ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Atomic, Molecular and Optical Physics  (2)
  • Chemistry  (2)
  • 1990-1994  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Synthesis, Structure, and Electronic Properties of Bis(tetramethylcyclopropylidene)methane and Bis(cyclopropylidene)methane (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 1591-1596 
    Details
    ISSN: 0009-2940
    Keywords: Allenes, highly strained ; Strain  -  structure correlation ; Hybridization effects, 13C, 13C coupling constants ; Calculations ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bis(tetramethylcyclopropylidene)methane (5) was prepared by treating 1-(dichloroethenylidene)-2,2,3,3-tetramethylcyclopropane (3) with tert-butyllithium in the presence of 2,3-dimethyl-2-butene. The parent allene 6 was obtained along a new route from bis(1-bromocyclopropyl) ketone (11) with low-valent titanium. Both 5 and 6 show unusually intense allene stretching bands in the IR spectra, and the signals of their central carbon atoms appear at remarkably high field in the 13C-NMR spectra. The unique structural features of 5 and 6, as evidenced by an X-ray crystal structural analysis of 5 and 1Jcc values, agree remarkably well with theoretical predictions made by semiempirical (MNDO) and ab initio (4-31G) calculations and on the basis of the simple picture offered by the hybridization model using the iterative maximum overlap (IMO) approach.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240720
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Fluorination effect on the structural properties in benzocyclobutenes and benzocyclobutadienes (1993)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 48 (1993), S. 319-332 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structural features of benzocyclobutenes, benzocyclobutadienes, and some of their fluoroderivatives are studied at the HF/SCF niveau employing a 6-31G* basis set. A Mills-Nixon-type of distortion (lengthening of the annelated bonds with concomitant shortening of the adjacent bonds in the benzene moiety) is found in all molecules, with the exception of polyannelated benzocyclobutenes with perflouro-substituted methylene groups. The latter compounds exhibit a weak anti-Mills-Nixon effect. Peripheral double bonds in benzocyclobutadienes enhance the double-bond localization in the benzene ring, but the main effect originates from angular deformations of the σ-skeleton. Salient structural features are rationalized by rehybridization at the carbon junction atoms and variation of Coulson's π-bond orders. Finally, several scales for quantifying the Mills-Nixon effect are briefly discussed. © 1993 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560480506
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    The relative stability of the tautomers of α-Hydroxytetronic acid (1994)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 50 (1994), S. 385-394 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relative stability of the four tautomeric forms of α-hydroxytetronic acid was calculated with full geometry optimization at the STO-3G, 3-21G, 6-31G*, and 6-31G** SCF levels. Correlation effects were estimated using the MP2 method. Intramolecular hydrogen bonds are found to be of primary importance for the relative stability of the various tautomers, and the same tautomer that in the case of L-ascorbic acid is experimentally observed in the crystal as well as in solution is found to be the most stable one, if polarization functions on the hydrogen atoms are taken into account. It is concluded that even in the gas phase this tautomer predominates in α-hydroxytetronic acid as well as in L-ascorbic acid. © 1994 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560500602
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Vibrational spectra, ab initio calculations and normal coordinate analysis for 3-methyl-3-vinylcyclopropene (1993)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 24 (1993), S. 31-41 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Raman spectra (3400-10 cm-1) of liquid and solid 3-methyl-3-vinylcyclopropene, C3H2(CH3)CHCH2, and its isotopomer C3D2(CH3)CHCH2 were recorded. The temperature dependence of some band intensities and qualitiative depolarization ratios show that the thermodynamically preferred conformation is s-trans. The structural parameters and conformational stability of s-trans and gauche rotamers were obtained from ab initio calculations by employing both 3-21G and 6-31G* basis sets. Barriers to internal rotation and fundamental vibrational frequencies were calculated utilizing the 3-21G basis set. The ab initio results are consistent with the experimentally indicated greater stability of the s-trans relative to the gauche conformer.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250240105
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...