Go toArchive
Browse byFacets
Bookbag ( 0 )
'Radical Anions' in keywords
Results  2 Items
Sorted by   
Publication Year
1999 (1)
1982 (1)
1Author    M. Atthias, W. Anner1, W. Olfgang, K. Aim, Volker Lorenzenb, W. Ilhelm, P. ReetzRequires cookie*
 Title    Hexaborate Cluster Radical Anions [B6Haln Hal'^« ]*" and [B6Hal5R]*_ (Hai, Hai' = CI, Br, I; R = H, alkyl). Chemical or Electrochemical Generation, Vibrational, UV-Vis and EPR Spectroscopy  
 Abstract    Paramagnetic hexaborate clusters with mixed halide, halide/alkyl or halide/hydride substi­ tution were prepared from oxidizable dianionic precursors and were characterized by cyclic voltammetry, EPR, vibrational and UV-VIS spectroscopy. The EPR studies reveal increasing g anisotropy and EPR linewidths on replacing Cl by Br and especially by I substituents; on the other hand, the replacement of one halide by one alkyl (CH3 or CFFCN) or hydride substituent in [BftHalsR]*-causes decreasing radical persistence and g anisotropy. These results indicate a fairly uniform participation of the cluster core and the substituent sphere in the spin distribution as a major factor for the stability of these non-7r radicals. 
  Reference    Z. Naturforsch. 54b, 1103—1108 (1999); received June 2 1999 
  Published    1999 
  Keywords    EPR Data, Halogenohexaborates, Radical Anions, Vibrational Spectra 
  Similar Items    Find
 TEI-XML for    default:Reihe_B/54/ZNB-1999-54b-1103.pdf 
 Identifier    ZNB-1999-54b-1103 
 Volume    54 
2Author    Gemot Frenking, Nikolaus Heinrich, Jochen Schmidt, Helmut SchwarzRequires cookie*
 Title    Neutrale und ionische Keto/Enoltautomere: Zum Ursprung der Stabilitätsumkehr und zu ungewöhnlichen Substituenten-Effekten Neutral and Ionic Keto/Enol Tautomers: On the Origin of Stability Reversal and Unusual Substituent Effects  
 Abstract    The reversal in stability for neutral keto/enol tautomers and their cation radicals is mainly due to the removal of an electron from an ^-orbital of the enol, which has anti-bonding properties for the C-0-bond. The total electronic energy gained in the oxidation of enols is more than sufficient to compensate for the increase in nuclear/nuclear repulsion when comparing keto/enol tautomers; this, however, does not hold for the keto systems investigated. The marked methyl substituent effect found in O, C-l, and C-2 substituted enol cation radicals is not reflected in the charge distribution of the corresponding ions. Comparison of the MNDO calculated heats of formation of ions with that of their neutral counterparts indicates that the changes in bond dissociation energies account at least qualitatively for the experimentally observed effects. 
  Reference    Z. Naturforsch. 37b, 1597—1601 (1982); eingegangen am 30. Juni 1982 
  Published    1982 
  Keywords    Molecular Orbital Calculations, Methyl Substituent Effects, Gas Phase Ion Stability, Radical Cations, Radical Anions 
  Similar Items    Find
 TEI-XML for    default:Reihe_B/37/ZNB-1982-37b-1597.pdf 
 Identifier    ZNB-1982-37b-1597 
 Volume    37