An ESR study of some group IV B radical adducts with aromatic ketones

Hyperfine coupling constants are reported for the paramagnetic adducts of silyl, germyl and stannyl radicals with five aromatic ketones. The spin distribution in these systems is compared with the H atom adducts and analogous hydrocarbon radicals. The large 117-Sn and 119-Sn satellite splittings observed in the stannyl adducts indicate that these radicals exist in a conformation with the O-Sn bond ortghogonal to the py-system. The ESR spectrum of the previously unknown anthronyl radical has been recorded and analysed.