441 research outputs found

    Bis[(4-methyl­phen­yl)ethyn­yl] telluride

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    The tellurium atom in the title bis-ethynyl telluride, Te(C9H7)2 or C18H14Te, is located on a crystallographic twofold axis, the C—Te—C angle being 92.23 (15)°. The dihedral angle between the rings is 87.27 (7)°. In the crystal structure, mol­ecules are connected in chains parallel to the b axis and mediated by C—Hâ‹ŻÏ€ inter­actions

    A Novel and Simple MAC Protocol for High Speed Passive Optical LANs

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    Synthesis of 1,3-diynes via detelluration of bis(ethynyl)tellurides

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    The synthesis of symmetric conjugated diyne systems with electron-withdrawing or electron-donating substituents via a palladium-catalyzed detelluration of bis(arylethynyl)tellurides and bis(alkylethynyl)tellurides is described. This procedure is effected under atmospheric conditions in DMF using Pd(OAc)2 as a catalyst and AgOAc as an additive in the presence of triethylamine. This route offers efficient access to conjugated diyne systems in short reaction time. X-ray crystallographic structure and solid-state conformation of bis(p-tolylethynyl)telluride show a supramolecular chain aligned along the b axis, sustained by C-H...π interactions.Neste artigo Ă© descrita a sĂ­ntese de sistemas diĂ­nicos conjugados contendo substituintes elĂ©tronatratores e elĂ©tron-doadores via a deteluração catalizada por palĂĄdio de bis-(ariletinil)teluretos e bis-(alquiletinil)teluretos. Este procedimento foi realizado sob condiçÔes atmosfĂ©ricas em DMF usando Pd(Oac)2 como catalisador e AgOAc como um aditivo na presença de trietilamina. Esta rota oferece acesso eficiente a sistemas diĂ­nicos conjugados em um curto perĂ­odo de tempo. A estrutura cristalogrĂĄfica por difração de raios X do telureto de bis(p-toluiletinila) e a conformação no estado sĂłlido mostram uma cadeia supramolecular alinhada ao longo do eixo b, sustentada por interaçÔes CH...π.FAPESPCNP

    An approximation for performance evaluation of stationary single server queues

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    7-Methyl-5-[(4-methylbenzene)sulfonyl]-2H,5H-[1,3]dioxolo[4,5-f]indole: crystal structure and Hirshfeld analysis

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    In the title indole derivative, C17H15NO4S, the fused dioxolo-indole system is essentially planar [r.m.s. deviation of the 12 ïŹtted atoms = 0.0249 A ˚ ] and is effectively perpendicular to the appended 4-tolyl ring, forming a dihedral angle of 89.95 (6). Overall, the molecule has the shape of the letter L. In the crystal, supramolecular layers in the ab plane are formed via weak 4-tolyl-C—H....(C6ring of indole) and S—O.... 1,3-dioxole) contacts. The aforementioned interactions along with interatomic H...H and H...O contacts are all shown to make signiïŹcant contributions to the calculated Hirshfeld surfaces

    Computation of Blocking Probability for Large Circuit Switched Networks

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    2-[(4-Chlorophenyl)sulfanyl]-2-methoxy-1-phenylethan-1-one: crystal structure and Hirshfeld surface analysis

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    The title compound, C15H13ClO2S, comprises (4-chlorophenyl)sulfanyl, benzaldehyde and methoxy residues linked at a chiral methine-C atom (the crystal is racemic). A twist in the methine-C—C(carbonyl) bond [O—C—C—O torsion angle = 19.3 (7)⁰] leads to a dihedral angle of 22.2 (5)⁰ between the benzaldehyde and methine+methoxy residues. The chlorobenzene ring is folded to lie over the O atoms, with the dihedral angle between the benzene rings being 42.9 (2)⁰. In the crystal, the carbonyl-O atom accepts two C—H...O interactions with methyl- and methine-C—H atoms being the donors. The result is an helical supramolecular chain aligned along the c axis; chains pack with no directional interactions between them. An analysis of the Hirshfeld surface points to the important contributions of weak H...H and C...C contacts to the molecular packing

    2-[(4-Chlorophenyl)selanyl]-3,4-dihydro-2H-benzo[h]chromene-5,6-dione: crystal structure and Hirshfeld analysis

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    The title organoselenium compound, C19H13ClO3Se {systematic name: 2-[(4-chlorophenyl)selanyl]-2H,3H,4H,5H,6H-naphtho[1,2-b]pyran-5,6-dione}, has the substituted 2-pyranyl ring in a half-chair conformation with the methylene-C atom bound to the methine-C atom being the flap atom. The dihedral angle between the two aromatic regions of the molecule is 9.96 (9)° and indicates a step-like conformation. An intramolecular Se...O interaction of 2.8122 (13) Å is noted. In the crystal, π–π contacts between naphthyl rings [inter-centroid distance = 3.7213 (12) Å] and between naphthyl and chlorobenzene rings [inter-centroid distance = 3.7715 (13) Å], along with C—Cl...π(chlorobenzene) contacts, lead to supramolecular layers parallel to the ab plane, which are connected into a three-dimensional architecture via methylene-C—H...O(carbonyl) interactions. The contributions of these and other weak contacts to the Hirshfeld surface is described
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