Die chemie der schweren carben-analogen R2M,M = Si,Ge, Sn: X. 7-sila-norbornadiene: reaktionen mit halogenen und thermolyse in genewart von metallorganischen oder organischen halogeniden

The 7-sila norbornadienes (I–IV) react rapidly with halogens at −20 to +20°C to yield Me₂SiHal₂ (Hal = Cl, Br, I) and the naphthalene or benzene derivatives (V–VIII). Bromine in CCl₄ at 0°C, however, caused surprising rearrangement in I giving the 2-bromosilylated naphthalene (IX), since an attack at the alkene group seemed to be preferred. Methylation and methoxylation of IX gave respectively X and XI. Careful hydrolysis of IX yielded the disiloxane VII. Insertions of Me₂Si into the SiHal, SiH, SiC, or SnC bonds were not observed at 160–200°C, whereas insertions into SnCl or SnH bonds occurred smoothly via a one-step mechanism. Halogen is abstracted from different CHal bonds leading to Me₂SiHal₂ and sometimes to Me₄Si₂Hal₂. The degradation of the silylene precursors in these cases is always first order and resembles that of spontaneous thermolysis.     

Chemie der schweren carben-analogen R2M, M = Si, Ge, Sn : XVIII. Eine unerwartete Ge---C-Spaltung des als Dimethylgermylen-Speicher dienenden 7,7-Dimethyl-7-germanorbornadiens

During thermolysis of the 7-germanorbornadiene 1 in chlorobenzene at 70°C in the presence of concentrated hydrochloric acid, besides the well-known formation of free germylene Me₂Ge and its consecutive product dimethylchlorogermane 2, the polar splitting of only one Ge---C bond in 1 has been observed for the first time. It does not yield Me₂Ge, but instead it rapidly forms the 1-germyl-1,4-dihydronaphthalene 3. The kinetics of this reaction at 53°C are of 2nd order, t_1/2 = 20 min, k = 0.22 l mol⁻¹ min⁻¹. At room temperature 3 is formed quantitatively. Also, at 70°C the slower formation of the germylene Me₂Ge from 1 can be suppressed completely if HCl gas is bubbled through the reaction mixture, thus favouring the rapid formation of 3. As a by-product the 1,2-dihydronaphthalene 5 is generated.     

Enthalpie der Polymerisation von 7-Oxabicyclo[2.2.1]-heptan sowie exo- und endo-2-Methyl-7-oxabicyclo-[2.2.1]-heptan

Ohne Zusammenfassung     

Spektroskopische Untersuchungen an R3MF-Verbindungen (M = Si,Ge, Sn)

Spectroscopical Investigations on R₃MF Compounds (M = Si, Ge, Sn) The IR and RAMAN spectra of a number of R₃MF compounds (M? Si, Ge, Sn) have been recorded. The frequencies of the vibrational spectra were almost completely assigned. The measurements of the IR-spectra were investigated (as for as possible) in all states of aggregations. The force of the intermolecular interactions were discussed by means of the spectroscopic data.     

Die KristallStrukturen von K6[Ge2Te6] und K6[Sn2Te6] und ihre kristall-chemische Beziehung zum K6[Si2Te6]-Typ

Crystal Structures of K₆[Ge₂Te₆] and K₆[Sn₂Te₆] and their Relations to the K₆[Si₂Te₆] Type K₆[Ge₂Te₆] and K₆[Sn₂Te₆], the first members of the families of telluro-digermanates and telluro-distannates have been prepared and their structures determined. The space group is C 2/c with cell constants a = 16.010(8), b = 13.619(8), c = 9.713(5) Å, β = 95.19(5)° and Z = 4 for the Ge compound. The Sn compound has space group P 2₁/c, a = 9.590(5), b = 13.654(8), c = 9.606(5) Å, β = 116.84(5) and Z = 2. The structures were established by direct methods, using four-circle diffractometer data. The final R value for 828 (1677) independent reflexions is 0.068 (0.047) for the Ge (Sn) compound. Both structures have discrete X₂Te₆ groups (X = Ge, Sn) in staggered conformation connected by K atoms in distorted octahedral or trigonal prismatic environments and bear direct subgroup relationships to that of K₆[Si₂Te₆]. The average X? Te distance is 2.579 (2.724) Å and the X? X distance 2.492 (2.814) Å.     

