ELECTRON-SPIN-RESONANCE SPECTRA OF MERCURATED ARENE RADICAL CATIONS

When certain arenes are oxidized with mercury trifluoroacetate in trifluoroacetic acid, the ESR spectra of the arene radical cations observed show that progressive mercuration occurs. The aromatic protons with the largest hyperfine coupling constants are replaced by mercury, and satellites due to Hg199 hyperfine coupling can be observed. Mercuration also reduces the g value of the radicals. This behavior is reported for acenaphthene, anthracene, biphenylene, pyracene, hexahydropyrene, triptycene, terphenyl, tetramethylnaphthopyran, and dibenzodioxin. The introduction of mercury causes a reduction in the g value of the radical cation, but it does not affect the hyperfine coupling constants of the remaining protons. For the nuclei involved in the mercurideprotonation process, alpha(Hg199)/ alpha(H1) = ca. 20.6.