Azidocuprate(II). Die Kristallstruktur von (PPh4)2[Cu2(N3)6]

Azidocuprates(II). Crystal Structure of (PPh₄)₂[Cu₂(N₃)₆] (PPh₄)₂[Cu(N₃)₄] and (PPh₄)₂[Cu₂(N₃)₆], which is already known, are prepared from the corresponding chloro cuprates and excess silver azide in dichloro methane suspension. The azido cuprates form nonexplosive brown crystals of low sensitivity to moisture and are characterized by i.r. spectroscopy. (PPh₄)₂[Cu₂(N₃)₆] was submitted to a X-ray crystallographic structural analysis (4284 observed, independent reflexions, R = 0.034). The compound crystallizes triclinic in the space group P1 with one formula unit per unit cell. The lattice parameters are a = 1047.4 pm; b = 1131.1 pm; c = 1179.4 pm; α = 101.26°; β = 109.31°; γ = 103.42°. The compound consists of PPh₄^⊕ cations and centrosymmetric anions [Cu₂(N₃)₆]^2?, which meet D_2h-symmetry fairly well. In the anions the copper atoms are linked to a planar Cu₂N₂ four-membered ring by the N α atoms of two azide groups. The other azido ligands are bonded terminally and complete coordination number 4 at the Cu atoms which show planar geometry.     

Synthese und Kristallstruktur von (PPh4)2[Mo2Cl10]

Synthesis and Crystal Structure of (PPh₄)₂[Mo₂Cl₁₀] The title compound is obtained in the reaction of [MoCl₄(Ph? C?C? Ph)]₂ with tetraphenylphosphonium chloride in dichloro methane, forming brown crystals. It is characterized by the i.r. spectrum and a crystal structure analysis by the aid of X-ray diffraction data. The complex crystallizes triclinic in the space group P1 with one formula unit per unit cell. The cell dimensions are a = 1122 pm, b = 1137 pm, c = 1283 pm; α = 63.4°, β = 69.1°, γ = 86.5°. The crystal structure determination (2959 observed, independent reflexions, R = 4.5%) shows the constants of the unit cell to consist of on centrosymmetric anion, two cations and one disordered molecule of dichloro methane. The distance Mo? Mo in the anion is 380 pm, which excludes direct magnetic interaction between the molybdenum atoms.     

Die Bromokomplexe von Molybdän(IV) [MoBr6]2⊖ und [Mo2Br10]2⊖. Die Kristallstruktur von (PPh3Me)2[MoBr6] · 2 CH2Br2

Bromo Complexes of Molybdenum(IV) [MoBr₆]^2? and [Mo₂Br₁₀]^2?. Crystal Structure of (PPh₃Me)₂[MoBr₆] · 2 CH₂Br₂ The bromomolybdates(IV) (PPh₃Me)₂[MoBr₆] · 2 CH₂Br₂ and (PPh₄)₂[Mo₂Br₁₀] are obtained by reactions of molybdenum tetrabromide with PPh₃MeBr and PPh₄Br, respectively. They form black-brown, hydrolysis sensitive crystal powders. The crystal structure of (PPh₃Me)₂[MoBr₆] · 2 CH₂Br₂ was determined by X-ray diffraction (2376 independent observed reflexions, R = 0.082). Crystal data: a = 1024, b = 1131, c = 1179 pm, α = 108.2°, β = 106.8°, γ = 99.0°, space group P1 , Z = 1. The compound consists of PPh₃Me⁺ ions, CH₂Br₂ molecules and nearly octahedral [MoBr₆]^2? ions with MoBr bond lengths between 252.7 and 254.0 pm.     

