Scalar-field Pressure in Induced Gravity with Higgs Potential and Dark Matter

A model of induced gravity with a Higgs potential is investigated in detail in view of the pressure components related to the scalar-field excitations. The physical consequences emerging as an artifact due to the presence of these pressure terms are analysed in terms of the constraints parting from energy density, solar-relativistic effects and galactic dynamics along with the dark matter halos.Comment: 26 pages, 3 figures, Minor revision, Published in JHE

Contrasting behavior of bis[2-(4,4-dimethyl-2-oxazolinyl)phenyl] chalcogenides (Se/Te) toward mercuric chloride: Facile cleavage of the Te-C bond

The reactions of R2Se (3) and R2Te (4) (R = 2-(4,4-dimethyl-2-oxazolinyl)phenyl) with HgCl2 and Pd(COD)Cl-2 are described. The reaction of selenoether 3 with HgCl2 affords the expected complex R2SeHgCl2 (5), which is stable in solution. In contrast, the analogous tellurium complex R2TeHgCl2 (6) undergoes slow dismutation in chlorinated solvents to give the fragments RTeCl (7) and RHgCl (8)

Synthesis of diaryl selenides using the in situ reagent SeCl2

Reactions of in situ prepared SeCl2 With Grignard reagents (prepared from bromobenzene, o-tolyl bromide, 2,6-dimethyl-4-tert-butyl-l-bromobenzene, and 1-bromo-2-methylnaphthalene) and dilithiated benzamides (prepared from N-phenyl, N-cyclohexyl, and N-isopropyl benzamide) are described. (C) 200

Organoselenium chemistry: role of intramolecular interactions

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Synthesis and characterization of a novel chiral azomethine diselenide

The first chiral diselenide 9 having an ortho-azomethine functional group has been synthesized by the reaction of bis(o-formylphenyl) diselenide with the chiral amine R(+)-(1-phenylethylamine). The chiral diselenide 9 was further characterized by derivatizing it into the corresponding selenenyl halides. The derivatives are characterized by single crystal X-ray diffraction studies. In the solid state, the bromide derivative 11 shows the strongest (SeN)-N-... intramolecular interaction. The chiral azomethine diselenide 9 has been further reduced to afford the diselenide 13. The monoselenide analogues of 9 and 13 have also been synthesized. (c) 200

Convenient synthesis, characterization and GPx-like catalytic activity of novel ebselen derivatives

The synthesis and characterization of benzisochalcogenazolones (ebselen derivatives 16-21) is described. The synthesis of 16-21 was achieved by treating the bromo precursors 11-13 with an appropriate dilithium dichalcogenide. The synthesis of benzisoselenazolones 16 and 18 was also accomplished by an alternative route, that is, by treating the corresponding methoxymethyl selenides 22 and 23 with 1 equiv. of bromine. The synthesis of methoxymethyl selenides 22 and 23 was accomplished by lithiation of the bromo precursors followed by treatment with bis(methoxymethyl) diselenide. The benzisoselenazolones 16 and 17 were characterized by single-crystal X-ray techniques. The GPx-like catalytic activities of compounds 16-18 and 21 were determined by using the coupled reductase assay. Compound 16 was found to be less active than ebselen 8 whereas compounds 17 and 18 were more active than ebselen in this assay. Compound 21 showed a 1.5-fold higher activity than its selenium analogue 17. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Intramolecular interactions between chalcogen atoms: organoseleniums derived from 1-bromo-4-tert-butyl-2,6-di(formyl)benzene

The synthesis and characterization of a series of low-valent organoselenium compounds derived from 1-bromo-4-tert-butyl-2,6-di(formyl)benzene (22) is described. The synthesis of diselenide 25 was achieved by the lithiation route whereas bis(4-tert-butyl-2,6-di(formyl)phenyl) diselenide (26) was synthesized by treating 22 with disodium diselenide. A series of monoselenides (27, 28, and 29) was obtained by facile nucleophilic substitution of bromine in 22, using the corresponding selenolates as nucleophiles. The halogenation reactions of bis(4-tert-butyl-2,6-di(formyl)phenyl) diselenide (26) did not afford the corresponding selenenyl halides but resulted in the isolation of an unexpected cyclic selenenate ester 34 as a product. The selenide 32 was synthesized by the treatment of dimethoxymethyl diselenide with trilithiated 2-bromo-5-tert-butyl-NM-di(phenyl)isophthalamide. The existence of potential (SeO)-O-... intramolecular nonbonding interactions was examined by IR, H-1, and Se-77 NMR spectroscopy, X-ray crystallography, and computational studies. The X-ray crystal structures of 26 and 27, having two ortho formyl groups, reveal the absence of any (SeO)-O-... interactions. However, the (SeO)-O-... interactions were observed in the selenenate ester 34 where one of the formyl groups has been utilized for the selenenate ring formation. The crystal structures of 26 and 27 exhibited intermolecular short-range C-H... Se interactions (hydrogen bonding). Although there are four heteroatoms in carbamoyl moieties ortho to selenium capable of forming a five-membered ring on intramolecular coordination, no such intramolecular (SeX)-X-... (X = N, O) interaction was observed in the crystal structure of 32. The density functional theory calculations at the B3LYP/6-31G* level predicted that for all the diformyl systems (47a-c, 48a-c), the anti,anti conformer (when both formyl oxygen atoms point away from the selenium) is more stable. This preference was found to be reversed in the monoformyl-substituted systems (50a,b, 51a,b), where the syn conformer (when formyl oxygen is near the selenium) is energetically more favorable than the anti conformer

Anion binding with some 22- and 28-membered selenaaza macrocycles: Structural aspects and Se-77 NMR studies

A series of macrocyclic adducts of the 22- and 28-membered selenaaza macrocycles (1 and 2, respectively) with different counter anions such as halides, sulfate, perchlorate, phosphate, trifluoroacetate and nitrate has been prepared. The adducts have been characterized by elemental analysis, IR, H-1 NMR, Se-77 NMR and ESI-MS analysis. The Se-77 NMR spectrum of the SO42- adduct (7) shows an upfield shift compared to the parent macrocycle. The bromo (5), iodo (6), sulfate (7), trifluroacetate (10) adducts of the 22-membered selenaaza macrocycle and perchlorate (16), trifluroacetate (18) adducts of the 28-membered selenaaza macrocycle have been structurally characterized. The crystal structures show extensive hydrogen bonding networks. The molecular structures of all the compounds show the macrocycle to be fully protonated except the trifluroacetate adduct of the 22-membered macrocycle (10), which is only diprotonated. The binding constants of the neutral 22-membered selenaaza macrocycle towards, fluoride, bromide, iodide and sulfate ion have been determined by the NMR titration method. (c) 200

Aspects of intramolecularly coordinated organochalcogen derivatives

Recent progress in the area of intramolecularly coordinated organochalcogens, in particular, organoselenium derivatives, is reviewed. Intramolecular coordination facilitates isolation of (a) stable organoselenenyl iodides, (b) chiral diselenides, (c) organotriselenides, d) cleavage of Te-C bond, e) metal-free synthesis of chalcogenaaza macrocycles, and f) isolation of cyclic selenenate esters. The synthesis of organoselenium compounds incorporating two ortho-coordinating groups is also discussed