Einelektronen-Redox-Reaktionen von Octamethyl[4]radialen: Nachweis der Alternanz geradzahliger Radialene

One-Electron Redox Reactions of Octamethyl4]radialene: Proof of the Alternancy of Even-Membered Radialenes The photoelectron spectrum of octamethyl4]radialene ( = tetrakis(dimethylmethylidene)cyclobutane) yields the rather low first vertical ionization of only 7.30 eV and, therefore, the molecule can be oxidized by AlCl₃/CH₂Cl₂ 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 C₈(CH₃)₈ during the redox reactions are presumably hindered by the steric overcrowding in persubstituted 4]radialenes.