ESR.‐Messungen an Radikal‐Anionen Trimethylsilyl‐substituierter π‐Elektronensysteme

The ESR spectra of the radical anions of several trimethylsilyl substituted polyenes, benzenes and naphthalenes have been recorded; most of them are surprisingly stable under the conditions of measurement. Accurate values could be obtained for the splitting parameters – not only of the protons, but also of the 29Si isotopes in natural abundance. The coupling constants of the 29Si nuclei in trimethylsilyl substituents are of the same order of magnitude as the corresponding values of the protons attached to centers of comparable π‐spin population. The results indicate some Si ← Cπ delocalization.