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Einelektronen‐Redox‐Reaktionen von Octamethyl[4]radialen: Nachweis der Alternanz geradzahliger Radialene
Author(s) -
Bock Hans,
Rohn Günther
Publication year - 1991
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19910740609
Subject(s) - chemistry , redox , cyclooctatetraene , steric effects , cyclobutane , cryptand , photochemistry , molecule , metal , ion , radical ion , medicinal chemistry , stereochemistry , crystallography , inorganic chemistry , organic chemistry , ring (chemistry)
One‐Electron Redox Reactions of Octamethyl[4]radialene: Proof of the Alternancy of Even‐Membered Radialenes The photoelectron spectrum of octamethyl[4]radialene ( = tetrakis(dimethylmethylidene)cyclobutane ) yields the rather low first vertical ionization of only 7.30 eV and, therefore, the molecule can be oxidized by AlCl 3 /CH 2 Cl 2 to its radical cation. The ESR and ENDOR signal patterns recorded are almost identical with those of the radical anion, generated in a [2.2.2]cryptand THF solution by reduction at a potassium metal mirror. Their near congruency is in accord with the alternant π molecular properties of even‐membered radialenes as predicted by HMO theory, and larger changes of the D 2d structure of C 8 (CH 3 ) 8 during the redox reactions are presumably hindered by the steric overcrowding in persubstituted [4]radialenes.