Über Glasbildung und Eigenschaften von Chalkogenidsystemen. IV. Bleithiogermanat (II,IV)-Gläser und ihre Eigenschaften

On Glass-Forming and Properties of Chalkogenide Systems. IV. Leadthiogermanate(II, IV) Glasses and their Properties PbS forms with GeS₂ in the presence of GeS stable glasses in a large range of composition. Melts containing an excess of sulphur yield inhomogenious products. Substituting PbS for GeS, the values of the atomic volume of the glasses at first decrease. The glass transition points as well as the optical and electrical properties are noticed and the crystalline phases received on annealing are discussed with respect to the glass-forming region. The results give the fundamentals to consider the vitreous materials of the system PbS? GeS? GeS₂ as leadthiogermanate(II, IV) glasses.     

Die Oxydation von CO an Katalysatoren auf der Basis poröser Gläser

Oxidation of CO over Catalysts Supported by Porous Glasses It is reported on the catalytic activity of metal catalysts (Ag, Mn, Ni, Cu/Zn, Fe/Cr) supported by porous glasses for the oxidation of CO. In comparison with impregnated carrier catalysts metal catalysts prepared by ionexchange of porous glasses (Ag⁺) show a higher activity for oxidation of CO. The preparation of ionexchanged forms of porous glasses is described.     

Über Glasbildung und Eigenschaften von Chalkogenidsystemen. V. Glasbildung im System SnS?GeS?GeS2 und die Mossbauer-Spektren der Gläser

On Glass-Forming and Properties of Chalkogenide Systems. V. Glass-Formation in the System SnS? GeS? GeS₂ and the Mössbauer Spectra of the Glasses. In the glasses of the system GeS? GeS₂ it is possible to substitute SnS for GeS in a large scale. Within wide limits the values of the atomic volume and transition temperatures are little influenced by the substitution. The ¹¹⁹Sn-Mössbauer-spectra are very similar to the spectrum of the compound SnGeS₃ which crystallizes from the glasses on annealing.     

Diskussion Intramolekularer Wechselwirkungen an RC6H4(CH3)2SiF-, RC6H4(CH3)2SiOCH3-, RC6H4O(CH3)2SiF-, RC6H4OSi(CH3)3- und (CH3)3MF- [M  C,Si, Ge,Sn] Verbindungen

Chalcogenide Glasses with Organic Components. I. Glasses of the Selenium-Arsenic-Bromine-Azobenzene System New glasses were prepared by melting suitable glasses of the system Se? As? Br and of Bis(selenenylbromido)-azobenzene, and cooling them subsequently. Azobenzene groups are connected with the inorganic glass by selenium-carbon bonds. These substances represent the link between polymers as part of the organic chemistry and inorganic glasses. The structures of these products are discussed on the basis of thermal, conductivity, and infrared spectroscopic studies and of density measurements.     

Über Glasbildung und Eigenschaften von Chalkogenidsystemen. VII. Anwendung der Theorie des freien Volumens auf Gläser und Schmelzen im System Germanium-Selen

Application of the Free Volume Theory to Glasses and Melts in the System Germanium–Selenium The temperature dependence on the molar volume of glasses and melts was measured for the compositions: Ge₅Se₇, Ge₂Se₃, Ge₃Se₇, GeSe₃, GeSe₅. Values of the free volume were calculated. Correlating this values according to free volume theory with data from the literature concerning the viscosity of the melts allows the estimation of the minimum required volume of the voids. Se is found as the unit of viscous flow for GeSe₂?Se-melts. The mechanism is discussed.     

Über Glasbildung und Eigenschaften von Chalkogenidsystemen. IX. Zur Struktur der GeS/GeS2- und GeSe/GeSe2-Gläser

Glass Formation and Properties of Chalcogenide Systems. IX. On the Structure of GeS/GeS₂ and GeSe/GeSe₂ Glasses Mole volume, glass transition temperature, and coefficient of thermal expansion were measured on glasses prepared by standardized conditions. Near the composition Ge₂S₃ and Ge₂Se₃ the properties show a singularity or point of inflexion, respectively. Random models of structure are inconsistent with such a behaviour. A model of higher chemical order is proposed which can explain the observed dependence of the glass properties on composition and is in accordance with radial distribution studies.     

Radiale Verteilungsfunktionen. I. Strukturuntersuchungen an CoII-Chromophoren in Natriumborat-Gläsern

Radial Distribution Functions. I. Structural Studies on Co^II Chromophores in Sodium Borate Glasses Co^II chromophores in sodium borate glass were investigated spectroscopically and by X-ray intensity measurements. In glasses with low alkali content (x<0,17) cobalt is surrounded by six oxygens in a distorted octahedron at a distance of 2.02–2.12 Å, whereas in alkali rich glasses a distorted tetrahedral co-ordination with significant shorter d(CoO) = 1.94?2.09 Å is obtained. The results are reported and discussed with respect to the factors which influence the kind of co-ordination.     