Thiochlorowolframate von Wolfram(V) und -(VI). Die Kristallstrukturen von PPh4[WSCl4] und (PPh4)2[WS2Cl4] · 2 CH2Cl2

Thiochlorowolframates with Tungsten(V) and (VI). Crystal Structures of PPh₄[WSCl₄] and (PPh₄)₂[WS₂Cl₄] · 2 CH₂Cl₂ Diamagnetic (NEt₄)₂[WSCl₄]₂, having tungsten atoms linked via sulfur atoms, is obtained by the reaction of WCl₅ with NEt₄SH as well as by the reduction of WSCl₄ with NEt₄I in dichloromethane. If the reduction is performed with PPh₄I, PPh₄[WSCl₄] with monomer anions is formed. Reaction of WCl₆ with H₂S in dichloromethane yields brown, insoluble WS₂Cl₂ which has terminal W?S groups and bridging W? S? W groups according to its IR spectrum. WS₂Cl₂ and PPh₄Cl react to afford PPh₄[WS₂Cl₃] · 2 CH₂Cl₂ and (PPh₄)₂[WS₂Cl₄] · 2 CH₂Cl₂. IR spectra are reported. The crystal structures of PPh₄[WSCl₄] and (PPh₄)₂[WS₂Cl₄] · 2 CH₂Cl₂ were determined by X-ray diffraction. PPh₄[WSCl₄]: tetragonal, space group P4/n, Z = 2, a = 1292.3 pm, c = 763.2 pm; R = 0.054 for 898 observed reflexions. The [WSCl₄]^? ion has the structure of a square pyramid with a rather short W?S bond of 206 pm length. (PPh₄)₂[WS₂Cl₄] · 2 CH₂Cl₂: triclinic, space group P1 , a = 1017.7, b = 1114.5, c = 1243.4 pm, α = 70.61, β = 79.73, γ = 80.80°; R = 0.076 for 1804 reflexions. The [WS₂Cl₄]^2? has cis configuration; as it is situated on an inversion center it shows positional disorder.     

Kristallstruktur und elektrische Leitfähigkeit von Li2–2xMn1+xCl4-Spinelltyp-Mischkristallen

Crystal Structure and Electric Conductivity of Spinel-Type Li_2–2xMn_1+xCl₄ Solid Solutions The electric conductivity of the fast lithium ion conductors Li_2–2xMn_1+xCl₄ was measured by impedance spectroscopic methods. The conductivities obtained, e.g. ～ 4 × 10^?1 Ω^?2 cm^?1 at 570 K, depend only little on the lithium content. The crystal structure of Li_1.6Mn_1.2Cl₄ was determined by neutron powder and X-ray single crystal diffraction (space group Fd3 m, Z = 8, a = 1 049.39(6) pm, R_w = 1.4% on the basis of 170 reflections). The lithium deficient chloride crystallizes in an inverse spinel structure like the stoichiometric compound Li₂MnCl₄ according to the formula (Li_0,8)[Li_0,4Mn_0,6]₂Cl₄ with vacancies ( ) at the tetrahedral sites. The decrease of the M_oct? Cl distances with the increase of x reveals that the ionic radius of Mn²⁺ in chlorides is equal or even smaller than that of Li⁺ opposite to fluorides and oxides. The ? Cl distances of spinel type chlorides are 237 ( _tet) and 274 pm ( _oct), respectively. The mechanism of the ionic conductivity is discussed.     

Die Kristallpackung in drei Modifikationen von PPh4[ReO(S4)2] und PPh4[ReS(S4)2]

The Crystal Packing in three Modifications of PPh₄[ReO(S₄)₂] and PPh₄[ReS(S₄)₂] Mixed crystals PPh₄[ReS(S₄)₂]_0,63[ReO(S₄)₂]_0,37 were obtained from PPh₄Cl, ReCl₅ and Na₂S₄ in acetonitrile. Their crystal structure corresponds to the known structure of this kind of compound (space group P2₁/n). In a similar reaction with ReBr₅ instead of ReCl₅, PPh₄[ReO(S₄)₂] was obtained in small yield. Its triclinic crystal structure was determined by X‐ray crystallography (space group P1). It contains cation pairs (PPh₄⁺)₂ such as they have been found in many other instances. In contrast, the crystal structures of the mixed crystals and of one known modification of PPh₄[ReS(S₄)₂] have PPh₄⁺ columns similar to compounds crystallizing in the space group P4/n, albeit in a severely distorted manner; their space group P2₁/n is a subgroup of P4/n with a doubled unit cell. In another modification of PPh₄[ReS(S₄)₂] (space group P2₁/c) the columns are less distorted, but arranged in a different way.     

