Ag25Bi3O18, ein gemischtvalentes Bismutat

Ag₂₅Bi₃O₁₈, a Mixed Valent Bismuthate Applying oxygen pressures of 10 MPa black crystals of Ag₂₅Bi₃O₁₈ are prepared for the first time by solid state reaction of Ag₂O and ‘Bi₂O₅’. The crystal structure determination (P3 , a = 11.5887(2), c = 6,2386(1) å, Z = 1, 1369 diffractometer data, R_w = 0.034) proves the presence of trivalent (d(Bi-O) = 2.21, and 2.51 å (3×)) and pentavalent bismuth (d(Bi-O) = 2.13 å (6×)). The structure allows a change in the oxidation states (Bi³⁺ → Bi⁵⁺) by pressure induced shift of the oxygen atoms leading to a delocalisation of the 6s² valence electrons. First evidence for this phenomenon is given by the pressure dependence of the NIR reflectivity. The thermal decomposition was recorded by DTA/TG and measurements of the resistivity were performed.     

Crystal structure of kuznetsovite Hg3(AsO4)Cl

The crystal structure of a rare supergene mineral kuznetsovite Hg₃(As0₄)Cl, previously determined from powder data, is refined (space group P2₁3, a = 8.379(3) å, V = 588.3(4) å⁰³, Z = 4, d_calc = 8.763 glcm³, 3.44 < θ < 24.96?, 563 I_hkl(msd)/211 I_hkl(indep), R₁ = 0.0997, wR₂ = 0.2515). It is formed from the Cl^? and (AsO₄)^3- anions (As-O 1.74(3) and 1.79(1) å) and the trigonal cations Hg ₃ ⁴⁺ (Hg-Hg 2.675(5) å, HgHgHg 60?). The coordination polyhedron around each mercury atom involves two mercury atoms, two oxygen atoms at short Hg-0 distances (2.17(3) and 2.28(3) å, < OHgO 94.3(13)?), and more remote oxygen and chlorine atoms (Hg-0 2.601(6) å, Hg-Cl 2.838(9) å). The polyhedron is irregular and close to a trigonal antiprism. The Hg₃ triangles alternate with AsO₄ tetrahedra along each coordinate axis. Taking into consideration only short Hg-0 bonds (2.17(3) and 2.28(3) å), one can isolate a framework with chlorine ions lying in the cavities.     

Synthesis,Crystal Structure,and Magnetic Properties of {[Cu(phen)]2(C4H2O4)2} · 4.5H2O with C4H4O4 = Maleic Acid

Reaction of CuCl₂ · 2H₂O, phenanthroline, maleic acid and NaOH in CH₃OH/H₂O (1:1 v/v) at pH = 7.0 yielded blue {[Cu(phen)]₂(C₄H₂O₄)₂} · 4.5H₂O, which crystallizes in the monoclinic space group C2/c (no. 15) with cell dimensions: a = 18.127(2)Å, b = 12.482(2)Å, c = 14.602(2)Å, β = 103.43(1)°, U = 3213.5(8)ų, Z = 4. The crystal structure consists of the centrosymmetric dinuclear {[Cu(phen)]₂(C₄H₂O₄)₂} complex molecules and hydrogen bonded H₂O molecules. The Cu atoms are each square‐pyramidally coordinated by two N atoms of one phen ligand and three carboxyl O atoms of two maleato ligands with one carboxyl O atom at the apical position (d(Cu‐N) = 2.008, 2.012Å, equatorial d(Cu‐O) = 1.933, 1.969Å, axial d(Cu‐O) = 2.306Å). Two square‐pyramids are condensed via two apical carboxyl O atoms with a relatively larger Cu···Cu separation of 3.346(1)Å. The dinuclear complex molecules are assembled via the intermolecular π—π stacking interactions into 1D ribbons. Crossover of the resulting ribbons via interribbon π—π stacking interactions forms a 3D network with the tunnels occupied by H₂O molecules. The title complex behaves paramagnetically between 5—300 K, following the Curie‐Weiss law _χm(T—θ) = 0.435 cm³ · mol^—1 · K with θ = 1.59 K.     