Die säurekatalysierte Isomerisierung von 7-Oxabicyclo[2.2.1]-heptadien- und Oxepin-Derivaten [1]

The acid catalyzed isomerization of several substituted oxanorbornadienes 4 and oxepines 10 - easily available from 4 by a photochemical and a consecutive thermal step - allows the synthesis of several highly substituted phenols and 2,4-cyclohexadienones in a straightforward manner and with good to excellent yields. The formation of the methoxycarbonyl-hexadienes 18e and 18f upon photolysis of 9e and 17f in methanol supports the structure elucidation. The relative importance of the McLAFFERTY and EMERY effects in the mass spectral degradation of methoxycarbonyl and methyl substituted phenols are discussed.     

Darstellung und Eigenschaften der Alkali-hexajodatogermanate (IV), M2[Ge(JO3)6]

Preparation and Properties of the Alkali Hexaiodatogermanates(IV), M₂[Ge(IO₃)₆] Germanium dioxide aquate and alkali nitrates react with iodic acid to yield alkali hexaiodatogermanates(IV), M₂[Ge(IO₃)₆], (M = NH₄, K, Rb, Cs). The unit-cell dimensions of the trigonal cell are for K₂[Ge(JO₃)₆] a₀ = 11.16 Å, c₀ = 11.34 Å, z = 3. The compounds M[M^IV(IO₃)₆] (M^I = NH₄, K, Rb, Cs, M^IV = Ge, Sn, Pb, Ti, Zr, Mn) are isomorphous¹).     

Die Kristallstruktur der Verbindung Li6[Si2O7]

Zusammenfassung Die Kristallstruktur von Li₆[Si₂O₇] wird mit Hilfe von Patterson-Projektionen und dreidimensionalen Fourier-Synthesen sowie nach der Methode der kleinsten Quadrate bestimmt. Die Gitterparameter der tetragonalen Elementarzelle (P42₁m-D _2d ³ ) betragen:a=7,71₅;c=4,88 Å. Die Verbindung zählt zu den Sorosilicaten mit isolierten [Si₂O₇]-Gruppen. Die Lithiumionen weisen gegenüber Sauerstoff die Koordinationszahlen 4 und 5 auf. Als mittlere Abstände [Å] wurden ermittelt: Si-O : 1,64 Li-O : 1,95 [4] und 2,18 [5].

---

The crystal structure ofLi ₆[Si ₂ O ₇]

The crystal structure of Li₆[Si₂O₇] has been determined by means of Patterson projections, 3-dimensional Fourier syntheses and the least-squares method. The lattice parameters of the tetragonal unit cell (P42₁m-D _2d ³ ) area=7.71₅ andc=4.88 Å. The compound belongs to the sorosilicates having isolated [Si₂O₇]-groups. The coordination numbers of the lithium ions are 4 and 5. The average interatomic distances were found to be: Si-O : 1,64 Å; Li-O : 1.95 [4] and 2.18 [5] Å.

---

---

Mit 3 Abbildungen     

Synthese,Struktur und Eigenschaften der Tetraarsenidometallate(V) M7[TAs4] (M = K,Rb; T = Nb,Ta)

Synthesis, Structure, and Properties of the Tetraarsenidometallates(V) M₇[TAs₄] (M = K, Rb; T = Nb, Ta) The tetraarsenidometallates(V) M₇[TAs₄] (M = K, Rb; T = Nb, Ta) have been prepared from RbAs, KAs, Rb₃As, K₃As, and Nb or Ta in sealed Nb(Ta) ampoules at T = 1100 K. They crystallize in a new structure type oP24 (Pmn2₁, no. 31); K₇[NbAs₄]: a = 1019.2(2) pm, b = 916.2(2) pm, c = 830.6(1) pm; K₇[TaAs₄]: a = 1017.3(2) pm, b = 915.5(2) pm, c = 830.5(2) pm; Rb₇[NbAs₄]: a = 1059.2(4) pm, b = 952.8(4) pm, c = 860.4(4) pm; Z = 2 formula units per unit cell). The compounds form dark red crystals and they are sensitive against air and moisture. They are semiconductors with E_g = 1.80 eV. The thermal decomposition in dynamical vacuum gives evidence for the existance of K₄TAs₃ and K₂TAs₂ (T = Nb, Ta). Main structural units are polar oriented tetrahedra [TAs₄] with d (T – As) = 252.2(1) pm; 251.3(1) pm; 253.0(4) pm, respectively. The As atoms are trigonal prismatically coordinated by M and T atoms. These trigonal prisms form anionic and cationic layers [M₄As₂]^2? and _∞²[M₃TAs₂]²⁺ alternating along the b axis. The structure is comparable with that of Co₂P and can be described as a stuffed shear variant of the Na₆□ZnO₄ type of structure.     

