An electron spin resonance study of trivinylmethyl and hepta-2,6-dien-4- ynyl radicals

Trivinylmethyl radicals were generated by hydrogen abstraction from trivinylmethane and hepta-2,6-dien-4-ynyl radicals were produced by bromine abstraction from 1-bromohepta-2,6-dien-4-yne. The e.s.r. spectra of the radicals were obtained and the hyperfine splittings compared with computed spin densities. Methane-based stabilisation energies were computed for a variety of delocalised radicals by the semi-empirical UMNDO method. The hydrogen hyperfine splittings of the delocalised radicals were shown to decrease monotonically with increase in the stabilisation energies.