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  • 1
    Electronic Resource
    Electronic Resource
    Photoelektronenspektren und Konformationsverhalten von Azinen (1984)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1061-1068 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photoelectron Spectra and Conformational Properties of AzinesThe photoelectron spectra of six acyclic (1 - 6) and five cyclic azines (7 - 11) have been interpreted with regard to gas phase conformations. The variation of the interactions between the n- and the π-orbitals has been studied by MNDO calculations on formaldehyde azine (1). A comparison of the π-ionizations of the azines 1, 2, and 4 with the corresponding values of the isoelectronic 1,3-dienes, for which s-trans conformations are known, indicates common conformational properties for both classes of molecules. Due to their π-ionization potentials, s-trans conformations are the most probable also for the remaining compounds (3,5 - 11). Since the n/s̰ and n/s̰* interactions depend on the substituents, the n-ionizations of 1 - 11 are of limited value for conformational analyses.
    Notes: Die HeI-Photoelektronenspektren von sechs acyclischen (1 - 6) und fünf cyclischen Azinen (7 - 11) wurden im Hinblick auf die in der Gasphase vorliegenden Konformationen der Verbindungen ausgewertet. Die konformationsabhängige Wechselwirkung der beiden n- und der beiden π-Orbitale wurde mit Hilfe von MNDO-Rechnungen an Formaldehydazin (1) untersucht. Ein Vergleich der π-Ionisationsbanden der Azine 1, 2 und 4 mit denjenigen der isoelektronischen 1,3-Diene mit s-trans-Konformation läßt keinerlei Unterschiede im Konformationsverhalten erkennen. Auch für die übrigen Verbindungen (3,5 - 11) sind aufgrund der Lage ihrer π-MOs s-trans-Konformationen wahrscheinlich. Die n-MOs von 1 - 11 sind wegen Substituenten-abhängiger n/s̰- und n/s̰*-Wechselwirkungen von geringerem Wert für Konformationsaussagen.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19841170320
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  • 2
    Electronic Resource
    Electronic Resource
    Photoelektronenspektren und Konformationen bi- und tricyclischer Hexahydro-1,2,4,5-tetrazine (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 853-861 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photoelectron Spectra and Conformations of Bi- and Tricyclic Hexahydro-1,2,4,5-tetrazinesThe photoelectron spectra of three tricyclic (2-4) and three bicyclic (5-7) hexahydro-1,2,4,5-tetrazines have been interpreted with regard to gas phase conformations. The interactions of the n-orbitals have been studied by MINDO/2 calculations for different conformations of hexahydro-1.2.4,5-tetrazine (1). The observed n-electron ionization potentials permit the identification of tetraequatorial forms of 2-4 and diequatorial-diaxial forms of 5-7 as the dominant conformers. In addition, for 2 and 5 other less stable conformers could be detected.
    Notes: Die Photoelektronenspektren von drei tricyclischen (2-4) und von drei bicyclischen (5-7) Hexahydro-1,2,4,5-tetrazinen wurden hinsichtlich der in der Gasphase vorliegenden Konformeren ausgewertet. Für die infrage kommenden Konformationen wurden zum Studium der Wechselwirkung der n-Orbitale MINDO/2-Rechnungen an der Stammverbindung (1) ausgeführt. Anhand der beobachteten n-Ionisationsbanden lassen sich bei 2-4 tetraäquatoriale und bei 5-7 diäquatorial-diaxiale Formen als stabilste Konformere identifizieren. Bei 2 und 5 wurden daneben weniger stabile Konformere nachgewiesen.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120311
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  • 3
    Electronic Resource
    Electronic Resource
    The lone-pair orbitals of triaziridine (1988)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 1 (1988), S. 267-273 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The PE spectra of four stable bicyclic triaziridines with trifluoromethyl, methyl, phenyl, spirocyclopentane and spirocyclohexane substituents are measured. From a comparison of these experimental data with MNDO calculations the energies and the interactions of the nitrogen lone-pair orbitals were obtained. The trifluoromethyl group may be reliably simulated by a fluorine atom. The ionization potentials are unexpectedly high and so are the cyclovoltammetric anodic potentials. The MNDO valence electron densities are in agreement with the comparatively small differences in the chemical shifts of the differently substituted nitrogens of the triaziridine rings.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610010504
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  • 4
    Electronic Resource
    Electronic Resource
    Photoelektronenspektroskopische Untersuchungen an Hexahydro-1,3,5-triazinen (1986)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 554-562 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photoelectron Spectroscopic Investigation of Hexahydro-1,3,5-triazinesThe PE spectra of the 1,3,5-trialkylhexahydro-1,3,5-triazines 1 - 4, of tri-1-pyrroline (5), α-tripiperideine (6), hexamethyltriisopyrazole (7) and of tri-4,5-dihydropyridazine (8) or those of their decomposition products have been obtained and interpreted with respect to the electronic structure and the conformation of the compounds. The spectra of 1 - 6 are consistent with a diequatorial-monoaxial arrangement of the nitrogen substituents in the hexahydro-1,3,5-triazine ring. 7 probably has a monoequatorial-diaxial conformation. The spectrum obtained from 8 is not in accord with the presence of the trimeric form in the gas phase.