Crystal and molecular structures of bis-(5-methyl-5-butoxy-hexanedionato-2,4) Copper(II) and bis-(2,2-dimethyl-5-cyclohexyl-pentanedionato-3,5) Copper(II)

Two new volatile complexes of Cu(II) containing methoxy groups were studied in a combined X-ray diffraction investigation of the mono- (KUMA automatic diffractometer, MoK_α radiation) and polycrystals (DRON-3M, CuK_α radiation). The structures are molecular and consist of the trans-complexes of bis-(5-methyl-5-butoxy-hexanedionato-2,4)copper(II), C₂₂H₃₈CuO₆, and bis-(2,2-dimethyl-5-cyclohexyl-pentanedionato-3,5) Copper(II), C₂₈H₄₆CuO₆. The crystal data of C₂₂H₃₈CuO₆: a = 8.939(1), b = 8.887(2), c = 8.326(1) å, α = 107.92(2), Β = 108.15(1), γ = 85.52(2)?, space group P1,V= 597.9(2) å³, Z = 1, d_x = 1.283 g/cm³. The crystal data of C₂₈H₄₆CuO₆: a = 18.625(3), b = 16.126(2), c= 13.613(3) å, Β = 132.19?, space group P2₁/n, V= 3029.3(9) å³, Z = 4, d_x= 1.189 g/cm³. In both cases, the square planar environment of the Cu atom with Cu...O distances of 1.90 å is completed by interactions with two carbon atoms of the terminal groups of the two neighboring molecules at Cu...C distances of 3.66 å (average).     

Gd10C4Cl18 und Gd10C4Cl17, zwei Seltenerdmetall-Clusterverbindungen mit interstitiellen C2-Gruppen

Gd₁₀C₄Cl₁₈ and Gd₁₀C₄Cl₁₇, Two Lanthanoid Cluster Compounds with Interstitial C₂ Units The compounds Gd₁₀C₄Cl₁₈ ( I ) and Gd₁₀C₄Cl₁₇ ( II ) are prepared by heating stoichiometric amounts of GdCl₃, Gd, and graphite in sealed tantalum tubes at 1070 ( I ) and 1 120 K ( II ). Single crystal investigations ( I : P2₁/c, Z = 2, a = 918.2, b = 1 612.0, c = 1 288.6 pm, β = 119.86°; II : P1 , Z = 1, a = 849.8, b = 917.4, c = 1 146.2 pm, α = 104.56°, β = 95.98°, γ = 111.35°) revealed the occurrence of novel Gd₁₀C₄Cl₁₈ clusters. The metal framework is formed by edge-sharing of two Gd₆ octahedra. These are centred by C₂ units (d_{C? C} = 147 pm) and Cl atoms bridge all available edges of the octahedra. The structure of I corresponds to a packing of such quasi molecular clusters, in II they are linked to chains via common Cl atoms. Both structures are discussed in terms of a model of close packed spheres as well as in the concept of condensed clusters.     

Bi5,6Ni5I: Eine partiell oxidierte intermetallische Phase mit Kanalstruktur

Bi_5,6Ni₅I: A Partly Oxidized Intermetallic Phase with Channel Structure Bi_5,6Ni₅I was prepared from the elements by chemical vapour deposition. Single-crystal investigations (space group I2/m, a = 1 852.1(3), b = 418.45(6), c = 1 373.8(3) pm, β = 90.42(2)°, V = 1 064.7(3) · 10⁶ pm³) revealed parallel doublewalled channels of nickel and bismuth atoms. The central pseudo 5 axis of each channel is occupied by 6/5 disordered bismuth atoms per lattice translation along [010]. Double rows of iodine atoms fill the distorted hexagonal arrangement of the channels. Bi_5,6Ni₅I is stabilized by metallic bonding in the framework metal atoms and additional heteropolar interactions between bismuth and iodine atoms as well as between bismuth and nickel atoms. Bi_5,6Ni₅I shows metallic conductivity and ferromagnetic ordering below 17 K.     

