Hochauflösende Festkörper-NMR-Untersuchungen an Kieselsäuren. I. Hochauflösende 29Si-Festkörper-NMR-Untersuchungen an polykristallinen Phyllokieselsäuren (H2Si2O5)x bei tiefem und hohem Magnetfeld

Solid-State High Resolution N.M.R. Studies of Silicic Acids. I. Solid-State High Resolution ²⁹Si N.M.R. Studies of Polycrystalline Phyllosilicic Acids (H₂Si₂O₅)_x at Low and High Magnetic Fields ²⁹Si NMR studies of two samples of phyllosilicic acid show that these samples represent two phases of (H₂Si₂O₅)_x, which can be distinguished by the different isotropic values of the chemical shift, while the amounts and the signs of the anisotropy of their ²⁹Si-shielding tensors agree. The sample A (α-phase) consists of a pure phyllosilicic acid with a regular layer structure, while the sample B (δ-phase) is characterized as a phyllosilicic acid with partial high-condensed areas. From N.M.R. data a model is deduced to describe the structure of this sample. The field-dependence of the line widths for both phases leads to the conclusion that in phyllosilicic acids a distribution of the structural parameters of the SiO₄ tetrahedrons appears. The discussion of the shielding anisotropy data of both (H₂Si₂O₅)_x phases suggests a picture of the crystal structures, which is in disagreement with the known crystal structure of (H₂Si₂O₅)_x-I.     

Hochauflösende Festkörper-NMR-Untersuchungen an Kieselsäuren. III Hochauflösende 29 Si-Festkörper-NMR-Untersuchungen an synthetischen siliciumreichen Kieselsäurehydraten

Solid-State High-Resolution N.M.R. Studies of Silicic Acids. III. Solid-State High-Resolution ²⁹Si-N.M.R. Studies of Synthetic Highly Siliceous Silicic Acid Hydrates Solid-state high-resolution ²⁹Si-N.M.R. experiments were used to study the structure of the silicate layers in three synthetic highly siliceous silicic acid hydrates obtained by cation exchange reactions from the synthetic sodium silicate hydrates ilerite, magadiite and kenyaite. For each of the studied samples two well-separated N.M.R. signals have been recorded which could be assigned to Q³ - (O?Si(OSi?)₃–) and Q⁴-(?Si(OSi?)₄–) units of the silicate layers of the corresponding silicic acid hydrate. On the basis of these results the same model was used to describe the structure of the silicate layers in the studied compounds which has been already used for the interpretation of the N.M.R. results in case of the synthetic sodium silicate hydrates. Compared with the sodium silicate hydrates in the studied silicic acid hydrates a somewhat large Q⁴/Q³-ratio and a high-field shifted Q³signal have been detected. These observations were attributed to structural changes which appeared as a result of the cation exchange reactions.     

1H-Festkörper-NMR-Untersuchungen am synthetischen Pektolith Ca2NaHSi3O9

Solid-state ¹H N.M.R. Studies of Synthetic Pectolite Ca₂NaHSi₃O₉ A synthetic pectolite Ca₂NaHSi₃O₉ is studied by means of conventional ¹H pulse-fourier-transform wide line n.m.r. and methods of solid-state high-resolution ¹H n.m.r. (MREV8 multiple pulse technique, combined multiple pulse magic angle spinning experiments). The n.m.r. spectra consist of a dominant signal due to SiOH groups and a small signal which can be assigned to water molecules. The parameters of the ¹H n.m.r. spectra for the SiOH groups are discussed in comparison with the known structure of pectolite. It can be shown that the structural details for the proton of the SiOH groups are reflected by the ¹H n.m.r. spectra.     

