Beschreibung:
<jats:p>Semiquinones of 6,7-dihydroxy- 1,2,3,4-tetrahydroisoquinolines and -naphthalenes are investigated by ESR-spectroscopy in the presence of diorganothalliumhydroxide. The ESR-spectra show a significant temperature dependence of the coupling constants of the β-methylene protons due to ring inversion of the partially hydrogenated ring. Computer simulation of the spectra gave the rate constants and the activation parameters for this ring inversion process. The heterocyclic compounds show considerably lower rate constants due to implication of N-inversion. In comparison to analogous cyclohexene-semidione systems, our systems showed rate constants about 10 times higher than those of their monocyclic counterparts.</jats:p>