Diiodacetylenkomplexe von Wolfram(IV). Die Kristallstruktur von PPh4[WCl5(C2l2)] · 0,5 CH2Cl2

Diiodoacetylene Complexes of Tungsten(IV). Crystal Structure of PPh₄[WCl₅(C₂I₂)] · 0.5 CH₂Cl₂ Tungsten hexachloride and diiodoacetylene react in CCl₄ solution forming [WCl₄(I? C?C? I)]₂ which has a dimer structure with chloro bridges. In CH₂Cl₂, it reacts with PPh₄Cl yielding PPh₄[WCl₅(I? C?C? I)] · 0.5 CH₂Cl₂. In both compounds the C₂I₂ ligands attain a marked increase in thermal stability by their side-one coordination to the tungsten atoms. The crystal structure of the PPh₄^⊕ salt was determined with X-ray diffraction data (3879 observed reflexions, R = 0.050). PPh₄[WCl₅(C₂I₂)] · 0.5 CH₂Cl₂ crystallizes in the space group P2₁/n with 8 formula units per unit cell. The lattice constants are a = 1723.0, b = 1681.2, c = 2214.6 pm and β = 94.38°. There are two crystallographically independent [WCl₅(C₂I₂)]^? ions which differ only slightly from one another. The C₂I₂ ligand has a staggered arrangement relative to the W? Cl groups, with C? C bond lengths of 127 pm. The infrared spectra are discussed.     

Darstellung und Eigenschaften von Tetra(n-butyl)ammonium-cis-trifluorophthalocyaninato(2–)zirconat(IV) und -hafnat(IV); Kristallstruktur von (nBu4N)cis[Hf(F)3pc2–]

Preparation and Properties of Tetra(n-butyl)ammonium cis -Trifluorophthalocyaninato(2–)zirconate(IV) and -hafnate(IV); Crystal Structure of (ⁿBu₄N) ^cis [Hf(F)₃pc^2–] cis-Dichlorophthalocyaninato(2–)metal(IV) of zirconium and hafnium reacts with excess tetra(n-butyl)-ammoniumfluoride trihydrate to yield tetra(n-butyl)-ammonium cis-trifluorophthalocyaninato(2–)metalate(IV), (ⁿBu₄N)^cis[M(F)₃pc^2–] (M = Zr, Hf). (ⁿBu₄N)^cis[Hf(F)₃pc^2–] crystallizes in the monoclinic space group P2₁/n (# 14) with cell parameters a = 13.517(1) Å, b = 13.856(1) Å, c = 23.384(2) Å, α = 92.67(1)°, Z = 4. The Hf atom is in a ”︁square base-trigonal cap”︁”︁ polyhedron, coordinating three fluorine atoms and four isoindole nitrogen atoms (N_iso). The Hf atom is sandwiched between the (N_iso)₄ and F₃ planes (d(Hf–Ct_N) = 1.218(3) Å; d(Hf–Ct_F) = 1.229(3) Å; Ct_N/F: centre of the (N_iso)₄, respectively F₃ plane). The average Hf–N_iso and Hf–F distances are 2.298 and 1.964 Å, respectively, the average F–Hf–F angle is 84.9°. The pc^2– ligand is concavely distorted. The optical spectra show the typical metal independent π-π* transitions of the pc^2– ligand at c. 14700 and 29000 cm^–1. In the FIR/MIR spectra vibrations of the MF₃ skeleton are detected at 545, 489, 274 cm^–1 (M = Zr) and 536, 484, 263 cm^–1 (M = Hf), respectively.     

