Isotopic perturbation of a degenerate valence isomerization. A ¹³C NMR study of deuterio‐1,5‐dimethylsemibullvalene

Abstract

Abstract Mono deuterio‐1,5‐dimethylsemibullvalene is studied by the isotopic perturbation method with respect to the equilibrium of the valence isomerization. It emerges that deuterium prefers the cyclopropane position. From the temperature dependence of the splittings in the 13 C NMR spectra the ground state enthalpy difference in mono deuterio‐1,5‐dimethylsemibullvalene is calculated to be 484 J mol −1 .