy a tetrahedral Ba₃La interstitial with 40.6(2) % occupation (Cmcm, a = 464.43(4) pm, b = 1526.7(1) pm, c = 676.30(6) pm). BaLaSi₂H_0.80 is thus an interstitial Zintl phase hydride like LaSiH_1–x, but unlike BaSiH_2–x does not feature any covalent Si–H bonds. Si–Si distances within the polyanion increase upon hydrogenation from 240.1(6) and 242.9(5) pm to 244.7(2) pm and 245.5(2) pm. This is probably due to oxidation of the polyanion by hydrogen, which leads to the formation of hydride ions and the depopulation of the polyanion's antibonding π* states. Interatomic Ba–D [260.9(4) pm, 295.7(5) pm] and La–D distances [241.2(7) pm] are in the typical range of ionic hydrides.     

Ein grünes,paramagnetisches Goldfluorid – Sn1−xAuxF4?

A Green Paramagnetic Gold Fluoride – Sn_1?xAu_xF₄? Green single crystals were obtained by heating (Au-tube, 450° – 500°C) a mixture of SnF₂ and AuF₃ (Sn : Au = 1 : 1) which correspond to the SnF₄-type [2, 3] (two single crystals, A: 762 I_o, R1 = 2.4%; B: 1591 I_o, R1 = 1.2% (SHELXL-93); I4/mmm (No. 139); B: a = 404.8(1) pm, c = 796.4(1) pm, c/a = 1.97, Z_F2 = 0.2354). Due to atom absorption and Mössbauer measurements the crystals contain Au. The compound is paramagnetic and follows the Curie-Weiß law (14.7–251.3 K, θ = ?12 K, μ/μ_B = 1.55). ESR-experiments confirm that Au is surrounded by 6 F^? according to Sn in SnF₄ (2 short (187.5 pm) and 4 longer (202.4 pm) distances). The observed Mössbauer spectra could not be interpreted yet, but they don't correspond to any known.     

Darstellung und Kristallstruktur von SnTl4Se3 mit einer Anmerkung zu TlSe

Preparation and Crystal Structure of SnTl₄Se₃ with a Note on TlSe We describe the preparation and crystal structure of SnTl₄Se₃. It crystallizes as a low symmetric distorted derivative with the In₅Bi₃ type of structure, which itself should be considered as a subfamily of the Cr₅B₃ type of structure: a = 852.2(2) pm, c = 1 272.2(6) pm, c/a = 1.49, Z = 4. Short Sn? Se distances of 311 pm, and 326 pm, respectively, are obtained in [SnSe_2/2] chains running along [001]. Furthermore, short Tl? Se distances are found in quasimolecular bent moieties Tl₂Se: 300 pm, 313 pm, and 347 pm, respectively. SnTl₄Se₃ is a semiconductor. The conductivity of some closely related phases are also reported. Finally, the structure of the well known compound TlSe has been refined for the first time, in order to get some more information about Tl¹⁺? Se distances for square-antiprismatic coordinated Tl¹⁺ ions.     

The crystal structure of barium manganese(II) iron(III) fluoride BaMnFeF7

The crystal structure of the monoclinic compound BaMnFeF₇ has been determined: a = 553.2(1), b = 1098.0(2), c = 918.3(1) pm, β = 94.67(1)°, V = 555.9(3) × 10^?24 cm³, Z = 4. All atoms are in general positions of space group $\text{P2}{}_1\text{c}$, weighted R = 0.031, using 1771 independent single-crystal reflections with I > 2σ(I). The structure consists of edge-sharing dinuclear Mn₂F^6?₁₀ units (MnMn = 322.2 pm), linked via corners by intermediate FeF₆ octahedra, at which two cis ligands remain unbridged. The average distances in the distorted octahedra are MnF = 211.6 pm and FeF = 192.7 pm. The barium atoms are irregularly 12-coordinated with a mean distance BaF = 290.5 pm. The structure is discussed in relation to the trigonal weberite Na₂MnFeF₇ and others.     