Hochauflösende Elektronenmikroskopie an Yttriumiodidcarbidoxiden

High Resolution Electron Microscopy on Yttrium Iodide Carbide Oxides An investigation on the real structure of the yttrium iodide carbide oxides has been carried out by means of HRTEM. In the structures planar layer fragments with the general composition Y₂I₂C are linked via chains of corner sharing Y₄O tetrahedra building corrugated layers. A sequence of compounds with the general formula (Y₂I₂C)_nYO can be derived where n denotes the number of linked octahedra chains in the plane sections, and thus represents their width. Irregularities concerning the width of the planar segments have been detected. Besides the so far known members of the series Y₇I₆C₃O und Y₉I₈C₄O, with n = 3 and 4, respectively, an additional ordered compound with alternating 3 and 4 octahedra chains has been found. The introduction of the samples, which are very sensitive to air and moisture, into the microscope has been realised using a specially designed transfer system.     

Die Acidität kristalliner Kieselsäuren

Acidity of Crystalline Silicic Acids Crystalline silicic acids are strong solid acids with surface acidities ranging from H₀ < ?3 (H₂Si₁₄O₂₉ · 5.4 H₂O) to H_O ≈? 2.3(H₂Si₂O₅), measured with Hammett indicators. Thermal dehydration reduces the surface acidity to 2.3–3.3 only. The high acidity probably results from regular, extended hydrogen bonding systems including the surface water molecules. By disturbing the regular array of hydrogen bonds the acidity decreases to H_o = 5–6 which is considered to be the characteristic acidity of isolated silanol groups not involved in regular hydrogen bonding systems. The surface acidity is not directly related to the ease with which the protons are exchanged by alkali ions because of the cooperative nature of the cation exchange.     

Synthese,Aufbau und Eigenschaften Käfigartiger vinyl- und allylsilylierter Kieselsäuren

Synthesis, Constitution and Properties of Cage-like Vinyl- and Allylsilylated Silicic Acids By silyation of tetramethylammonium silicate [N(CH₃)₄]₈Si₈O₂₀ · 69 H₂O with vinyldimethylchlorosilane ( I ) and divinyltetramethyldisiloxane, respectively, or allyldimethylchlorosilane there were synthesized the crystalline silicic esters [CH₂?CH(CH₃)₂Si]₈Si₈O₂₀ and[CH₂?CH? CH₂(CH₃)₂Si]₈Si₈O₂₀. By means of gas chromatography, mass spectrometry, ¹H and ²⁹Si NMR the two compounds were identified to be cage-like double four-ring(D4R)-silicic esters containing eight vinyldimethylsilyl- or allyldimethylsilyl groups, Silylation with a mixture of I and trimethylchlorosilane yields in dependence on the ratio of silanes vinyldimethylsilyltrimethylsilyl D4R silicic esters with average numbers of unsaturated groups < 8.     

Metallkomplexe der Phosphinsäuren. XVIII. Ansa- und Oligokomplexe bifunktioneller Dithiophosphinsäuren

Metal Complexes of Phosphinic Acids. XVIII. Ansa- and Oligo-Complexes of Bifunctional Dithiophosphinic Acids The influence of R′ in the bifunctionell chelate ligands ^?S(S)P(R)? R′? (R)P(S)S^? on the association of their planar Ni^II and tetrahedral Co^II complexes is investigated by vapour pressure osmometry and in the case of diamagnetic Ni^II compounds also by ³¹P-NMR spectroscopy. While insoluble coordination polymers [S₂P(R)? R′? (R)PS₂M]_x (M = Ni^II, Co^II) are formed with R′ = p-(C₂H₄)₂C₆H₄ it can be shown, that in solutions of the complexes with R′ = o-(C₂H₄)₂C₆H₄ and R′ = o-(C₃H₆)₂C₆H₄ there exists an association equilibrium comprehending oligomers with n ? x. Above all in the latter case steric conditions seem to favour intramolecular chelating and thus formation of ansa-type complexes. Synthesis of the ligands and the complexes is described.     