Zr7(Sb,Se)4 – eine polare Variante des Nb7P4-Strukturtyps

Zr₇(Sb,Se)₄ – a Polar Variant of the Nb₇P₄ Structure Type Single crystals of Zr₇Sb_1.6(1)Se_2,4 were obtained by arc-melting of compressed mixtures of Zr, ZrSb₂, and ZrSe₂, followed by annealing at 1300 °C in an induction furnace using traces of iodine to promote crystal growth. The crystal structure (a = 375.98(4), b = 1662.6(2), c = 1476.7(2) pm, V = 923.1(2) 10⁶ pm³, Cmc2₁, Z = 4) was determined by single crystal X-ray means. Zr₇Sb_1.6(1)Se_2.4 forms a unique polar structure composed of condensed tri-capped trigonal prismatic Zr₉ clusters, being stabilized by interstitial Sb/Se atoms. The remaining Sb and Se atoms reside in mono- and bi-capped trigonal prismatic Zr₇ and Zr₈ clusters, respectively, of the extended cluster network. Characteristic structural distinctions and relations between Zr₇(Sb,Se)₄ and congeneric Zr₇P₄ are highlighted.     

Crystal structure of the copper(II) chloride complex with 3,5Dimethyil-4-Amino-l,2,4-Triazole and water

The crystal structure of the copper(II) chloride complex with 3,5-dimethyl-4-amino-1,2,4-triazole has been determined by XRD. The crystal is cubic, a = 17.754(4) å, V_cell = 5596(1) å³, space group Pa3, Z = 8, d_calc = 1.842 g/cm³, C₁₂H₂₈Cl₆Cu₃N¹²O₂, Syntex P2₁, λCuK_a, 3277 I_hkl measured, including 936 independent nonextinct I_hkl > 0 (R_int = 0.0557), an absorption correction applied using crystal habit data (Μ = 82.4 cm¹), R(F) = 0.0711, R(wF²) = 0.1899 for 831 F^hkl > 4Σ(F). The copper atoms are linked by three bridging bidentate ligands into a regular triangle; the ligands are coordinated by the N¹ and N² atoms of the triazole cycle and by the Μ₃-bridging oxygen atom. The coordination polyhedron of copper is a heavily distorted octahedron (2N, O, Cl) + Cl+O. The chemical formula of the compound is discussed. An unambiguous choice between the formulas (H₃O)[(Μ₃-OH)(Μ,η²-L)₃Cu₃Cl₆] and [(Μ₃-OH)(Μ,η²-L)₂(Μ₂, η²-LH)Cu₃Cl₆]·H₂O is impossible, since the hydrogen atoms were not localized experimentally.     

A 2D Acentric Coordination Polymer, [Mn(HIDA)2(H2O)2], with a Strong Second‐Order Nonlinear Optical Effect

The crystal structure of [Mn(HIDA)₂(H₂O)₂] (Tetragonal, P4¯2₁c (no.114), a = b = 8.10(2)Å, c = 9.605(3)Å, α = β = γ = 90°, Z = 2, R = 0.051, wR² = 0.123 for 460 observed reflections) consists of infinite acentric 2D square grids with HIDA^— ions as bridging ligands. The 2D grids are interlocked(along the c axis) by hydrogen bonding. The Mn atoms are octahedrally coordinated by four O atoms of four HIDA^— ions (d(Mn—O)= 2.183(4)Å ) and two O atoms of two water molecules (d(Mn—OW) = 2.154(5)Å ). The results show that this acentric coordination polymer exhibits strong powder second harmonic generation (SHG) efficiency, ca. 1.9 times that of potassium dihydrogen phosphate, and remarkable thermal stability.     