Synthesis and Crystal Structures of Novel Copper(I) Clusters with Bridging Silyl Amide Ligands

Treatment of copper(I) chloride with R₂Si(NLiPh)₂ (R = Me, Ph) in thf led to the formation of the octanuclear cluster compounds [Cu₈{(R₂Si(NPh)₂}₄] [R = Me ( 1 ), Ph ( 2 ).] Compound 1 crystallizes in the tetragonal space group P4/n, with a = 1505.41(5) and c = 1911.32(7) pm. The X‐ray crystal structure determination revealed a cube shaped Cu₈ cluster core with μ₄ bridging Me₂Si(NPh)₂^2– ligands. The copper atoms display an almost linear coordination with Cu–N distances in the range of 191.1(3)–191.4(3) pm. The Cu–Cu distances are 265.7(1)–267.3(1) pm. Compound 2 forms monoclinic crystals, space group P2₁/n, with a = 1461.87(4), b = 2483.77(6), c = 2725.49(8) pm, β = 100.77(1)°. The cluster core of compound 2 consists formally of two mutually perpendicular arranged trigonal prisms, which share a common square face. Like in the case of compound 1 the square faces of the cluster core are capped by μ₄ bridging Ph₂Si(NPh)₂^2– ligands. The copper atoms adopt a nearly linear N–Cu–N coordination with Cu–N distances of 190.0(4)–195.1(4) pm. The Cu–Cu distances are 252.3(1)–305.6(1) pm.     

Die Kristallstruktur des Oxophosphazens [Ph3PNPPh2NP(O)Ph2]

Crystal Structure of the Oxophosphazene [Ph₃PNPPh₂NP(O)Ph₂] Single crystals of [Ph₃PNPPh₂NP(O)Ph₂] were obtained as a by‐product from the synthesis of [NaNPPh₃]₆ as a result of partial hydrolysis. According to the crystal structure determination the compound forms a molecular structure with a PNPNP chain with PN distances between 155.3(6) and 159.8(5) pm and PNP bond angles of 143.2(4) and 140.7(4)°. Space group P1¯, Z = 2, lattice dimensions at 213 K: a = 922.7(1); b = 1040.1(1); c = 1908.0(1) pm; α = 90.55(1)°; β = 103.01(1)°; γ = 92.87(1)°; R = 0.0859.     

Synthese und Charakterisierung heterobimetallischer Bis(trimethylsilyl)phosphanide von Barium und Zinn

Synthesis and Characterization of Hetero-bimetallic Bis(trimethylsilyl)phosphanides of Barium and Tin The reaction of barium bis[bis(trimethylsilyl)amide] with one equivalent of bis(trimethylsilyl)phosphane in 1,2-dimethoxyethane (dme) yields the heteroleptic dimeric (dme)barium bis(trimethylsilyl)amide bis(trimethylsilyl)phosphanide. This colorless compound crystallizes in the monoclinic space group P2₁/n with a = 1 259.1(3), b = 1 822.7(4), c = 1 516.1(3) pm, β = 110.54(3)° and Z = 4. The central moiety of the centrosymmetric molecule is the planar Ba₂P₂-cycle with Ba? P-bond lengths of 329 and 334 pm. In the presence of bis[bis(trimethylsilyl)amino]stannylene hetero-bimetallic bis(trimethylsilyl)phosphanides of tin(II) and barium are isolated. If the reaction of Ba[N(SiMe₃)₂]₂ and Sn[N(SiMe₃)₂]₂ in the molar ratio of 1:2 with six equivalents of HP(SiMe₃)₂ is performed in toluene, barium bis{tin(II)-tris[bis(trimethylsilyl)phosphanide]} can be isolated. This compound crystallizes in the orthorhombic space group P2₁2₁2₁ with a = 1 265.1(1), b = 2 290.1(3), c = 2 731.9(3) pm and Z = 4. The anions {Sn[P(SiMe₃)₂]₃}^? bind as two-dentate ligands to the barium atom which shows the extraordinary low coordination number of four. The addition of tetrahydrofuran (thf) to the above mentioned reaction solution leads to the elimination of tris(trimethylsilyl)phosphane and the formation of thf complexes of barium bis{tin(II)-bis(trimethylsilyl)phosphanide-trimethylsilylphosphandiide}. The derivative crystallizes from toluene in the monoclinic space group P2₁/c with a = 1 301.9(2), b = 2 316.3(3), c = 3 968.7(5) pm, β = 99.29(1)° and Z = 8.     