Beiträge zur Untersuchung anorganischer nichtstöchiometrischer Verbindungen. XXX. Elektronenmikroskopische Untersuchung in Hochauflösung an metastabilen Niob-Wolfram-Oxiden Vergleich mit der rechnerischen Simultation

Contributions to the Investigation of Inorganic Non-stoichiometric Compounds. XXX. High Resolution Electron Microscopy Investigation of Metastable Niobium Tungsten Oxides. Comparison with Computer Simulated Images . Starting with solid solution series (Nb, W)O_x, where WO₃ + NbO₂ was substituted for Nb₂O₅, a gentle oxidation leads from the original block sizes of [3 × 4], [4 × 4], [4 × 5] or [5 × 5] octahedra to a doubling of blocks in the new ternary oxides, e. g. 2 × [5 × 5] → [5 × 10]. As HRTEM of the oxidation products revealed, these new larger blocks are connected in a special way including so-called “L-type-tunnels”. Using a LaB₆-cathode with our electron microscope, we now for the first time can directly see the positions of these tunnels.     

Untersuchungen an katalytisch aktiven Oberflächenverbindungen. II. Zur Existenz unterschiedlicher Vanadium(V)-oxid-Oberflächenphasen auf SiO2 und ihre katalytischen Eigenschaften

Studies on Catalytically Active Surface Compounds. II. On the Existence of Different Vanadium(V) Oxide Surface Phases on SiO₂ and their Catalytic Properties In dependence on the SiOH concentration of the Aerosil surface two different disperse vanadium(V) oxide phases are obtained, which differ characteristically in their reflexion spectra, their chemisorption behaviour towards butene and their catalytic properties in the oxidation of butene and ethanol. At high values of the original concentration of SiOH groups a δ″ phase is formed which gives after desorption of adsorbed water at 250°C, a reflexion spectrum that points at a tetrahedral coordination of the V^v; this phase shows a relative low activity for both reactions. At a lower original concentration of SiOH a δ″ phase of the vanadium(V) oxide is formed, the reflexion spectrum of which, points at an octahedrally coordinated vanadium(V) oxide. This phase is considerably more active than the former.     

Zum Anionenaufbau von Tetra-n-butylammoniumsilicaten und ihren wäßrigen Lösungen

On the Anion Constitutions of Tetrabutylammonium Silicates and their Aqueous Solutions The anion distribution of tetra-n-butylammonium-(TBA)-silicate solutions with molar TBA/SiO₂ ratios between 0.6 and 4 and silica concentrations between 0.1 M and 2.2 M has been investigated by trimethylsilylation and ²⁹Si NMR techniques. In contrast to concentrated tetramethylammonium- and tetraethylammonium silicate solutions in TBA silicate solutions a preference of double ring silicate anions does not occur. In TBA silicate solutions a broad distribution of silicate anions consisting of monomeric, oligomeric chain and ring, as well as polymeric silicate anions has been observed. Crystalline TBA silicates with TBA/SiO₂ ratios of 0.78 to 1 contain mainly double five-ring silicate anions Si₁₀O₂₅^10? whereas for TBA/SiO₂ ratios higher than 1.4 the double three-ring anion Si₆O₁₅^6? predominates. A recently prepared TBA silicate with low TBA content (TBA/SiO₂ = 0.23) has been found to consist of double four-ring silicate anions with 6 SiOH groups per double four-ring.     