On the π‐Electron Distribution in Biphenylene Analogues

The bonding situation in a series of biphenylene analogues – benzo[b]biphenylene and its dication, 4,10‐dibromobenzo[b]biphenylene, naphtho[2,3‐b]biphenylene and its dianion, benzo[a]biphenylene, (biphenylene)tricarbonylchromium, benzo[3,4]cyclobuta[1,2‐c]thiophene, benzo[3,4]cyclobuta[1,2‐c]thiophene 2‐oxide, benzo[3,4]cyclobuta[1,2‐c]thiophene 2,2‐dioxide, 4,10‐diazabenzo[b]biphenylene, biphenylene‐2,3‐dione, benzo[3,4]cyclobuta[1,2‐b]anthracene‐6,11‐dione, and 3,4‐dihydro‐2H‐benzo[3,4]cyclobuta[1,2]cycloheptene – where one of the two benzo rings of biphenylene is replaced by a different π‐system (B) was investigated on the basis of the NMR parameters of these systems. From the vicinal ¹H,¹H spin‐spin coupling constants, the electronic structure of the remaining benzo ring (A) is derived via the Q‐value method. It is found that increasing tendency of B to tolerate exocyclic double bonds at the central four‐membered ring of these systems favors increased π‐electron delocalization in the A ring. The analysis of the chemical shifts supports this conclusion. NICS (nucleus‐independent chemical shift) values as well as C,C bond lengths derived from ab initio calculations are in excellent agreement with the experimental data. The charged systems benzo[b]biphenylene dication and naphtho[2,3‐b]biphenylene dianion ( 7 ²⁻) are also studied by ¹³C NMR measurements. The charge distribution found closely resembles the predictions of the simple HMO model and reveals that 7 ²⁻ can be regarded as a benzo[3,4]cyclobuta[1,2‐b]‐substituted anthracene dianion. It is shown that the orientation of the tricarbonylchromium group in complexes of benzenoid aromatics can be derived from the vicinal ¹H,¹H coupling constants.     

Ring Currents in Benzo‐ and Benzocyclobutadieno‐Annelated Biphenylene Derivatives

The effect of benzo and benzocyclobutadieno annelation on the current density induced in a series of biphenylene derivatives is examined at the B3LYP/cc‐pVDZ level of theory, by using the CTOCD‐DZ method. Angular benzo annelation increases, whereas linear benzo annelation decreases the intensity of paratropic (antiaromatic) current density along the four‐membered ring of biphenylene. The opposite effect is found for benzocyclobutadieno annelation. It is shown that the extent of local aromaticity of the four‐membered ring in biphenylene congeners can vary from highly antiaromatic to nonaromatic, as a result of different modes of annelation.     

Synthesis of Aromatic Compounds by Catalytic C?C Bond Activation of Biphenylene or Angular [3]Phenylene

Substituted phenanthrenes and picenes were easily prepared by reaction of biphenylene or angular [3]phenylene with various alkynes in the presence of a catalytic amount of [IrCl(cod)]₂/dppe (cod=1,5‐cyclooctadiene, dppe=1,2‐bis(diphenylphosphino)ethane). The reaction is based on C? C bond activation of the cyclobutane ring. The reaction tolerates the presence of bulky groups on the alkyne, such as the ferrocene moiety. In addition, a catalytic system based on [RhCl(cod)]₂/dppe enabled the, hitherto unreported, reaction of biphenylene with nitriles to provide phenanthridines.     

Eigenschafts-Korrelationen bei Chalkogenidgläsern. I. Das System Germanium-Antimon-Schwefel

Correlations between Properties of Chalcogenide Glasses. I. The System Germanium—Antimony—Sulphur Glass formation and properties of the glasses in the system Ge–Sb–S are described. The limits of the glass-forming region correspond approximately to the lines joining GeS, GeS₃ and Sb₂S₃ in the composition diagram. The results indicate two regions of liquid immiscibility, both at high sulphur and high antimony contents. The densities increase linearly with the average molecular weights per formula-unit of the glasses. Glass transition temperatures are in the range from 200 to 350°C, and values of Vickers hardness between 150 and 300 kp/mm² have been measured. Both properties are in a linear relationship with the approximate values for the atomization energies of the glasses.     

Synthesis and thermal properties of disiloxane-arylene polymers by dehydrocoupling polymerization of bis(dimethylsilyl)arylene with water

Disiloxane-arylene polymers having phenylene, biphenylene, and fluorenylene groups as arylene units were synthesized by dehydrocoupling polymerization of corresponding bis(silane) derivatives with water. The reactivity of Si-H was not affected by the structure of aromatic groups in the reaction. The polymers containing biphenylene and fluorenylene units are amorphous and show higher glass transition temperatures than the polymer from 1,4-bis(dimethylsilyl)benzene.     

