Nuclear magnetic resonance data for sulfur-33 nuclei in pure compounds are extremely sparse. Although the first observation of a <sup>33</sup>S NMR signal was reported in 1951, it was not until 17 years later that additional data were published. Of the seven compounds investigated, only two, carbon disulfide and 1,2-ethanedithiol, can be considered organic; the chemical shift of the latter compound was not measured. The original objective of the present study, although not achieved, was to determine if a measurable chemical shift exists between the aromatic sulfur atom in thiophene and the nonaromatic one in tetrahydrothiophene. This is part of a more extensive investigation of the potential uses of new spectroscopic methods in studies of the structure of coals and related materials. The <sup>33</sup>S NMR spectrum of thiophene and our unsuccessful attempt to observe the <sup>33</sup>S resonance in tetrahydrothiophene are described in this note.
H. L. Retcofsky and R. A. Friedel, "Sulfur-33 Magnetic Resonance Spectrum of Thiophene," Appl. Spectrosc. 24, 379-380 (1970)