Molecular Dipole Moments and Stark Effects. III. Dipole Moment Determinations
TL;DR: In this article, the authors determined the dipole moments of eight molecules by the Stark splittings of the rotational transitions in the microwave region, and the molecules and their moments in Debye units are: As${\mathrm{F}}_{3}$, 2.025; C${H}$I, 1.815\ifmmode\pm\else\textpm\fi{}0.
Abstract: Dipole moments of eight molecules were determined by the Stark splittings of the rotational transitions in the microwave region. The molecules and their moments in Debye units are: As${\mathrm{F}}_{3}$, 2.815\ifmmode\pm\else\textpm\fi{}0.025; C${\mathrm{H}}_{3}$I, 1.647\ifmmode\pm\else\textpm\fi{}0.014; C${\mathrm{H}}_{3}$Cl, 1.869\ifmmode\pm\else\textpm\fi{}0.010; C${\mathrm{H}}_{3}$Br, 1.797\ifmmode\pm\else\textpm\fi{}0.015; C${\mathrm{H}}_{3}$C${\mathrm{F}}_{3}$, 2.321\ifmmode\pm\else\textpm\fi{}0.034; P${\mathrm{F}}_{3}$, 1.025\ifmmode\pm\else\textpm\fi{}0.009; ${\mathrm{N}}_{2}$O, 0.166\ifmmode\pm\else\textpm\fi{}0.002; and ClCN, 2.802\ifmmode\pm\else\textpm\fi{}0.020. In all cases Stark effects followed very closely theoretical expectations.
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TL;DR: In contrast to the very large number of special methods applicable to syntheses in the heterocyclic series, relatively few general methods are available as discussed by the authors, and the 1,3-dipolar addition offers a remarkably wide range of utility in the synthesis of five-membered heterocycles.
Abstract: In contrast to the very large number of special methods applicable to syntheses in the heterocyclic series, relatively few general methods are available. The 1,3-dipolar addition offers a remarkably wide range of utility in the synthesis of five-membered heterocycles. Here the “1,3-dipole”, which can only be represented by zwitterionic octet resonance structures, combines in a cycloaddition with a multiple bond system – the “dipolarophile” – to form an uncharged five-membered ring. Although numerous individual examples of this reaction were known, some even back in the nineteenth century, fruitful development of this synthetic principle has been achieved only in recent years.
2,285 citations
TL;DR: In der 1.3-Dipol-Addition as mentioned in this paper, ein nur bescheidener Satz an Aufbaumethoden von allgemeiner Verwendungsbreite is gegenuber.
Abstract: Einer sehr grosen Zahl spezieller Synthesewege in die heterocyclische in die Reihe steht ein nur bescheidener Satz an Aufbaumethoden von allgemeiner Verwendbarkeit gegenuber. Eine erstaunliche Anwendungsbreite bei der Synthese funfgliedriger Heterocyclen kommt der 1.3-Dipolaren Addition zu. Dabei vereinigt sich der nur mit zwitterionischen Oktett-Grenzformeln wiederzugebende „1.3-Dipol” mit einem Mehrfachbindungssystem, dem „Dipolarophil”, in einer Cycloaddition zum ladungsfreien funfgliedrigen Ring. Wenngleich die Kenntnis zahlreicher Einzelbeispiele bis ins vorige Jahrhundert zuruckreicht, gelangte das Syntheseprinzip erst in den letzten Jahren zu fruchtbarer Entfaltung.
1,135 citations
TL;DR: The “Polarity” Issues“Apolar”, yet Dipolar 1726 4.1.
Abstract: 3.2.1. Linear F-Alkyl/H-Alkyl Diblocks 1720 3.2.2. Unsaturated Diblocks 1721 3.2.3. Branched Diblocks 1722 3.2.4. Diblocks with Heteroatoms 1723 3.2.5. Diblocks with Heavy Halogens 1724 3.3. Triblocks and Multiblocks 1724 3.3.1. FnHmFn Triblocks 1724 3.3.2. HmFnHm Triblocks 1725 3.3.3. Star-Shaped Triblocks 1725 3.3.4. Multiblocks and Polyaffine Compounds 1726 4. Basic Properties of (F-Alkyl)alkyl Diblocks 1726 4.1. The “Polarity” Issues“Apolar”, yet Dipolar 1726 4.2. Surfactant Properties 1727 4.2.1. Surfactant Effects of FnHm Diblocks at Interfaces with Air, Fluorocarbons, and Hydrocarbons 1728
404 citations
01 Dec 1991
TL;DR: This new calibration atlas is based on frequency rather than wavelength calibration techniques for absolute references, and additional data from alternate methodology are used for difference frequency measurements within each band investigated by the frequency measurements techniques.
Abstract: This new calibration atlas is based on frequency rather than wavelength calibration techniques for absolute references. Since a limited number of absolute frequency measurements is possible, additional data from alternate methodology are used for difference frequency measurements within each band investigated by the frequency measurements techniques. Data from these complementary techniques include the best Fourier transform measurements available. Included in the text relating to the atlas are a description of the heterodyne frequency measurement techniques and details of the analysis, including the Hamiltonians and least-squares-fitting and calculation. Also included are other relevant considerations such as intensities and lincshape parameters. A 390-entry bibliography which contains all data sources used and a subsequent section on errors conclude the text portion. The primary calibration molecules are the linear triatomics, carbonyl sulfide and nitrous oxide, which cover portions of the infrared spectrum ranging from 488 to 3120 cm-1. Some gaps in the coverage afforded by OCS and N2O are partially covered by NO, CO, and CS2. An additional region from 4000 to 4400 cm-1 is also included. The tabular portion of the atlas is too lengthy to include in an archival journal. Furthermore, different users have different requirements for such an atlas. In an effort to satisfy most users, we have made two different options available. The first is NIST Special Publication 821, which has a spectral map/facing table format. The spectral maps (as well as the facing tables) are calculated from molecular constants derived for the work. A complete list of all of the molecular transitions that went into making the maps is too long (perhaps by a factor of 4 or 5) to include in the facing tables. The second option for those not interested in maps (or perhaps to supplement Special Publication 821) is the complete list (tables-only) which is available in computerized format as NIST Standard Reference Database #39, Wavelength Calibration Tables.
299 citations
TL;DR: In this article, a basis set of moderate size optimized for the computation of the dipole polarizability of reasonably large molecules consisting of hydrogen and p-block elements up to iodine is presented.
Abstract: The development is described of a basis set of moderate size optimized for the computation of the dipole polarizability of reasonably large molecules consisting of hydrogen and p-block elements up to iodine. The mean polarizability, polarizability anisotropy and dipole moment for hydrides of the first four rows of the periodic table, obtained at both the SCF and MP2 levels, are compared with those obtained using the previously developed 6–31 G(+ sd + sp) basis set, as well as larger basis sets, and with experiment. For the series of diatomic halogens, X2, and the halomethanes, CH3X (X = F, C1, Br, I), electric properties are obtained in excellent agreement with those resulting from use of larger basis sets, and also with experiment.
232 citations