排序方式: 共有137条查询结果,搜索用时 500 毫秒
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Geometry and thermodynamic characteristics of complexes X2MYH2 (M = Al, Ga, In; X = F, Cl, Br, I; Y = N, P, As) and their components were found by the B3LYP density functional method with the LANL2DZ(d,p) basic set. The nitrogen complexes X2MNH2 have a planar structure, whereas the phosphorus and arsenic complexes are pyramidal. Upon HX elimination, the dissociation energy of the M-Y bonds considerably increases (by 150-270 kJ mol-
1), which makes the dissociation of X2MYH2 into components thermodynamically unfeasible even at temperatures about 1000°C. A linear correlation between the dissociation enthalpies of M-Y bonds in the X3MYH3 and X2MYH2 complexes was found for each central atom M, which makes it possible to estimate the dissociation enthalpies of coordination-unsaturated compounds of the Group IIIa elements from the dissociation enthalpies of their coordination-saturated analogs. The enthalpies of dimerization of X2MYH2 fall in the range from 40 (Y = P, As) to 260 kJ mol-
1 (Y = N), which makes the process X3MNH3 = [X2MNH2]2 + HX with the retention of the metal-nitrogen bond more favorable than the dissociation of the initial complex into the components. Thus, dimers [X2MNH2]2 can be intermediates in chemical deposition of nitrides from the gas phase of donor-acceptor complexes. 相似文献
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Endarko E Maclean M Timoshkin IV Macgregor SJ Anderson JG 《Photochemistry and photobiology》2012,88(5):1280-1286
The antimicrobial properties of light is an area of increasing interest. This study investigates the sensitivity of the significant foodborne pathogen Listeria monocytogenes to selected wavelengths of visible light. Results demonstrate that exposure to wavelength region 400–450 nm, at sufficiently high dose levels (750 J cm?2), induced complete inactivation of a 5 log10 population. Exposure to wavelengths longer than 450 nm did not cause significant inactivation. Analysis of 10 nm bandwidths between 400 and 450 nm confirmed 405(±5) nm light to be most effective for the inactivation of L. monocytogenes, with a lesser bactericidal effect also evident at other wavelengths between 400 and 440 nm. Identification of the optimum bactericidal wavelength enabled the comparison of inactivation using 405(±5) nm filtered light and a 405 nm light‐emitting diode (LED) array (14 nm FWHM). Results demonstrate similar inactivation kinetics, indicating that the applied dose of 405 nm light is the important factor. Use of the 405 nm LED array for the inactivation of L. monocytogenes and other Listeria species resulted in similar kinetics, with up to 5 log10 reductions with a dose of 185 J cm?2. Comparative data for the 405 nm light inactivation of L. monocytogenes and other important foodborne pathogens, Escherichia coli, Salmonella enteritidis and Shigella sonnei, are also presented, with L. monocytogenes showing higher susceptibility to inactivation through 405 nm light exposure. 相似文献
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Vapor pressure as a function of temperature above solid and liquid (BrBNH)3 and the thermodynamic parameters of (BrBNH)3 sublimation and vaporization have been determined using static tensimetry with membrane null-manometer. The thermal decomposition
of tribromoborazine has been studied in the saturated and unsaturated vapor regions. Irreversible decomposition occurred at
noticeable rates at temperatures higher than 343 K and was accompanied by HBr evolution. In the unsaturated vapor region,
thermal decomposition has far lower rates than in the saturated vapor region because of diffusion limitations. The activation
energy of condensed-phase thermal decomposition of B,B′,B″-tribromoborazine is 65 ± 3 kJ/mol, and this value proves that tribromoborazine
decomposition at low temperatures is not accompanied by opening of the boron-nitrogen cycle. 相似文献
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Stubenhofer M Lassandro G Balázs G Timoshkin AY Scheer M 《Chemical communications (Cambridge, England)》2012,48(58):7262-7264
Reactions of Cp* substituted pentelidene complexes with the primary phosphine Cp*PH(2) yield novel polycyclic phosphorus/arsenic and carbon containing cage compounds via cascade-like reactions. These reactions include a sequence of nucleophilic addition reactions, intramolecular hydrophosphination (partially hydroarsination) reactions, retro-Diels-Alder reactions with Cp*H elimination and subsequent [2+4]-cycloadditions. 相似文献
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The complete sets of the fundamental optical functions of molybdenum dichalcogenides have been considered for the first time. The energies of their bulk and surface plasmons of two types are determined. It is found that the energies of long-wavelength plasmons correlate with the energies of the deep minima in the reflectivity and ?2 E 2 spectra and the maxima in the reflectivity phase spectra. 相似文献
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Igor V. Kazakov Michael Bodensteiner Alexey Y. Timoshkin 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(3):312-314
The molecular structures of trichlorido(2,2′:6′,2′′‐terpyridine‐κ3N,N′,N′′)gallium(III), [GaCl3(C15H11N3)], and tribromido(2,2′:6′,2′′‐terpyridine‐κ3N,N′,N′′)gallium(III), [GaBr3(C15H11N3)], are isostructural, with the GaIII atom displaying an octahedral geometry. It is shown that the Ga—N distances in the two complexes are the same within experimental error, in contrast to expected bond lengthening in the bromide complex due to the lower Lewis acidity of GaBr3. Thus, masking of the Lewis acidity trends in the solid state is observed not only for complexes of group 13 metal halides with monodentate ligands but for complexes with the polydentate 2,2′:6′,2′′‐terpyridine donor as well. 相似文献