Fluoride und Fluorosäuren. V. Kristallstruktur der 1:4-Phase im System Wasser-Fluorwasserstoff und eine neue Untersuchung einer der 1:2-Phasen

Fluorides and Fluoro Acids. V. Crystal Structure of the 1:4 Phase in the System Water-Hydrogen Fluoride and a New Investigation of One of the 1:2 Phases In the quasi binary system H₂O? HF the 1:2 phase of known crystal structure was recognized as the stable high-temperature phase. A more accurate redetermination of its structure (monoclinic, space group P2₁/c, Z = 4, a = 3.477, b = 6.024, c = 11.358 Å, β = 96.70° at ?100°C, R = 0.032 for 1356 observed MoKα data) confirmed the previous results of a layer structure formed by strong hydrogen bonds. H₃OF · HF appears besides H₃OHF₂ as a possible structural formula. — The crystal structure of the 1:4 phase of the system was also determined (triclinic, P1 , Z = 2, a = 5.574, b = 6.429, c = 6.874 Å, α = 115.79, β = 96.63, γ = 108.79° at ?113°C, R = 0.049 for 1942 observed MoKα data). By strong hydrogen bonds the atoms form rings, which are condensed to parallel ribbons. Possible structural formulae, based on the distribution of interatomic distances, are H₃OH₃F₄, H₃OH₂F₃ · HF and H₃OF · 3 HF. — Interatomic distances in the hydrogen bonds F? H…?F and O? H…?F of both structures and the known one of the 1:1 phase are discussed in comparison.     

Crystal Structure of BaNb6.3(1)Ti3.6(1)O16 containing Nb6O12, fused Ti3O13 Clusters and Ti3O10 Units

A new phase, BaNb_6.3(1)Ti_3.6(1)O₁₆, has been synthesised. Electron diffraction studies indicate an hexagonal substructure with unit cell parameters a ≈ 8.9 Å and c ≈ 9.5 Å. In some of the ED patterns superstructure reflections are present, indicating a supercell with a = √3 · a_sub and c = c_sub. However, X‐ray single‐crystal diffraction studies of a crystallite yielding reflections corresponding to the supercell revealed it to be monoclinic, with the unit cell parameters a = 26.811(2) Å, b = 15.4798(2) Å, c = 9.414(2) Å, β = γ = 90° and α = 90.0(3)°. The average crystal structure was refined, using the subcell with a = 8.937(2) Å, b = 15.479(2) Å, c = 9.414(2) Å, β = γ = 90° and α = 90.0(3)°, space group Cm11, and Z = 4, to R_I = 3.24% and R_wI = 3.44%. The structure can be described as an hexagonal close packing layers of Nb₆ octahedra, Ba, and O atoms (A1, A2) and layers of O atoms (B1, B2), appearing in the packing sequence: A1B1A2B2. The Nb₆ octahedra are found in isolated Nb₆O₁₂O₆ clusters, and the Ti atoms in Ti₃O₁₃ and Ti₃O₁₀ units in octahedral and tetrahedral voids formed by O atoms, respectively. The Ti positions were found to be only partly occupied. Microanalysis indicates that some Nb atoms are located in the Ti₃ triangles. A model is presented that interprets these not fully occupied Ti₃ triangles as a result of a superimposing of three different structures. Two of these consist of two fused Ti₃O₁₃ units, forming an Ti₆O₁₉ unit, and a Ti₃O₁₀ unit, while the third consists of alternating Ti₃O₁₃ units.     

Die metallreiche Schichtstruktur von Ta6STe3

The Metal‐rich Layer Structure of Ta₆STe₃ Ta₆S_1+xTe_3–x was prepared from an appropriate mixture of 2 H–Ta_1.3S₂, TaTe₂, and Ta in a fused tantalum tube at 1273 K within 3 d. The results of a X‐ray single crystal structure analysis for a phase near the Te‐rich limit of the homogeneity range are reported. Ta₆S_1.00Te_3.00(1) crystallizes in the triclinic space group P1, a = 993.14(8) pm, b = 1032.18(8) pm, c = 1378.78(11) pm, α = 79.32(1)°, β = 81.36(1)°, γ = 85.74(1)°, Z = 6, Pearson symbol aP60, 6048 I_o > 2σ (I_o), 286 variables, wR₂ = 0.067. The metal‐rich layer structure of Ta₆STe₃ comprises distorted icosahedral Ta₁₃ clusters and related deltahedral cluster fragments complemented by chalcogen atoms. The centred clusters consist of 11, 12, 13, 14, or 16 atoms. They interpenetrate into lamellae in which the tantalum and chalcogen atoms are spatially segregated according to [Q–Ta₃–Q]. The signature of the structure is a lenticular heptagonal antiprismatic Ta₃₀ cluster which seems to be excised from the pentagonal antiprismatic columnar structure of Ta₆S. The Ta₃₀ clusters and distorted icosahedral Ta₁₃ clusters are connected and fused into puckered layers. The rest of the tantalum valences are used for heteronuclear bonding. The chalcogen atoms having three to six next tantalum atoms coat the corrugated, tetrahedrally close‐packed layers. Ta₆STe₃ is a moderate metallic conductor (ρ_{293 K} = 3 × 10^–4 Ωcm) exhibiting typical temperature independent paramagnetic properties.     