Die Tieftemperaturmodifikationen von Ag6Si2O7 und Ag6Ge2O7 – Darstellung,Kristallstruktur und Vergleich der Ag?Ag-Abstände

On the Low Temperature Modifications of Ag₆Si₂O₇ and Ag₆Ge₂O₇ – Synthesis, Crystal Structure, and Comparison of Ag? Ag Distances For the first time, single crystals of Ag₆Si₂O₇ and Ag₆Ge₂O₇ have been obtained by solid state reactions of the binary oxides at temperatures of 350°C while applying oxygen pressures of 700 bar. According to the results of X-ray crystal structure determinations both compounds crystallize isostructural in P2₁ (Ag₆Si₂O₇: a = 5.3043(5) Å, b = 9.7533(7) Å, c = 15.9283(13) Å, β = 91.165(8)°, 3881 independent reflections, R1 = 3.3%, wR2 = 7.2%; Ag₆Ge₂O₇: a = 5.3713(4) Å, b = 9.9835(8) Å, c = 16.2249(14) Å, β = 90.904(8)°, 2111 independent reflections, R1 = 4.3%, wR2 = 6.0%, Z = 4). The crystal structures contain two independent M₂O₇^6? anions, one in a staggered, and the other in an ecliptic conformation. The cationic partial structure may be described as a distorted bcc arrangement of Ag⁺ and M⁴⁺. Comparison of the structures with respect to the Ag? Ag separations reveals the latter to be probably due to intrinsic d¹⁰–d¹⁰ bonding interactions as far as the range of 2.89 Å to 3.25 Å is considered.     

Neue Suboxid-Cluster [O5Ba18] in den Kristallstrukturen von Ba21M2O5 (M = Si,Ge)

Novel Suboxide Clusters [O₅Ba₁₈] in the Crystal Structures of Ba₂₁M₂O₅ (M = Si, Ge) The compounds Ba₂₁M₂O₅ (M = Si, Ge) crystallize in the cubic system with space group Fd3m, lattice constants 2 038.3(10) pm (Si), 2 039.8(9) pm (Ge) resp. and Z = 8. The crystal structure contains isolated Si/Ge atoms coordinated by barium atoms in an icosahedral arrangement. The oxygen atoms are situated in the centers of barium octahedra, four of which share common faces with an additional central octahedron. The novel clusters [O₅Ba₁₈] in principal are related to those in the crystal structures of the binary Cs/Rb suboxides.     

Fe4Si2Sn7O16: Eine Kombination von FeSn6-Oktaedern mit Schichten von (Fe3Sn)O6-Oktaedern; Präparation,Eigenschaften und Kristallstruktur [1]

Fe₄Si₂Sn₇O₁₆: A Combination of FeSn₆-Octahedra with Layers of (Fe₃Sn)O₆-Octahedra; Preparation, Properties, and Crystal Structure Fe₄Si₂Sn₇O₁₆ has been prepared by a solid state reaction at 900 °C from a mixture of Fe₂O₃, SnO₂, Sn, and Si. The compound is a paramagnetic semiconductor. Results of Mössbauer and suszeptibility measurements as well as bond length-bond strength calculations lead to the possible ionic formulation Fe₄²⁺Si₂⁴⁺Sn₁²⁺Sn₁⁴⁺O₁₆^2–. The compound crystallizes in the trigonal space group P3m1 (no. 164), with one formula unit per cell. Lattice parameters obtained by powder measurements are: a = 6.8243(6) Å, c = 9.1404(6) Å, γ = 120°, V = 368.6(1) ų. The structure consists of layers of edge linked oxygen octehedra exactly centered by Sn and Fe in the ratio 1 : 3. Three plains of isolated SiO₄ tetrahedra, FeSn₆ octahedra and again SiO₄ terahedra are inserted between two such layers. The layers are stacked along [001] and linked three-dimensionally by oxygen.     