    Notes: Die PE-Spektren der 1,3,5-Trialkylhexahydro-1,3,5-triazine 1 - 4, des Tri-1-pyrrolins (5), des α-Tripiperideins (6), des Hexamethyltriisopyrazols (7) und des Tri-4,5-dihydropyridazins (8) sowie diejenigen einiger Zerfallsprodukte wurden aufgenommen und hinsichtlich der elektronischen Struktur und der Konformation der Verbindungen ausgewertet. Die PE-Spektren von 1 - 6 stehen mit einer diäquatorial-monoaxialen, dasjenige von 7 mit einer monoäquatorial-diaxialen Stellung der Stickstoffsubstituenten am Hexahydro-1,3,5-triazin-Ring im Einklang. Das von 8 erhaltene Spektrum spricht gegen das Vorliegen dieser Verbindung in trimerer Form in der Gasphase.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19861190219
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  • 5
    Electronic Resource
    Electronic Resource
    Gas-Phase Thermolysis of 4-Substituted 3,5-Dihydro-3,3,5,5-tetramethyl-4H- pyrazoles Studied by Photoelectron Spectroscopy and Flash Vacuum Pyrolysis (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1161-1168 
    Details
    ISSN: 0009-2940
    Keywords: Electronic structure ; PE spectroscopy ; Gas-phase thermolysis ; 4H-Pyrazoles, 3,s-dihydro- ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gas-phase thermolyses of the 3,5-dihydro-4 H-pyrazoles 1 - 4 have been studied by photoelectron spectroscopy and flash vacuum pyrolysis. In the PE-controlled thermolysis, 1-4 extrude molecular nitrogen, and the fragments cyclize immediately to different three-membered rings. In the case of 2 and 3, the former 4-substituent becomes part of the three-membered ring, whereas 1 and 4 afford short living 0x0- and iminocyclopropanes. At higher temperatures and in flash vacuumpyrolysis, acyclic compounds and smaller molecules are formed in a second step. Based on MNDO, AM1, and PM3 calculations, the ionization potentials of 3,5-dihydro-3,3,5,5-tetramethyl-4-methylene-4H-pyrazole (3) have been assigned to molecular orbitals. To aid the identification of the pyrolysis products, PE spectra of the methylenethiirane 9 and the methylenecyclopropanes 11 and 13 have been measured and interpreted with the aid of SCF calculations.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901230533
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  • 6
    Electronic Resource
    Electronic Resource
    Electronic Structure and Gas-Phase Thermolysis of Substituted Tetrazolines Studied by Photoelectron Spectroscopy (1988)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 1213-1217 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photoelektronenspektren, elektronische Struktur und Gasphasenthermolyse von substituierten TetrazolinenDie elektronische Struktur und die Gasphasenthermolyse der Tetrazoline 1-5 wurden durch Photoelektronenspektroskopie untersucht. Die Verbindungen 1-4 zerfallen durch Cycloreversion in Methylazid und die entsprechenden Imine. Demgegenüber wird aus 5 unter Ringkontraktion ein Diaziridin gebildet. Zur Zuordnung der PE-Spektren wurden an den Verbindungen 1, 2, 4 und 5 MNDO-Rechnungen, zur Konformationsanalyse von 5 auch AM1-Rechnungen durchgeführt.
    Notes: The electronic structures and the gas-phase thermolyses of tetrazolines 1 -5 have been studied by photoelectron spectroscopy. For compounds 1-4 cycloreversion to imine and methyl azide is observed, whereas compound 5 is contracted to give the respective diaziridine. To assign the PE spectra, MNDO calculations were performed for compounds 1, 2, 4, and 5; some conformational properties of 5 have also been studied by AM 1 calculations.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19881210702
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  • 7
    Electronic Resource
    Electronic Resource
    Electronic Structure and Gas-Phase Thermolysis of 2-Tetrazenes with Acyclic or Cyclic Amino Groups Studied by Photoelectron SpectroscopyDedicated to Professor Wolfgang Luettke on the occasion of his 75th birthday. (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2073-2079 
    Details
    ISSN: 0009-2940
    Keywords: Electronic structure ; PE spectroscopy ; Thermolysis, gas-phase ; Imines ; Radicals ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electronic structures and the gas-phase thermolyses of the 2-tetrazenes 2-13 have been studied by He(I) photoelectron spectroscopy. The compounds are characterized by at least three ionization potentials with energies less than 10 eV which are assigned to the molecular orbitals π3 (HOMO), n+, π2, and n-. In the thermolyses either the formal disproportionation products (amine and imine) of the respective aminyl radical are found, or the latter is stabilized by loss of an alkyl radical affording also an imine. Further products which can be explained by radical reactions are detected in flash vacuum pyrolyses. The tricyclic cis-2-tetrazene 13 is cleaved by [2 + 2 + 2] cycloreversion. The methoxymethylsubstituted compound 8 exhibits a more complex cleavage pattern.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271033
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