Radical Cations of Dialkylmercury Derivatives, Radiation Synthesis and Electron Spin Resonance Detection

Article abstract of DOI:10.1039/DT9900000637

Exposure of very dilute solutions of Hg(CD3)2 in tetrachloromethane to ⁶⁰Co γ-rays at 77 K gave a species whose e.s.r. spectrum is characteristic of the parent cation.Interpretation of the g-values and ¹⁹⁹Hg tensor component B derived from a computer synthesis of the spectrum suggests that the unpaired electron is strongly confined to the linear ? orbital having a node through the mercury atom.This has a large 6p(Hg) character.No extra features were obtained using Hg(¹³CH3)(CH3), confirming that the spin density on the CH3 groups is small (<20percent).When CFCl3 was the solvent extra poorly defined splittings were observed which are assigned to weak, but specific interaction with one solvent molecule (¹⁹F).The spectra for Hg(CH3)2 in this solvent were analysed in terms of the same solvent features together with coupling to a least five and probably seven protons.The small 1H coupling was almost isotropic at +/-4.5 G.In contrast, Hg(C2H5)2 gave no resolved coupling to ¹⁹F, but there was a large, well defined, triplet splitting (42 G) assigned to two specific CH3 protons.This suggests that rotation about the C-C bonds is restricted.We were unable to detect free rotation on annealing, although the lines broadened considerably, prior to radical loss.Attempts to detect ^.CH3 or ^.CH2CH3 radicals in these systems were unsuccessful, but clear evidence for ^.CD3 radicals was obtained for Hg(CD3)2 in CFCl3 on annealing.

Full text of DOI:10.1039/DT9900000637

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