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111.
Popescu DL Chanda A Stadler MJ Mondal S Tehranchi J Ryabov AD Collins TJ 《Journal of the American Chemical Society》2008,130(37):12260-12261
Recent broad-ranging mechanistic studies of FeIII-TAML peroxide activators enable a strategy for designing catalysts with improved (i) hydrolytic and (ii) operational stabilities, (iii) faster activation of H2O2 and other peroxides, and (iv) a pH of highest activity closer to 7. Combining all items of insight leads to [Fe{1-NO2C6H3-3,4-(NCOCMe2NCO)2CF2}(OH2)]- (1a) which exhibits the most desirable technical performance in its class. 相似文献
112.
We have observed seven infrared laser transitions when exciting a He discharge in a silver hollow cathode. To our knowledge, five of the seven laser transitions have not been reported previously in the literature. 相似文献
113.
Spatial analysis of synthetic aperture radar (SAR) image data holds much promise for characterizing and discriminating environmental scene elements. The autocorrelation function (ACF) has been identified as a potentially useful spatial metric because it admits an analysis with conventional linear system theory. Recent models of spatial scattering suggest that ACF-based texture analysis of SAR image data is capable of discriminating between a variety of area extensive targets. The incorporation of texture in an image classification or segmentation system requires some understanding of the uncertainties in the texture estimates. In this paper, the authors introduce a particular ACF model and examine the errors associated with estimating its parameters from image measurements. They also conduct an analysis of two important classes of errors: imaging system errors and estimation errors. They found that as the proportion of raw signal used to create the image increases the effects of system errors rapidly degrade ACF performance. This has implications for operationally produced image products that do not use an autofocusing procedure. They also found that the agreement between theoretical and observed estimation errors is quite good, so that the scale of these errors may be accurately estimated during a spatial analysis of the image data. They found some residual bias that may be attributed to both the use of the ACF itself and to the way the ACF model was constructed 相似文献
114.
A Carbene‐Rich but Carbonyl‐Poor [Ir6(IMe)8(CO)2H14]2+ Polyhydride Cluster as a Deactivation Product from Catalytic Glycerol Dehydrogenation 下载免费PDF全文
Jesús Campos Liam S. Sharninghausen Prof. Robert H. Crabtree Dr. David Balcells 《Angewandte Chemie (International ed. in English)》2014,53(47):12808-12811
The title cluster, a deactivation product in the catalytic dehydrogenation of glycerol, was characterized by XRD, DFT calculations, HRMS, FTIR spectroscopy, and NMR spectroscopy. Experimental/computational studies located the 14 H ligands, and all 1H and 13C{1H} NMR resonances were assigned. The structure contains an unprecedented Ir6H14 core with two CO and eight IMe ligands. 相似文献
115.
Ryan Gianatassio Shuhei Kawamura Cecil L Eprile Klement Foo Jason Ge Aaron C. Burns Michael R. Collins Phil S. Baran 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(37):10009-10013
A simple method to convert readily available carboxylic acids into sulfinate salts by employing an interrupted Barton decarboxylation reaction is reported. A medicinally oriented panel of ten new sulfinate reagents was created using this method, including a key trifluoromethylcyclopropanation reagent, TFCS‐Na. The reactivity of six of these salts towards C H functionalization was field‐tested using several different classes of heterocycles. 相似文献
116.
Silver nanowires both included in and extruded from a purely siliceous mesoporous support have been produced from silver ion containing precursors prepared through dry salt occlusion. 相似文献
117.
Strachan JD Adler H Alling P Ancher C Anderson H Anderson JL Ashcroft D Barnes CW Barnes G Batha S Bell MG Bell R Bitter M Blanchard W Bretz NL Budny R Bush CE Camp R Caorlin M Cauffman S Chang Z Cheng CZ Collins J Coward G Darrow DS DeLooper J Duong H Dudek L Durst R Efthimion PC Ernst D Fisher R Fonck RJ Fredrickson E Fromm N Fu GY Furth HP Gentile C Gorelenkov N Grek B Grisham LR Hammett G Hanson GR Hawryluk RJ Heidbrink W Herrmann HW Hill KW Hosea J Hsuan H Janos A Jassby DL Jobes FC 《Physical review letters》1994,72(22):3526-3529
118.
Josef Ischtwan Peter Schwerdtfeger Sigrid D. Peyerimhoff Michael A. Collins Trygve Helgaker Poul Jørgensen Hans Jørgen Aa. Jensen 《Theoretical chemistry accounts》1994,89(2-3):157-168
Summary The intrinsic reaction-path, reactants, transition state and products for the reaction of NH (3–)+H2 (1
g
+
) NH2 (2B1)+H (2S) involving the lowest triplet electronic state of NH3 were calculated using multi-configuration (MC) SCF methods. The calculated change of internal energy for the reaction of 11.0 kcal mol–1 agrees with the experimental value within 2 kcal mol–1. The barrier to reaction is 23.4 kcal mol–1 high. The harmonic MCSCF reaction-path potential was calculated and canonical variational transition state theory calculations of the rate constants performed over a temperature range from 400 to 2500 K. The computed rate constants are generally two orders of magnitude smaller than those of the comparable reaction of OH with H2, whereas those of the reverse reaction are by a factor of 20 larger than those of OH2 with H. 相似文献
119.
Element specificity is one of the key factors underlying the widespread use and acceptance of X-ray absorption spectroscopy (XAS) as a research tool in the environmental and geo-sciences. Independent of physical state (solid, liquid, gas), XAS analyses of metal(loid)s in complex environmental matrices over the past two decades have provided important information about speciation at environmentally relevant interfaces (e.g. solid–liquid) as well as in different media: plant tissues, rhizosphere, soils, sediments, ores, mineral process tailings, etc. Limited sample preparation requirements, the concomitant ability to preserve original physical and chemical states, and independence from crystallinity add to the advantages of using XAS in environmental investigations. Interpretations of XAS data are founded on sound physical and statistical models that can be applied to spectra of reference materials and mixed phases, respectively. For spectra collected directly from environmental matrices, abstract factor analysis and linear combination fitting provide the means to ascertain chemical, bonding, and crystalline states, and to extract quantitative information about their distribution within the data set. Through advances in optics, detectors, and data processing, X-ray fluorescence microprobes capable of focusing X-rays to micro- and nano-meter size have become competitive research venues for resolving the complexity of environmental samples at their inherent scale. The application of μ-XANES imaging, a new combinatorial approach of X-ray fluorescence spectrometry and XANES spectroscopy at the micron scale, is one of the latest technological advances allowing for lateral resolution of chemical states over wide areas due to vastly improved data processing and detector technology. 相似文献
120.
Sutton LR Donaubauer WA Hampel F Hirsch A 《Chemical communications (Cambridge, England)》2004,(15):1758-1759
Mixtures of isomers are available from the reaction of benzene hexathiol with three equivalents of p-tolualdehyde and kinetic traps avoided under the reported catalytic conditions, establishing tris(thioacetals) as potential building blocks for covalently self-assembled complex structures. 相似文献