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  • 11
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 488 (1982), S. 177-186 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Mass Spectrum and Vibrational Analysis of (MeSn)4S6, a Compound Analogous to AdamantaneMass spectra of the cage compounds (MeSn)4S6 and (MeSn)4Se6 are given and compared. The ionisation potential of the bond Sn—X is lowered by changing from X = S in X = Se, whereas the dissociation energy of the bond Sn—C is raised simultaneously. Shiftings of methyl groups are frequent for both compounds.IR and Raman spectra are given for (MeSn)4S6 and evaluated by means of a normal coordinate analysis based on the crystallographic parameters. The distribution of the potential energy for the normal modes in terms of internal coordinates exhibits a smaller deviation from the ideal Td symmetry than in the case of (MeSn)4Se6. The stretching force constants are f(Sn—S) = 168(1) and f(Sn—C) = 222(2) N/m. The ionic SnS44- has f(Sn—S) = 175 N/m. The values are compared with f(Sn—Se) = 154(1) und 159 N/m in the units (MeSn)4Se6 and SnSe44-.
    Notes: Die Massenspektren der Käfigverbindungen (MeSn)4S6 und (MeSn)4Se6 werden angegeben und verglichen. Erkennbar ist eine Abnahme des Ionisierungspotentials der Bindung Sn—X beim übergang von X = S zu X = Se mit gleichzeitiger Zunahme der entsprechenden Sn—C-Dissoziationsenergie. Bei beiden Verbindungen sind Methylgruppenwanderungen häufig.Für (MeSn)4S6 werden IR- und Raman-Spektren mitgeteilt und mit Hilfe einer von kristallographischen Lageparametern ausgehenden Normalkoordinatenanalyse ausgewertet. Die Verteilung der potentiellen Energien der einzelnen Normalschwingungen auf innere Koordinaten zeigt für (MeSn)4S6 eine geringere Abweichung von der idealen Td-Symmetrie als im Falle des (MeSn)4Se6. Die Valenzkraftkonstanten betragen f(Sn—S) = 168(1) und f(Sn—C) = 222(2) N/m. Im ionischen SnS44- ist f(Sn—S) mit 175 N/m nur geringfügig größer entsprechend einem analogen Befund für (MeSn)4Se6 und SnSe44- mit f(Sn—Se) = 154(1) und 159 N/m.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 12
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1973 (1973), S. 1263-1268 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Peptide Synthesis in the Aqueous Phase, I.  -  Polyethyleneimine as a Water Soluble Support for the N-Carboxyanhydride MethodThe model peptide Ala-Trp-Ile (9) attached through an arginine bridge to a water soluble polyethyleneimine (1) is prepared via the N-carboxyanhydride method. The amount of arginine bound to 1 has been found to be 18 mol %. The polymer linked to the model peptide 9 can be specifically and quantitatively cleaved by trypsin into Ala-Trp-Ile-Arg (8) and 1. Further treatment of 8 with carboxypeptidase B quantitatively affords the model peptide 9 and the carboxy terminal bridging arginine (10).
    Notes: Das Modellpeptid Ala-Trp-Ile (9) wird nach der N-Carboxyanhydrid-Methode an wasserlöslichem, polymerem Äthylenimin (1), das zu 18 Mol-% mit Arginin-Brücken besetzt ist (3), synthetisiert. Mit Trypsin erfolgt spezifisch und quantitativ die Abspaltung des Ala-Trp-Ile-Arg (8) vom polymeren Träger. Durch Carboxypeptidase B wird 8 spezifisch und quantitativ zu 9 und dem ursprünglich carboxylendständigen Brücken-Arginin (10) gespalten.
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  • 14
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 18 (1979), S. 677-677 
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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