Thiochloro-Verbindungen von fünfwertigem Niob und Wolfram: WSCl3, [WSCl4]22−, [NbSCl4]− Die Kristallstruktur von PPh4[NbSCl4]

Thio-chloro Compounds of Pentavalent Niobium and Tungsten: WSCl₃, [WSCl₄]₂^2?, [WSCl₅]^2?, [NbSCl₄]^?. Crystal Structure of PPh₄[NbSCl₄] Black WSCl₃ was obtained by reduction of (WSCl₄)₂ with C₂Cl₄. With PPh₄Cl in CH₂Cl₂ it yields (PPh₄)₂[WSCl₄]₂ which has a dimeric structure with chloro bridges according to its i. r. spectrum. Iodide reduces PPh₃Me[WSCl₅] in CH₂Cl₂ to (PPh₃Me)₂[WSCl₅], from which (PPh₃Me)₂[WSBr₅ · BBr₃] is obtained by reaction with BBr₃. From PPh₄Cl in CH₂Cl₂ and raw NbSCl₃ (obtained by solid state reaction of NbCl₅ with B₂S₃) PPh₄[NbSCl₄] is formed. The crystal structure of PPh₄-[NbSCl₄] was determined and refined with X-ray diffraction data (residual index R = 0.066 for 1017 reflexions). It crystallizes in the AsPh₄[RuNCl₄] structure type (space group P4/n) with the lattice constants a = 1303 and c = 760 pm. The quadratic-pyramidal [NbSCl₄]^? ion has a Nb?S bond length of 209 pm. The i. r. spectra of all compounds are discussed.     

Synthese und Kristallstruktur von (PPh4)2[Mo2NCl9]2, einem μ-Nitridokomplex mit Molybdän(V), und -(VI)

Synthesis and Crystal Structure of (PPh₄)₂[Mo₂NCl₉]₂, a μ-Nitrido Complex with Molybdenum (V) and (VI) The title compound is formed as a by-product in the partial oxidation of Mo₂NCl₇ with chlorine in POCl₃ solution, when the reaction mixture is treated with PPh₄Cl. The crystals, which are sensitive to moisture, are black in reflectance and red in transmittance. A more effective synthesis is the direct reaction of PPh₄[MoNCl₄] with MoCl₅ in dichloro methane. (PPh₄)₂[Mo₂NCl₉]₂ was characterized by the i.r. spectrum and by a structural analysis with X-ray data. The compound crystallizes triclinic in the space group P1 with two formula units per unit cell (9225 independent observed reflexions, R = 0.058). The cell parameters are (20°C): a = 1144 pm, b = 1517 pm, c = 2000 pm, α = 79.8°, β = 80.1°, γ = 72.1°. (PPh₄)₂[Mo₂NCl₉]₂ consists of PPh₄⊕ cations and the anions [Mo₂NCl₉]₂^22?, which dimerize via chloro bridges with Mo? Cl bons lengths of 243 pm and 287 pm. In the [Mo₂NCl₉]₂^2? units the molybdenum atoms are linked by Mo^VI?N? Mo^V bridges (bond angles 179° and 174°, resp.) with Mo? N bond lengths of 167 pm and 212 pm.     

Synthese und Kristallstruktur von (PPh4)2Se6

Synthesis and Crystal Structure of (PPh₄)₂Se₆ (PPh₄)₂Se₆ has been prepared by the reaction of selenium with K₂Se₂ in dimethylformamide solution in the presence of K₃[Mn(CN)₆] and PPh₄Br, forming black crystal needles. According to the crystal structure determination the compound consists of PPh⁺₄ ions and chainlike hexaselenide ions. Space group P6 , Z = 2,4683 Observed unique reflections, R = 0.066. Lattice dimensions at ?90°C: a = 951.0, b = 1094.8, c = 2137.4 pm, α = 82.66°, β = 83.36°, γ = 89.96°.     

Darstellung,spektroskopische Charakterisierung und Normalkoordinatenanalyse der bindungsisomeren Tetrachloroiodoselenocyanatoosmate(IV). Kristallstruktur von trans‐(PPh4)2[OsCl4I(NCSe)]