Crystal structure of (Et4N) [(µ-H)Fe3(µ3-Se)(CO)9]

The crystal structure of (Et₄N)[(μ-H)Fe₃(μ₃-Se)(CO)₉] is determined;the crystals are monoclinic, a = 11.172(2), b =32.332(5), c =13.552(3) ?, μ =91.86(2)‡, V _cell =4893(2) ? ³, space group P2₁/n, Z =8, d _calc =1.710 g/cm ³, CAD-4 diffractometer, MoK_α radiation;the total number of data collected 4395,including 4086 independent reflections(R_int =0.0701), R(F) =0.0566, wR(F ²) =0.1202 for 1963 F _hkl > 4Σ(F). The data were corrected for the 37.8% linear drop of intensities of the control reflections due to crystal decay. The Fe-H bond lengths are 1.5(1)-1.72(9) ?. As in the case of three-osmium clusters,the presence of the Μ-H ligand leads to a lengthening of the Fe-Fe bond by approximately 0.1 ? and to push-away of the equatorial carbonyl ligands leading to an increase in the FeFeC angle by approximately 5–10‡, whereas the axial CO and (Μ ₃-Se) remain unchanged.     

Crystal Structure and Properties of Strontium Phosphate Apatite with Oxocuprate Ions in Hexagonal Channels

Strontium phosphate apatites containing different amounts of copper were prepared by a solid state reaction at 1100 °C or by arc melting above 1600 °C in air. The samples were characterized by X‐ray diffraction, ICP analysis, scanning electron microscopy, IR spectroscopy, MAS—¹H—NMR, diffuse reflectance spectroscopy, and SQUID magnetometry. X‐ray crystal structure determination was carried out for a single crystal obtained from the melt. The compound is formulated as Sr₅(PO₄)₃(CuO₂)_1/3 and has an apatite structure (space group P6₃/m, a = 9.7815(4)Å, c = 7.3018(4)Å, Z = 2) with linear CuO₂^3— ions occupying hexagonal channels. For solid state synthesized samples, Rietveld refinement of powder XRD patterns was performed. The samples obtained at 1100 °C acquire the composition Sr₅(PO₄)₃Cu_xOH_y, with x changing from 0.01 to 0.62 and y < 1—x. The copper content can be increased to x = 0.85 by annealing in argon at 950 °C. The compounds represent a hydroxyapatite in which part of the protons is substituted by Cu⁺ and Cu²⁺ ions. The ions form linear O—Cu—O units which are progressively condensed creating the Cu—O—Cu bridges on increasing copper content. IR and NMR data testify existence of OH groups, non‐disturbed and disturbed by neighboring Cu atoms. In the electron spectra, the samples exhibit absorption bands at 7800‐7900, 14200‐14500 and 17500‐17550 cm^—1, which were assigned to Cu²⁺ d‐electron transitions. By annealing the sample with x = 0.1 in oxygen at 800 °C copper is fully oxidized while retaining in channels in unusual for Cu²⁺ linear coordination.     