Planar Chiral Phosphoramidites with a Paracyclophane Scaffold: Synthesis,Gold(I) Complexes,and Enantioselective Cycloisomerization of Dienynes

The key structural feature of the new phosphoramidites is a paracyclophane scaffold in which two aryl rings are tethered by both a 1,8‐biphenylene unit and a O?P?O bridge. Suitable aryl substituents generate planar chirality. The corresponding gold(I) complexes promote the cycloisomerization of prochiral nitrogen‐tethered dienynes. These reactions afford bicyclo[4.1.0]heptene derivatives displaying three contiguous stereogenic centers, with very high diastereoselectivity and up to 95 % ee.     

Metal-stabilized carbanions : III. The effect of coordination with π-tricarbonylchromium on the paratropic properties of biphenylene. An NMR study

The ¹H- and ¹³C-NMR spectra of biphenylene and its mono- and bis-tricarbonylchromium complexes have been recorded and analyzed. The comparison of the data for the complexes with those for the free ligand suggests that a substantial reduction of the paratropic character of the molecule occurs upon complexation. In the bis-complexed biphenylene, the two electronic sextets behave as separate non-interacting systems.     

Zum Ionenaustausch in porösen Gläsern

Ionexchange on Porous Glasses Porous alkali-boron-silicate glasses show the following sequence of coefficients of the ionexchange-selectivity: The degree of ionexchange for divalent ions is only very little. The ionexchange capacity is influenced by the degree of phase-separation of the original glasses and has the origin in BOH groups. The energies of activation for the ionexchange reactions are 10.6–11.8 kcal/mol.     

Oxidative Addition of Carbon–Carbon Bonds to Gold

The oxidative addition of strained C? C bonds (biphenylene, benzocyclobutenone) to DPCb (diphosphino‐carborane) gold(I) complexes is reported. The resulting cationic organogold(III) complexes have been isolated and fully characterized. Experimental conditions can be adjusted to obtain selectively acyl gold(III) complexes resulting from oxidative addition of either the C(aryl)? C(O) or C(alkyl)? C(O) bond of benzocyclobutenone. DFT calculations provide mechanistic insight into this unprecedented transformation.     

Über Chalkogenolate. 133. Untersuchungen über Ester von Halogenoameisensäuren 1. Chloroameisensäure-, Chloromonothioameisensäure- und Chlorodithioameisensäurealkylester

On Chalcogenolates. 133. Studies on Esters of Haloformic Acids. 1. Alkyl Esters of Chloroformic, Chloromonothioformic, and Chlorodithioformic Acids The prepared esters RO? CO? Cl, RS? CO? Cl, RO? CS? Cl, and RS? CS? Cl with R = alkyl have been characterized by means of electron absorption, infrared, nuclear magnetic resonance, and mass spectra.     

New preparative procedure for photoluminescent metallopolymers having a biphenyl‐2,2′‐diyl iridium(III) unit bound to a phosphine copolymer ligand

We first prepared polymer‐bound photoluminescent iridium complexes bearing a cyclometalated 2,2′‐biphenylene ligand via an easy procedure in which the metallopolymer was synthesized by the reaction of a metal precursor with a polymer ligand. The iridium compound, [Ir(cod)(biph)Cl]₂ (where cod and biph are 1,5‐cyclooctadiene and biphenyl‐2,2′‐diyl, respectively), was used as the iridium material, and a copolymer built by the radical copolymerization of 4‐styryldiphenylphosphine and methyl methacrylate was employed as the polymer ligand. The obtained metallopolymers were highly crosslinked by iridium atoms forming P? Ir? P bonds. The content of the iridium was experimentally clarified to be in the range of 0.06–0.6 mmol/g of the polymer. Photoluminescence of the iridium polymer in the solid state was observed at 597 nm when the polymer was irradiated at 350 nm. As the Ir content in the copolymer increased to 0.2 mmol/g, the intensity of the luminescence also increased, but more iridium content decreased the intensity. Furthermore, the intensity of the photoluminescence in these photoluminescent polymers depended on the molecular weight of the copolymer ligands. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4204–4213, 2006     

Synthesis of poly(biphenylene ketone)s via palladium catalyzed cross-coupling reactions with ketone diacetals

Dibromobenzophenone diacetals (BrC₆H₄)₂C(OR)₂ undergo cross-coupling reactions with (Bu₃SnC₆H₄)₂O in the presence of palladium catalysts to give poly (diacetal ether)s whose molecular weights reflect the solubility changes of the growing polymer chains as a function of the diacetal precursors, R = Me < 1/2 CH₂CH₂ < 1/2 CH₂CHMe and are significantly higher than those of polymers derived from dibromobenzophenone. New di-zinc reagents based on diacetal derivatives were synthesized and used as organometallic coupling reagents with a range of dibromoarenes, resulting in a series of previously inaccessible poly (biphenylene ketone)s and poly (biphenylene ketone sulfone)s. While poly (biphenylene ether ketone)s are insoluble, poly (biphenylene ketone)s readily dissolve in concentrated sulfuric acid. The effects of reaction parameters on the molecular weight of poly (biphenylene ketone) were determined. © 1994 John Wiley & Sons, Inc.