Metallkomplexe der Phosphinsäuren. XVII. Untersuchungen zur Oligomerisation von NiII- und CoII-Komplexen bifunktioneller Dithiophosphinsäuren HS(S)P(R)-R′-(R)P(S)SH [2]

Metal Complexes of Phosphinic Acids. XVII. Investigations on the Oligomerisation of Ni^II and Co^II Complexes of Bifunctional Dithiophosphinic Acids Alkali or ammonium salts of bifunctional dithiophosphinic acids react with Ni²⁺ or Co²⁺ to give complexes [S₂P(R)? (CH₂)_n? (R)PS₂M]_m or _x (R = 4-methoxyphenyl; M = Ni²⁺, Co²⁺; n = 4? 10) some of which are soluble in organic solvents and of low molecular weight (m), while others are insoluble (x). According to magnetic and spectroscopic measurements all of them contain planar NiS₄ or tetrahedral CoS₄ chromophors. While the insoluble compounds are regarded as coordination polymers, it is shown by osmometric measurements and by ³¹P{¹H} spectroscopy, that there exists the equilibrium monomers (ansa type) ? oligomers in solutions of the soluble complexes. The influence of n on the solubility and the equilibrium is discussed. The association can be explained by simple statistic considerations.     

Über Chalkogenolate. LXIV. Untersuchungen über Thiomeisensäuren 7. Kristallstruktur von Tetraäthylammoniumcyandithioformiat

On Chalkogenolates. LXIV. Studies on Thioformic Acids. 7. Crystal Structure of Tetraethylammonium Cyanidithioformate Tetraethylammonium cyandithioformate [(C₂H₅)₄N][NCCS₂] crystallizes in the orthorhombic space group Pbem? D (no. 57): a = 7.715; b = 13.945; c = 12.255 Å and Z = 4. Planar cyandithioformate ions are packed parallel the xy plane at z = 0.25 and 0.75. The nitrogen atoms of the ammonium groups build columns along the glide plane c. Structural refinements were completed to a weighted R = 0.078.     

Beiträge zur Untersuchung anorganischer nichtstöchiometrischer Verbindungen. XXIII. Neue Bauelemente bei metastabilen Blockstrukturen im System Nb2O5/WO3 Elektronenmikroskopische Untersuchung in Hochauflösung

Contributions to the Investigation of Inorganic Non-stoichiometric Compounds. XXIII. New Building Elements of Metastable Block Structures in the System Nb₂O₅/WO₃, Investigation by High Resolution Electron Microscopy Under equilibrium conditions the region of existence of block structures in the system Nb₂O₅/WO₃ ends with a phase having the composition 9 Nb₂O₅:8 WO₃ corresponding to values of O/ΣM = 2.654 (M = Nb, W) and W/Nb = 0.44. We now investigated to what extent this region of existence of block structures could be expanded towards a higher content of WO₃. Starting out from the known phases Nb₂O₅:WO₃ = 6:1, 7:3, 8:5 and 9:8 in which Nb and W are present in their maximum states of oxidation, we obtained series of solid solutions by substituting W for Nb. Thereby the initial structure (block sizes [3×4], [4×4], [4×5] and [5×5] M–O-octahedra) and also the respective O/ΣM remained unchanged. Upon complete oxidation of these series of solid solutions which led into reduced systems (e. g. NbO₂/Nb₂O₅/WO₃) at ～500°C metastable products were gained, which also have block structures. Corresponding to the extent of substitution of the initial series of solid solution and the resulting ratio O/ΣM of the oxidation products the new structures are to a wide extent built of large blocks that have an extension (at maximum [5X15] M–O-octahedra) we have not observed so far. These blocks could be seen using high resolution transmission electron microscopy. The investigations on the oxidation products of the solid solutions of thc 8:5 and 9:8 series and illso it model concerning the mechanism of oxidation are described.     