Preparation, Crystal Structure, and Normal Coordinate Analysis of Linkage Isomeric Pentachloroiodoselenocyanatoosmates(IV). Crystal Structure of trans‐(PPh₄)₂[OsCl₄I(NCSe)] By treatment of the solution of (n‐Bu₄N)₂[OsCl₅I] in dichloromethane with suspended Pb(SeCN)₂ the linkage isomers trans‐(n‐Bu₄N)₂[OsCl₄I(NCSe)] ( 1 ) and trans‐(n‐Bu₄N)₂[OsCl₄I(SeCN)] ( 2 ) are formed, which have been separated by ion exchange chromatography on diethylaminoethyl cellulose. The X‐Ray structure determination on a single crystal of trans‐(PPh₄)₂[OsCl₄I(NCSe)] (triclinic, space group P1¯, a = 10.8950(13), b = 11.076(2), c = 20.980(2)Å, α = 96.940(10), β = 98.747(9), γ = 104.419(11)°, Z = 2) reveals, that the nearly linear selenocyanate group in trans position to the iodine atom is coordinated with the Os‐N‐C angle of 171.1°. Based on the molecular parameters of the X‐ray determination ( 1 ) and estimated data ( 2 ) the IR and Raman spectra of both linkage isomers are assigned by normal coordinate analysis. The valence force constants are f_d(OsN) = 1.70 und f_d(OsSe) = 1.15 mdyn/Å.     

Darstellung und Schwingungsspektren von Dichloro- und Dibromodithiophosphat Die Kristallstrukturen von [PPh3Me] [PS2Cl2] und [PPh4] [PS2Br2]

Preparation and Vibrational Spectra of Dichloro and Dibromodithiophosphate. Crystal Structures of [PPh₃Me][PS₂Cl₂] and [PPh₄][PS₂Br₂] Dichloro and dibromodithiophosphates [Cat⁺][PS₂X₂^?] with a large organic cation can be obtained from P₄S₁₀, CatX and HX in CH₂Cl₂ (Cat⁺ = PPh₄⁺, PPh₃Me⁺; X = Cl, Br). The vibrational spectra (i.r. and Raman) of the [PS₂X₂]^? ions are reported and discussed; force constants were calculated. The crystal structures of [PPh₃Me][PS₂Cl₂] and [PPh₄][PS₂Br₂] were determined and refined with X-ray diffraction data. In both cases, simple anions [PS₂X₂]^? are present. [PPh₃Me][PS₂Cl₂]: orthorhombic, space group P2₁2₁2₁, a = 1089, b = 1334, c = 1476 pm, Z = 4, refinement to a residual index R = 0.046 for 1116 reflexions; the structure is isotopic with [PPh₃Me][VO₂Cl₂]. [PPh₄][PS₂Br₂]: tetragonal space group I4 , a = 1301, c = 721 pm, Z = 2, refinement to R = 0.065 for 357 reflexions; the structure is isotypic with [AsPh₄][FeCl₄] with [PS₂Br₂]^? ions occupying positions of 4 -symmetry with statistical orientation (statistical superposition of Br and S positions).     

Die Reaktionen von Dimethylsulfoxid mit Molybdäntetrabromid und Molybdändibromid-dinitrosyl Die Kristallstruktur von [MoBr2(NO)2(OSMe2)2]

Reactions of Dimethyl Sulfoxide with Molybdenum Tetrabromide and Molybdenum Dibromide Dinitrosyl. Crystal Structure of [MoBr₂(NO)₂(OSMe₂)₂] In the cold molybdenum tetrabromide reacts with an equivalent amount of dimethyl sulfoxide forming the solvate [MoBr₄(OSMe₂)₂]; excess dimethyl sulfoxide yields [MoO₂Br₂(OSMe₂)₂] which is also obtained by other methods. Molybdenum dibromidedinitrosyl forms the solvate [MoBr₂(NO)₂(OSMe₂)₂] in the reaction with dimethyl sulfoxide. According to the i.r. spectra all complexes display O-coordination of the OSMe₂ molecules. [MoBr₂(NO)₂(OSMe₂)₂] crystallizes monoclinic in the space group P2₁/c with four formula units per unit cell. The cell dimensions are a = 1236, b = 892, c = 1305 pm, β = 95.2°. 1662 independent observed reflexions were used for refinement; R = 3.8%. The molybdenum atoms are six-coordinated, the O atoms of the dimethyl sulfoxide molecules are in trans-position to the nitrosyl ligands, which form linear groups Mo? N? O.     

