title: 33S NMR spectra of sulfonium salts: calculated and experimental.
abstract: 33S NMR chemical shifts were calculated by the scaled DFT and EMPI approaches for the fluoride, chloride and bromide of trimethylsulfonium ion (1) and S-methyltetrahydrothiophenium ion (2), in addition to the free cations. Experimental values were obtained for the iodides of 1 (delta +48, CS2 = 0 ppm) and 2 (delta +95), and were found to agree with the calculated values well within the standard deviation of 35 ppm (3.5% of the shielding range) established in earlier work for a great variety of sulfur compounds. An earlier literature value of delta +750 for the iodide of 2 is therefore to be replaced. Calculations provide a shift of delta +68 for S-methylthianium ion with equatorial methyl, indicating that the reported value of delta +670 for the iodide is also incorrect.
authors.affiliation: High Field Nuclear Magnetic Resonance Laboratory, Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, USA.
authors.forename: L Charles
authors.initials: LC
authors.lastname: Dickinson
authors.forename: Donald B
authors.initials: DB
authors.lastname: Chesnut
authors.forename: Louis D
authors.initials: LD
authors.lastname: Quin
mesh_terms: D001965:Bromides / Q000737:chemistry; D002412:Cations; D002712:Chlorides / Q000737:chemistry; D005459:Fluorides / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015394:Molecular Structure; D013452:Sulfonium Compounds / Q000737:chemistry*; D013460:Sulfur Isotopes / Q000737:chemistry; D013876:Thiophenes / Q000737:chemistry
chemical_list: D001965:Bromides; D002412:Cations; D002712:Chlorides; D013452:Sulfonium Compounds; D013460:Sulfur Isotopes; D013876:Thiophenes; D005459:Fluorides