29Si- und 23Na-Festkörper-MAS-NMR-Untersuchungen an Modifikationen des Na2Si2O5

²⁹Si and ²³Na Solid State MAS NMR Investigations of Modifications of the Sodium Phyllosilicate Na₂Si₂O₅ . The results of ²⁹Si- and ²³Na-MAS NMR investigations on four modifications of the synthetic Na₂Si₂O₅ demonstrate that the α-, β- and δ-modifications are characterized unequivocally by the parameters of the corresponding NMR spectra. The studies on γ-Na₂Si₂O₅ show that this sample contains a large amount of secondary compounds. For α- und β-Na₂Si₂O₅ the the structural details of the silicate sheets are reflected by the ²⁹Si MAS NMR spectra while from the ²³Na MAS NMR spectra conclusions about the coordination number of the sodium atoms can be derived. The ²⁹Si MAS NMR investigations on δ-Na₂Si₂O₅ indicate that the silicate sheet of this modification consist of identical SiO₄-tetrahydra the parameter of which differ from those of α- and β-Na₂Si₂O₅. The ²³Na MAS NMR studies show that in the interlayer space of δ-Na₂Si₂O₅ two nonidentical sodium atoms exists. The NMR results give rise to the suggestion that one of the sodium is surrounded by five and the other one by six oxygen atoms.     

Synthesen,Einkristall-Röntgenstrukturanalysen und 29Si-Festkörper-NMR-Untersuchungen eines zwitterionischen λ5-Spirosilicats und eines käfigartigen Octa(silasesquioxans)

Syntheses, Single-Crystal X-Ray Analyses and Solid-State ²⁹Si NMR Studies of a Zwitterionic λ⁵-Spirosilicate and a Cage-like Octa(silasesquioxane) The zwitterionic λ⁵-spirosilicate bis[2,3-naphthalenediolato(2 ?)][2-(dimethylammonio)phenyl]silicate ( 1 ; isolated as 1 · 1/2 CH₃CN) was synthesized by reaction of the [2-(dimethylamino)phenyl]dimethoxyorganosilanes 5, 6 and 7 [2-(Me₂N)C₆H₄Si(OMe)₂R: R = Ph ( 5 ), cyclo? C₆H₁₁ ( 6 ), Me ( 7 )] with 2,3-dihydroxynaphthalene in acetonitrile at room temperature. Reaction of 1 · 1/2 CH₃CN or [2-(dimethylamino)phenyl]trimethoxysilane ( 3 ) with water in acetonitrile yielded the cage-like octa{[2-(dimethylamino)phenyl]silasesquioxane} ( 2 ). The crystal structures of 1 · 1/2 CH₃CN and 2 were studied by X-ray diffraction. In addition, 1 · 1/2 CH₃CN and 2 were characterized by solid-state (²⁹Si CP/MAS) and solution NMR studies (¹H, ¹³C, ²⁹Si).     

Über die Umsetzung von P4E3I2 (E = S,Se) mit einigen Carbonsäuren und Dithiocarbonsäuren

On the Reaction of P₄E₃I₂ (E = S, Se) with some Carboxylic Acids and Dithiocarbamic Acids By the reaction of α-P₄E₃I₂ (E = S, Se) with carboxylic acids, dithiobenzoic acid or dithiocarbamic acids in the presence of triethylamin or with (C₆H₅)₃SnR, or of β-P₄E₃I₂ with tin-organic compounds α-P₄E₃(I)R, α(β)-P₄E₃R₂ [R = ? OC(O)C₆H₅, ? OC(O)CH₃, ? SC(S)NC₅H₁₀, ? SC(S)N(C₂H₅)₂], α-P₄S₃(I)SC(S)C₆H₅, α-P₄S₃(SC(S)C₆H₅)₂ and β-P₄E₃(I)R (R = ? OC(O)C₆H₅, ? OC(O)CH₃) were prepared in solution and identified by ³¹P NMR spectroscopy. In addition α-P₄S₃(NC₅H₁₀)(SC(S)NC₅H₁₀) was detected. The β-isomers could be obtained also with lesser yields by the reaction with the dithiocarbamic acids, too. The substitution of the second iodine ligand in β-P₄E₃I₂ resulted mainly in β-P₄S₃(R_exo)₂ and by inversion of the configuration at a phosphorus atom, in β-P₄E₃R_exoR_endo. α-P₄S₃I₂ reacted with methanol in CS₂ to α-P₄S₃(OCH₃)(SC(S)OCH₃) and α-P₄S₃(SC(S)OCH₃)₂. The ³¹P NMR data of the compounds are discussed. The ³¹P NMR spectra of the α(β)-P₄E₃ dithiocarbamates indicate dynamic processes in the solution, e. g. α-P₄S₃(I)(SC(S)NR₂) showed an intramolecular conversion, due to the anisobidentate dithiocarbamate ligand. This behaviour had not previously been noticed for compounds with a P₄S₃-skeleton.     