Novel Layered Structures Formed by Iodocuprate Clusters Stabilized by Dialkylsulphide Ligands

From solutions of copper iodide and dodecyldimethylsulphonium iodide in acetonitrile, single crystals of [Cu₄I₄(DodecylMeS)₄] ( 1 ) and [Cu₃I₄(DodecylMeS)₃](DodecylMe₂S) ( 2 ) could be obtained. Both compounds crystallize in the triclinic crystal system, space group P1¯ ( 1 : a = 957.23(1), b = 967.25(2), c = 3818.38(6) pm, α = 90.3837(6)°, β = 86.4687(7)°, γ = 75.0996(7)°, 2 : a = 874.23(1), b = 979.29(1), c = 4388.75(4) pm, α = 90.4472(3)°, ß = 94.7088(3)°, γ = 116.1162(3)°). 1 consists of tetrahedral Cu₄ clusters, which are capped by four iodide ions over the tetrahedral faces. 2 contains trigonal Cu₃ clusters, which are coordinated by four iodide ions, one centered over the plane, three bridging over the edges of the Cu₃ triangle. In both compounds, the S atoms of (DodecylMeS) ligands coordinate to the Cu atoms. In 2 , a (DodecylMe₂S) cation is also present.     

Synthesis,Crystal Structure,Vibrational Spectra,and Thermal Behaviour of [Ph4P]2[Bi2(μ‐Br)2Br6 (CH3COCH3)2]

[Ph₄P]₂[Bi₂Br₈(CH₃COCH₃)₂] ( 1 ) was obtained by the reaction of [Ph₄P]Br and BiBr₃ in acetone. Single crystals were grown by allowing a layer of n‐hexane to diffuse into the acetonic solution of 1 . The crystal structure was determined by means of X‐ray diffraction. 1 crystallises with monoclinic symmetry in the space group P2₁/n, No. 14 with the lattice parameters: a = 13.358(2), b = 12.637(2), c = 18.565(3) Å, β = 102.62(1)°, V = 3058.1(8) ų and Z = 4. The structure is characterised by the anion [Bi₂Br₈(CH₃COCH₃)₂]^2– which is embedded in a matrix of [Ph₄P]⁺ cations. The anion can be described as two edge‐sharing square pyramids with the apical bromide ions in anti‐position. Acetone co‐ordinates the bismuth atoms via oxygen atoms and increases the co‐ordination number of central bismuth atoms to six which results in the formation of a distorted bi‐octahedron. The distortion is due to the difference in terminal and bridging Bi–Br bond lengths. FT‐IR and Raman spectroscopic data are presented. In addition, the thermal behaviour of the compound was studied with the aid of TG/DSC coupled with MS revealing that acetone leaves the crystal in two steps. The compound melts at 203 °C and transforms into a glass on cooling.     

Structure and Bonding of the Mixed‐Valent Platinum Trihalides,PtCl3 and PtBr3

The isotypical crystal structures of the mixed valent trihalides PtCl₃ and PtBr₃ were redetermined by single crystal methods (space group R3¯; trigonal setting; PtCl₃: a = 21.213Å, c = 8.600Å, c/a = 0.4054; Z = 36; 1719 hkl; R = 0.035; PtBr₃: a = 22.318Å, c = 9.034Å; c/a = 0.4048; Z = 36; 1606 hkl; R = 0.027). A cubic closest packing of X^— anions forms the basis of an optimized arrangement of cuboctahedrally [Pt₆X₁₂] cluster molecules with Pt^II and enantiomers of helical chains of edge‐condensed [PtX₂X_4/2] octahedra with Pt^IV in cis‐Δ‐ and cis‐Λ‐configuration, respectively. The bond lengths vary with the function of the X^— ligands (d¯(Pt^II—X) = 2.315 and 2.445Å; d¯(Pt^II—Pt^II) = 3.336 and 3.492Å; d(Pt^IV—X) = 2.286 — 2.417Å and 2.437 — 2.563Å). The Pt^II atoms are shifted outwards the X₁₂ cuboctahedra by 0.045Å and 0.024Å, respectively. The symmetry governed Periodic Nodal Surface, PNS, perfectly separates the regions of different valencies. Quantum chemical calculations exclude the possible additional interactions between Pt^II and one of the exo‐ligands of Pt^IV.     