Die Kristallstrukturen der Cyanidofluoridoborate K[BFx(CN)4–x], x = 0–4

The crystal structure of K[BF₃(CN)] (Pbcn (Nr. 60) with a = 13.3486(15) b = 6.5239(7) c = 10.0085(11) Å, and eight formula units per unit cell) has been determined and the one of K[BF₂(CN)₂] was confirmed and improved. The different networks in the complete series of borates K[BF_x(CN)_4–x], x = 0–4 are compared and discussed.     

Die Kristallstruktur von (PPh4)2[Mo2(O2C?Ph)4Br2] · 2 CH2Br2

Crystal Structure of (PPh₄)₂[Mo₂(O₂C? Ph)₄Br₂] · 2 CH₂Br₂ The title compound, prepared by the reaction of Mo₂(O₂C? Ph)₄ with PPh₄Br and PPh₄N₃, respectively, under the assistance of CH₂Br₂, was characterized by an X-ray structure determination. Space group P2₁/n, Z = 2, R = 0.074 (5261 independent observed reflexions). The lattice dimensions are at ?70°C: a = 1562.9, b = 1406.2, c = 1662.1 pm, β = 94.11°. the compound consists of PPh₄^⊕ ions, CH₂Br₂ molecules, and centrosymmetric anions [Mo₂(O₂C? Ph)₄Br₂]^2?. The axis Br? Mo?Mo–Br is nearly linear (bond angle 175.6°) with bond lengths MoMo = 212.3 pm and Mo? Br = 303 pm, corresponding with a weak electrostatic Mo? Br bond. In the FIR spectrum the Mobr stretching vibration is found at 85 cm^?1, which corresponds with the low value of the force constant of 0.24 N · cm^?1.     

Darstellung und Kristallstruktur von Ethylendiammonium-Selenostannaten(IV) sowie von [2 SnSe2 · en]∞

Preparation and Crystal Structure of Ethylenediammonium Selenostannates(IV) and [2 SnSe₂ · en]∞ The selenostannates(IV) [enH₂]₂[Sn₂Se₆] · en 1 and [enH₂][Sn₃Se₇] · 1/2en 2 have been prepared by the methanolothermal reaction of SnSe₂ with ethylenediamine (en) (160°C, 13 bar) in the presence of respectively Se or BaSe. The [Sn₂Se₆]^4? anion in 1 consists of two edgebridged SnSe₄ tetrahedra and displays crystallographic C_i symmetry. The crystal structure of 2 contains polyselenostannate(IV) sheet anions [Sn₂Se₇²], for which the basic elements are trigonal SnSe₅ bipyramids. Each of the three symmetry independent Sn atoms is linked to the other Sn atoms via Sn? Se? Sn bridges leading to the formation of Sn₃Se₁₀ units. Methanolothermal reaction of SnSe₂ with en alone yields the edge-bridged chain structure [2 SnSe₂ en]∞ 3 , in which each of the Sn atoms is bonded to four Se atoms. Every second Sn atom is also coordinated by an en molecule and displays, therefore, an octahedral geometry. The remaining Sn atoms are coordinated tetrahedrally by Se atoms.     

Die Kristallpackung von (PPh4)2[NiCl4] · 2 MeCN und PPh4[CoCl0,6Br2,4(NCMe)]

The Crystal Packings of (PPh₄)₂[NiCl₄] · 2 MeCN and PPh₄[CoCl_0.6Br_2.4(NCMe)] (PPh₄)₂[NiCl₄] · 2 MeCN was obtained from the reaction of PPh₄Cl and NiCl₂ in acetonitrile in the presence of S₂Cl₂, PPh₄[Cl₂H] being a side product. The product of the reaction of CoS₂ with S₂Br₂ (containing rests of S₂Cl₂) at 400 °C was treated with PPh₄Br in acetonitrile yielding PPh₄Br₃ and PPh₄[CoCl_0.6Br_2.4(NCMe)]. The crystal structures of the title compounds were determined by X‐ray diffraction. (PPh₄)₂[NiCl₄] · 2 MeCN (space group I 4, a = 1839.3 pm, c = 1375.3 pm) has a crystal packing derived from the BiPh₄[ClO₄] structure type with a fourfold increased unit cell and one half of the ClO₄^– positions substituted by pairsof acetonitrile molecules. The crystal structure of PPh₄[CoCl_0.6Br_2.4(NCMe)] (space group I4₁/a, a = 1804.7 pm, c = 3198.8 pm) is related to the AsPh₄[RuNCl₄] type with an eightfold increased unit cell. The [CoCl_0.6Br_2.4(NCMe)]^– ions are disordered in two orientations and some halogen positions are randomly occupied by Cl and Br atoms. Family trees of group–subgroup relations show the symmetry relations.     

