Zur Rekombinationsenthalpie von Radikalen — Thermochemie der Ringöffnung von Cyclophanen

Radical Recombination Enthalpy. — Thermochemistry of the Ringopening of Cyclophanes By thermolysis of the cyclophanes 1, 5, 8, 11, 14, 18, and 21 in the presence of NO or O2 the enthalpy profiles for the ring opening were determined from the temperature, NO, or O2 dependance of the trapping rates of the intermediate diradicals. The experimental enthalpy wells, which varied between 3 and 12 kcal · mol‐1, can be simulated well with a reaction forcefield making use of the EVBH method of Malrieu et al. This result gives confidence that also meaningful recombination barriers of radicals can be obtained by this method.