Research on in part “loosely” coordinated trinuclear molybdenum cluster compounds — the synthesis and crystal structure of {Mo3(μ3-S)(μ-S)3[S2P(OEt)2]4 ṁ P(C6H5)3} (0.86CH2Cl2)

The synthesis and crystal structure of novel trinuclear molybdenum cluster compound with somewhat “loose” coordination site {Mo₃(μ₃-S)(μ-S)₃[S₂P(OEt)₂l₄ ? P(C₆H₅)₃} ? (0.86 CH₂C1₂) have been reported. The cluster crystallizes in the space group with two molecules in a unit cell whose parameters are a=10.472(4), b=14.375(2), c=21.695(3)Å; α=74.04(1)°, β=76.50(2)°, γ=72.22 (2)°, V=2950ų and D_o=1.693 g ? cm^?3. On the basis of 4840 independent reflections with I≥2σ(I), the structure was solved by heavy atom method and Fourier method and refined by full-matrix least-squares techniques to a final R=0.058. The distances between Mo atoms in this cluster are 2.731(1), 2.748(1) and 2.753(1)Å respectively. The meat value of Mo—Mo bond lengths is slightly shorter than those in other trinuclear Mo clusters with “loosely coordinated” site. In addition, the PPh₃ ligand is loosely coordinated to one Mo atom in direction opposite to the μ₃-S with Mo—P bond length of 2.647(3)Å. This is different from the other structurally analogous clusters, in which the loosely coordinated ligand is trans to μ₂-S. A summary of Mo—Mo and Mo—L bonding for such clusters is given.     

Mg2[BN2]Cl and Mg8[BN2]5I: Novel Magnesium Nitridoborate Halides — Syntheses,Crystal Structures,and Vibrational Spectra

The title compounds have been synthesized at 1473 K from stoichiometric mixtures of the binary components Mg₃N₂, MgX₂ (X = Cl, I) and BN in arc‐welded steel ampoules encapsulated in evacuated silica tubes. Mg₂[BN₂]Cl ( 1 ) and Mg₈[BN₂]₅I ( 2 ) crystallize in the orthorhombic space groups Pbca (no. 61) and Imma (no. 74), respectively, with a = 6.6139(8)Å, b = 9.766(1)Å, c = 10.600(1)Å, Z = 8 for 1 and a = 13.535(3)Å, b = 9.350(2)Å, c = 11.194(2)Å, Z = 4 for 2 . The crystal structures are characterized mainly by Mg₆ trigonal prisms which are condensed to 3D frameworks in different ways. Part of the trigonal prisms are centered by the [N—B—N]^3— anions and other voids in the framework by the X^— anions. The magnesium environment around Cl^— is a very distorted monocapped trigonal prism (CN = 6+1) and that of I^— is a bicapped heptagonal prism (CN = 14+2). The bond lengths and bond angles for the relevant [BN₂]^3— anions are d(B—N) = 1.330 — 1.338Å, ∠N—B—N = 175.8° in 1 and d(B—N) = 1.330 — 1.339Å, ∠N—B—N = 176.8° — 178.0° in 2 . The vibrational spectra of the title compounds have been recorded and interpreted based on the D_∞h symmetry of the relevant [N—B—N]^3— groups considering the site symmetry splitting.     

Crystal structure of lead(II) dipivaloylmethanate

The volatile complex of lead(II) with 2,2,6,6-tetramethylheptane-3,5-dione is investigated by X-ray diffractometry. Crystal data: a = 10.901(2), b = 21489(4), c = 10.203(2) å, space group Pccn (N 56), V = 2503.4(8) å³, M = 573.74, Z = 4, d_calc = 2.522 g/cm³. The crystal structure is of molecular type; the molecule of the complex has a nonplanar structure. The lead atom is coordinated by four oxygen atoms of the two bidentate ligands. Films of the complex on substrates of Si and SiO₂ single crystals, melted quartz, and glass were obtained by thermal evaporation in vacuum. X-Ray diffraction analysis of the polycrystals and films of the complex showed that the films are distinctly textured along the b axis.