Darstellung und Eigenschaften von Alkalimetall-Tetrathioterephthalaten. Die Kristallstruktur von K2[S2C?C6H4?CS2] · 2 H2O

Preparation and Properties of Alkalimetal-Benzene-1,4-dicarbotetrathioates. The Crystal Structure of K₂[S₂C? C₆H₄? CS₂] · 2 H₂O By oxidation of α,α′-dichloro-p-xylene with elemental sulfur alkali metal salts of tetrathioterephthalic acid (H₂TTTP) are formed. The complexing properties of the bischelating TTTP-dianion are investigated. Only one stable complex, the dimeric [(CO)₅Mn]₂TTTP, was obtained so far. K₂TTTP crystallizes with a = 744.1(2), b = 1322.1(3), c = 691.5(2) pm, β = 106.11(2)°, Z = 2. The centrosymmetric dianion is nonplanar.     

Ternäre Hydroxide. I. Synthese,Struktur und Eigenschaften von Li2[Sn(OH)6] · 2 H2O

Ternary Hydroxides. I. Synthesis, Structure, and Properties of Li₂[Sn(OH)₆] · 2 H₂O Colourless crystals of Li₂[Sn(OH)₆] · 2 H₂O were synthesized by reaction of SnCl₄ with LiOH in aqueous solution. The crystal structure was determined from single crystal data. Li₂[Sn(OH)₆] · 2 H₂O: monoclinic, P2₁/n (Nr. 14), a = 502.3(1), b = 692.3(1), c = 1020.2(3) pm, β = 99.78(1)°, V = 349.6(2) · 10⁶ pm³, Z = 2, R/Rw = 0.0192/0.0472, N(I) > 2σ(I) = 1527, N(Par.) = 54. Within the crystal structure only slightly distorted octahedrally [Sn(OH)₆]^2? ions are bonded via hydrogen bonds with water molecules forming layers, which themselve are linked by tetrahedrally coordinated Li ions; the structure is in accordance with the IR-data and the results of the ¹¹⁹Sn solid state NMR-spectroscopy; the hydrat water is eliminated at 117.1°C, the condensation reaction – forming the ternary oxide – takes place at 257.7°C.     

Synthesen und Kristallstrukturen der Polytellurido-Komplexe [K(15-Krone-5)2]2[MTe7] mit M = Zn und Hg

Synthesis and Crystal Structures of the Polyellurido Complexes [K(15-Crown-5)₂]₂[MTe₇] with M = Zn and Hg The title compounds were obtained in the presence of 15-crown 5 from solutions of zinc and mercury acetate, respectively, in DMF by addition of a solution of K₂Te₃ in DMF at 0°C (M = Zn) and -50°C (M = Hg). They form black crystal needles with metallic luster. Their crystal structures were determined by X-ray diffraction. The structures of [K(15-crown-5)₂]₂ZnTe₇ and [K(15-crown-5)₂]₂HgTe₇ show two-dimensional disorder as evidence by diffuse scattering. The averaged structures that were determined with the Bragg reflexions correspond to space group Pbcn and have very similar lattice parameters. Nevertheless, the structures differ. [HgTe₇]^2? ions consist of two condensed five membered rings. They are arranged to form strands in the c direction; within of one strand the ions have a definite orientation, but in different strands two different orientations occur randomly. A [ZnTe₇]^2? ion can be thought of consisting of a Zn²⁺ ion, a Te₄^2? ion bonded in a chelate manner and a Te₃^2? ion bonded with one terminal Te atom to the Zn²⁺. The [ZnTe₇]^2? ions are associated to strands in the c direction with two different strand orientations occuring randomly.     

Synthese,Kristallstrukturen und Eigenschaften von Lanthanoid(III)-Komplexen mit 7-Oxa-bicyclo[2.2.1]heptan-2,3-dicarbonsäure

Synthesis, Crystal Structures, and Properties of Lanthanoid(III) Complexes with 7-Oxa-bicyclo[2.2.1]heptane-2,3-dicarboxylic Acid The synthesis of coordination compounds [ML(HL)(H₂O)] with M = La³⁺, Ce³⁺, Pr³⁺, Nd³⁺ and H₂L = 7-oxa-bicyclo[2.2.1]heptane-2-exo,3-cis-dicarboxylic acid ( 1 ) has been described. Results of IR spectroscopy and thermal decomposition are given. As a result of X-ray analyses, the four investigated lanthanoid(III) complexes are isotypic. Their stereochemistry approximates to the tri-capped trigonal prism with nine O atoms coordinating the metal atom. The bicyclic ligand acts as a tridentate chelating monoanion HL^? as well as a pentadentate dianion L^2? with both chelating and bridging function. One coordination place at the metal atom is occupied by a water molecule.