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  • Analytical Chemistry and Spectroscopy  (8)
  • Animals
  • 1970-1974  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 1 (1973), S. 243-253 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: From a study of the rotational Raman spectra of disilane and hexadeutero-disilane the following rotational constants were determined: for Si2H6, B0 = 0.16998 ± 0.00003 cm-1; for Si2D6, B0 = 0.13796 ± 0.00004 cm-1. The rotational constants were used to provide values for the internuclear distances in these modecules.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 4 (1970), S. 383-393 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A mass spectrometric examination of five homoannularly chlorinated ferrocenes of the general formula (C5H(5-n))Fe(C5H5) where n = 1 to 5 (Series 1), and five heteroannularly chlorinated ferrocenes of the general formula (C5H(5-n)Cln)2Fe where n = 1 to 5 (Series 2) has been made. This study affords the first look at the mass spectral results of incremental additions of the same substituent up to the ultimate replacement of all hydrogens in the ferrocene molecule. The molecular ion is the most intense peak in both series. The primary fragmentation processes are, for Series 1: [M - FeCl2], [M - C5H(5-n)Cln], [M - C5H5] and [M - HCl]; and for series 2: [M - FeCl2] and [M - C5H(5-n)Cln]. The [M - FeCl2]+. peak is speculatively attributed to a fulvalene derivative. A heteroannular pathway is proposed for HCl elimination. Significant [Fe]+. and [FeCl]+ peaks occur in all compounds. In all compounds having three or more hydrogens on one ring, a peak due to [C3H3]+ is seen. Metastable studies, precise mass measurements and isotopic abundance ratios of chlorine were used to confirm many of the fragmentation processes.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: INDO calculations for previously proposed activated complexes for scrambling in ethane molecular ion suggest that the structure equivalent to diborane is more stable than one in which hydrogens on the same side of the molecule exchange positions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: INDO Molecular orbital calculations of the energetically most favourable conformation of the molecular ions of phenyl acetate and its o-fluoro- and o-chloro-analogs indicate bond formation between carbonyl oxygen and ortho halogen. For the molecular ions of phenetole and its o-fluoro and o-chloro-analogs, no ring formation is observed. These results are in accord with the frequency factor changes found for the ortho substitution in these systems by halogens.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An aspect of the mechanism of the hydroxyl H/ortho H scrambling in the molecular ion of benzoic acid was studied by the open-shell INDO molecular orbital method. Energies of te unrearranged structure, the planar structure in which H is attached to carbonyl oxygen and rotational conformers of the latter were studied to determine a pathway of minimum energy for rotation. The same calculations were made for salicylic acid, m-fluorobenzoic acid and p-fluorobenzoic acid. The results of these calculations agree quite well with experimental results.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The application of mass spectrometry, including precise mass measurements of molecular ions and selected fragment peaks, in determining the structure of twenty-nine substituted polyfluorobenzenes and two polyfluoropyridines is discussed. These compounds are divided into five categories: (a) fluorinated benzenes; (b) alkyl substituted polyfluorobenzenes; (c) halogen substituted polyfluorobenzenes; (d) oxygen containing substituents in polyfluorobenzenes and (e) nitrogen and sulfur containing polyfluoroaromatics. It is shown that the nature of substituents, their size, position on the ring and the completeness of fluorination are all vitally important in determining the fragmentation processes. The rupture of the various carbon to halogen and carbon to hydrogen bonds are discussed. Metastable peaks were found in some cases and their precursors were traced.
    Additional Material: 31 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The main fragmentation of the compounds MX3-noxn (oxH=8-quinolinol. n = 3; M=AL, Ga, In, Sc, Cr or Fe. n = 2; M=In or Fe; X=Cl or Br. InIox2. n = 1; M=AL, In or Fe; X= Cl or Br) involves loss of X and intact ox. radicals. The comparative abundances of the fragments are primarily related to the common oxidation states of the metals. For example, all the Mox3 compounds show the ions [Mox3]+ and [Mox2]+. The ions [Mox]+ and [M]+ are present when M=Ga, In, Cr or Fe but for the elements with only one oxidation state (Al or Sc) [M]+ is absent and [Mox]+ has only very low abundance. When M= Cr or Fe metal-containing ions arising from loss of species such as CO, H2O, HX, C2H2, H and OH by fragmentation of the ox ligand are also present; this behaviour is rationalised in terms of the ability of these metals to undergo a unit change in oxidation state. When n=1 the ions [MXox2]+ and [Mox2]+ and when n= 2 the ions [MX2ox]+ and [Mox3]+ are present; these ions arise by ionization and fragmentation of species formed by redistribution reactions in the mass spectrometer.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The carbon-13 NMR spectra of 16 aliphatic phosphorus compounds with -PCl2, -P(OCH3)2, -P(CH3)2 or -PS(CH3)2 groups were determined and interpreted on the basis of the usual α, β-deshielding and γ-shielding effects. The α-effects of all the groups were quite large (15 to 30 ppm), though the β-effects were small (0 to 3 ppm). The γ-effects were also small (0·2 to 1·6 ppm), but of significance in suggesting reduced steric compression relative to that found for methyl and most of the common organic functional groups. This may be attributed to the greater length of the C—P bond. The phosphorus-31 NMR spectra of these compounds also show the existence of interaction with γ-carbons by exhibiting small additive upfield shifts.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
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