Reaktionen von Uranpentabromid Die Kristallstrukturen von PPh4[UBr6], PPh4 [UBr6] · 2CCl4, (PPh4)2[UBr6] · 4CH3CN und (PPh4)2[UO2Br4] · 2CH2Cl2

Reactions of Uranium Pentabromide. Crystal Structures of PPh₄[UBr₆], PPh₄[UBr₆] · 2CCl₄, (PPh₄)₂[UBr₆] · 4CH₃CN, and (PPh₄)₂[UO₂Br₄] · 2CH₂Cl₂ PPh₄[UBr₆] and PPh₄[UBr₆] · 2CCl₄ were obtained from UBr₅ · CH₃CN and tetraphenylphosphonium bromide in dichloromethane, the latter being precipitated by CCl₄. Their crystal structures were determined by X-ray diffraction. PPh₄[UBr₆]: 2101 observed reflexions, R = 0.090, space group C2/c, Z = 4, a = 2315.5, b = 695.0, c = 1805.2 pm, β = 96.38°. PPh₄[UBr₆] · 2CCl₄: 2973 reflexions, R = 0.074, space group P2₁/c, Z = 4, a = 1111.5, b = 2114.2, c = 1718.7 pm, β = 95.42°. Hydrogen sulfide reduces uranium pentabromide to uranium tetrabromide. Upon evaporation, bromide is evolved from solutions of UBr₅ with 1 or more then 3 mol equivalents of acetonitrile in dichlormethane yielding UBr₄ · CH₃CN and UBr₄ · 3CH₃CN, respectively. These react with PPh₄Br in acetonitrile affording (PPh₄)₂[UBr₆] · 4CH₃CN, the crystal structure of which was determined: 2663 reflexions, R = 0.050, space group P2₁/c, Z = 2, a = 981.8, b = 2010.1, c = 1549.3 pm, β = 98.79°. By reduction of uranium pentabromide with tetraethylammonium hydrogen sulfide in dichloromethane (NEt₄)₂[U₂Br₁₀] was obtained; (PPh₄)₂[U₂Br₁₀] formed from UBr₄ and PPh₄Br in CH₂Cl₂. Both compounds are extremely sensitive towards moisture and oxygen. The crystal structure of the oxydation product of the latter compound, (PPh₄)₂[U0₂Br₄]· 2 CH₂Cl₂, was determined: 2163 reflexions, R = 0.083, space group C2/c, Z = 4, a = 2006.3, b = 1320.6, c = 2042,5 pm, β = 98.78°. Mean values for the UBr bond lengths in the octahedral anions are 266.2 pm for UBr₆-, 276.7 pm for UBr₆^2? and 282.5 pm for UO₂Br₄^2?     

Die Kristallstruktur von (AsPh4)2[W2NCl10]

Crystal Structure of (AsPh₄)₂[W₂NCl₁₀] The title compound is formed by a slow reaction of AsPh₄[WNCl₄] in acetonitrile solution in form of dark brown crystals. The crystal structure was solved by X-ray diffraction methods (R = 4.7%; 1461 observed, independent reflexions). (AsPh₄)₂[W₂NCl₁₀] crystallizes in the monoclinic space group P2₁/n with two formula units per unit cell. The structure consists of AsPh₄^θ and [W₂NCl₁₀]^2θ ions. The tungsten atoms with oxidation numbers five and six respectively, are linked by a linear, asymmetric nitrido bridge (r WN = 171 and 203 pm). The trans-effect of the W? N-multiple bonds causes a significant difference between axial (W? Cl_ax 243 pm) and equatorial (mean W? Cl_eq 230 pm) bond lengths.