Electron spin resonance studies of γ-irradiated lithium alkyls. The methylene anion
Abstract
Exposure of methyl lithium to 60Co γ-rays at 77 K gave a radical having a 1:2:1 triplet e.s.r. spectrum characteristic of ·CH–2 anions. The perdeuterated compound gave a singlet due to ·CD–2 anions. Similarly, ethyl lithium gave a quintet due to (CH3ĊH)– anions and isobutyl lithium gave a poorly resolved multiplet assigned to EtĊMe– anions. No evidence for the tautomeric change (CH3ĊH)–→(CH2[graphic omitted]CH2)– could be obtained. The fall in the β-proton hyperfine coupling on going from CH3CH2(26 G) to CH3CH–(21 G) is explained in terms of a decrease in hyperconjugation.