Unstable intermediates. Part LXIX. Trapped electrons: an electron spin resonance study of radiation damage in hydrogen cyanide and methyl cyanide

A recent postulate by F. Williams and his co-workers that various organic cyanides can trap electrons in the dipole field of the molecules in the crystalline state has been critically assessed by means of e.s.r. spectroscopy. An analysis of the e.s.r. spectra of γ-irradiated hydrogen cyanide and methyl cyanide suggests that this novel concept is unnecessary and that the species involved in the latter material is better described as a radical-anion, MeCN–, which, as a consequence of the crystal structure, is weakly bonded to a neighbouring molecule in such a way that the electron is equally shared between two cyanide molecules. The major paramagnetic species in hydrogen cryanide irradiated at 77°K is H2CN, and some evidence for the formation of H(Me)CN in methyl cyanide is also adduced. An analysis of the magnetic data for the radical CH2CN is also reported.