Über Chalkogenolate. 85. Untersuchungen über Halbester der Trithiokohlensäure 3. Schwingungsspektren von Alkylthioxanthogensäuren und Wasserstoffbrücken in den freien Säuren

On Chalcogenolates. 85. Studies on Hemiesters of Trithiocarbonic Acid 3. Vibrational Spectra of Alkyl Thioxanthic Acids and Hydrogen Bondings in the Free Acids The IR spectra of alkyl thioxanthic acids RS? CS(SH) with R = CH₃, C₂H₅, ⁿC₃H₇, ⁱC₃H₇, ⁿC₄H₉, ^sC₄H₉, ^tC₄H₉, and CH₃S? CS(SD) as well as the Raman spectrum of the Compound with R = CH₃ have been assigned. The formation of hydrogen bondings in the free acids has been studied by means of i.r. spectra, ¹H-n.m.r. spectra, and electron absorption spectra. The energies of the hydrogen bondings have been calculated.     

Über Chalkogenolate. 139. Untersuchungen über Dialkylester von Chalkogenokohlensäuren. 2. O,Se- und S,Se-Dialkylmonothiomonoselenocarbonate

On Chalcogenolates. 139. Studies on Dialkyl Esters of Chalcogenocarbonic Acids. 2. O,Se- and S, Se-Dialkyl Monothiomonoselenocarbonates The hitherto unknown esters RSe? CS? OR′, where R = C₂H₅, ⁿC₃H₇ and R′ = C₂H₅, ⁿC₃H₇, are formed by reaction of NaSeR with Cl? CS? OR′ and of RSe? CS? Cl with HOR′. At the first time, the esters RSe? CO? SR′ with R = R′ = C₂H₅, ⁿC₃H₇ have been prepared by reaction between NaSeR and Cl? CO? SR′. The compounds have been characterized by means of diverse spectroscopic methods.     

Über Chalkogenolate. 134. Untersuchungen über Ester von Halogenoameisensäuren 2. Darstellung und Eigenschaften von Se-Alkylestern der Chloromonothiomonoselenoameisensäure [1]

On Chalcogenolates. 134. Studies on Esters of Haloformic Acids 2. Synthesis and Properties of Se-Alkyl Esters of Chloromonothiomonoselenoformic Acid The hitherto unknown esters RSe? CS? Cl with R ? C₂H₅ and ⁿC₃H₇ have been prepared by reaction of thiophosgene with the corresponding alkane selenol. The compounds have been characterized with electron absorption, nuclear magnetic resonance (¹H, ¹³C, and ⁷⁷Se), infrared, and mass spectra.     

B2Si2O6 – ein amorphes anorganisches Netzwerk mit Si–Si‐Bindungen

B₂Si₂O₆ – an Amorphous Inorganic Network Containing Si–Si Bonds B₂Si₂O₆ has been synthesized via sol‐gel processing, reacting Si₂Cl₆ with boric acid in abs. dioxane. The resulting amorphous product is the first borosilicate containing Si–Si bonds. B₂Si₂O₆ has been characterized by IR, NMR, DTA, XANES, and TEM. The spectroscopic results indicate that BSiO₃ is an individual phase and not a mixture of Si₂O₃ and B₂O₃. A random network model of B₂Si₂O₆ can be derived, where structural units of Si₂O₆ are connected via common vertices to trigonal planar coordinated boron atoms.