Einkristalluntersuchungen an LiMF6 (M = Rh,Ir), Li2RhF6 und K2IrF6

Single Crystal Investigations on LiMF₆ (M = Rh, Ir), Li₂RhF₆, and K₂IrF₆ LiRhF₆, LiIrF₆, Li₂RhF₆, and K₂IrF₆ were obtained again, but for the first time investigated by single crystal X‐ray methods. Rubyred LiRhF₆ and yellow LiIrF₆ crystallize isostructural in the trigonal space group R3 – C²_3i (Nr. 148) with the lattice parameters LiRhF₆: a = 502.018(7) pm, c = 1355.88(3) pm, Z = 3 and d(Rh–F) = 185.5(1) pm; LiIrF₆: a = 506.148(4) pm, c = 1362.60(2) pm, Z = 3, d(Ir–F) = 187.5(3) pm (LiSbF₆‐Typ). Yellow Li₂RhF₆ crystallizes tetragonal in the space group P4₂/mnm – D¹⁴_4h (Nr. 136) with a = 463.880(8) pm, c = 905.57(2) pm, Z = 2 and d(Rh–F) = 190.3(4)–191.4(3) pm (Trirutil‐Typ). Yellow K₂IrF₆ crystallizes trigonal in the space group P3m1 – D³_3d (Nr. 164) with a = 578.88(7) pm, c = 465.06(5) pm, Z = 1 and d(Ir–F) = 194.0(6) pm, isotypic with K₂GeF₆.     

Synthese und Struktur von [(Ph3PAu)6Co(CO)2](PF6) und [(Ph3PAu)7Co(CO)2](PF6)2

Synthesis and Structure of [(Ph₃PAu)₆Co(CO)₂](PF₆) and [(Ph₃PAu)₇Co(CO)₂](PF₆)₂ By the reaction of (Ph₃PAu)₄Co[(CO)₃]⁺ with OH^? in the presence of excess Ph₃PAuCl the larger cluster cations [(Ph₃PAu)₆Co(CO)₂]⁺ ( 1 ) and [(Ph₃PAu)₇Co(CO)₂]²⁺ ( 2 ) can be built up with 1 being the main product. 1 crystallizes with PF^?₆ as counterion in the monoclinic space group C2/c with a = 3008.3(6); b = 1339.1(2); c = 2909.4(6) pm; β = 103.08(1)°; Z = 4. The inner core of the cluster cation 1 with the symmetry C₂ has the form of a bicapped trigonal bipyramid with the heteroatom in equatorial position, and distances Au? Au between 280.4(1) and 288.4(1) pm and Co? Au between 254.9(1) and 257.1(2) pm. 2 · (PF₆)₂ crystallizes in the triclinic space group P1 with a = 2155.7(1); b = 1720.6(1); c = 3543.6(1) pm; α = 91.89(1)°; β = 97.51(1); γ = 89.92(1)°; Z = 4. The unit cell contains two symmetry independent cluster cations 2 of about the same geometry. The cluster skeleton Au₇Co can be described as fragment of an icosahedron formed by seven gold atoms with the Co atom in its center. The Au? Au distances range from 274.8(3) to 332.6(3) pm, and the Co? Au distances are 256.8(6) to 264.7(5) pm. The bonding in 1 and 2 is discussed.     

