Comparison of proton hyperfine coupling constants for the monomer and dimer radical cations of dimethyl sulphide and dimethyl selenide

The finding that 1H coupling constants for Me2S+ and Me2Se+ exceed those for the corresponding dimer radical cation Me2S[graphic omitted]SMe2+ and Me2Se[graphic omitted]SMe2+ by a factor of three in each case is attributed to the anti-bonding character of the σ* semi-occupied molecular orbital in the dimeric species.