title: Dibromonitroso benzene sulphonate spin-adducts--why no hyperfine coupling to bromine?
abstract: Both 79Br and 81Br nuclei have very large magnetic moments and hence can give rise to large hyperfine splittings. However, for the title compound, dibromonitroso-p-benzene sulphonate (DBNBS), which is a widely used spin-trap, liquid-phase spectra of radical adducts are characterised by narrow EPR features with no bromine splitting, despite the expected delocalisation of spin-density onto bromine. I find that for such radicals in the solid-state the 14N parallel features are very broad, although the seven expected hyperfine features from the 79Br and 81Br nuclei were not clearly defined. I use these results to offer an explanation for the complete absence of any hyperfine splitting from bromine in the isotropic spectra.
authors.affiliation: Bone and Joint Research Unit, St. Bartholomew's and the Royal London School of Medicine and Dentistry, UK.
authors.forename: M C
authors.initials: MC
authors.lastname: Symons
mesh_terms: D001557:Benzenesulfonates / Q000737:chemistry*; D001966:Bromine / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry; D007554:Isotopes; D015394:Molecular Structure; D009603:Nitroso Compounds / Q000737:chemistry*; D013113:Spin Labels
chemical_list: D001557:Benzenesulfonates; D005609:Free Radicals; D007554:Isotopes; D009603:Nitroso Compounds; D013113:Spin Labels; C048757:3,5-dibromo-4-nitrosobenzenesulfonate; D001966:Bromine