Short Te …︁ Te bonding contacts in a new layered ternary telluride: Synthesis and crystal structure of 2D Nb3GexTe6 (x ≃ 0.9)

The new layered ternary compound Nb₃Ge_xTe₆ (x ? 0.90) was prepared by direct combination of the elements taken in the stoichiometric proportions 3 : 1 : 6, heated at 1 000 °C for 10 days in silica tubes and quenched to room temperature. The phase crystallizes in the orthorhombic symmetry, space group Pnma (#62), with the following single crystal refined parameters: a = 643.18(5) pm, b = 1391.98(11)pm and c = 1 154.07(5) pm, with Z = 4. The structure was refined to an R of 3.4% (R_w = 4.6%), with 1969 independent reflexions and 49 parameters. The structure is based on the close stacking of trigonal prismatic (TP) slabs in the AA/BB mode. The slabs can be seen as built up from face sharing biprisms, which are filled either by one or by two niobium cations situated in the middle of the trigonal prisms. The germanium is located in the middle of the common face of two prisms, leading to a rather unusual anionic square coordination. The refinements showed that this latter cation does not fill completely its square site. No cation was found in the van der Waals gap between the slabs. The mean d_{Ge? Te} distance (276.5 pm) is in agreement with Ge^II cations, while some Te …? Te distances (from 333.84 to 361.65pm) are too short for anions in a simple contact. These bonding distances, already mentionned in some MTe₂ compounds, are to be ascribed to charge transfer in the structure, with a partial oxidation state for the tellurium anions. Short Nb? Nb and Nb? Ge distances (292.0 and 281.3 pm, respectively) imply intercationic bonding within the slabs.     

Reaktionen von Lanthanoidhalogeniden mit Alkalibenzylverbindungen. Darstellung und Kristallstrukturen von [(tmeda)(C6H5CH2)2Y(μ-Br)2Li(tmeda)], [(tmeda)2SmBr(μ-Br)2Li(tmeda)] und [(dme)2SmBr(μ-Br)]2

Reactions of Lanthanide Halides with Alkalibenzyl Compounds. Synthesis and Crystal Structures of [(tmeda)(C₆H₅CH₂)₂Y(μ-Br)₂Li(tmeda)], [(tmeda)₂SmBr(μ-Br)₂Li(tmeda)] and [(dme)₂SmBr(μ-Br)]₂ Alkali-benzyl compounds react via a metathesis reaction with lanthanide halides to benzyl complexes of the rare earths. Reaction of [(C₆H₅CH₂)Li(tmeda)] with YBr₃ leads to the complex [(tmeda)Y(C₆H₅CH₂)₂ (μ-Br)₂Li(tmeda)] 1 , in which Yttrium and lithium are linked via two bromide bridges. However, the reaction of [(C₆H₅CH₂)Li(tmeda)] with SmBr₃ in toluene/tmeda leads under reduction of the Sm ion to the compound [(tmeda)₂SmBr(μ-Br)₂Li(tmeda)] 2 . 2 reacts with DME to yield the dimeric compound [(dme)₂SmBr(μ-Br)]₂ 3 . The structures of 1 – 3 were determined by X-ray single crystal structure analysis:

• 1: Space group P2₁/c, Z = 4, a = 829.5(6) pm, b = 1477.9(11) pm, c = 2575.0(10) pm, β = 92.03(6)°,
• 2: Space group P2₁, Z = 2, a = 954,7(3) pm, b = 1338.5(6) pm, c = 1244.9(5) pm, β = 107.51(3)°,
• 3: Space group P1 , Z = 1, a = 797.2(7) pm, b = 818.3(7) pm, c = 1169.7(8) pm, α = 100.96(6)°, β = 92.03(6)°, γ = 91.75(7)°.

     

Substituierte Halogenocarbonylmetallate des Chroms,Molybdäns und Wolframs. IV. Die Kristallstruktur von Tetramethylammonium-Chloropentacarbonylwolframat

Substituted Halocarbonyl Metallates of Chromium, Molybdenum, and Tungsten. IV. Crystal Structure of Tetramethylammonium Chloropentacarbonyltungstate The structure of tetramethylammonium chloropentacarbonyltungstate has been determined from single crystal X-ray data. The compound crystallizes with four formula units in the monoclinic unit cell (space group P2₁/c) of the dimensions a = 1111.3(4) pm, b = 1110.3(4) pm c = 1204.1(3) pm, β = 99.63(3)°, V = 1464.8 × 10⁶ pm³ (R = 0.028). The anion possesses approximately C_4v symmetry with the principal interatomic distances d(W–C(cis)) = 203 pm, d(W–C(trans)) = 197 pm d(W–Cl) = 256.6 pm. No unusual contacts between cation and anion have been found.