Temperaturabhängigkeit der Phosphor-HFS bei Iminophosphoran- Radikalen / Temperature Dependence of ESR-Phosphorus Coupling Constants of Iminophosphorane Radicals

Abstract

ESR-spectra of iminophosphorane radicals exhibit a strong temperature dependent coupling constant of the phosphorus nucleus. This splitting is described by a superposition of π-σ- and hyperconjugative interactions with the free electron. Because of hindered internal rotation of the iminophosphorane group the hyperconjugation term becomes temperature dependent. Differences in the phosphorus data of ortho- and para-iminophosphorane radicals respectively may be explained by a change of the potential barriers hindering the internal rotation